path: root/GradeBook_lib.tcl

#!/bin/sh
# (C) 2010 by Eugeniy Mikhailov, <evgmik@gmail.com>
# vim:set ft=tcl: \
exec tclsh "$0" "$@"

# require Tcl version of at least 8.5 since I use 'ni' and 'in' in expressions for lists
package require Tcl 8.5
package require math::statistics

source ./libBasicTableOperations.tcl

# internal version of this code
set VERSION 2.0.0

# ########################################################################
# this should be in config file but these are reasonable defaults
array set GradebookServerConfig [list \
	icon_dir "/~evmik/icons" \
	use_icons true \
	grades_db_dir "./courses" \
	passwords_db_file "./passwd.db" \
	html_access_stats_url "/~evmik/grade_book_stats/" \
	verbosity_level 100 \
	log_file "log" \
	]
# ########################################################################

# ########################## procs begin #################################

proc get_list_of_courses_db {} {
	# obtain list of all courses DB
	global GradebookServerConfig
	set grades_db_dir $GradebookServerConfig(grades_db_dir)
	set db_files_list [lsort [glob -tails -d ${grades_db_dir}/ *]]
	return $db_files_list
}

proc get_grading_scheme {} {
	# pair of letter grade and lower boundary for this grade
	# should be sorted in descended order!
	set grading_scheme [ list  \
		A	 0.94 \
		A- 0.90 \
		B+ 0.87 \
		B  0.84 \
		B- 0.80 \
		C+ 0.77 \
		C  0.74 \
		C- 0.70 \
		D+ 0.67 \
		D  0.64 \
		D- 0.60 \
		F  0.00 \
	]
	return  $grading_scheme
}

# Grades category and their html names
proc get_grades_category {} {
	set eval_str "SELECT CategoryName  FROM GradesCategoryTable"
	set grades_category {} 
	set err [catch {
		db eval $eval_str v {
			lappend grades_category  $v(CategoryName) 
		}
	} errStat ]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
	#set grades_category [list \
		#"unset"\
		#Quiz\
		#HomeWork\
		#LabReport\
		#MidTerm\
		#FinalExam\
	#]
	return $grades_category
}


proc default_grades_category {} {
	set grades_category [list \
			"unset"\
			deleted\
			Quiz\
			HomeWork\
			LabReport\
			Participation\
			MidTerm\
			FinalExam\
		]
	return $grades_category
}
	
proc getGradingWeights { } {
	set category_name_weight_list {}
	set eval_str [concat SELECT CategoryName,CategoryWeight FROM GradesCategoryTable]
	set err [catch {
		db eval $eval_str v {
			set category $v(CategoryName)
			set weight $v(CategoryWeight)
			if { ![string is double -strict $weight] } { 
				htmlInfoMsg "weight for category: $category is not a number, setting it to 0"
				set weight 0 
				ModifyWeightForGradesCategory db $category 0
			}
			lappend category_name_weight_list $category $weight
			}
		} errStat ]
		if { $err } {
			dbg "we should never be here if GradesCategoryTable exists" msg_level_critical
			dbg $errStat msg_level_critical
			htmlErrorMsg $errStat
		}
	return $category_name_weight_list	
}

proc isCalculateTotalForCategorySet { category } {
	if {![existsColumnWithRowvalueInTable GradesCategoryTable CategoryName  $category ]} {
		dbg  "Category: $category does not exists in the GradesCategoryTable, setting CalculateTotal to false" msg_level_info
		return false
	}
	set flag [SelectColvalueFromTable GradesCategoryTable NeedsTotal CategoryName $category]
	if { $flag } {
		return true 
	} else {
		return false
	}
}

proc howManyGradesToDropForCategorySet { category } {
	if {![existsColumnWithRowvalueInTable GradesCategoryTable CategoryName  $category ]} {
		dbg  "Category: $category does not exists in the GradesCategoryTable, setting number of grades to drop to 0" msg_level_info
		return 0
	}
	if { ![doesColumnExists NumberToDrop GradesCategoryTable] } {
		dbg  "Do not have column  NumberToDrop  in the table  GradesCategoryTable, setting number of grades to drop to 0" msg_level_info
		return 0
	}
	set num [SelectColvalueFromTable GradesCategoryTable NumberToDrop CategoryName $category]
	if { ![string is double -strict $num] } {
		dbg  "Number of grades to drop is not a number, returning 0" msg_level_info
		return 0
	}
	if { ![string is integer -strict $num] } {
		set new_num [expr {round($num)}]
		dbg  "Number of grades to drop is a double: $num, rounding it to $new_num" msg_level_info
		return $new_num
	}
	return $num
}

proc allUserNamesInGroup { group } {
	set eval_str [concat SELECT UserName FROM \'GradesTable\' WHERE GroupName == \'$group\']
	set username_list {}
	set err [catch {
		db eval $eval_str v {
			lappend username_list $v(UserName)
			}
		} errStat ]
		if { $err } {
			dbg "we should never be here if UserName in GradesTable  exists" msg_level_critical
			dbg $errStat msg_level_critical
			htmlErrorMsg $errStat
		}
	return $username_list	
}

proc findColumnNamesInCategory { category } {
	set all_column_names [getColListFromTable GradesTable]
	set all_col_in($category) {}

	foreach col $all_column_names {
		# detect what column category it is
		set col_category [SelectColValue4User $col _Col_Category_]
		if { $col_category eq $category } {
			lappend all_col_in($category) $col
		}
	}
	return $all_col_in($category)
}

proc getMaxPointsForColumn { col } {
		set col_max [SelectColValue4User $col _Max_Points_]
		if { $col_max eq "" } {
			htmlInfoMsg "Column \{$col\} does not have Max Point value set"
			set col_max 0
		}
		return $col_max
}

proc calculteMaxPointsInCategory { category } {
	set all_col_in($category) [ findColumnNamesInCategory $category ]

	set col_number_in_category [llength $all_col_in($category)]
	set max_points($category) 0

	foreach col $all_col_in($category) {
		set col_max [getMaxPointsForColumn $col ]
		set max_points($category) [expr { $max_points($category) + $col_max }]
	}
	return [list $max_points($category) $col_number_in_category $all_col_in($category)]
}

proc listSum { l } {
	set sum 0
	foreach e $l {
		set sum [ expr {$e + $sum}]
	}
	return $sum
}

proc dropTheLowestGrades {num_to_drop grades grades_max_possible} {
	# this procedure drops the grade with the lowest weight i.e. grade/max_grade

	# this is recursively called so 1st to check is exit condition
	if { $num_to_drop <= 0 } {
		set grades_sum [listSum $grades]
		set grades_max_sum [listSum $grades_max_possible]
		return [list $grades_sum $grades_max_sum]
	}

	# let's find the index of  grade with the smallest grade/max_possible ratio
	set sm_ind -1; # non existing
	set smallest_ratio 10000; # something very big (larger than 1)
	set max_grade_for_smallest_ratio 0; # something small
	set i 0
	foreach  max_val $grades_max_possible {
		# grades with zero max_possible belong to bonuses
		# and it is impossible to calculate its weight anyway
		if { $max_val != 0 } {
			set grade [lindex $grades $i]
			set grade_weight [expr {1.0*$grade/$max_val}]
		} else {
			# we cannot divide by zero
			# so we just put something very big (much larger than 1)
			set grade_weight 1000000; # larger than default smallest_ratio
		}

		# update lowest contribution
		# FIXME: this logic is not as easy in the general case but it works
		# when max grades are about the same in the same category
		if { $grade_weight < $smallest_ratio } {
			# this easy case
			set sm_ind $i
			set smallest_ratio $grade_weight
			set max_grade_for_smallest_ratio $max_val
		}
		if { ($grade_weight == $smallest_ratio) && ($max_val > $max_grade_for_smallest_ratio) } {
			# for same grade_weight we should remove the one which has the largest max_val
			# this bust overall percentage for a student
			set sm_ind $i
			set smallest_ratio $grade_weight
			set max_grade_for_smallest_ratio $max_val
		}
		incr i 
	}	
	if { $sm_ind >=0 } {
		# let's remove lowest contribution
		set grades [lreplace $grades $sm_ind $sm_ind]
		set grades_max_possible [lreplace $grades_max_possible $sm_ind $sm_ind]
	}
	incr num_to_drop -1

	return [dropTheLowestGrades $num_to_drop $grades $grades_max_possible]
}

proc calculteSumOfPointsForStudentInCategory { student category } {
	# these will be sum of students gains and max possible
	set gained_points 0
	set max_points 0 ;
	# some assignment can be incomplete for a reasonable excuse (i.e. medical)
	# alternatively if the category has a flag of drop the lowest score it will be counted
	# as excused points as well
	set num_of_excuses 0

	# these will contain values from not excused points
	set list_col_val {}
	set list_col_max {}

	# create the list of grades and respective maximums
	# but exclude excused grades from calculations
	set all_col_in($category) [ findColumnNamesInCategory $category ]
	foreach col $all_col_in($category) {
		set col_val [SelectColValue4User $col $student]
		set col_max_possible [getMaxPointsForColumn $col]
		if { $col_val eq "" } {
			set col_val 0
		}
		# special cases for grades which are not a number: excuses or other notes
		set isItExcuse false
		if { ![string is double -strict $col_val] } {
			if { [regexp -nocase -- {excuse} $col_val] } {
				# this grade will not be counted and maximum points for this student adjusted accordingly
				set col_val 0
				set isItExcuse true
				incr num_of_excuses
			} else {
				htmlInfoMsg "the user $student has a grade $col_val  in column $col,  which is not a number. Using 0 instead"
				set col_val 0
			} 
		}
		if { !$isItExcuse } {
			lappend list_col_val $col_val
			lappend list_col_max $col_max_possible
		}
	}

	set num_of_the_lowest_grades_to_drop [howManyGradesToDropForCategorySet $category]
	# excused points are counted towards lowest grades to be dropped
	set num_of_the_lowest_grades_to_drop [expr {$num_of_the_lowest_grades_to_drop - $num_of_excuses}]
	# note the following procedure is smart to not drop negative number of grades
	# and additionally counts the sum
	set ret [dropTheLowestGrades $num_of_the_lowest_grades_to_drop $list_col_val $list_col_max]
	set PointsSum(gained_points)  [lindex $ret 0]
	set PointsSum(max_points)     [lindex $ret 1]
	return [array get PointsSum]
}

proc calculteWeightedTotals { } {
	# we will do everything with in one transaction
	# otherwise I see performance degradation on some computers
	# when there are a lot if update statements
	begin_db_transaction

	set grades_category [ get_grades_category ]
	#global grades_category
	set all_column_names [getColListFromTable GradesTable]
	
	set students_list [ allUserNamesInGroup student ]
	set students_list [concat $students_list [ allUserNamesInGroup dropped ] ]

	# locate all column names of this category
	foreach category $grades_category {
		set flag_delete_CategoryWeightedTolal false
		set CategoryWeightedTolalName  ${category}Total
		if { [isCalculateTotalForCategorySet $category] } {
			set all_col_in($category) [ findColumnNamesInCategory $category ]

			set tmpList [ calculteMaxPointsInCategory $category ]
			set max_points($category) [lindex $tmpList 0]
			set num_of_cols($category) [lindex $tmpList 1]

			if { $num_of_cols($category) >= 2 } {
				# no weighted total column created for categories which do no have at least 2 columns
				# check if Weighted Category Column exists
				if { $CategoryWeightedTolalName ni $all_column_names } {
					dbg "Column $CategoryWeightedTolalName does not exist, will create it now" msg_level_info
					AddColumnNonWeb $CategoryWeightedTolalName weighted_column 0 
				}
			} else {
				set flag_delete_CategoryWeightedTolal true 
			}
			if { [doesColumnExists $CategoryWeightedTolalName GradesTable] } {
				UpdateColValue4UserNameNonWeb $CategoryWeightedTolalName _Max_Points_   $max_points($category)

				# calculated weighted sum for each student in this category
				foreach student $students_list {
					array set PointsSum [ calculteSumOfPointsForStudentInCategory $student $category ]
					set points_sum($category,$student) $PointsSum(gained_points)
					set max_points($category,$student) $PointsSum(max_points)
					if { $max_points($category,$student) != 0 } {
						# normalizing
						set points_sum($category,$student) [expr { 1. * $points_sum($category,$student) / $max_points($category,$student) } ]
					}
					UpdateColValue4UserNameNonWeb $CategoryWeightedTolalName $student   $points_sum($category,$student)
				}
			}
		} else {
			set flag_delete_CategoryWeightedTolal true 
		}
		if { $flag_delete_CategoryWeightedTolal && ([doesColumnExists $CategoryWeightedTolalName GradesTable]) } {
			end_db_transaction
			DeleteColumnFromTable GradesTable $CategoryWeightedTolalName
			begin_db_transaction
		}
	}

