path: root/GradeBook.tcl

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

# internal version of this code
set VERSION 1.0

package require sqlite3
package require ncgi 
package require md5

::ncgi::parse

# defaults
set sortCol LastName
set user guest
set password guest
set action defaultview
# defaults end

# read cookies
set user [::ncgi::cookie user]
set sortCol [::ncgi::cookie sortCol]
set password [::ncgi::cookie password]
set action [::ncgi::value action defaultview]
# end of read cookies

# script uri
if { [catch {set script_name $env(SCRIPT_NAME)} errStat] } { set script_name unknown}
# figure out course db filename
if { [catch {set request_uri $env(REQUEST_URI)} errStat] } { set request_uri unknown}
regsub -all $script_name $request_uri "" coursedbfname 
regsub -all {\?.*$} $coursedbfname "" coursedbfname
regsub -all {^/} $coursedbfname "" coursedbfname

set script_name "$script_name/$coursedbfname"


# ########################## procs begin #################################
proc dbg {msg {level 1}} {
	if { $level <=2 } {
		set fid [open log a+]
		puts $fid $msg 
		close $fid
	}
}

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 password_hash {group_name {guest}} {id_number {}} {section_num {} } } {
	set eval_str [concat INSERT INTO GradesTable (FirstName, LastName, UserName, PasswordHash, GroupName, IdNum, SectionNum) VALUES('$first_name', '$last_name', '$user_name', '$password_hash', '$group_name', '$id_number', '$section_num')]
	set err [catch {db eval $eval_str  } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" 3
	} 
}

proc CreateGradesTable {db} {
	set err [catch {db eval {CREATE TABLE GradesTable(FirstName text, LastName text, UserName text, PasswordHash text, GroupName text, UserHiddenColums text, UserHiddenGroups text, IdNum text, SectionNum text)} } errStat] 
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" 1
	} 

	# add special users aka special info rows
	AddUserNonWeb  {} {}  _Col_Category_ {} inforow
	AddUserNonWeb  {} {}  _Max_Points_   {} inforow

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

proc AddAccessRightNonWeb { action instructor_right ta_right student_right guest_right } {
	set eval_str [concat INSERT INTO AccessRightsTable (actionname, instructor, ta, student, guest) VALUES('$action', '$instructor_right', '$ta_right', '$student_right', '$guest_right')]
	set err [catch {db eval $eval_str  } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" 3
	} 
}

proc CreateAccessRightsTable {db} {
	set err [catch {db eval {CREATE TABLE AccessRightsTable(actionname text,               instructor integer, ta integer, student integer,  guest integer)} } errStat]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" 1
	} 
	# guest should have no rights make sure that 0 is evereywhere except logon
	#                    actionname        instructor   ta   student  guest
	AddAccessRightNonWeb logon             1            1    1        1
	AddAccessRightNonWeb showgrades        1            1    1        0
	AddAccessRightNonWeb sort              1            1    0        0
	AddAccessRightNonWeb addcolumnrequest  1            1    0        0
	AddAccessRightNonWeb addcolumn         1            1    0        0
	AddAccessRightNonWeb deletecolumn      1            1    0        0
	AddAccessRightNonWeb showcontrols      1            1    1        0
	AddAccessRightNonWeb changegrades      1            1    0        0
	AddAccessRightNonWeb updategrades      1            1    0        0
	AddAccessRightNonWeb changecolumn      1            1    0        0
	AddAccessRightNonWeb updatecolumn      1            1    0        0
	AddAccessRightNonWeb logoff            1            1    1        0
	AddAccessRightNonWeb changefirstname   1            0    0        0
	AddAccessRightNonWeb changelastname    1            0    0        0
	AddAccessRightNonWeb changeusername    1            0    0        0
	AddAccessRightNonWeb userhidecolumn    1            1    1        0
	AddAccessRightNonWeb userunhidecolumn  1            1    1        0
	AddAccessRightNonWeb userhidegroup     1            0    0        0
	AddAccessRightNonWeb userunhidegroup   1            0    0        0
}

proc htmlErrorMsg { msg } {
			puts "<div class=\"errormsg\">error: $msg</div>"
}

