var clientFactory = require("ssb-client");
var config = require("ssb-config");
var pull = require("pull-stream");
var Pushable = require("pull-pushable");
var many = require("pull-many");

// Change to 'true' to get debugging output
DEBUG = !false

DEFAULT_OPTS = {
	lt: Date.now(),
	gt: -Infinity
}
GRAPH_TYPE = "follow"
MAX_HOPS = 1
MAX_REPLY_RECURSIONS = 10

// only instantiate a ssb-client once, so we don't have to create a new connection every time we load a channel page
let client = null;

class ChannelController {
	constructor(opts) {
		this.opts = opts,
		this.outputStream = Pushable(),
		this.idsInChannel = {},
		this.rootMessages = {}, // used to check for replies

		this.getMessagesFrom = function(channelName, followedIds, preserve, cb) {
			var hashtagStream = createHashtagStream("#" + channelName);
			var channelStream = createChannelStream(channelName);
			var stream = many([hashtagStream, channelStream]);

			var self = this;
			pull(stream, pull.filter(function(msg) {
				return followedIds.includes(msg.value.author.toLowerCase());
			}), pull.drain(function(msg) {
				self.pushMessage(msg);
			}, function() {
				self.getReplies();
			}));

			cb(this.outputStream, preserve);
		},
		this.pushMessage = function(newMsg) {
			this.idsInChannel[newMsg.value.author] = true;
			if(newMsg.value.timestamp > opts.gt && newMsg.value.timestamp < opts.lt) {
				this.rootMessages[newMsg.key] = newMsg;
				requestBlobs(newMsg);
			}
		},
		this.getReplies = function() {
			let replyStreams = [];

			for(let userId of Object.keys(this.idsInChannel)) {
				replyStreams.push(createUserStream(userId));
			}

			let self = this;
			pull(
				many(replyStreams),
				pull.filter(function(msg) {
					let messageIsValid = msg.value && msg.value.content && msg.value.content.root;
					return messageIsValid && !(msg.key in self.rootMessages) && (msg.value.content.root in self.rootMessages);
				}),
				pull.drain(function(msg) {
					self.pushMessage(msg);
				},
				function() {
					self.sortAndPushAllMessages();
					getProfilePicturesOf(Object.keys(self.idsInChannel));
				})
			);
		},
		this.sortAndPushAllMessages = function() {
			let self = this;
			let messages = Object.keys(this.rootMessages).map(function(msgId) { return self.rootMessages[msgId]; });
			for(let msg of messages.sort((a, b) => b.value.timestamp - a.value.timestamp)) {
				this.outputStream.push(msg);
			}
			this.exit();
		},
		this.exit = function() {
			debug("ending stream")
			this.outputStream.end();
			delete this;
		}
	}
}

function requestBlobs(msg) {
	if(msg.value && msg.value.content) {
		if(msg.value.content.mentions && Symbol.iterator in Object(msg.value.content.mentions)) {
			for(let mention of msg.value.content.mentions) {
				if(mention.type && mention.link) {
					if(typeof mention.link == "string") {
						getBlob(mention.link)
					}
					else {
						debug("Message has non-string mention.link value: " + JSON.stringify(mention.link));
					}
				}
			}
		}
	}
}

function getProfilePicturesOf(relevantIds) {
	let profilePictureStreams = []
	let profilePictureFound = {};

	for(let userId of relevantIds) {
		profilePictureFound[userId] = false;
		profilePictureStreams.push(createMetadataStream(userId));
	}
	let collectedStream = many(profilePictureStreams);

	if(relevantIds.length == 0) { // avoid the edge case where checkIfDone is never called
		// exit(cb, preserve);
		return;
	}

	pull(
		collectedStream,
		pull.drain(function(msg) {
			if(!profilePictureFound[msg.value.author] && msg.value.content.image) {
				if(typeof msg.value.content.image == "string") {
					debug("Getting profile picture at " + msg.value.content.image + " for user " + msg.value.author);
					getBlob(msg.value.content.image);
					profilePictureFound[msg.value.author] = true;
				}
				else if(typeof msg.value.content.image == "object" && typeof msg.value.content.image.link == "string") {
					debug("Getting profile picture at " + msg.value.content.image.link + " for user " + msg.value.author);
					getBlob(msg.value.content.image.link);
					profilePictureFound[msg.value.author] = true;
				}
				else {
					debug("Message has unknown msg.value.content.image value: " + JSON.stringify(msg.value.content.image));
				}
			}
		})
	);
}

function getBlob(blobId) {
	debug("Ensuring existence of blob with ID " + blobId);
	client.blobs.has(blobId, function(err, has) {
		if(err) {
			debug("[ERROR] ssb.blobs.has failed on the blob with ID " + blobId);
		}
		if(!err && !has) {
			debug("Wanting blob with ID " + blobId);
			client.blobs.want(blobId, () => {});
		}
	});
}

function debug(message) {
	if(DEBUG) {
		var timestamp = new Date();
		console.log("[channels-lib] [" + timestamp.toISOString() + "] " +  message);
	}
}

function createHashtagStream(channelName) {
	var search = client.search && client.search.query;
        if(!search) {
                console.log("[FATAL] ssb-search plugin must be installed to us channels");
        }

        var query = search({
                query: channelName
        });

	return query;
}

/*
function createHashtagStream(channelTag) {
	var query = client.query.read({
		query: [{
                       	"$filter": {
                               	value: {
                                       	content: {
                                       		mentions: [
                                       			channelTag
                                       		]
                                        	}
                        		}
       	        	}
                }],
               reverse: true
	});

	return query;
}
*/

function createChannelStream(channelName) {
	var query = client.query.read({
		query: [{
                       	"$filter": {
                               	value: {
                                       	content: {
                                               	channel: channelName
                                        	}
                        		}
       	        	}
                }],
               reverse: true
	});

	return query;
}

function createUserStream(userId) {
	var query = client.createUserStream({
		id: userId
	});

	return query;
}

function createMetadataStream(userId) {
	var query = client.query.read({
		query: [{
                       	"$filter": {
                               	value: {
                               		author: userId,
                                       	content: {
                                               	type: "about"
                                        	}
                        		}
       	        	}
                }]
	});

	query.streamName = userId; // mark the stream object so we can tell which stream a message came from later

	return query;
}

function getConfig() {
	return {
		host: config.host || "localhost",
		port: config.port || 8008
	}
}

module.exports = {
	getMessages: function(ssbClient, channelName, ssbOpts, preserve, cb, hops=MAX_HOPS) {
		client = ssbClient;

		client.friends.hops({
			dunbar: Number.MAX_SAFE_INTEGER,
			max: hops
		}, function(error, friends) {
			if(error) {
				throw "Couldn't get a list of friends from scuttlebot:\n" + error;
			}

			var followedIds = Object.keys(friends).map(id => id.toLowerCase());
			let controller = new ChannelController(ssbOpts || DEFAULT_OPTS);
			controller.getMessagesFrom(channelName, followedIds, preserve, cb);
		});
	}
}