	# now calculation of weighted grand total
	set grand_total_col_name "Grand Total"
	if { $grand_total_col_name ni $all_column_names } {
		dbg "Column $grand_total_col_name does not exist, will create it now" msg_level_info
		AddColumnNonWeb $grand_total_col_name weighted_column 0 
	}
	foreach student $students_list {
		set grand_total($student) 0
		foreach {category weight} [getGradingWeights] {
			if { ![info exist max_points($category)] } {
				set tmpList [ calculteMaxPointsInCategory $category ]
				set max_points($category) [lindex $tmpList 0]
			}
			if { ![info exist points_sum($category,$student)] } {
				array set PointsSum [ calculteSumOfPointsForStudentInCategory $student $category ]
				set points_sum($category,$student) $PointsSum(gained_points)
				set max_points($category,$student) $PointsSum(max_points)
				if { $max_points($category,$student) != 0 } {
					# normalizing
					set points_sum($category,$student) [expr { 1. * $points_sum($category,$student) / $max_points($category,$student) } ]
				}
			}
			if { $max_points($category,$student) == 0} {
				dbg "Category: $category has 0 for total maximum points. Skipping it." msg_level_info
				continue
			}
			set grand_total($student) [ expr { $grand_total($student) + $weight*$points_sum($category,$student) } ]
		}
		UpdateColValue4UserNameNonWeb $grand_total_col_name $student $grand_total($student)
	}
	set max_weighted_sum 0
	foreach {category weight} [getGradingWeights] {
		set max_weighted_sum [ expr {$max_weighted_sum +$weight} ]
	}
	UpdateColValue4UserNameNonWeb $grand_total_col_name _Max_Points_ $max_weighted_sum

	# ending transaction 
	end_db_transaction
}

proc grade_Category2html_name { category } {
	switch $category {
		"unset"      {set html_name --Select--}
		deleted      {set html_name Deleted}
		Quiz         {set html_name Quiz}
		HomeWork     {set html_name HomeWork}
		LabReport    {set html_name LabReport}
		Participation {set html_name Participation}
		MidTerm      {set html_name MidTerm}
		FinalExam    {set html_name FinalExam}
		default      {set html_name unknown}
	}
	return $html_name
}

proc dbg {msg {category msg_level_critical} {location ""}} {
	global GradebookServerConfig
	if { $location ne "" } {
		set location " in $location"
	}
	switch $category {
		msg_level_info       {set msg_header "Info$location:";       set level 6}
		msg_level_warning    {set msg_header "Warning$location:";    set level 4}
		msg_level_dbg        {set msg_header "Debug$location:";      set level 3}
		msg_level_log        {set msg_header "Log$location:";        set level 2}
		msg_level_critical   {set msg_header "Error$location:";      set level 1}
		default              {set msg_header "Unknown$location:";    set level 0}
	}

	if { $level <= $GradebookServerConfig(verbosity_level) } {
		set fid [open $GradebookServerConfig(log_file) a+]
		puts $fid "$msg_header $msg"
		close $fid
	}
}

proc timestamp { } {
	return [clock format [clock seconds] -format "%Y-%m-%dT%H:%M:%S"]
}

proc ColName2SqlSafeForm {colname} {
	set bad_symbols [list {\}} {\{} {\\} {\'} {\"} {\]} {\[} ]
	foreach bs $bad_symbols {
		regsub -all $bs $colname "" colname 
	}
	return $colname
}

proc AddUserNonWeb { first_name last_name user_name {group_name {guest}} {id_number {}} {section_num {} } } {
	set eval_str [concat INSERT INTO GradesTable (FirstName, LastName, UserName, GroupName, IdNum, SectionNum) VALUES('$first_name', '$last_name', '$user_name', '$group_name', '$id_number', '$section_num')]
	set err [catch {db eval $eval_str  } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
}

proc AddCourseInfoTableItem {  item value } {
	set eval_str [concat INSERT INTO  CourseInfoTable (Item, Value) VALUES('$item', '$value') ]
	set err [catch {db eval $eval_str  } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
}

proc UpdateCourseInfoTableItem {  item value } {
					set sql_str [concat UPDATE CourseInfoTable  SET \"Value\"=\'$value\' where Item=\"$item\"]
					set err2 [catch {
						db eval $sql_str
					} errStat2 ]
					if { $err2 } {
						htmlErrorMsg  $errStat2 
						dbg  "the following error happen: $errStat2" msg_level_critical
					} 
}

proc CreateCourseInfoTable {db} {
	set err [catch {db eval {CREATE TABLE CourseInfoTable(Item text, Value text)} } errStat] 
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
	AddCourseInfoTableItem course_title     "Title Unset"
	AddCourseInfoTableItem course_year      "Year Unset"
	AddCourseInfoTableItem course_semester  "Semester Unset"
}

proc SelectItemFromCourseInfoTable { item } {
	set value {}
	set eval_str "SELECT Value  FROM CourseInfoTable  where Item=:item"
	set err [catch {
		db eval $eval_str v {
			set value $v(Value)
		}
	} errStat ]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
	return $value
}

proc GetDefaultGradesTableColumn {} {
	# this is the list of crucial  GradesTable columns
	# column name and type
	set l [list \
		FirstName text\
		LastName text\
		UserName text\
		GroupName text\
		UserHiddenColums text\
		UserHiddenGroups text\
		UserHiddenGradeCategories text\
		IdNum text\
		SectionNum text\
		]
	return $l
}

proc ModifyNeedsTotalForGradesCategory {db category flag} {
	if {![existsColumnWithRowvalueInTable GradesCategoryTable CategoryName  $category ]} {
		dbg  "Category: $category does not exists in the GradesCategoryTable, creating it" msg_level_info
		AddGradesCategory db $category
	}
	UpdateColumnWithValueInTableWhere GradesCategoryTable  NeedsTotal $flag CategoryName $category 
}

proc ModifyWeightForGradesCategory {db category weight} {
	if {![existsColumnWithRowvalueInTable GradesCategoryTable CategoryName  $category ]} {
		dbg  "Category: $category already does not exists in the GradesCategoryTable, creating it" msg_level_info
		AddGradesCategory db $category
	}
	UpdateColumnWithValueInTableWhere GradesCategoryTable  CategoryWeight $weight CategoryName $category
}

proc ModifyNumberOfLowestGradesToDropGradesCategory {db category num} {
	if {![existsColumnWithRowvalueInTable GradesCategoryTable CategoryName  $category ]} {
		dbg  "Category: $category already does not exists in the GradesCategoryTable, creating it" msg_level_info
		AddGradesCategory db $category
	}
	if { ![doesColumnExists NumberToDrop GradesCategoryTable] } {
		dbg  "Do not have column  NumberToDrop  in the table  GradesCategoryTable may be you are using older version of database format" msg_level_info ModifyNumberOfLowestGradesToDropGradesCategory
		return
	}
	UpdateColumnWithValueInTableWhere GradesCategoryTable  NumberToDrop $num CategoryName $category
}

proc AddGradesCategory {db category} {
	if {[existsColumnWithRowvalueInTable GradesCategoryTable CategoryName  $category ]} {
		dbg  "Category: $category already exists in the GradesCategoryTable" msg_level_info
		return
	}
	set eval_str [concat INSERT INTO GradesCategoryTable (CategoryName) VALUES('$category')]
	set err [catch {db eval $eval_str  } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
	ModifyWeightForGradesCategory db $category 0
	ModifyNeedsTotalForGradesCategory db $category false
	ModifyNumberOfLowestGradesToDropGradesCategory db $category 0
}

proc CreateGradesCategoryTable {db} {
	# construct sql string for table creation
	set sql_str {CREATE TABLE GradesCategoryTable(CategoryName text, CategoryWeight float, NeedsTotal text, NumberToDrop integer)}
	set err [catch {db eval $sql_str } errStat] 

	if { $err && ($errStat ne "table GradesCategoryTable already exists") } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 

	foreach category [default_grades_category] {
		AddGradesCategory db $category 
	}
}

proc UpdateGradesCategores { db permission_list user } {
	global script_name
	set subaction [::ncgi::value subaction {}]
	set nv [::ncgi::nvlist]
	array set colval  $nv
	if { $subaction eq "Cancel" } {
		return
	}
	if { $subaction eq "Submit" } {
		begin_db_transaction
		set eval_str "SELECT CategoryName  FROM GradesCategoryTable"
		set err [catch {
				db eval $eval_str v {
					if { [info exist colval($v(CategoryName)_weight)] } {	
						ModifyWeightForGradesCategory db $v(CategoryName) $colval($v(CategoryName)_weight)
					}
					if { [info exist colval($v(CategoryName)_needs_total)] } {	
						# check box existance means it set to true
						ModifyNeedsTotalForGradesCategory db $v(CategoryName) true
					} else {
						ModifyNeedsTotalForGradesCategory db $v(CategoryName) false
					}
					if { [info exist colval($v(CategoryName)_NumberToDrop)] } {	
						ModifyNumberOfLowestGradesToDropGradesCategory db $v(CategoryName) $colval($v(CategoryName)_NumberToDrop) 
					}
				}
			} errStat ]
		end_db_transaction
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" msg_level_critical
		} 
	}

	calculteWeightedTotals
}

proc EditGradesCategories { db permission_list user } {
	global script_name
	lappend column_list CategoryName CategoryWeight NumberToDrop NeedsTotal
	set sql_column_list [join $column_list ","]
	puts {<div class="change_categories">}
	puts {<div class="categories_table">}
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	# output only selected columns
	set eval_str "SELECT $sql_column_list  FROM GradesCategoryTable"
	set show_header 1
	set err [catch {
		db eval $eval_str v {
			if { $show_header } {
				set show_header 0
				puts  {<table class="categories_table" border="1">}
				puts  "<tr>"
				foreach col  $v(*) {
					puts -nonewline "<th>$col</th>"
				}
				puts  "<tr>"
			} else {
				puts  "<tr>"
			}
			foreach index $v(*) {
				if { $index != "*" } {
					switch $index {
						"CategoryWeight" {
							puts "<td><input type=\"text\" name=\"$v(CategoryName)_weight\" value=\"$v(CategoryWeight)\" size=5></td>"
						}
						"NeedsTotal" {
							if { $v(NeedsTotal) eq "true" } {
								set checkbox_flag "checked"
							} else {
								set checkbox_flag ""
							}
							puts "<td><input type=\"checkbox\" name=\"$v(CategoryName)_needs_total\" value=\"\" $checkbox_flag></td>"
						}
						"NumberToDrop" {
							puts "<td><input type=\"text\" name=\"$v(CategoryName)_NumberToDrop\" value=\"$v(NumberToDrop)\" size=5></td>"
						}
						default {
							puts -nonewline "<td>$v($index)</td>"
						}
					}
				}
			}
			puts "</tr>"
		}
	} errStat ]
	puts  "</table>"
	if { $err } {
		htmlErrorMsg  $errStat EditGradesCategories
		dbg  "the following error happen: $errStat" msg_level_critical EditGradesCategories
	} 
	puts {<input type="hidden" name="action" value="update_grades_categories"/>}
	puts {<input type="submit" name="subaction" value="Submit" />}
	puts {<input type="submit" name="subaction" value="Cancel" />}
	puts {</form>}
	puts {</div>}
	puts {</div>}
	#puts "<a href=\"$script_name\">Cancel changes</a>"

}

proc isThereUserNameInTheGradesTable { username } {
	set eval_str [concat SELECT UserName FROM \'GradesTable\' WHERE UserName == \'$username\']
	set username_list {}
	set err [catch {
		db eval $eval_str v {
			lappend username_list $v(UserName)
		}
	} errStat ]
	if { $err } {
		dbg "we should never be here if UserName in GradesTable  exists" msg_level_critical
		dbg $errStat msg_level_critical
		htmlErrorMsg $errStat
		return false
	}
	if { 0 == [llength $username_list] } {
		return false
	} else {
		return true
	}
}

proc CheckAndCreateAsNeededInfoRow { row_name } {
	if { ![isThereUserNameInTheGradesTable $row_name] } {
		AddUserNonWeb  {} {}  $row_name   inforow
	}
}

proc CreateGradesTable {db} {
	# construct sql string for table creation
	set sql_str {CREATE TABLE GradesTable(}
	set flag_firsttime true
	foreach {col coltype} [GetDefaultGradesTableColumn] {
		if { $flag_firsttime} {
			set flag_firsttime false
			set sql_str [concat $sql_str $col $coltype]
		} else {
			set sql_str [concat  $sql_str , $col $coltype]
		}
	}
	set sql_str [concat $sql_str )]
	puts $sql_str

	set err [catch {db eval $sql_str } errStat] 
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 

