"use strict";

var async = require('async');
var winston = require('winston');
var nconf = require('nconf');
var templates = require('templates.js');
var nodemailer = require('nodemailer');
var sendmailTransport = require('nodemailer-sendmail-transport');
var smtpTransport = require('nodemailer-smtp-transport');
var htmlToText = require('html-to-text');
var url = require('url');

var User = require('./user');
var Plugins = require('./plugins');
var meta = require('./meta');
var translator = require('../public/src/modules/translator');

var transports = {
	sendmail: nodemailer.createTransport(sendmailTransport()),
	gmail: undefined
};

var app;
var fallbackTransport;

(function(Emailer) {
	Emailer.registerApp = function(expressApp) {
		app = expressApp;

		// Enable Gmail transport if enabled in ACP
		if (parseInt(meta.config['email:GmailTransport:enabled'], 10) === 1) {
			fallbackTransport = transports.gmail = nodemailer.createTransport(smtpTransport({
				host: 'smtp.gmail.com',
				port: 465,
				secure: true,
				auth: {
					user: meta.config['email:GmailTransport:user'],
					pass: meta.config['email:GmailTransport:pass']
				}
			}));
		} else {
			fallbackTransport = transports.sendmail;
		}

		return Emailer;
	};

	Emailer.send = function(template, uid, params, callback) {
		callback = callback || function() {};
		if (!app) {
			winston.warn('[emailer] App not ready!');
			return callback();
		}

		async.waterfall([
			function(next) {
				async.parallel({
					email: async.apply(User.getUserField, uid, 'email'),
					settings: async.apply(User.getSettings, uid)
				}, next);
			},
			function(results, next) {
				if (!results.email) {
					winston.warn('uid : ' + uid + ' has no email, not sending.');
					return next();
				}
				params.uid = uid;
				Emailer.sendToEmail(template, results.email, results.settings.userLang, params, next);
			}
		], callback);
	};

	Emailer.sendToEmail = function(template, email, language, params, callback) {
		callback = callback || function() {};

		var lang = language || meta.config.defaultLang || 'en_GB';

		async.waterfall([
			function (next) {
				async.parallel({
					html: function(next) {
						renderAndTranslate('emails/' + template, params, lang, next);
					},
					subject: function(next) {
						translator.translate(params.subject, lang, function(translated) {
							next(null, translated);
						});
					}
				}, next);
			},
			function (results, next) {
				var data = {
					to: email,
					from: meta.config['email:from'] || 'no-reply@' + getHostname(),
					from_name: meta.config['email:from_name'] || 'NodeBB',
					subject: results.subject,
					html: results.html,
					plaintext: htmlToText.fromString(results.html, {
						ignoreImage: true
					}),
					template: template,
					uid: params.uid,
					pid: params.pid,
					fromUid: params.fromUid
				};
				Plugins.fireHook('filter:email.modify', data, next);
			},
			function (data, next) {
				if (Plugins.hasListeners('filter:email.send')) {
					Plugins.fireHook('filter:email.send', data, next);
				} else {
					Emailer.sendViaFallback(data, next);
				}
			}
		], function (err) {
			callback(err);
		});
	};

	Emailer.sendViaFallback = function(data, callback) {
		// Some minor alterations to the data to conform to nodemailer standard
		data.text = data.plaintext;
		delete data.plaintext;

		// NodeMailer uses a combined "from"
		data.from = data.from_name + '<' + data.from + '>';
		delete data.from_name;

		winston.verbose('[emailer] Sending email to uid ' + data.uid);
		fallbackTransport.sendMail(data, callback);
	};

	function render(tpl, params, next) {
		if (meta.config['email:custom:' + tpl.replace('emails/', '')]) {
			var text = templates.parse(meta.config['email:custom:' + tpl.replace('emails/', '')], params);
			next(null, text);
		} else {
			app.render(tpl, params, next);
		}
	}

	function renderAndTranslate(tpl, params, lang, callback) {
		render(tpl, params, function(err, html) {
			translator.translate(html, lang, function(translated) {
				callback(err, translated);
			});
		});
	}

	function getHostname() {
		var configUrl = nconf.get('url');
		var parsed = url.parse(configUrl);

		return parsed.hostname;
	}

}(module.exports));