overleaf/services/real-time/app/coffee/WebsocketController.coffee

logger = require "logger-sharelatex"
metrics = require "metrics-sharelatex"
WebApiManager = require "./WebApiManager"
AuthorizationManager = require "./AuthorizationManager"
DocumentUpdaterManager = require "./DocumentUpdaterManager"
ConnectedUsersManager = require "./ConnectedUsersManager"
WebsocketLoadBalancer = require "./WebsocketLoadBalancer"
Utils = require "./Utils"

module.exports = WebsocketController =
	# If the protocol version changes when the client reconnects,
	# it will force a full refresh of the page. Useful for non-backwards
	# compatible protocol changes. Use only in extreme need.
	PROTOCOL_VERSION: 2
	
	joinProject: (client, user, project_id, callback = (error, project, privilegeLevel, protocolVersion) ->) ->
		user_id = user?._id
		logger.log {user_id, project_id, client_id: client.id}, "user joining project"
		metrics.inc "editor.join-project"
		WebApiManager.joinProject project_id, user, (error, project, privilegeLevel) ->
			return callback(error) if error?

			if !privilegeLevel or privilegeLevel == ""
				err = new Error("not authorized")
				logger.error {err, project_id, user_id, client_id: client.id}, "user is not authorized to join project"
				return callback(err)
				
			client.join project_id

			client.set("privilege_level", privilegeLevel)
			client.set("user_id", user_id)
			client.set("project_id", project_id)
			client.set("owner_id", project?.owner?._id)
			client.set("first_name", user?.first_name)
			client.set("last_name", user?.last_name)
			client.set("email", user?.email)
			client.set("connected_time", new Date())
			client.set("signup_date", user?.signUpDate)
			client.set("login_count", user?.loginCount)
			
			callback null, project, privilegeLevel, WebsocketController.PROTOCOL_VERSION
			logger.log {user_id, project_id, client_id: client.id}, "user joined project"
			
			# No need to block for setting the user as connected in the cursor tracking
			ConnectedUsersManager.updateUserPosition project_id, client.id, user, null, () ->
		
	# We want to flush a project if there are no more (local) connected clients
	# but we need to wait for the triggering client to disconnect. How long we wait
	# is determined by FLUSH_IF_EMPTY_DELAY.
	FLUSH_IF_EMPTY_DELAY: 500 #ms		
	leaveProject: (io, client, callback = (error) ->) ->
		metrics.inc "editor.leave-project"
		Utils.getClientAttributes client, ["project_id", "user_id"], (error, {project_id, user_id}) ->
			return callback(error) if error?

			logger.log {project_id, user_id, client_id: client.id}, "client leaving project"
			WebsocketLoadBalancer.emitToRoom project_id, "clientTracking.clientDisconnected", client.id
			
			# bail out if the client had not managed to authenticate or join
			# the project.  Prevents downstream errors in docupdater from
			# flushProjectToMongoAndDelete with null project_id.
			if not user_id?
				logger.log {client_id: client.id}, "client leaving, unknown user"
				return callback()
			if not project_id?
				logger.log {user_id: user_id, client_id: client.id}, "client leaving, not in project"
				return callback()
		
			# We can do this in the background
			ConnectedUsersManager.markUserAsDisconnected project_id, client.id, (err) ->
				if err?
					logger.error {err, project_id, user_id, client_id: client.id}, "error marking client as disconnected"
					
			setTimeout () ->
				remainingClients = io.sockets.clients(project_id)
				if remainingClients.length == 0
					# Flush project in the background
					DocumentUpdaterManager.flushProjectToMongoAndDelete project_id, (err) ->
						if err?
							logger.error {err, project_id, user_id, client_id: client.id}, "error flushing to doc updater after leaving project"
				callback()
			, WebsocketController.FLUSH_IF_EMPTY_DELAY
			
	joinDoc: (client, doc_id, fromVersion = -1, options, callback = (error, doclines, version, ops, ranges) ->) ->
		metrics.inc "editor.join-doc"
		Utils.getClientAttributes client, ["project_id", "user_id"], (error, {project_id, user_id}) ->
			return callback(error) if error?
			return callback(new Error("no project_id found on client")) if !project_id?
			logger.log {user_id, project_id, doc_id, fromVersion, client_id: client.id}, "client joining doc"
					
			AuthorizationManager.assertClientCanViewProject client, (error) ->
				return callback(error) if error?
				DocumentUpdaterManager.getDocument project_id, doc_id, fromVersion, (error, lines, version, ranges, ops) ->
					return callback(error) if error?