	# add special users aka special info rows
	CheckAndCreateAsNeededInfoRow _Col_Category_
	CheckAndCreateAsNeededInfoRow _Max_Points_
	CheckAndCreateAsNeededInfoRow _Visible_To_Students_
	CheckAndCreateAsNeededInfoRow _The_Highest_Grade_
	CheckAndCreateAsNeededInfoRow _The_Lowest_Grade_
	CheckAndCreateAsNeededInfoRow _The_Mean_Grade_
	CheckAndCreateAsNeededInfoRow _The_Median_Grade_
	CheckAndCreateAsNeededInfoRow _The_StDev_Grade_

	# reasonable defaults for hidden columns
	#set instructor_hidden_columns [list UserHiddenColums UserHiddenGroups IdNum]
	#UpdateColValue4GroupNameNonWeb UserHiddenColums instructor $instructor_hidden_columns
}

proc AddAccessRightNonWeb { action instructor_right ta_right student_right dropped_student_right guest_right } {
	set eval_str [concat INSERT INTO AccessRightsTable (actionname, instructor, ta, student, dropped, guest) VALUES('$action', '$instructor_right', '$ta_right', '$student_right', '$dropped_student_right', '$guest_right')]
	set err [catch {db eval $eval_str  } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
}

proc AddDefaultAccessRight { action instructor_right ta_right student_right dropped_student_right guest_right } {
	global defaultAccessRights
	if { ![info exist defaultAccessRights] } {
		set defaultAccessRights {}
	}
	# check if such action and its access table exists and remove it
	# so it will be replaced with a new one
	if { $action in $defaultAccessRights } {
		set indx [lsearch -all -exact $defaultAccessRights $action]
		foreach i $indx {
			set defaultAccessRights [lreplace $defaultAccessRights $i $i]
			# we do it one more time to remove the access table for removed action
			set defaultAccessRights [lreplace $defaultAccessRights $i $i]
		}
	}
	# finally we adding new action with it access table
	lappend defaultAccessRights $action [list instructor $instructor_right ta $ta_right student $student_right dropped $dropped_student_right guest $guest_right]
}

proc FillDefaultAccessRights {} {
	# guest should have no rights make sure that 0 is everywhere except logon
	#                     actionname                instructor   ta   student dropped   guest
	AddDefaultAccessRight logon                     1            1    1       1         1
	AddDefaultAccessRight showgrades                1            1    1       1         0
	AddDefaultAccessRight sort                      1            1    0       0         0
	AddDefaultAccessRight addcolumnrequest          1            1    0       0         0
	AddDefaultAccessRight addcolumn                 1            1    0       0         0
	AddDefaultAccessRight deletecolumn              1            1    0       0         0
	AddDefaultAccessRight showcontrols              1            1    1       1         0
	AddDefaultAccessRight changegrades              1            1    0       0         0
	AddDefaultAccessRight updategrades              1            1    0       0         0
	AddDefaultAccessRight edit_grades_categories    1            0    0       0         0
	AddDefaultAccessRight update_grades_categories  1            0    0       0         0
	AddDefaultAccessRight changecolumn              1            1    0       0         0
	AddDefaultAccessRight updatecolumn              1            1    0       0         0
	AddDefaultAccessRight logoff                    1            1    1       1         0
	AddDefaultAccessRight changefirstname           1            0    0       0         0
	AddDefaultAccessRight changelastname            1            0    0       0         0
	AddDefaultAccessRight changeusername            1            0    0       0         0
	AddDefaultAccessRight userhidecolumn            1            1    1       1         0
	AddDefaultAccessRight userunhidecolumn          1            1    1       1         0
	AddDefaultAccessRight userhidegroup             1            0    0       0         0
	AddDefaultAccessRight userunhidegroup           1            0    0       0         0
	AddDefaultAccessRight userhidegradecategory     1            0    0       0         0
	AddDefaultAccessRight userunhidegradecategory   1            0    0       0         0
	AddDefaultAccessRight editcourseinfo            1            0    0       0         0
	AddDefaultAccessRight updatecourseinfo          1            0    0       0         0
	AddDefaultAccessRight editnewuserinfo           1            0    0       0         0
	AddDefaultAccessRight addnewuserinfo            1            0    0       0         0
	AddDefaultAccessRight choosenewpassword         1            1    1       1         0
	AddDefaultAccessRight setnewpassword            1            1    1       1         0
	AddDefaultAccessRight changegroupname           1            0    0       0         0
	AddDefaultAccessRight setgroupname              1            0    0       0         0
	AddDefaultAccessRight hidecolfromstudents       1            1    0       0         0
	AddDefaultAccessRight unhidecolfromstudents     1            1    0       0         0
	AddDefaultAccessRight resetforgottenpassword    0            0    0       0         1
	AddDefaultAccessRight update_grades_stats       1            0    0       0         0
	AddDefaultAccessRight edit_user_grade_request   1            1    0       0         0
	AddDefaultAccessRight edit_user_grade           1            1    0       0         0
}

proc getDefaultPermissionsForGroup { group } {
	global defaultAccessRights
	if { ![info exist defaultAccessRights] } {
		FillDefaultAccessRights
	}
	set permission_list [list GroupName $group]
	foreach {action dummy} $defaultAccessRights {
			lappend permission_list $action [getDefaultPermission $action $group]
	}
	return $permission_list
}

proc FillMissingPermissionsWithDefaults { permission_list default_permission_list} {
	# permission_list takes precedense over default_permission_list
	set group [lindex $permission_list 1]
	set default_group [lindex $default_permission_list 1]
	if { $group ne $default_group } {
		dbg "attempt to join permission lists for different groups: $group and $default_group" msg_level_warning
		return $permission_list
	}
	foreach {action permission} $default_permission_list {
		if { $action ni $permission_list} {
			lappend permission_list $action $permission
		}
	}
	return $permission_list
}

proc getDefaultPermission { action group } {
	global defaultAccessRights
	if { ![info exist defaultAccessRights] } {
		FillDefaultAccessRights
	}
	if { $action ni $defaultAccessRights } {
		# unknown action is always forbidden
		return 0
	}

	# find permissions for action
	set indx [lsearch -all -exact $defaultAccessRights $action]
	# increment index since permissions follows action element
	incr indx
	set permissions [lindex $defaultAccessRights $indx]

	if { $group ni $permissions } {
		# unknown groups have no rights
		return 0
	}

	# find permission for the group
	set indx [lsearch -all -exact $permissions $group]
	# increment index since permission follows group element
	incr indx
	return [lindex $permissions $indx]
}

proc AddDefaultAccessRightToTableForActionNonWeb { action } {
	global defaultAccessRights
	if { ![info exist defaultAccessRights] } {
		FillDefaultAccessRights
	}
	set instructor_right      [getDefaultPermission $action instructor]
	set ta_right              [getDefaultPermission $action ta]
	set student_right         [getDefaultPermission $action student]
	set dropped_student_right [getDefaultPermission $action dropped]
	set guest_right           [getDefaultPermission $action guest]
	AddAccessRightNonWeb $action $instructor_right $ta_right $student_right $dropped_student_right $guest_right
}

proc CreateAccessRightsTable {db} {
	set err [catch {db eval {CREATE TABLE AccessRightsTable(actionname text,               instructor integer, ta integer, student integer, dropped integer,  guest integer)} } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
	FillDefaultAccessRights
	AddDefaultAccessRightToTableForActionNonWeb logon
	AddDefaultAccessRightToTableForActionNonWeb showgrades
	AddDefaultAccessRightToTableForActionNonWeb sort
	AddDefaultAccessRightToTableForActionNonWeb addcolumnrequest
	AddDefaultAccessRightToTableForActionNonWeb addcolumn
	AddDefaultAccessRightToTableForActionNonWeb deletecolumn
	AddDefaultAccessRightToTableForActionNonWeb showcontrols
	AddDefaultAccessRightToTableForActionNonWeb changegrades
	AddDefaultAccessRightToTableForActionNonWeb updategrades
	AddDefaultAccessRightToTableForActionNonWeb edit_grades_categories
	AddDefaultAccessRightToTableForActionNonWeb update_grades_categories
	AddDefaultAccessRightToTableForActionNonWeb changecolumn
	AddDefaultAccessRightToTableForActionNonWeb updatecolumn
	AddDefaultAccessRightToTableForActionNonWeb logoff
	AddDefaultAccessRightToTableForActionNonWeb changefirstname
	AddDefaultAccessRightToTableForActionNonWeb changelastname
	AddDefaultAccessRightToTableForActionNonWeb changeusername
	AddDefaultAccessRightToTableForActionNonWeb userhidecolumn
	AddDefaultAccessRightToTableForActionNonWeb userunhidecolumn
	AddDefaultAccessRightToTableForActionNonWeb userhidegroup
	AddDefaultAccessRightToTableForActionNonWeb userunhidegroup
	AddDefaultAccessRightToTableForActionNonWeb userhidegradecategory
	AddDefaultAccessRightToTableForActionNonWeb userunhidegradecategory
	AddDefaultAccessRightToTableForActionNonWeb editcourseinfo
	AddDefaultAccessRightToTableForActionNonWeb updatecourseinfo
	AddDefaultAccessRightToTableForActionNonWeb editnewuserinfo
	AddDefaultAccessRightToTableForActionNonWeb addnewuserinfo
	AddDefaultAccessRightToTableForActionNonWeb choosenewpassword
	AddDefaultAccessRightToTableForActionNonWeb setnewpassword
	AddDefaultAccessRightToTableForActionNonWeb changegroupname
	AddDefaultAccessRightToTableForActionNonWeb setgroupname
	AddDefaultAccessRightToTableForActionNonWeb hidecolfromstudents
	AddDefaultAccessRightToTableForActionNonWeb unhidecolfromstudents
	AddDefaultAccessRightToTableForActionNonWeb resetforgottenpassword
	AddDefaultAccessRightToTableForActionNonWeb update_grades_stats
	AddDefaultAccessRightToTableForActionNonWeb edit_user_grade_request
	AddDefaultAccessRightToTableForActionNonWeb edit_user_grade
}

proc htmlErrorMsg { msg {loc ""} } {
	if { $loc eq "" } {
		puts "<div class=\"errormsg\">error: $msg</div>"
	} else {
		puts "<div class=\"errormsg\">error in $loc: $msg</div>"
	}
}

proc htmlInfoMsg { msg } {
	puts {<div class=infomsg>}
	puts "$msg"
	puts {</div>}
}

proc htmlReplaceEmptyString { string } {
	#  empty string replaced with "---"
	regsub {^$} $string "---" string 
	# white spaces only string replaced with "---"
	regsub {^\s+$} $string "---" string 
	set string
}

proc action2atributes { action_name } {
	# return list of action_name, text description, and icon name
	# for each action
	global GradebookServerConfig
	set icon_dir $GradebookServerConfig(icon_dir)
	case $action_name {
		userhidecolumn        { set attrib [list $action_name "hide"   $icon_dir/hide.png ]}
		changefirstname       { set attrib [list $action_name "change first name" $icon_dir/edit.png ]}
		changelastname        { set attrib [list $action_name "change last name"         $icon_dir/edit.png ]}
		changeusername        { set attrib [list $action_name "change user name"         $icon_dir/edit.png ]}
		hidecolfromstudents   { set attrib [list $action_name "hide from students"  $icon_dir/students_unhide.png ]}
		unhidecolfromstudents { set attrib [list $action_name "show to students"  $icon_dir/students_hide.png ]}
		changegrades          { set attrib [list $action_name "change grades"              $icon_dir/edit.png ]}
		deletecolumn          { set attrib [list $action_name "delete"                     $icon_dir/delete_column.png ]}
		changecolumn          { set attrib [list $action_name "change column"              $icon_dir/tune.png ]}
		default               { set attrib [list $action_name "unknown" $icon_dir/tbd.png ]}
	}
	return $attrib
}

proc number2letter_grade { num } {
	# grading_scheme MUST be sorted in descending order!
	# here we do proper percent rounding
	set num [expr {round(100.0*$num)/100.0}]
	set grading_scheme [get_grading_scheme]
	foreach {letter threshold} $grading_scheme {
		if { $num >= $threshold } {
			return $letter
		}
	}
	# should never reach this point if grading scheme set properly
	return "NA"
}

