//Set up environmental variables, pulled from ~/.env file used as process.env.DB_HOST
const os = require('os') //Used to get path of home directory
const result = require('dotenv').config({ path:(os.homedir()+'/.env') })

const ports = {
	express: 3000,
	socketIo: 3001
}

//Allow user of @ in in require calls. Config in package.json
// Point module-alias at the repo root explicitly. The bare /register entry
// locates package.json by walking up from its own directory, which lands
// inside .pnpm/ under pnpm's symlinked store and fails to find it.
require('module-alias')(require('path').join(__dirname, '..'))

//Auth helper, used for decoding users web token
let Auth = require('@helpers/Auth')

//Note model, used to authorise socket room joins
let Note = require('@models/Note')

//Helmet adds additional security to express server
const helmet = require('helmet')

//Setup express server
const express = require('express')
const app = express()
app.use( helmet() )
// allow for the parsing of url encoded forms
app.use(express.urlencoded({ extended: true }));


//
// Request Rate Limiter 
//
const rateLimit = require('express-rate-limit')
//Limiter for the entire app
const limiter = rateLimit({
	windowMs: 10 * 60 * 1000, // 10 minutes
	max: 1000 // limit each IP to 1000 requests per windowMs
})
 
// apply to all requests
app.use(limiter);


var http = require('http').createServer(app);
var io = require('socket.io')(http, {
	path:'/socket'
});

//Set socket IO as a global in the app
global.SocketIo = io

let noteDiffs = {}

//
// Room names are namespaced. Previously note rooms were keyed on the bare
// note_raw_text.id and user rooms on the bare user.id, sharing one flat
// keyspace -- so user 7 and note_raw_text 7 were the same room.
//
const userRoom = userId => `user:${userId}`
const noteRoom = rawTextId => `note:${rawTextId}`

io.on('connection', function(socket){

	//When a user connects, add them to their own room
	// This allows the server to emit events to that specific user
	// access socket.io in the controller with SocketIo global
	socket.on('user_connect', token => {
		Auth.decodeToken(token)
		.then(userData => {
			socket.join(userRoom(userData.userId))

			//Track active logged in user accounts
			const usersInRoom = io.sockets.adapter.rooms[userRoom(userData.userId)]
			io.to(userRoom(userData.userId)).emit('update_active_user_count', usersInRoom.length)

		}).catch(error => {
			//Don't add user to room if they are not logged in
			// console.log(error)
		})
	})

	socket.on('get_active_user_count', token => {
		Auth.decodeToken(token)
		.then(userData => {
			socket.join(userRoom(userData.userId))

			//Track active logged in user accounts
			const usersInRoom = io.sockets.adapter.rooms[userRoom(userData.userId)]
			io.to(userRoom(userData.userId)).emit('update_active_user_count', usersInRoom.length)

		}).catch(error => {
			// console.log(error)
		})
	})

	//Renew Session tokens when users request a new one
	socket.on('renew_session_token', token => {

		//Decode the token they currently have
		Auth.decodeToken(token)
		.then(userData => {

			if(userData.active == 1){
				//Create a new one using credentials and session keys from current
				Auth.createToken(userData.userId, userData.masterKey, userData.sessionId, userData.created)
				.then(newToken => {

					//Emit new token only to user on socket
					socket.emit('recievend_new_token', newToken)
				})
			} else {
				//Attempting to reactivate disabled session, kills it all
				Auth.terminateSession(userData.sessionId)
			}
		})
	})

	//
	// The client asks for a NOTE, not a room. The server authorises the request
	// against the session and derives the room itself, so a client can no longer
	// name an arbitrary room and be handed its buffered diffs.
	//
	socket.on('join_room', ({ noteId, token } = {}) => {

		Auth.decodeToken(token)
		.then(userData => {

			return Note.getRawTextIdForUser(noteId, userData.userId)
			.then(rawTextId => {

				// No claim on this note -> no room, no diffs
				if(rawTextId == null){ return }

				const room = noteRoom(rawTextId)

				// Remember what this socket is allowed into, so leave_room and
				// note_diff never have to trust a client-supplied room again
				socket.authorizedRooms = socket.authorizedRooms || {}
				socket.authorizedRooms[noteId] = { room, rawTextId }

				socket.join(room)

				//If there are past diffs for this note, send them to the user
				if(noteDiffs[rawTextId] != undefined){

					//Sort all note diffs by when they were created.
					noteDiffs[rawTextId].sort((a,b) => { return a.time - b.time })

					//Emit all sorted diffs to user
					socket.emit('past_diffs', noteDiffs[rawTextId])
				}

				const usersInRoom = io.sockets.adapter.rooms[room]
				if(usersInRoom){
					//Update users in room count
					io.to(room).emit('update_user_count', usersInRoom.length)
				}
			})
		})
		.catch(() => {
			//Not logged in, or no access. Join nothing.
		})
	})

	socket.on('leave_room', ({ noteId } = {}) => {

		// Only rooms this socket was actually authorised into
		const entry = socket.authorizedRooms && socket.authorizedRooms[noteId]
		if(!entry){ return }

		socket.leave(entry.room)
		delete socket.authorizedRooms[noteId]

		const usersInRoom = io.sockets.adapter.rooms[entry.room]
		if(usersInRoom){
			io.to(entry.room).emit('update_user_count', usersInRoom.length)
		}
	})

	socket.on('note_diff', (data = {}) => {

		// Room comes from what this socket was authorised into, never from the
		// payload
		const entry = socket.authorizedRooms && socket.authorizedRooms[data.noteId]
		if(!entry){ return }

		const room = entry.room
		const rawTextId = entry.rawTextId

		//Log each diff for note
		if(noteDiffs[rawTextId] == undefined){ noteDiffs[rawTextId] = [] }