					# Encode any binary bits of data so it can go via WebSockets
					# See http://ecmanaut.blogspot.co.uk/2006/07/encoding-decoding-utf8-in-javascript.html
					encodeForWebsockets = (text) -> unescape(encodeURIComponent(text))
					escapedLines = []
					for line in lines
						try
							line = encodeForWebsockets(line)
						catch err
							logger.err {err, project_id, doc_id, fromVersion, line, client_id: client.id}, "error encoding line uri component"
							return callback(err)
						escapedLines.push line
					if options.encodeRanges
						try
							for comment in ranges?.comments or []
								comment.op.c = encodeForWebsockets(comment.op.c) if comment.op.c?
							for change in ranges?.changes or []
								change.op.i = encodeForWebsockets(change.op.i) if change.op.i?
								change.op.d = encodeForWebsockets(change.op.d) if change.op.d?
						catch err
							logger.err {err, project_id, doc_id, fromVersion, ranges, client_id: client.id}, "error encoding range uri component"
							return callback(err)

					AuthorizationManager.addAccessToDoc client, doc_id
					client.join(doc_id)
					callback null, escapedLines, version, ops, ranges
					logger.log {user_id, project_id, doc_id, fromVersion, client_id: client.id}, "client joined doc"
					
	leaveDoc: (client, doc_id, callback = (error) ->) ->
		metrics.inc "editor.leave-doc"
		Utils.getClientAttributes client, ["project_id", "user_id"], (error, {project_id, user_id}) ->
			logger.log {user_id, project_id, doc_id, client_id: client.id}, "client leaving doc"
			client.leave doc_id
			# we could remove permission when user leaves a doc, but because
			# the connection is per-project, we continue to allow access
			# after the initial joinDoc since we know they are already authorised.
			## AuthorizationManager.removeAccessToDoc client, doc_id
			callback()
	updateClientPosition: (client, cursorData, callback = (error) ->) ->
		metrics.inc "editor.update-client-position", 0.1
		Utils.getClientAttributes client, [
			"project_id", "first_name", "last_name", "email", "user_id"
		], (error, {project_id, first_name, last_name, email, user_id}) ->
			return callback(error) if error?
			logger.log {user_id, project_id, client_id: client.id, cursorData: cursorData}, "updating client position"

			AuthorizationManager.assertClientCanViewProjectAndDoc client, cursorData.doc_id, (error) ->
				if error?
					logger.warn {err: error, client_id: client.id, project_id, user_id}, "silently ignoring unauthorized updateClientPosition. Client likely hasn't called joinProject yet."
					return callback()
				cursorData.id      = client.id
				cursorData.user_id = user_id if user_id?
				cursorData.email   = email   if email?
				# Don't store anonymous users in redis to avoid influx
				if !user_id or user_id == 'anonymous-user'
					cursorData.name = ""
					callback()
				else
					cursorData.name = if first_name && last_name
						"#{first_name} #{last_name}"
					else if first_name
						first_name
					else if last_name
						last_name
					else
						""
					ConnectedUsersManager.updateUserPosition(project_id, client.id, {
						first_name: first_name,
						last_name:  last_name,
						email:      email,
						_id:        user_id
					}, {
						row:    cursorData.row,
						column: cursorData.column,
						doc_id: cursorData.doc_id
					}, callback)
				WebsocketLoadBalancer.emitToRoom(project_id, "clientTracking.clientUpdated", cursorData)

	getConnectedUsers: (client, callback = (error, users) ->) ->
		metrics.inc "editor.get-connected-users"
		Utils.getClientAttributes client, ["project_id", "user_id"], (error, {project_id, user_id}) ->
			return callback(error) if error?
			return callback(new Error("no project_id found on client")) if !project_id?
			logger.log {user_id, project_id, client_id: client.id}, "getting connected users"
			AuthorizationManager.assertClientCanViewProject client, (error) ->
				return callback(error) if error?
				ConnectedUsersManager.getConnectedUsers project_id, (error, users) ->
					return callback(error) if error?
					callback null, users
					logger.log {user_id, project_id, client_id: client.id}, "got connected users"
					

	applyOtUpdate: (client, doc_id, update, callback = (error) ->) ->
		Utils.getClientAttributes client, ["user_id", "project_id"], (error, {user_id, project_id}) ->
			return callback(error) if error?
			return callback(new Error("no project_id found on client")) if !project_id?
			WebsocketController._assertClientCanApplyUpdate client, doc_id, update, (error) ->
				if error?
					logger.warn {err: error, doc_id, client_id: client.id, version: update.v}, "client is not authorized to make update"
					setTimeout () ->
						# Disconnect, but give the client the chance to receive the error
						client.disconnect()
					, 100
					return callback(error)
				update.meta ||= {}
				update.meta.source = client.id
				update.meta.user_id = user_id
				metrics.inc "editor.doc-update", 0.3

				logger.log {user_id, doc_id, project_id, client_id: client.id, version: update.v}, "sending update to doc updater"

				DocumentUpdaterManager.queueChange project_id, doc_id, update, (error) ->
					if error?
						logger.error {err: error, project_id, doc_id, client_id: client.id, version: update.v}, "document was not available for update"
						client.disconnect()
					callback(error)

	_assertClientCanApplyUpdate: (client, doc_id, update, callback) ->
		AuthorizationManager.assertClientCanEditProjectAndDoc client, doc_id, (error) ->
			if error?
				if error.message == "not authorized" and WebsocketController._isCommentUpdate(update)
					# This might be a comment op, which we only need read-only priveleges for
					AuthorizationManager.assertClientCanViewProjectAndDoc client, doc_id, callback
				else
					return callback(error)
			else
				return callback(null)
	
	_isCommentUpdate: (update) ->
		for op in update.op
			if !op.c?
				return false
		return true