proc htmlGradesTableHeadersRaw { permission_list user sql_column_str hidden_columns v_array_list } {
	global GradebookServerConfig
	global script_name
	array set permission $permission_list
	array set v $v_array_list
	puts  "<tr>"
	foreach col  $v(*) {
		if { $col in $hidden_columns } continue
		# detect what column category it is
		set category [SelectColValue4User $col _Col_Category_]
		puts -nonewline "<th class=\"$category\"><a href=\"$script_name?action=sort&sortCol=$col\">$col</a>"
		# below list has action and action_label pairs
		set action_list {userhidecolumn}
		switch $col {
			FirstName { lappend action_list changefirstname  }
			LastName  { lappend action_list changelastname  }
			UserName  { lappend action_list changeusername  }
			UserHiddenColums { } 
			UserHiddenGroups { } 
			UserHiddenGradeCategories { } 
			IdNum { } 
			GroupName  {   }
			SectionNum {   }
			default {
				switch $category {
					"weighted_column" {
						# modify actions for weighted_column
						if { $permission(GroupName) eq "instructor" } {
							if { [SelectColValue4User $col _Visible_To_Students_] eq "true" } {
								lappend action_list hidecolfromstudents 
							} else {
								lappend action_list unhidecolfromstudents 
							}
						}
					}
					default {
						lappend action_list changegrades deletecolumn changecolumn 
						if { [SelectColValue4User $col _Visible_To_Students_] eq "true" } {
							lappend action_list hidecolfromstudents 
						} else {
							lappend action_list unhidecolfromstudents 
						}
					}
				}
			}
		}
		set separator {<br>}
		foreach act $action_list {
			set attributes [action2atributes $act]
			set act_label [lindex $attributes 1]
			set act_icon  [lindex $attributes 2]
			if { [isActionGranted $act $permission_list $user] } {
				if { $GradebookServerConfig(use_icons) } {
					puts -nonewline "$separator<a href=\"$script_name?action=$act&columnname=[::ncgi::encode $col]\">"
					puts -nonewline "<img src=\"$act_icon\" alt=\"$act_label\" title=\"$act_label\">"
					puts -nonewline "</a>"
				} else {
					puts -nonewline "$separator<span class=\"column_control_$act\"><a href=\"$script_name?action=$act&columnname=[::ncgi::encode $col]\">"
					puts -nonewline "$act_label"
					puts -nonewline "</a></span>"
				}
			} 
		}
		puts -nonewline "</th>"
		puts ""
	}
	puts "</tr>"
}

proc getColAndValForUserName { user_name sql_column_str hidden_columns } {
	set eval_str [concat SELECT $sql_column_str FROM GradesTable WHERE UserName=\"$user_name\"]
	set err [catch {
		db eval $eval_str v {
		}
	} errStat ]
	if { $err } {
		dbg "we should never be here if UserName: $user_name exist in the table" msg_level_critical
		dbg $errStat msg_level_critical
		htmlErrorMsg $errStat
		return
	} else {
		return [array get v]
	}
}

proc htmlFormatMaxPossibleRaw { sql_column_str hidden_columns } {
	# show max point values in html format
	puts  "<tr>"
	array set v [getColAndValForUserName _Max_Points_ $sql_column_str $hidden_columns]
	foreach c $v(*) {
		if { $c in $hidden_columns } continue
		switch $c {
			"FirstName" {set  out_str "Max"}
			"LastName"  {set  out_str "Possible"}
			"GroupName" {set  out_str ""}
			"UserName"  {set  out_str "_Derived_"}
			default     {
				if { ![info exists v($c)] } { 
					set out_str "N/A"
				} else {
					set out_str $v($c)
				}
			} 
		}
		puts "<td> <b>$out_str</b> </td>"
	}
	puts "</tr>"
}

proc htmlFormatTheStatsForGradeRaw { stats_needed sql_column_str hidden_columns } {
	# show max or min point values in html format
	switch $stats_needed {
		"high" {set sql_user_name _The_Highest_Grade_}
		"low"  {set sql_user_name _The_Lowest_Grade_}
		"mean"  {set sql_user_name _The_Mean_Grade_}
		"median"  {set sql_user_name _The_Median_Grade_}
		"stdev"  {set sql_user_name _The_StDev_Grade_}
		default {
			htmlErrorMsg "Required stats ($stats_needed) to output is not known"
			return ""
		}
	}
	array set v [getColAndValForUserName $sql_user_name $sql_column_str $hidden_columns]
	set html_str "<tr>\n"
	foreach columnname $v(*) {
		if { ![info exists v($columnname)] } {
			# this raw does not exist abandone raw compillation
			return ""
		}
		if { $columnname in $hidden_columns } continue
		switch $columnname {
			"FirstName" {set  col_value "Class"}
			"LastName"  {
				switch $stats_needed {
					"high" {set  col_value "High"}
					"low"  {set  col_value "Low"}
					"mean"  {set  col_value "Mean"}
					"median"  {set  col_value "Median"}
					"stdev"  {set  col_value "StDev"}
					default {set  col_value "UNKNOWN"}
				}
			}
			"UserName"  {set  col_value "_Derived_"}
			default     {
				if { ![info exists v($columnname)] } { 
					set col_value "N/A"
				} else {
					set col_value $v($columnname)
				}
			} 
		}
		set html_str [join [list $html_str "\n" [htmlFormatColVal $col_value $columnname $sql_user_name $sql_user_name {} {b}] ] {}]
	}
	set html_str [join [list $html_str "\n" "</tr>"]]
	return $html_str
}

proc getPhotoUrl { IdNum } {
	# generate url pointing to a photo of a user with the given IdNum
	global GradebookServerConfig
	set photo_album_base_url $GradebookServerConfig(photo_album_base_url)
	set photo_album_cache $GradebookServerConfig(photo_album_cache)
	set photo_album_cache_url $GradebookServerConfig(photo_album_cache_url)
	set photo_file "${IdNum}.jpg"
	set cached_photo_file "$photo_album_cache/${photo_file}"
	if { ${IdNum} eq "" } {
		# useless/invalid IdNum
		return "" 
	} 
	if { [file exist "$cached_photo_file"] } {
		# return link to locally cached file
		set url "$photo_album_cache_url/$photo_file"
	} else {
		# return link to the main WM photobase
		set url "$photo_album_base_url/${photo_file}"
		#cachePhoto $url
	}
	return $url
}

proc htmlFormatColVal { col_value columnname user user_shown permission_list {font_style {}} } {
	global script_name
	global GradebookServerConfig
	set html_str {} 
	set font_style_strt {}
	set font_style_end  {}
	if { $font_style ne "" } {
		set font_style_strt  "<$font_style>"
		set font_style_end   "</$font_style>"
	}
	set category [SelectColValue4User $columnname _Col_Category_]
	set max_points [SelectColValue4User $columnname _Max_Points_]
	set special_user_names [list _Max_Points_ _The_Highest_Grade_ _The_Lowest_Grade_ _The_Mean_Grade_ _The_Median_Grade_ _The_StDev_Grade_	]
	if { (([SelectColValue4User GroupName $user_shown] ne "inforow") || ($user in $special_user_names)) && ($category eq "weighted_column") && ($max_points != 0) } {
		if { $col_value eq "" } {
			set col_value 0
		}
		# calculate letter grade to Grand Total
		if { ($columnname eq "Grand Total") && ($user ne "_The_StDev_Grade_") } {
			set col_value_letter_grade [number2letter_grade $col_value]
		} else {
			# leave intact for stdev
			set col_value_letter_grade $col_value
		}
		# promote to percent format
		set col_value [format "%04.2f%%" [expr {100.* $col_value} ] ]
		# add letter grade to Grand Total
		if { ($columnname eq "Grand Total") && ($user ne "_The_StDev_Grade_") } {
			set col_value [ concat $col_value "=" <b> $col_value_letter_grade </b>]
		}
	}
	set col_str_value [htmlReplaceEmptyString $col_value]
	set col_str_value ${font_style_strt}${col_str_value}${font_style_end}

	# embedded actions on values assignment
	set embeded_actions_excluded_special_columns [ list \
		PasswordHash GroupName UserHiddenColums \
		FirstName \
		LastName  \
		UserName \
		IdNum \
		SectionNum \
		UserHiddenGroups \
		UserHiddenGradeCategories \
		]
	
	if { ([SelectColValue4User GroupName $user_shown] ne "inforow") && ($user ni $special_user_names) && ($category ne "weighted_column") && ($columnname ni $embeded_actions_excluded_special_columns) } {
		if { [isActionGranted edit_user_grade $permission_list $user] && ($user_shown ne "_UNSET_") } {
			set col_str_value "<a href=\"$script_name?action=edit_user_grade_request&user2modify=$user_shown&column2modify=$columnname\">${col_str_value}</a>"
		}
	}

	# additional actions on values assignment
	switch  $columnname {
		GroupName  {
			set action_html_code {}
			switch $col_value {
				inforow { set action_html_code {} }
				default {
					if { [isActionGranted changegroupname $permission_list $user] && ($user_shown ne "_UNSET_") } {
						set separator {<br>}
						set action_html_code "$separator<span class=\"controls\"><a href=\"$script_name?action=changegroupname&user2modify=$user_shown\">Change</a></span>"
					}
				}
			}
			set html_str [join [list ${html_str} "<td class=\"$category\">$col_str_value $action_html_code</td>"] {}]
		}
		IdNum {
			set html_str [join [list ${html_str} "<td class=\"$category\">"] {} ]
			set IdNum $col_value
			set photo_url [ getPhotoUrl $IdNum ]
			if { $photo_url ne "" } {
				# 90x90 is WM default
				set photo_img_width  $GradebookServerConfig(photo_img_width)
				set photo_img_height $GradebookServerConfig(photo_img_height)
				set html_str [join [list ${html_str} "<img src='${photo_url}' height='$photo_img_height' width='$photo_img_width'>"] {} ]
			}
			set html_str [join [list ${html_str} "$col_str_value</td>"] {} ]
		}
		default    {
			set html_str [join [list ${html_str} "<td class=\"$category\">$col_str_value</td>"] {}]
		}
	}
	return $html_str
}

proc htmlDBout {db permission_list user {sort_col {}}} {
	array set permission $permission_list
	global GradebookServerConfig
	global script_name
	#global grades_category
	set grades_category [ get_grades_category ]
	set defSortCol LastName 

	# testing for the existence of the sorting column
	if { ![doesColumnExists $sort_col GradesTable] } {
		dbg "changing to default sorting column $defSortCol" msg_level_info
		set sort_col $defSortCol
	}

	puts  {<div class="gradestable">}
	set show_header 1
	# get names of all columns
	set column_list [getColListFromTable GradesTable]
	# set hidden column list
	switch $permission(GroupName) {
		instructor { set hidden_columns {} }
		ta         { set hidden_columns [list GroupName UserHiddenColums UserHiddenGroups UserHiddenGradeCategories IdNum] }
		student    { set hidden_columns [list UserName GroupName UserHiddenColums UserHiddenGroups  UserHiddenGradeCategories IdNum SectionNum] }
		dropped    { set hidden_columns [list UserName GroupName UserHiddenColums UserHiddenGroups  UserHiddenGradeCategories IdNum SectionNum] }
		guest      { set hidden_columns $column_list }
		default    { set hidden_columns $column_list }
	}
	# add user hidden columns
	set hidden_columns [concat $hidden_columns [SelectColValue4User UserHiddenColums $user]]
	# remove hidden columns from sql request
	foreach col $hidden_columns {
		set column_list [removeElementFromList $col $column_list]
	}
	# check which GradesCategory user does not want to see
	set UserHiddenGradeCategories [concat $hidden_columns [SelectColValue4User UserHiddenGradeCategories $user]]
	foreach col $column_list {
		if { [SelectColValue4User $col  _Col_Category_] in $UserHiddenGradeCategories } {
			set column_list [removeElementFromList $col $column_list]
		}
		if { ( ($permission(GroupName) eq "student") || ($permission(GroupName) eq "dropped") ) && ( [SelectColValue4User $col _Visible_To_Students_] ne "true") } {
			switch $col {
				FirstName {; #nothing bad to see first name}
				LastName  {; #nothing bad to see last name}
				default { set column_list [removeElementFromList $col $column_list]}
			}
		}
	}

