'use strict';

const express = require('express');
const bodyParser = require('body-parser');
const cookieParser = require('cookie-parser');
const cors = require('cors');
const config = require('config');
const async = require('async');
const logger = require('./logger');
const mail = require('./mail');
const request = require('request');
const OAuth2 = require('oauth').OAuth2;

const api = require('./api');
const cache = require('./cache');
const db = require('./db');

let utils;

const lib = {

	app: null,
	server: null,

	init: (cb) => {

		utils = require('./utils');

		let app = lib.app = express();

		lib.server = app.listen(config.get('serverPort'));

		app.use(cookieParser());

		app.use(bodyParser.json());
		app.use(bodyParser.urlencoded({ extended: true }));

		let corsOptions = Object.assign({}, config.get('cors'));

		app.use(cors(corsOptions));
		app.options('*', cors(corsOptions));

		let oauth2 = new OAuth2(
			config.get('apis.github.client'),
			config.get('apis.github.secret'),
			'https://github.com/',
			'login/oauth/authorize',
			'login/oauth/access_token',
			null
		);

		let redirect_uri = config.get('serverDomain') + '/auth/github/authorize/callback';

		app.get('/auth/github/authorize', (req, res) => {
			let params = [
				`client_id=${config.get('apis.github.client')}`,
				`redirect_uri=${config.get('serverDomain')}/auth/github/authorize/callback`,
				`scope=user:email`
			].join('&');
			res.redirect(`https://github.com/login/oauth/authorize?${params}`);
		});

		app.get('/auth/github/link', (req, res) => {
			let params = [
				`client_id=${config.get('apis.github.client')}`,
				`redirect_uri=${config.get('serverDomain')}/auth/github/authorize/callback`,
				`scope=user:email`,
				`state=${req.cookies.SID}`
			].join('&');
			res.redirect(`https://github.com/login/oauth/authorize?${params}`);
		});

		function redirectOnErr (res, err){
			return res.redirect(`${config.get('domain')}/?err=${encodeURIComponent(err)}`);
		}

		app.get('/auth/github/authorize/callback', (req, res) => {
			let code = req.query.code;
			let access_token;
			let body;
			let address;
			const state = req.query.state;

			async.waterfall([
				(next) => {
					oauth2.getOAuthAccessToken(code, {redirect_uri}, next);
				},

				(_access_token, refresh_token, results, next) => {
					access_token = _access_token;
					request.get({
						url: `https://api.github.com/user?access_token=${access_token}`,
						headers: {'User-Agent': 'request'}
					}, next);
				},

				(httpResponse, _body, next) => {
					body = _body = JSON.parse(_body);
					if (state) {
						return async.waterfall([
							(next) => {
								cache.hget('sessions', state, next);
							},

							(session, next) => {
								if (!session) return next('Invalid session.');
								db.models.user.findOne({_id: session.userId}, next);
							},

							(user, next) => {
								if (!user) return next('User not found.');
								if (user.services.github && user.services.github.id) return next('Account already has GitHub linked.');
								db.models.user.update({_id: user._id}, {$set: {"services.github": {id: body.id, access_token}}}, {runValidators: true}, (err) => {
									if (err) return next(err);
									next(null, user, body);
								});
							},

							(user) => {
								cache.pub('user.linkGitHub', user._id);
								res.redirect(`${config.get('domain')}/settings`);
							}
						], next);
					}
					db.models.user.findOne({'services.github.id': body.id}, (err, user) => {
						next(err, user, body);
					});
				},

				(user, body, next) => {
					if (user) {
						user.services.github.access_token = access_token;
						return user.save(() => {
							next(true, user._id);
						});
					}
					db.models.user.findOne({ username: new RegExp(`^${body.login}$`, 'i' )}, (err, user) => {
						next(err, user);
					});
				},

				(user, next) => {
					if (user) return next('An account with that username already exists.');
					request.get({
						url: `https://api.github.com/user/emails?access_token=${access_token}`,
						headers: {'User-Agent': 'request'}
					}, next);
				},

				(httpResponse, body2, next) => {
					body2 = JSON.parse(body2);
					if (!Array.isArray(body2)) return next(body2.message);
					body2.forEach(email => {
						if (email.primary) address = email.email.toLowerCase();
					});
					db.models.user.findOne({'email.address': address}, next);
				},

				(user, next) => {
					const verificationToken = utils.generateRandomString(64);
					if (user) return next('An account with that email address already exists.');
					db.models.user.create({
						_id: utils.generateRandomString(12),//TODO Check if exists
						username: body.login,
						email: {
							address,
							verificationToken: verificationToken
						},
						services: {
							github: {id: body.id, access_token}
						}
					}, next);
				},

				(user, next) => {
					mail.schemas.verifyEmail(address, body.login, user.email.verificationToken);
					next(null, user._id);
				}
			], (err, userId) => {
				if (err && err !== true) {
					err = utils.getError(err);
					logger.error('AUTH_GITHUB_AUTHORIZE_CALLBACK', `Failed to authorize with GitHub. "${err}"`);
					return redirectOnErr(res, err);
				}

				const sessionId = utils.guid();
				cache.hset('sessions', sessionId, cache.schemas.session(sessionId, userId), err => {
					if (err) return redirectOnErr(res, err.message);
					let date = new Date();
					date.setTime(new Date().getTime() + (2 * 365 * 24 * 60 * 60 * 1000));
					res.cookie('SID', sessionId, {
						expires: date,
						secure: config.get("cookie.secure"),
						path: "/",
						domain: config.get("cookie.domain")
					});
					logger.success('AUTH_GITHUB_AUTHORIZE_CALLBACK', `User "${userId}" successfully authorized with GitHub.`);
					res.redirect(`${config.get('domain')}/`);
				});
			});
		});

		app.get('/auth/verify_email', (req, res) => {
			let code = req.query.code;

			async.waterfall([
				(next) => {
					if (!code) return next('Invalid code.');
					next();
				},

				(next) => {
					db.models.user.findOne({"email.verificationToken": code}, next);
				},

				(user, next) => {
					if (!user) return next('User not found.');
					if (user.email.verified) return next('This email is already verified.');
					db.models.user.update({"email.verificationToken": code}, {$set: {"email.verified": true}, $unset: {"email.verificationToken": ''}}, {runValidators: true}, next);
				}
			], (err) => {
				if (err) {
					let error = 'An error occurred.';
					if (typeof err === "string") error = err;
					else if (err.message) error = err.message;
					logger.error("VERIFY_EMAIL", `Verifying email failed. "${error}"`);
					return res.json({ status: 'failure', message: error});
				}
				logger.success("VERIFY_EMAIL", `Successfully verified email.`);
				res.redirect(config.get("domain"));
			});
		});

		cb();
	}
};

module.exports = lib;