		// Carry the raw-text id through. This used to `delete data.id`, stripping
		// the only identifier before storing and broadcasting -- so a client with
		// several notes open on one socket could not tell which note a patch
		// belonged to, and applied every one to whichever editor it found first.
		const payload = Object.assign({}, data, { rawTextId, time: +new Date })
		delete payload.noteId

		noteDiffs[rawTextId].push(payload)

		// Everyone in the note room except the sender
		socket.to(room).emit('incoming_diff', payload)
	})

	socket.on('truncate_diffs_at_save', (checkpoint = {}) => {

		const entry = socket.authorizedRooms && socket.authorizedRooms[checkpoint.noteId]
		if(!entry){ return }
		checkpoint.rawTextId = entry.rawTextId

		// NOTE: the comparison below is `diffSet[i].hash == checkpoint`, comparing
		// a hash string against the whole checkpoint object, so it never matches
		// and sliceTo stays 0 -- meaning the entire diff set is discarded at every
		// save. That happens to be the fail-safe outcome (the saved text becomes
		// the new baseline), and the correct slice direction for a real fix is
		// ambiguous, so it is deliberately left alone rather than guessed at.
		let diffSet = noteDiffs[checkpoint.rawTextId]
		if(diffSet && diffSet.length > 0){

			//Make sure all diffs are sorted before cleaning
			noteDiffs[checkpoint.rawTextId].sort((a,b) => { return a.time - b.time })

			// Remove all diffs until it reaches the current hash
			let sliceTo = 0
			for (var i = 0; i < diffSet.length; i++) {
				if(diffSet[i].hash == checkpoint){
					sliceTo = i
					break
				}
			}

			noteDiffs[checkpoint.rawTextId] = diffSet.slice(0, sliceTo)

			if(noteDiffs[checkpoint.rawTextId].length == 0){
				delete noteDiffs[checkpoint.rawTextId]
			} 
			//Debugging
			else {
				console.log('Diffset after save')
				console.log(noteDiffs[checkpoint.rawTextId])
			}

		}
	})

	socket.on('disconnect', function(socket){
		// console.log('user disconnected');
	});
});


http.listen(ports.socketIo, function(){
	console.log(`Socke.io: Listening on port ${ports.socketIo}`)
});

//Enable json body parsing in requests. Allows me to post data in ajax calls
app.use(express.json({limit: '5mb'}))

//App Auth, all requests will come in with a token, decode the token and set global var
app.use(function(req, res, next){

	//Always null out master key, never allow it set from outside
	req.headers.userId = null
	req.headers.masterKey = null
	req.headers.sessionId = null

	//auth token set by axios in headers
	let token = req.headers.authorizationtoken
	if(token !== undefined && token.length > 0){
		Auth.decodeToken(token, req)
		.then(userData => {

			//Update headers for the rest of the application
			req.headers.userId = userData.userId
			req.headers.masterKey = userData.masterKey
			req.headers.sessionId = userData.sessionId

			//Tell front end remaining uses on current token
			res.set('remainingUses', userData.remainingUses)

			next()
		})
		.catch(error => {

			next('Unauthorized')
		})
	} else {
		next() //No token. Move along.
	}
})


// Test Area
// const printResults = true
// let UserTest = require('@models/User')
// let NoteTest = require('@models/Note')
// let AuthTest = require('@helpers/Auth')
// Auth.test()
// UserTest.keyPairTest('genMan30', '1', printResults)
// .then( ({testUserId, masterKey}) => 
// 	NoteTest.test(testUserId, masterKey, printResults))
// .then( message => { 
// 	if(printResults) console.log(message) 
// 	Auth.testTwoFactor()
// })
// .catch((error) => {
// 	console.log(error)
// })

//Test 
app.get('/api', (req, res) => res.send('Solidscribe /API is up and running'))

//Serve up uploaded files
app.use('/api/static', express.static( __dirname+'/../staticFiles' ))

//Public routes
var public = require('@routes/publicController')
app.use('/api/public', public)

//user endpoint
var user = require('@routes/userController')
app.use('/api/user', user)

//notes endpoint
var notes = require('@routes/noteController')
app.use('/api/note', notes)

//tags endpoint
var tags = require('@routes/tagController')
app.use('/api/tag', tags)

//notes endpoint
var attachment = require('@routes/attachmentController')
app.use('/api/attachment', attachment)

//quick notes endpoint
var quickNote = require('@routes/quicknoteController')
app.use('/api/quick-note', quickNote)

//cycle tracking endpoint
var metricTracking = require('@routes/metrictrackingController')
app.use('/api/metric-tracking', metricTracking)

//Output running status
app.listen(ports.express, () => { 
	console.log(`Express: Listening on port ${ports.express}!`)
})

//
//Error handlers
//
//Default error handler just say unauthorized for everything
app.use(function (err, req, res, next) {
	if (err) {
		res.status(401).send('Unauthorized')
		return
	}
	next()
})