	# add UserName column since a lot depends on it knowledge
	if {{UserName} ni $column_list} {
		lappend column_list UserName
	}
	
	set sql_column_str [colList2sqlColStr $column_list]
	# set users of what group user can see, i.e. set WHERE statement
	set where_statement {}
	switch $permission(GroupName) {
		instructor { 
			# hide unwanted user groups
			set user_groups_for_hide [SelectColValue4User UserHiddenGroups $user]
			if {$user_groups_for_hide != {} } {
				foreach grp $user_groups_for_hide {
					if { $where_statement == {} } {
						set where_statement "WHERE GroupName<>\"$grp\""
					} else {
						set where_statement [concat $where_statement "AND GroupName<>\"$grp\""]
					}
				}
			}
		}
		ta         { set where_statement "WHERE GroupName=\"student\"" }
		student    { set where_statement "WHERE UserName=\"$user\"" }
		dropped    { set where_statement "WHERE UserName=\"$user\"" }
		guest      { dbg "Guest must not be allowed to set table view port. Aborting. This line is never executed" msg_level_critical; exit }
		default      { dbg "Default must not be allowed to set table view port. Aborting. This line is never executed." msg_level_critical; exit }
	}
	if { $sql_column_str ne "" } {
		# assign type cast  for different sort_col
		if { [SelectColValue4User $sort_col  _Col_Category_] in [concat $grades_category weighted_column]} {
			set ordered_by_str [concat CAST(\"$sort_col\" AS REAL)] 
		} else {
			set ordered_by_str \"$sort_col\" 
		}
		#get all allowed columns and rows
		set eval_str [concat SELECT $sql_column_str FROM GradesTable $where_statement ORDER BY $ordered_by_str]
		set err [catch {
				db eval $eval_str v {
					if { $show_header } {
						set show_header 0
						puts  {<table class="gradestable" border="1">}
						set v_array_list [array get v]
						htmlGradesTableHeadersRaw $permission_list $user $sql_column_str $hidden_columns $v_array_list
						htmlFormatMaxPossibleRaw     $sql_column_str $hidden_columns
						puts [htmlFormatTheStatsForGradeRaw high $sql_column_str $hidden_columns]
						puts [htmlFormatTheStatsForGradeRaw mean $sql_column_str $hidden_columns]
						puts [htmlFormatTheStatsForGradeRaw stdev $sql_column_str $hidden_columns]
						puts [htmlFormatTheStatsForGradeRaw median $sql_column_str $hidden_columns]
						puts [htmlFormatTheStatsForGradeRaw low $sql_column_str $hidden_columns]
					}

					puts  "<tr>"
					if { [info exist v(UserName)] } {
						set user_shown [htmlReplaceEmptyString $v(UserName)]
					} else {
						set user_shown "_UNSET_"
					}
					foreach columnname $v(*) {
						if { $columnname in $hidden_columns } continue
						if { $columnname != "*" } {
							# detect what column category it is
							set col_value  $v($columnname)
							puts [htmlFormatColVal  $col_value $columnname $user $user_shown $permission_list]
						}
					}
					puts "</tr>"
				}
			} errStat ]
		if { $err } {
			dbg "we should never be here if $sort_col exist in the table" msg_level_critical
			dbg $errStat msg_level_critical
			htmlErrorMsg $errStat
		}
		puts  "</table>"
	} else {
		puts {There is no grades yet.}
	}
	puts  {</div>}
}

proc htmlTop {permission_list} {
	ClassInfoHtml
	array set permission $permission_list
	if { $permission(GroupName) == "guest" } {
		askToLogin
	} else {
		Greetings
	}

}

proc html_Show_Classes_List {permission_list user} {
	# list available class DBs
	global GradebookServerConfig script_root_name
	puts "<div>"
	puts "Available classes are"
	puts "<ul>"
	foreach cdb  [get_list_of_courses_db] {
		set dbfile "$GradebookServerConfig(grades_db_dir)/$cdb"
		if { ![file exists $dbfile] } { continue }

		sqlite3 db $dbfile
		set CourseTitle     [SelectItemFromCourseInfoTable course_title]
		set CourseYear      [SelectItemFromCourseInfoTable course_year]
		set CourseSemester  [SelectItemFromCourseInfoTable course_semester]
		puts "<li><a href=\"$script_root_name/$cdb\">$CourseYear $CourseSemester - $CourseTitle</a>"
		db close
	}
	puts "</ul>"
	puts "</div>"
}

proc htmlFooter {permission_list} {
	array set permission $permission_list
	global VERSION
	global GradebookServerConfig
	global execution_start_time
	set execution_end_time [clock microseconds]
	set execution_time [ format "%.3g" [expr { ($execution_end_time - $execution_start_time)/1e6}] ]
	puts "<div class=\"footer\">"
	puts "Execution time $execution_time seconds. <br>"
	puts "GradeBook $VERSION by Eugeniy E. Mikhailov."
	puts "<p> <a href=\"$GradebookServerConfig(html_access_stats_url)\">Access statistics.</a>"
	puts "</div>"
}


proc SelectColValue4User { colname user } {
	return [SelectColvalueFromTable GradesTable $colname UserName $user]
}

proc ClassInfoHtml {} {
	set CourseTitle     [SelectItemFromCourseInfoTable course_title]
	set CourseYear      [SelectItemFromCourseInfoTable course_year]
	set CourseSemester  [SelectItemFromCourseInfoTable course_semester]
	puts "<div class=\"header\">"
	puts "<h1>Course grades for $CourseTitle</h1>"
	puts "<p class=date>"
	puts "$CourseYear - $CourseSemester"
	puts "</p>"
	puts "</div>"
}

proc Greetings {} {
	global user password script_name

	set FirstName UnknownFirstName
	set LastName  UnknownLastName


	# get First and Last name info
	set FirstName [SelectColValue4User FirstName $user]
	set LastName  [SelectColValue4User LastName  $user]
	
	puts "<div class=\"greetings\">"
	puts "<span class=login_info>$FirstName $LastName</span>, you  are logged in as <span class=login_info>$user</span>."
	#puts "<a href=\"$script_name?action=logoff\">logoff</a>"
	puts "</div>"
	
}

proc askToLogin {} {
	global script_name
	global user_requested password
	puts "<div class=\"login\">"
	puts "Either you are here first time or you password and user name does not match. <br>"
	puts "Please login <br>"
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	puts "Login (email): <input type=\"text\" name=\"user\" value=\"$user_requested\"><br>"
	puts {Password: <input type="password" name="password"><br>}
	puts {<input type="hidden" name="action" value="logon"/>}
	puts {<input type="submit" value="Submit" />}
	puts {<br>}
	puts {If you don not know your password, fill in login box and push <input type="submit" name="subaction" value="Reset password" />}
	puts {</form>}
	puts "</div>"
}

proc ResetForgottenPassword { permission_list user } {
	global script_name user_requested
	dbg "$user_requested which is identified as $user asked to reset the password" msg_level_log

	if { [SelectColValue4User UserName $user_requested] eq "" } {
		htmlErrorMsg "Sorry but user {$user_requested} is not registered in this class"
		dbg "{$user_requested} is not registered in this class" msg_level_info
		return
	}

	#reset password procedure goes here
	# FIXME sanitize email
	set newpassword [GenPassword]
	Set_New_Password_Non_Web $user_requested $newpassword
	SendNewPassword2User $user_requested $newpassword
}

proc GenPassword { } {
	set password_chars "1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	set len [string length $password_chars]

	set i 1
	set newpassword {}
	while { $i <= 8 } {
		incr i 1
		set indx [expr {int(rand()*$len)}]
		set newchar [string index $password_chars $indx]
		append newpassword $newchar
	}
	return $newpassword
}

proc SendNewPassword2User { user password } {
	dbg "Sending password to user $user" msg_level_info
	set CourseTitle  [SelectItemFromCourseInfoTable course_title]
	set FirstName    [SelectColValue4User FirstName $user]   
	set tmp_msg_file /tmp/tmp_msg4user_$user
	set fp [open $tmp_msg_file w]
	puts $fp "Dear ${FirstName},"
	puts $fp "Your  password to access $CourseTitle grades is"
	puts $fp "------------------------------------------"
	puts $fp "$password"
	puts $fp "------------------------------------------"
	close $fp
	if { [catch {exec mail -s "New password for $CourseTitle" "$user" < $tmp_msg_file} msg ] } {
		   htmlErrorMsg "Something seems to have gone wrong during mailing the password. Information about it: $::errorInfo"
			 dbg "Something seems to have gone wrong during mailing the password for {$user}. Information about it: $::errorInfo" msg_level_critical
	}
	#now it is safe to delete temporary file
	if { [catch {file delete $tmp_msg_file} msg] } {
		dbg "Cannot delete file {$tmp_msg_file} with temporary password message for user {$user}" msg_level_critical
	}
}

proc LogMeOn {} {
	#more correctly set cookies
	global user_requested password
	set user_requested [::ncgi::value user guest]
	set password [::ncgi::value password guest]
	dbg "Logging in and setting cookies" msg_level_info
	::ncgi::setCookie  -name user -value $user_requested
	::ncgi::setCookie  -name password -value $password
	
	set subaction [::ncgi::value subaction {}]
	if { $subaction eq "Reset password" } {
		return resetforgottenpassword
	}
	return defaultview
}

proc LogMeOff {} {
	dbg "Logging off" msg_level_info
	global user password
	#set user guest
	set password {}
	#::ncgi::setCookie  -name user -value $user
	::ncgi::setCookie  -name password -value $password
}

proc SetSortColumn {} {
	global sortCol 
	set sortCol [::ncgi::value sortCol LastName]
	::ncgi::setCookie  -name sortCol -value $sortCol
}

proc isActionGranted { action permission_list user } {
	array set permission $permission_list
	dbg "$user requested action $action" msg_level_info
	if { $action == "defaultview" } { 
		# this one permitted to everyone
		dbg "requested action $action for user $user is granted" msg_level_info
		return 1;
	}
	if { $action == "resetforgottenpassword" } {
		# this one permitted to everyone
		dbg "requested action $action for user $user is granted" msg_level_info
		return 1;
	}
	if { ![info exist permission($action) ] } {
		dbg "requested UNKNOWN action $action for user $user is not granted" msg_level_warning
		htmlErrorMsg "requested UNKNOWN action $action"
		return 0;
	}

	if {$permission($action) } {
		dbg "requested action $action for user $user is granted" msg_level_info
		return 1;
	} else {
		dbg "requested action $action for user $user is not granted" msg_level_info
		return 0;
	}
}

proc ChoseAction {action permission_list user} {
	array set permission $permission_list
	dbg "requested action: $action" msg_level_info
	if { [isActionGranted $action $permission_list $user] } {

		switch $action {
			sort             { SetSortColumn; ChoseAction defaultview $permission_list $user } 
			addcolumn        { 
				           AddColumn          $permission_list  $user;
				           htmlDefaultView    $permission_list  $user
					 } 
			addcolumnrequest { AddColumnRequest   $permission_list  $user } 
			deletecolumn     { 
			                   DeleteColumn       $permission_list  $user;
				           htmlDefaultView    $permission_list  $user
			                 } 
			changegrades	 { ChangeGrades       $permission_list  $user }	 
			updategrades     { UpdateGrades       $permission_list  $user 
				           htmlDefaultView    $permission_list  $user
			                 } 
			changecolumn     { ChangeColumn       $permission_list  $user }
			updatecolumn     { UpdateColumn       $permission_list  $user 
				           htmlDefaultView    $permission_list  $user
					 }
			showcontrols     { ShowControls       $permission_list  $user } 
			hidecolfromstudents   { HideColumnFromStudents     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			unhidecolfromstudents { UnHideColumnFromStudents     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			userhidecolumn   { UserHideColumn     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			userunhidecolumn { UserUnHideColumn     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			userhidegroup   { UserHideGroup     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			userunhidegroup { UserUnHideGroup     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			userhidegradecategory   { UserHideGradeCategory     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			userunhidegradecategory { UserUnHideGradeCategory     $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			showgrades       { htmlGradesTable db $permission_list  $user }
			edit_grades_categories   { EditGradesCategories db $permission_list  $user }
			update_grades_categories { UpdateGradesCategores db $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			editcourseinfo   { EditCourseInfo db $permission_list  $user }
			updatecourseinfo { UpdateCourseInfo db $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			editnewuserinfo  { EditNewUserInfo db $permission_list  $user }
			addnewuserinfo   { AddNewUserInfo db $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			choosenewpassword  { ChooseNewPassword db $permission_list  $user }
			setnewpassword     { SetNewPassword    db $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			resetforgottenpassword      { ResetForgottenPassword   $permission_list  $user }
			changegroupname   { ChangeGroupName  $permission_list  $user }
			setgroupname      { SetGroupName  $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			update_grades_stats { UpdateGradesTableStatistic $permission_list  $user
				           htmlDefaultView    $permission_list  $user }
			edit_user_grade_request   { htmlEditUserGradeValue  $permission_list  $user }
			edit_user_grade  { EditUserGradeValue  $permission_list  $user 
				           htmlDefaultView    $permission_list  $user }
			defaultview      { htmlDefaultView    $permission_list  $user }
			default          { htmlErrorMsg "requested action <b>$action</b> is granted but not implemented yet" }
		}	
	} else {
		# this action is permitted to everyone by default
		#ChoseAction defaultview $permission_list $user
		dbg "action $action isn not permitted for $user" msg_level_info
	}
}