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

proc htmlDBout {db permission_list user {sort_col {}}} {
	array set permission $permission_list
	global script_name
	set defSortCol LastName 

	if { $sort_col == {} } {
		set sort_col $defSortCol 
		dbg "empty sort col changed to $sort_col" 4
	} 
	# testing for the existense of the sorting column
	set eval_str [list SELECT * FROM GradesTable ORDER BY $sort_col]
	set err [catch {db eval $eval_str } errStat]
	if { $err } {
		dbg $errStat 3
		dbg "changing to default sorting column $defSortCol" 3
		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 UserName PasswordHash GroupName UserHiddenColums UserHiddenGroups IdNum] }
		student    { set hidden_columns [list FirstName LastName  UserName PasswordHash GroupName UserHiddenColums UserHiddenGroups  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]
	}
	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\"" }
		guest      { dbg "Guest must not be allowed to set table view port. Aborting. This line is never executed" 0; exit }
		default      { dbg "Default must not be allowed to set table view port. Aborting. This line is never executed." 0; exit }
	}
	# get all allowed columns and rows
	set eval_str [concat SELECT $sql_column_str FROM GradesTable $where_statement ORDER BY $sort_col]
	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(*) {
						# 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 hide}
						switch $col {
							FirstName { lappend action_list changefirstname "change first name" }
							LastName  { lappend action_list changelastname "change last name" }
							UserName  { lappend action_list changeusername "change user name" }
							PasswordHash  { }
							UserHiddenColums { } 
							UserHiddenGroups { } 
							IdNum { } 
							GroupName  {   }
							SectionNum {   }
							default {
								lappend action_list changegrades "change grades" deletecolumn delete  changecolumn "change column"
							}
						}
						set separator {<br>}
						foreach {act act_label} $action_list {
							if { [isActionGranted $act $permission_list $user] } {
								puts -nonewline "$separator<span class=\"controls\"><a href=\"$script_name?action=$act&columnname=[::ncgi::encode $col]\">$act_label</a></span>"
							} 
						}
						puts -nonewline "</th>"
						puts ""
					}
					puts "</tr>"
					puts  "<tr>"
				} else {
					puts  "<tr>"
				}
				foreach index $v(*) {
					if { $index != "*" } {
						# detect what column category it is
						set category [SelectColValue4User $index _Col_Category_]
						set col_value [htmlReplaceEmptyString $v($index)]
						puts -nonewline "<td class=\"$category\">$col_value</td>"
					}
				}
				puts "</tr>"
			}
		} errStat ]
	if { $err } {
		dbg "we should never be here if $sortCol exist in the table" 1
		dbg $errStat 1
		htmlErrorMsg $errStat
	}
	puts  "</table>"
	puts  {</div>}
}

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

}

proc htmlFooter {permission_list} {
	array set permission $permission_list
	global VERSION
	puts "<div class=\"footer\">"
	puts "GradeBook $VERSION code is written by Eugeniy E. Mikhailov"
	puts "</div>"
}


proc SelectColValue4User { colname user } {
	set value {}
	set eval_str "SELECT \"$colname\"  FROM GradesTable  where UserName=\"$user\""
	set err [catch {
		db eval $eval_str v {
			set value $v($colname)
		}
	} errStat ]
	if { $err } {
		htmlErrorMsg  $errStat 
		dbg  "the following error happen: $errStat" 3
	} 
	return $value
}

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 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=\"$script_name\" method=\"post\" />"
	puts "Login: <input type=\"text\" name=\"user\" value=\"$user\"><br>"
	puts {Password: <input type="password" name="password"><br>}
	puts {<input type="hidden" name="action" value="logon"/>}
	puts {<input type="submit" value="Submit" />}
	puts {</form>}
	puts "</div>"
}

proc LogMeOn {} {
	global user password
	set user [::ncgi::value user guest]
	set password [::ncgi::value password guest]
	dbg "Logging in and setting cookies" 4
	::ncgi::setCookie  -name user -value $user
	::ncgi::setCookie  -name password -value $password
}

proc LogMeOff {} {
	dbg "Logging off" 4
	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
	if { $action == "defaultview" } { 
		# this one permitted to everyone
		dbg "requested action $action for user $user is granted" 4
		return 1;
	}
	if { ![info exist permission($action) ] } {
		dbg "requested UNKNOWN action $action for user $user is not granted" 0
		htmlErrorMsg "requested UNKNOWN action $action"
		return 0;
	}

	if {$permission($action) } {
		dbg "requested action $action for user $user is granted" 4
		return 1;
	} else {
		dbg "requested action $action for user $user is not granted" 1
		return 0;
	}
}

proc ChoseAction {action permission_list user} {
	array set permission $permission_list
	dbg "requested action: $action" 1
	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 } 
			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 }
			showgrades       { htmlGradesTable db $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
	}
}

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 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_]

	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
	# opt list has option name and corresponding text pairs
	set opt_list [list \
		unset --Select--\
	       	Quiz Quiz\
	       	HomeWork HomeWork\
	       	LabReport LabReport\
	       	MidTerm MidTerm\
	       	FinalExam FinalExam\
		]
	foreach {name txt} $opt_list {
		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]

	# first we update category and maxpointpossible values of the old columnname
	UpdateColValue4UserNameNonWeb $oldcolumnname _Col_Category_ $column_category
	UpdateColValue4UserNameNonWeb $oldcolumnname _Max_Points_   $maxpointpossible

