var nodemailer = require('nodemailer');
var smtpTransport = require('nodemailer-smtp-transport');
var q = require('Q');

module.exports = function (app) {
    function MailService() {
        var self = this;

        self.send = _send;

        /**
         * @param .to {String} email list, separed by ','
         * @param .from {String}
         * @param .subject {String}
         * @param .body {String} the body of the e-mail. Accept HTML format.
         */
        function _send(params) {
            var deferred = q.defer();
            var mailSettings = app.config.settings.email;

            var transportConfig = smtpTransport({
                host: mailSettings.smtp,
                port: 587,
                secure: false,
                auth: {
                    user: mailSettings.user,
                    pass: mailSettings.password
                }
            });

            var transport = nodemailer.createTransport(transportConfig);

            // setup e-mail data with unicode symbols
            var mailOptions = {
                from: params.from,
                to: params.to,
                subject: params.subject,
                html: params.body
            };

            // send mail with defined transport object
            transport.sendMail(mailOptions, function (error, info) {
                if (error) {
                    deferred.reject(error);
                }
                else {
                    deferred.resolve(info);
                }
            });

            return deferred.promise;
        }
    }

    return new MailService();
}