proc EditUserGradeValue {permission_list user } {
	global script_name
	set subaction       [::ncgi::value subaction {}]
	set modified_user   [::ncgi::value user2modify {}]
	set modified_column [::ncgi::value column2modify {}]
	set new_value [::ncgi::value newcolumnvalue {}]

	if { $subaction eq "Cancel" } {
		return
	}

	if { $subaction eq "Submit" } {
		UpdateColValue4UserNameNonWeb $modified_column $modified_user $new_value
		calculteWeightedTotals
		set update_parent true
		UpdateColumnStatistic $modified_column $update_parent
	}
}

proc htmlEditUserGradeValue {permission_list user } {
	global script_name
	set modified_user [::ncgi::value user2modify {}]
	set modified_column [::ncgi::value column2modify {}]

	set current_group_name [SelectColValue4User GroupName $modified_user]
	set FirstName [SelectColValue4User FirstName $modified_user]
	set LastName [SelectColValue4User LastName $modified_user]
	set old_value [SelectColValue4User $modified_column $modified_user]
	puts "<div class=edit_user_grade_request>"
	puts "Change grade for student <b>$FirstName $LastName</b> with user name $modified_user"
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	puts "<b>$modified_column</b> old value: \{$old_value\},"
	puts "new value:  <input name=\"newcolumnvalue\" value=\"$old_value\" ><br>"
	puts {<input type="hidden" name="action" value="edit_user_grade">}
	puts [join [ list {<input type="hidden" name="user2modify" value="} $modified_user {">} ] ""]
	puts [join [ list {<input type="hidden" name="column2modify" value="} $modified_column {">} ] "" ]
	puts {<input type="submit" name="subaction" value="Submit" >}
	puts {<input type="submit" name="subaction" value="Cancel" >}
	puts {</form>}
	puts "</div>"
}

proc ChangeGroupName {permission_list user } {
	global script_name
	set modified_user [::ncgi::value user2modify {}]

	set current_group_name [SelectColValue4User GroupName $modified_user]
	set FirstName [SelectColValue4User FirstName $modified_user]
	set LastName [SelectColValue4User LastName $modified_user]
	puts "<div class=changegroupname>"
	puts "New group name for $FirstName $LastName with user name $modified_user"
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	puts {GroupName: <select name="groupname">}
	# opt list has option name and corresponding text pairs
	set opt_list [list \
			student student\
			dropped "Dropped Student"\
	    ta ta\
			instructor instructor
		]
	foreach {name txt} $opt_list {
		set out_str {}
		if { $name eq $current_group_name } {
			append out_str {<option value="} $name {" selected>} $txt {</option>}
		} else {
			append out_str {<option value="} $name {">} $txt {</option>}
		}
		puts $out_str
	}	
	puts {</select> <br>}
	puts {<input type="hidden" name="action" value="setgroupname"/>}
	puts "<input type=\"hidden\" name=\"user2modify\" value=\"$modified_user\"/>"
	puts {<input type="submit" name="subaction" value="Submit" />}
	puts {<input type="submit" name="subaction" value="Cancel" />}
	puts {</form>}
	puts "</div>"
}

proc SetGroupName { permission_list user } {
	set subaction      [::ncgi::value subaction {}]
	set modified_user [::ncgi::value user2modify {}]
	set new_group_name [::ncgi::value groupname {}]

	if { $subaction eq "Cancel" } {
		return
	}

	if { $new_group_name eq "" } {
		htmlErrorMsg "Empty groupname are not permitted"
		return
	}

	if { $subaction eq "Submit" } {
		UpdateColValue4UserNameNonWeb GroupName $modified_user $new_group_name
		UpdateGradesTableStatistic $permission_list  $user
	}
}


proc ChooseNewPassword {db permission_list user } {
	global script_name

	puts "<div class=choosenewpassword>"
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	puts "Please type new password:  <input type=\"password\" name=\"newpassword\" ><br>"
	puts {<input type="hidden" name="action" value="setnewpassword"/>}
	puts {<input type="submit" name="subaction" value="Submit" />}
	puts {<input type="submit" name="subaction" value="Cancel" />}
	puts {</form>}
	puts "</div>"
}

proc Set_New_Password_Non_Web {user newpassword} {
	global GradebookServerConfig
	if { $newpassword eq "" } {
		dbg "Attempt to set empty password which is not permitted" msg_level_info
		return
	}
	set password_hash [::md5::md5 -hex $newpassword]
	
	set err [catch {
		sqlite3 pdb $GradebookServerConfig(passwords_db_file)
	} errStat ]
	if { $err } {
		dbg  "$errStat with filename $GradebookServerConfig(passwords_db_file)" msg_level_critical
		return
	} 

	if { ![ is_User_Registered_in_Passwords_DB $user ] } {
		set sql_str [concat INSERT INTO  PasswordsTable (UserName, PasswordHash) VALUES('$user', '$password_hash')]
	} else {
		set sql_str [concat UPDATE  PasswordsTable SET \"PasswordHash\"=\'$password_hash\' where UserName=\"$user\"]
	}

	set err [catch {
		pdb eval $sql_str
	} errStat ]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_warning
	} 
}

proc SetNewPassword {db permission_list user } {
	global script_name

	set subaction      [::ncgi::value subaction {}]
	set newpassword      [::ncgi::value newpassword {}]

	if { $subaction eq "Cancel" } {
		return
	}

	if { $newpassword eq "" } {
		dbg "Attempt to set empty password which is not permitted" msg_level_info
		htmlErrorMsg "Empty passwords are not permitted"
		return
	}

	if { $subaction eq "Submit" } {
		Set_New_Password_Non_Web $user $newpassword
	}
}


proc AddNewUserInfo {db permission_list user } {
	set subaction      [::ncgi::value subaction {}]
	set first_name     [::ncgi::value first_name {}]
	set last_name      [::ncgi::value last_name {}]
	set login          [::ncgi::value login {}]
	set id_number      [::ncgi::value id_number {}]
	set section_number [::ncgi::value section_number {}]
	set group_name     [::ncgi::value group_name {}]

	if { $subaction eq "Cancel" } {
		return
	}

	if { $login eq "" } {
		htmlErrorMsg "Empty login names are not permitted"
		return
	}

	if { [SelectColValue4User UserName $login] ne "" } {
		htmlErrorMsg "User with login $login already exists"
		return
	}

	set permitted_groups [list instructor ta student guest]
	if { $subaction eq "Submit" } {
		if { $group_name ni $permitted_groups } {
			htmlInfoMsg "Unknown group name {$group_name} replaced with {guest}."
			set group_name guest
		}
		AddUserNonWeb $first_name $last_name $login $group_name $id_number $section_number
	}
}

proc EditNewUserInfo {db permission_list user } {
	global script_name

	puts "<div class=editnewuserinfo>"
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	puts "First Name:    <input type=\"text\" name=\"first_name\" ><br>"
	puts "Last Name:     <input type=\"text\" name=\"last_name\" ><br>"
	puts "Login (email): <input type=\"text\" name=\"login\" ><br>"
	puts "Id Number: <input type=\"text\" name=\"id_number\" ><br>"
	puts "Section Number: <input type=\"text\" name=\"section_number\" ><br>"
	puts "Group Name: <input type=\"text\" name=\"group_name\" ><br>"
	puts {<input type="hidden" name="action" value="addnewuserinfo"/>}
	puts {<input type="submit" name="subaction" value="Submit" />}
	puts {<input type="submit" name="subaction" value="Cancel" />}
	puts {</form>}
	puts "</div>"
}

proc EditCourseInfo {db permission_list user } {
	global script_name
	set CourseTitle     [SelectItemFromCourseInfoTable course_title]
	set CourseYear      [SelectItemFromCourseInfoTable course_year]
	set CourseSemester  [SelectItemFromCourseInfoTable course_semester]

	puts "<div class=editcourseinfo>"
	puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
	puts "Course title:    <input type=\"text\" name=\"course_title\" value=\"$CourseTitle\"><br>"
	puts "Course year:     <input type=\"text\" name=\"course_year\" value=\"$CourseYear\"><br>"
	puts "Course Semester: <input type=\"text\" name=\"course_semester\" value=\"$CourseSemester\"><br>"
	puts {<input type="hidden" name="action" value="updatecourseinfo"/>}
	puts {<input type="submit" name="subaction" value="Submit" />}
	puts {<input type="submit" name="subaction" value="Cancel" />}
	puts {</form>}
	puts "</div>"
}

proc UpdateCourseInfo { db permission_list user } {
	global script_name
	set subaction [::ncgi::value subaction {}]
	set CourseTitle     [::ncgi::value course_title {}]
	set CourseYear      [::ncgi::value course_year {}]
	set CourseSemester  [::ncgi::value course_semester {}]
	if { $subaction eq "Cancel" } {
		return
	}
	if { $subaction eq "Submit" } {
		UpdateCourseInfoTableItem course_title    $CourseTitle
		UpdateCourseInfoTableItem course_year     $CourseYear
		UpdateCourseInfoTableItem course_semester $CourseSemester
	}
	htmlInfoMsg "Please click <span class=\"controls\"><a href=\"$script_name?action=defaultview\">Refresh</a></span> to see updated course info."
}

proc UserHideGradeCategory {    permission_list  user } {
	set ctg_name [::ncgi::value grades_category {}]
	set currently_UserHiddenGradeCategories [SelectColValue4User UserHiddenGradeCategories $user]
	lappend currently_UserHiddenGradeCategories $ctg_name
	UpdateColValue4UserNameNonWeb UserHiddenGradeCategories $user $currently_UserHiddenGradeCategories
}

proc UserUnHideGradeCategory {   permission_list  user } {
	set ctg_name [::ncgi::value grades_category {}]
	set currently_UserHiddenGradeCategories [SelectColValue4User UserHiddenGradeCategories $user]
	set currently_UserHiddenGradeCategories [removeElementFromList $ctg_name $currently_UserHiddenGradeCategories]
	UpdateColValue4UserNameNonWeb UserHiddenGradeCategories $user $currently_UserHiddenGradeCategories
}

proc UserUnHideGroup { permission_list user } {
	set groupname [::ncgi::value groupname {}]
	set currently_hidden_groups [SelectColValue4User UserHiddenGroups $user]
	set currently_hidden_groups [removeElementFromList $groupname $currently_hidden_groups]
	UpdateColValue4UserNameNonWeb UserHiddenGroups $user $currently_hidden_groups
}
proc UserHideGroup { permission_list user } {
	set groupname [::ncgi::value groupname {}]
	set currently_hidden_groups [SelectColValue4User UserHiddenGroups $user]
	lappend currently_hidden_groups $groupname
	UpdateColValue4UserNameNonWeb UserHiddenGroups $user $currently_hidden_groups
}

proc HideColumnFromStudents { permission_list user } {
	set columnname [::ncgi::value columnname {}]
	UpdateColValue4UserNameNonWeb $columnname _Visible_To_Students_ false
}

proc UnHideColumnFromStudents { permission_list user } {
	set columnname [::ncgi::value columnname {}]
	UpdateColValue4UserNameNonWeb $columnname _Visible_To_Students_ true
}

proc UserHideColumn { permission_list user } {
	set columnname [::ncgi::value columnname {}]
	set currently_hidden_columns [SelectColValue4User UserHiddenColums $user]
	lappend currently_hidden_columns $columnname
	UpdateColValue4UserNameNonWeb UserHiddenColums $user $currently_hidden_columns
}

proc UserUnHideColumn { permission_list user } {
	set columnname [::ncgi::value columnname {}]
	set currently_hidden_columns [SelectColValue4User UserHiddenColums $user]
	set currently_hidden_columns [removeElementFromList $columnname $currently_hidden_columns]
	UpdateColValue4UserNameNonWeb UserHiddenColums $user $currently_hidden_columns
}

proc ChangeColumn { permission_list user } {
	set columnname [::ncgi::value columnname {}]
	set category "unset"
	set category  [SelectColValue4User $columnname _Col_Category_]
	set maxpoints [SelectColValue4User $columnname _Max_Points_]
	#global grades_category
	set grades_category [ get_grades_category ]

	puts {<div class="add_new_column">}
	puts "<form name=\"input\"  method=\"post\" >"
	set out_str {}
	append out_str {Column Name: <input type="text" name="newcolumnname" value="} $columnname {"><br>}
	puts $out_str
	set out_str {}
	append out_str {Category: <select name="category" value="} $category  {">}
	puts $out_str
	foreach {name} $grades_category {
		set txt [grade_Category2html_name $name]
		set out_str {}
		if { $name eq $category } {
			append out_str {<option value="} $name {" selected>} $txt {</option>}
		} else {
			append out_str {<option value="} $name {">} $txt {</option>}
		}

		puts $out_str
	}	
	puts {</select> <br>}
	set out_str {}
	append out_str {Max Point Possible:<input type="text" name="maxpointpossible" value="} $maxpoints {"> <br>}
	puts $out_str
	puts {<input type="hidden" name="action" value="updatecolumn"/>}
	set out_str {}
	append out_str {<input type="hidden" name="oldcolumnname" value="} $columnname {"/>}
	puts $out_str
	puts {<input type="submit" value="Submit" />}
	puts {</form>}
	puts {</div>}
}

proc UpdateColumn { permission_list user } {
	set oldcolumnname [::ncgi::value oldcolumnname {}]
	set newcolumnname [::ncgi::value newcolumnname {}]
	set column_category [::ncgi::value category {}]
	set maxpointpossible [::ncgi::value maxpointpossible {}]

