request = require "request"
_ = require "underscore"
logger = require "logger-sharelatex"
settings = require "settings-sharelatex"
metrics = require("metrics-sharelatex")

rclient = require("redis-sharelatex").createClient(settings.redis.documentupdater)
Keys = settings.redis.documentupdater.key_schema

module.exports = DocumentUpdaterManager =
	getDocument: (project_id, doc_id, fromVersion, callback = (error, exists, doclines, version) ->) ->
		timer = new metrics.Timer("get-document")
		url = "#{settings.apis.documentupdater.url}/project/#{project_id}/doc/#{doc_id}?fromVersion=#{fromVersion}"
		logger.log {project_id, doc_id, fromVersion}, "getting doc from document updater"
		request.get url, (err, res, body) ->
			timer.done()
			if err?
				logger.error {err, url, project_id, doc_id}, "error getting doc from doc updater"
				return callback(err)
			if 200 <= res.statusCode < 300
				logger.log {project_id, doc_id}, "got doc from document document updater"
				try
					body = JSON.parse(body)
				catch error
					return callback(error)
				callback null, body?.lines, body?.version, body?.ranges, body?.ops
			else if res.statusCode in [404, 422]
				err = new Error("doc updater could not load requested ops")
				err.statusCode = res.statusCode
				logger.warn {err, project_id, doc_id, url, fromVersion}, "doc updater could not load requested ops"
				callback err
			else
				err = new Error("doc updater returned a non-success status code: #{res.statusCode}")
				err.statusCode = res.statusCode
				logger.error {err, project_id, doc_id, url}, "doc updater returned a non-success status code: #{res.statusCode}"
				callback err

	flushProjectToMongoAndDelete: (project_id, callback = ()->) ->
		# this method is called when the last connected user leaves the project
		logger.log project_id:project_id, "deleting project from document updater"
		timer = new metrics.Timer("delete.mongo.project")
		# flush the project in the background when all users have left
		url = "#{settings.apis.documentupdater.url}/project/#{project_id}?background=true" +
			(if settings.shutDownInProgress then "&shutdown=true" else "")
		request.del url, (err, res, body)->
			timer.done()
			if err?
				logger.error {err, project_id}, "error deleting project from document updater"
				return callback(err)
			else if 200 <= res.statusCode  < 300
				logger.log {project_id}, "deleted project from document updater"
				return callback(null)
			else
				err = new Error("document updater returned a failure status code: #{res.statusCode}")
				err.statusCode = res.statusCode
				logger.error {err, project_id}, "document updater returned failure status code: #{res.statusCode}"
				return callback(err)

	queueChange: (project_id, doc_id, change, callback = ()->)->
		allowedKeys = [ 'doc', 'op', 'v', 'dupIfSource', 'meta', 'lastV', 'hash']
		change = _.pick change, allowedKeys
		jsonChange = JSON.stringify change
		if jsonChange.indexOf("\u0000") != -1
			# memory corruption check
			error = new Error("null bytes found in op")
			logger.error err: error, project_id: project_id, doc_id: doc_id, jsonChange: jsonChange, error.message
			return callback(error)

		updateSize = jsonChange.length
		if updateSize > settings.maxUpdateSize
			error = new Error("update is too large")
			error.updateSize = updateSize
			return callback(error)

		# record metric for each update added to queue
		metrics.summary 'redis.pendingUpdates', updateSize, {status: 'push'}

		doc_key = "#{project_id}:#{doc_id}"
		# Push onto pendingUpdates for doc_id first, because once the doc updater
		# gets an entry on pending-updates-list, it starts processing.
		rclient.rpush Keys.pendingUpdates({doc_id}), jsonChange, (error) ->
			return callback(error) if error?
			rclient.rpush "pending-updates-list", doc_key, callback