	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
	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 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" 3
					} 
}

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" 3
					} 
}

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" } {
		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 ]
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" 3
		} 
	}
}

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 $column_list ","]
		puts {<div class="changegrades">}
		puts {<div class="gradestable">}
		puts "<form name=\"input\" action=\"$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: $errStat" 3
		} 
		puts {<input type="hidden" name="action" value="updategrades"/>}
		puts [concat <input type="hidden" name="columnname" value="$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 getColListFromTable { table } {
		set eval_str [concat SELECT * FROM \'$table\' ]
		set err [catch {db eval $eval_str v {} } errStat]
		set old_column_list $v(*)
		return $old_column_list
}

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

proc colList2sqlColStr { col_list } {
	set sqlStr {}
	foreach col $col_list {
		if {$sqlStr ne ""} {
			set sqlStr $sqlStr,\"$col\"
		} else {
			set sqlStr \"$col\"
		}
	} 
	return $sqlStr
}
	

proc DeleteColumnNonWeb { columnname } {
	if { $columnname != "" } {

		# removing the column name to be deleted from total list

		set old_column_list [getColListFromTable GradesTable]
		set new_column_list [removeElementFromList $columnname $old_column_list]
		set sql_new_column_str [colList2sqlColStr $new_column_list]
		set eval_str "BEGIN TRANSACTION;
			CREATE TEMPORARY TABLE GradesTable_backup($sql_new_column_str);
			INSERT INTO GradesTable_backup SELECT $sql_new_column_str FROM GradesTable;
			DROP TABLE GradesTable;
			CREATE TABLE GradesTable($sql_new_column_str);
			INSERT INTO GradesTable SELECT $sql_new_column_str FROM GradesTable_backup;
			DROP TABLE GradesTable_backup;
			COMMIT;"
		set err [catch {db eval $eval_str  } errStat]
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" 3
		} 
	} else {
		htmlErrorMsg  "empty column names are not permitted"

	}
}

proc DeleteColumn { permission_list user } {
	global script_name
	set columnname [::ncgi::value columnname {}]
	DeleteColumnNonWeb $columnname
}

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

		set eval_str [concat ALTER TABLE GradesTable ADD \"$columnname2add\" text]
		set err [catch {db eval $eval_str } errStat]
		if { $err } {
			htmlErrorMsg  $errStat 
			dbg  "the following error happen: $errStat" 3
		} 

		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 
}

proc AddColumnRequest { permission_list user } { 
	global script_name
	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">}
	puts {<option value="unset">--Select--</option>}
	puts {<option value="Quiz">Quiz</option>}
	puts {<option value="HomeWork">HomeWork</option>}
	puts {<option value="LabReport">LabReport</option>}
	puts {<option value="MidTerm">MidTerm</option>}
	puts {<option value="FinalExam">FinalExam</option>}
	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
	dbg "outputing contol list"
	puts "<div class=\"controls\">"
	set action_list [ list  defaultview "Refresh" addcolumnrequest "Add Column" 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]
	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>"
			}
		}
	}
	
	puts "</div>"	
}

proc AccessGroupRights {db  user password } {
	dbg "access rights check for user: $user"
	set PasswordHash [::md5::md5 -hex $password]
	set eval_str [list SELECT GroupName FROM GradesTable WHERE UserName='$user' AND PasswordHash='$PasswordHash']
	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 $group"
	set eval_str [list SELECT actionname,$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"
	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}
		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 {} {
puts {
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
	<meta http-equiv="Content-Type" content= "text/html; charset=us-ascii" />
	<title>Grade Book</title>
	<link rel="stylesheet" type="text/css" href="/~evmik/GradeBook.css" />
</head>
}
}


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

set timestamp [clock format [clock seconds] -format "%Y-%m-%dT%H:%M:%S"]

#CreateGradesTable db
#CreateAccessRightsTable db
dbg [::ncgi::names] 4
# logon and logoff actions are granted to everyone
if { $action == "logon"  } { LogMeOn;   set action defaultview }   
if { $action == "logoff" } { LogMeOff;  set action defaultview } 


dbg "===== Connection at $timestamp for user $user ====="
::ncgi::header
htmlHeader
puts "<body>"
set dbfile "courses/$coursedbfname"
dbg "DB filename: $dbfile"
if { ($coursedbfname ne "") && [file exists $dbfile] } {
	sqlite3 db $dbfile
	set permission_list [AccessGroupRights db $user $password]
	htmlTop $permission_list
	ChoseAction $action $permission_list $user
} else {
	htmlErrorMsg "No requested database {$coursedbfname}. Please, check your url"
	dbg "Attemt to access non existing database: {$dbfile}"
}

htmlFooter $permission_list
puts "</body>"

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