	# transform colnames to sql safe form
	set oldcolumnname [ColName2SqlSafeForm $oldcolumnname]
	set newcolumnname [ColName2SqlSafeForm $newcolumnname]

	set needToRecalculateWeightedTotals false

	# first we update category and maxpointpossible values of the old columnname
	set old_column_category  [SelectColValue4User $oldcolumnname _Col_Category_]
	if { $old_column_category ne $column_category } {
		UpdateColValue4UserNameNonWeb $oldcolumnname _Col_Category_ $column_category
		set needToRecalculateWeightedTotals true
	}

	set old_maxpointpossible [SelectColValue4User $oldcolumnname _Max_Points_]
	if { $old_maxpointpossible ne $maxpointpossible } {
		UpdateColValue4UserNameNonWeb $oldcolumnname _Max_Points_   $maxpointpossible
		set needToRecalculateWeightedTotals true
	}

	if { $needToRecalculateWeightedTotals } {
		calculteWeightedTotals
	}

	if { $newcolumnname eq $oldcolumnname } {
		# no need to mess with renaming
		return
	}
	if { $newcolumnname == "" } {
		htmlErrorMsg  "empty column names are not permitted"
		return
	}

	RenameColumnNonWeb $oldcolumnname $newcolumnname
}

proc UpdateColValue4UserNameNonWeb { columnname username val } {
					set sql_str [concat UPDATE  GradesTable SET \"$columnname\"=\'$val\' where UserName=\"$username\"]
					set err2 [catch {
						db eval $sql_str
					} errStat2 ]
					if { $err2 } {
						htmlErrorMsg  $errStat2 
						dbg  "the following error happen: $errStat2" msg_level_critical
					} 
}

proc UpdateColValue4GroupNameNonWeb { columnname groupname val } {
					set sql_str [concat UPDATE  GradesTable SET \"$columnname\"=\'$val\' where GroupName=\"$groupname\"]
					set err2 [catch {
						db eval $sql_str
					} errStat2 ]
					if { $err2 } {
						htmlErrorMsg  $errStat2 
						dbg  "the following error happen: $errStat2" msg_level_critical
					} 
}

proc LeaveOnlyNumbersInList { l } {
	set new_list {}
	foreach {el} $l {
		if { [string is double -strict $el] } {
			lappend new_list $el
		}
	}	
	return $new_list
}

proc GetGroupValuesInColumn { group_name columnname } {
	set col_values {}
	set eval_str "SELECT \"$columnname\"  FROM GradesTable WHERE GroupName=\"$group_name\""
	set err [catch {
		db eval $eval_str v {
			if { [info exist v($columnname)] } {	
				lappend col_values $v($columnname)
			} 
		}
	} errStat ]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" msg_level_critical
	} 
	return $col_values
}

proc UpdateColumnHighestGrade { columnname } {
	# find maximum in the column with a given name among active students
	set val "N/A"
	set col_values [GetGroupValuesInColumn student $columnname]
	set col_values [LeaveOnlyNumbersInList $col_values]
	if { 0 != [llength $col_values] } {
		set val [expr max([join $col_values ,])]
	}
	CheckAndCreateAsNeededInfoRow _The_Highest_Grade_

	set column_category [SelectColValue4User $columnname _Col_Category_]

	UpdateColValue4UserNameNonWeb $columnname _The_Highest_Grade_ $val
}

proc UpdateColumnLowestGrade { columnname } {
	# find minimum in the column with a given name among active students
	set val "N/A"
	set col_values [GetGroupValuesInColumn student $columnname]
	set col_values [LeaveOnlyNumbersInList $col_values]
	if { 0 != [llength $col_values] } {
		set val [expr min([join $col_values ,])]
	}
	CheckAndCreateAsNeededInfoRow _The_Lowest_Grade_

	set column_category [SelectColValue4User $columnname _Col_Category_]

	UpdateColValue4UserNameNonWeb $columnname _The_Lowest_Grade_ $val
}

proc UpdateColumnMeanGrade { columnname } {
	# find minimum in the column with a given name among active students
	set val "N/A"
	set col_values [GetGroupValuesInColumn student $columnname]
	set col_values [LeaveOnlyNumbersInList $col_values]
	if { 0 != [llength $col_values] } {
		set val [::math::statistics::mean $col_values ]
		# rounding value to 2 digits
		set val [format "%04.2f" $val ]
	}
	CheckAndCreateAsNeededInfoRow _The_Mean_Grade_

	set column_category [SelectColValue4User $columnname _Col_Category_]

	UpdateColValue4UserNameNonWeb $columnname _The_Mean_Grade_ $val
}

proc UpdateColumnMedianGrade { columnname } {
	# find minimum in the column with a given name among active students
	set val "N/A"
	set col_values [GetGroupValuesInColumn student $columnname]
	set col_values [LeaveOnlyNumbersInList $col_values]
	if { 0 != [llength $col_values] } {
		set val [::math::statistics::median $col_values ]
		# rounding value to 2 digits
		set val [format "%04.2f" $val ]
	}
	CheckAndCreateAsNeededInfoRow _The_Median_Grade_

	set column_category [SelectColValue4User $columnname _Col_Category_]

	UpdateColValue4UserNameNonWeb $columnname _The_Median_Grade_ $val
}

proc UpdateColumnStDevGrade { columnname } {
	# find minimum in the column with a given name among active students
	set val "N/A"
	set col_values [GetGroupValuesInColumn student $columnname]
	set col_values [LeaveOnlyNumbersInList $col_values]
	if { 0 != [llength $col_values] } {
		set val [::math::statistics::stdev $col_values ]
		if { $val ne "" } {
			# rounding value to 2 digits
			set val [format "%04.2f" $val ]
		} else {
			set val "N/A"
		}
	}
	CheckAndCreateAsNeededInfoRow _The_StDev_Grade_

	set column_category [SelectColValue4User $columnname _Col_Category_]

	UpdateColValue4UserNameNonWeb $columnname _The_StDev_Grade_ $val
}


proc UpdateGradesTableStatistic { permission_list  user } {
	set grades_categories [get_grades_category]
	
	# remove unset and deleted categories from stats calculation
	set grades_categories [lsearch -all -inline -not -exact $grades_categories unset]
	set grades_categories [lsearch -all -inline -not -exact $grades_categories deleted]

	set all_column_names [getColListFromTable GradesTable]

	set columns_to_update {}
	# select columns only with grades
	foreach columnname $all_column_names {
		set column_category [SelectColValue4User $columnname _Col_Category_]
		if { $column_category in $grades_categories } {
			lappend columns_to_update $columnname
		}
	}
	# add column with totals for each grades category
	foreach category $grades_categories {
		lappend columns_to_update ${category}Total
	}
	lappend columns_to_update "Grand Total"
	
	# update all of this columns
	begin_db_transaction
	foreach columnname $columns_to_update {
		set update_parent_flag false
		UpdateColumnStatistic $columnname $update_parent_flag
	}
	end_db_transaction
}

proc UpdateColumnStatistic { columnname {update_parent_flag true} } {
	set all_column_names [getColListFromTable GradesTable]
	if { $columnname ni $all_column_names } {
		return
	}
	begin_db_transaction
	UpdateColumnHighestGrade $columnname
	UpdateColumnLowestGrade  $columnname
	UpdateColumnMeanGrade    $columnname
	UpdateColumnMedianGrade  $columnname
	UpdateColumnStDevGrade   $columnname
	end_db_transaction

	# check recursion exit conditions
	if { !$update_parent_flag } return
	if { $columnname eq "Grand Total" } return
	
	set column_category [SelectColValue4User $columnname _Col_Category_]
	# FIXME this miss propagation of update of non weighted column which does not require category total! for example it is typical for participation
	if { $column_category ne "weighted_column" } {
		set root_category_column ${column_category}Total
	} else {
		set root_category_column "Grand Total"
	}
	UpdateColumnStatistic $root_category_column
}

proc UpdateGrades { permission_list user } {
	global script_name
	set subaction [::ncgi::value subaction {}]
	set columnname [::ncgi::value columnname {}]
	set nv [::ncgi::nvlist]
	array set colval  $nv
	if { $subaction eq "Submit" } {
		begin_db_transaction
		set eval_str "SELECT UserName  FROM GradesTable"
		set err [catch {
				db eval $eval_str v {
					if { [info exist colval($v(UserName))] } {	
						UpdateColValue4UserNameNonWeb $columnname $v(UserName) $colval($v(UserName))
					}
				}
			} errStat ]
		end_db_transaction
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" msg_level_critical
		} else {
			calculteWeightedTotals
			set update_parent true
			UpdateColumnStatistic $columnname $update_parent
		}
	}
}

proc ChangeGrades { permission_list user } {
	global script_name
	set columnname [::ncgi::value columnname {}]
	if { $columnname != "" } {
		# output only selected columns
		set column_list {}
		lappend column_list FirstName LastName UserName
		lappend column_list \"$columnname\"
		set sql_column_list [join $column_list ","]
		puts {<div class="changegrades">}
		puts {If student have excuse for the grade to be excluded, use keyword <b>excuse</b> in conjunction with a reason.}
		puts {<br>}
		puts {For example : "medical excuse".}
		puts {<div class="gradestable">}
		puts "<form name=\"input\" action=\"$script_name\" method=\"post\" >"
		# output only selected columns
		set eval_str "SELECT $sql_column_list  FROM GradesTable WHERE UserName<>'_Col_Category_' AND UserName<>'_Max_Points_' AND GroupName='student' ORDER BY LastName"
		set show_header 1
		set err [catch {
				db eval $eval_str v {
					if { $show_header } {
						set show_header 0
						puts  {<table class="gradestable" border="1">}
						puts  "<tr>"
						foreach col  $v(*) {
							puts -nonewline "<th>$col</th>"
						}
						puts  "<tr>"
					} else {
						puts  "<tr>"
					}
					foreach index $v(*) {
						if { $index != "*" } {
							if { $index eq $columnname } {
								#column with grade
								puts "<th><input type=\"text\" name=\"$v(UserName)\" value=\"$v($columnname)\" size=5></th>"
							} else {
								puts -nonewline "<td>$v($index)</td>"
							}
						}
					}
					puts "</tr>"
				}
			} errStat ]
		puts  "</table>"
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" msg_level_critical
		} 
		puts {<input type="hidden" name="action" value="updategrades"/>}
		puts [concat <input type="hidden" name="columnname" value="$columnname"/>]
		puts {<input type="submit" name="subaction" value="Submit" />}
		puts {<input type="submit" name="subaction" value="Cancel" />}
		puts {</form>}
		puts {</div>}
		puts {</div>}
		#puts "<a href=\"$script_name\">Cancel changes</a>"
		
	} else {
		htmlErrorMsg  "empty column names are not permitted"
	}
}

proc removeElementFromList { element2remove old_list } {
	set new_list {}
	foreach element $old_list {
		if { $element2remove ne $element } {
			lappend new_list $element
		}
	}
	return $new_list
}

proc RenameColumnNonWeb { oldcolumnname newcolumnname } {
	if { $newcolumnname eq $oldcolumnname } {
		# no need to mess with renaming
		return
	}
	if { $newcolumnname == "" } {
		htmlErrorMsg  "empty column names are not permitted"
		return
	}
	set eval_str [concat SELECT * FROM GradesTable ]
	set err [catch {db eval $eval_str v {} } errStat]
	set old_column_list $v(*)
	# check if column with the suggested new name is already exist
	foreach cname $old_column_list {
		if { $cname eq $newcolumnname } {
			htmlErrorMsg  "The column name <b>$newcolumnname</b> is already exist"
			return
		}
	}
	# sqlite does not allow rename columns
	# I will first create new column identical to the old one
	set maxpointpossible 0
	set column_category _dummy_
	AddColumnNonWeb  $newcolumnname $column_category $maxpointpossible 
	set sql_str [concat UPDATE  GradesTable SET \"$newcolumnname\"=\"$oldcolumnname\"]
	set err [catch {db eval $sql_str } errStat]
	# then delete the old one
	DeleteColumnNonWeb $oldcolumnname
}


proc DeleteColumnNonWeb { columnname } {
	DeleteColumnFromTable GradesTable $columnname
}

proc DeleteColumn { permission_list user } {
	global script_name
	set columnname [::ncgi::value columnname {}]
	# I decide against actual deletion
	# DeleteColumnNonWeb $columnname

	# Instead I will rename column and put it to the special category
	set tstamp [clock format [clock seconds] -format "%Y-%m-%d %H:%M:%S"]
	set deleted_columnname [concat _deleted_ $tstamp $columnname]
	RenameColumnNonWeb $columnname $deleted_columnname

	# set column category to deleted one
	set old_column_category  [SelectColValue4User $deleted_columnname _Col_Category_]
	set category_deleted  deleted
	UpdateColValue4UserNameNonWeb $deleted_columnname _Col_Category_ $category_deleted
	UpdateColValue4UserNameNonWeb $deleted_columnname _Visible_To_Students_ false

	calculteWeightedTotals
}

proc AddColumnNonWeb { columnname2add column_category maxpointpossible {sql_type {text}} } {
	if { $columnname2add != "" } {

		set eval_str [concat ALTER TABLE GradesTable ADD \"$columnname2add\" $sql_type]
		set err [catch {db eval $eval_str } errStat]
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" msg_level_critical
		} 

		UpdateColValue4UserNameNonWeb $columnname2add _Col_Category_ $column_category
		UpdateColValue4UserNameNonWeb $columnname2add _Max_Points_   $maxpointpossible
	} else {
		htmlErrorMsg  "empty column names are not permitted"
	}
}

proc AddColumn { permission_list user } { 
	global script_name
	set columnname2add [::ncgi::value columnname2add {}]
	set column_category [::ncgi::value column_category {}]
	set maxpointpossible [::ncgi::value maxpointpossible {}]
	set columnname2add [ColName2SqlSafeForm $columnname2add]
	AddColumnNonWeb  $columnname2add $column_category $maxpointpossible 

	if { $column_category ne "weighted_column" } {
		calculteWeightedTotals
	}
}

proc AddColumnRequest { permission_list user } { 
	global script_name
	#global grades_category
	set grades_category [ get_grades_category ]
	puts {<div class="add_new_column">}
	puts "<form name=\"input\"  method=\"post\" >"
	puts {Column Name: <input type="text" name="columnname2add"><br>}
	puts {Category: <select name="column_category">}
	foreach {name} $grades_category {
		set txt [grade_Category2html_name $name]
		set out_str {}
		append out_str {<option value="} $name {">} $txt {</option>}
		puts $out_str
	}	
	puts {</select> <br>}
	puts {Max Point Possible:<input type="text" name="maxpointpossible"><br>}
	puts {<input type="hidden" name="action" value="addcolumn"/>}
	puts {<input type="submit" value="Submit" />}
	puts {</form>}
	puts {</div>}

}

proc ShowControls { permission_list user } {
	array set permission $permission_list
	global script_name
	#global grades_category
	set grades_category [ get_grades_category ]
	dbg "outputting contol list" msg_level_info
	puts "<div class=\"controls\">"
	set action_list [ list  \
			defaultview "Refresh"\
			addcolumnrequest "Add Column"\
			editcourseinfo "Edit Course Info"\
			editnewuserinfo "Add new user"\
			choosenewpassword "Choose new password"\
			edit_grades_categories "Edit Grades Categories and Weights"\
			update_grades_stats "Update Statistics"\
			logoff "Logoff"\
		]
	set separator { }
	foreach {act act_label} $action_list {
		if { [isActionGranted $act $permission_list $user] } {
			puts -nonewline "$separator<span class=\"controls\"><a href=\"$script_name?action=$act\">$act_label</a></span>"
		} 
	}
	puts "<br>"
	# unhide user hidden columns actions
	set currently_hidden_columns [SelectColValue4User UserHiddenColums $user]
	if { $currently_hidden_columns ne "" } {
		puts {Unhide columns: }
		foreach col $currently_hidden_columns {
			puts "<span class=\"controls\"><a href=\"$script_name?action=userunhidecolumn&columnname=[::ncgi::encode $col]\">$col</a></span>"
		}
	}
	# hide user groups 
	set user_groups_for_hide [list inforow student ta instructor dropped]
	set currently_hidden_groups [SelectColValue4User UserHiddenGroups $user]
	# remove already hidden group from offering
	foreach grp $currently_hidden_groups {
		set user_groups_for_hide [removeElementFromList $grp $user_groups_for_hide]
	}
	# output group to hide offering
	if { [isActionGranted userhidegroup $permission_list $user] } {
		if { $user_groups_for_hide ne "" } {
			puts "<br>"
			puts "HideGroup: "
			foreach grp $user_groups_for_hide {
				puts "<span class=\"controls\"><a href=\"$script_name?action=userhidegroup&groupname=[::ncgi::encode $grp]\">$grp</a></span>"
			}
		}
	}
	if { [isActionGranted userunhidegroup $permission_list $user] } {
		if { $currently_hidden_groups ne "" } {
			puts "<br>"
			puts {Unhide groups: }
			foreach grp $currently_hidden_groups {
				puts "<span class=\"controls\"><a href=\"$script_name?action=userunhidegroup&groupname=[::ncgi::encode $grp]\">$grp</a></span>"
			}
		}
	}

	# hide user  grades category
	set grades_category_for_hide $grades_category
	set currently_hidden_grades_category [SelectColValue4User UserHiddenGradeCategories $user]
	# remove already hidden category from offering
	foreach grd_category $currently_hidden_grades_category {
		set grades_category_for_hide [removeElementFromList $grd_category $grades_category_for_hide]
	}
	# output grades category  to hide offering
	if { [isActionGranted userhidegroup $permission_list $user] } {
		if { $grades_category_for_hide ne "" } {
			puts "<br>"
			puts "Hide grades in category: "
			foreach ctgry $grades_category_for_hide {
				puts "<span class=\"controls\"><a href=\"$script_name?action=userhidegradecategory&grades_category=[::ncgi::encode $ctgry]\">$ctgry</a></span>"
			}
		}
	}
	if { [isActionGranted userunhidegroup $permission_list $user] } {
		if { $currently_hidden_grades_category ne "" } {
			puts "<br>"
			puts {Unhide grades in category: }
			foreach ctgry $currently_hidden_grades_category {
				puts "<span class=\"controls\"><a href=\"$script_name?action=userunhidegradecategory&grades_category=[::ncgi::encode $ctgry]\">$ctgry</a></span>"
			}
		}
	}
	
	puts "</div>"	
}

proc Create_Passwords_Table {} {
	dbg  "Creating PasswordsTable" msg_level_info
	set err [catch {pdb eval {CREATE TABLE PasswordsTable(UserName text, PasswordHash text)} } errStat] 
	if { $err } {
		dbg  "While creating PasswordsTable the following error happen: $errStat" msg_level_critical
	} 
}

proc is_User_Registered_in_Passwords_DB { user_requested } {
	# note the use of : instead of $ (this sqlite feature)
	set eval_str {SELECT UserName FROM PasswordsTable WHERE UserName=:user_requested}
	set err [catch {
		pdb eval $eval_str registered_user_names_array {}
	} errStat ]
	if { $err } {
		if { $errStat eq "no such table: PasswordsTable" } {
			Create_Passwords_Table 
		} else {
			htmlErrorMsg  "Problem accessing passwords database, please, contact system administrator"
			dbg  "$errStat" msg_level_warning
		}
	} 
	if { ![ info exist registered_user_names_array(UserName) ] } {
		dbg "$user_requested does not exist in the passwords DB" msg_level_info
		return false
	} 
	return true
}

proc Authenticate_User { user_requested password } {
	# return the username of authentificated user or a guest like username
	global GradebookServerConfig
	set err [catch {
		sqlite3 pdb $GradebookServerConfig(passwords_db_file)
	} errStat ]
	if { $err } {
		htmlErrorMsg  "Problem accessing passwords database, please, contact system administrator"
		dbg  "$errStat with filename $GradebookServerConfig(passwords_db_file)" msg_level_critical
		return __non_existing_user__
	} 

	dbg "access rights check for user: $user_requested" msg_level_info
	set PasswordHash [::md5::md5 -hex $password]

	if { ![ is_User_Registered_in_Passwords_DB $user_requested ] } {
		pdb close
		return __non_existing_user__
	}

	set eval_str [list SELECT UserName FROM PasswordsTable WHERE UserName=:user_requested AND PasswordHash=:PasswordHash]
	set err [catch {
		pdb eval $eval_str valid_user_name_array {}
	} errStat ]
	if { $err } {
		htmlErrorMsg  "Problem accessing passwords database, please, contact system administrator"
		dbg  "$errStat" msg_level_critical
	} 

	if { [ info exist valid_user_name_array(UserName) ] } {
		dbg "Credentials match for $user_requested in the passwords DB" msg_level_info
		set user  $valid_user_name_array(UserName);
	} else {
		dbg "Credentials for $user_requested  do not match stored in password DB" msg_level_info
		set user __wrong_password_user__
	}
	
	pdb close
	return $user
}

proc AddMissingDefaultRights { permission_list group } {
}

proc AccessGroupRights {db  user } {
	dbg "access rights check for user: $user" msg_level_info
	set eval_str [list SELECT GroupName FROM GradesTable WHERE UserName='$user']
	db eval $eval_str group_name_array {}
	if { [ info exist group_name_array(GroupName) ] } {
		set group $group_name_array(GroupName);
	} else {
		set group guest
	}
	dbg "Detected group is $group" msg_level_info
	set eval_str [list SELECT actionname,$group FROM AccessRightsTable ]
	set permission_list [list GroupName $group]
	db eval $eval_str permissions { lappend permission_list $permissions(actionname) $permissions($group) }
	dbg "permissions for user $user belonging to the group $group are: $permission_list" msg_level_info

	set default_permission_list [getDefaultPermissionsForGroup $group]
	set permission_list [FillMissingPermissionsWithDefaults $permission_list $default_permission_list]
	return $permission_list
}


proc htmlGradesTable {db permission_list  user} {
	array set permission $permission_list
	global sortCol
	switch $permission(GroupName) {
		guest      { }
		student         { htmlDBout db $permission_list $user $sortCol}
		dropped         { htmlDBout db $permission_list $user $sortCol}
		ta         { htmlDBout db $permission_list $user $sortCol}
		instructor { htmlDBout db $permission_list $user $sortCol}
		default    { }
	}
}

proc htmlDefaultView { permission_list user } {
	ChoseAction showcontrols $permission_list $user
	ChoseAction showgrades $permission_list $user
}

proc htmlHeader {} {
	set CourseTitle     [SelectItemFromCourseInfoTable course_title]
	set CourseYear      [SelectItemFromCourseInfoTable course_year]
	set CourseSemester  [SelectItemFromCourseInfoTable course_semester]
	set page_title "Course grades for $CourseTitle, $CourseYear - $CourseSemester"

puts {<!doctype html>
<html lang="en-US">
<head>}
puts [join [list { } {<title>} $page_title {</title>}] ""]
puts {\
 <meta http-equiv="Content-Type" content= "text/html; charset=us-ascii">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <link rel="stylesheet" type="text/css" href="/~evmik/GradeBook.css">
</head>
}
}

proc htmlHeaderDBSelector {} {
puts {<!doctype html>
<html lang="en-US">
<head>
	<meta http-equiv="Content-Type" content= "text/html; charset=us-ascii" />
	<title>Grade Books Selector</title>
	<link rel="stylesheet" type="text/css" href="/~evmik/GradeBook.css" />
</head>
}
}

##################### end of procs ####################################

# vim: ts=2 sw=2 foldmethod=indent: