Nodemailer wrapper

mailer.js

var fs = require('fs'),
    path = require('path'),
    nodemailer = require('nodemailer'),
    template = require('template'),
    cache = {},
    config = require('../config');

function MailerError(msg) {
  this.msg = msg;
}
MailerError.prototype.toString = function() {
  return this.msg;
};

// Configure the mailer
if (!config.email || !config.email.mailer) {
  throw new MailerError('Missing mailer configuration');
} else {
  nodemailer.SMTP = config.email.mailer;
}

// Loads template from the template directory specified in config
// 
// Filenames are expected to reside in the specified directory, and to have a
// ``.email`` extension. Relative paths are also supported. For exampple, to
// load an email template that is in ``notifications`` subdirectory, you can 
// call loadTemplate like so:
//
//     loadTemplate('notifications/reset', function(err, data) {
//         // Do something with the template here
//     });
//
// The extension can be changed using the configuration option in the config
// module.
//
// @param name, name of the tempate, including any path prefixes
// @param next, callback to be executed after loaded (expects err, data)
// @api private
function loadTemplate(name, next) {
  var extension = config.email.extension || '.email',
      filename = path.join(config.email.templates, name + extension);
  if (cache[filename]) {
    next(null, cache[filename]);
  } else {
    fs.readFile(filename, function(err, data) {
      if (!err) {
        cache[filename] = template.create(data.toString());
        next(null, cache[filename]);
      } else {
        next(err, null);
      }
    });
  }
}

// Send out email using node mailer
//`
// Send out templated email using node mailer. The supplied data will be 
// interpolated into the specified template automatically.
//
// HTML template is not required. If the HTML template is not found, it will 
// not be used. HTML templates are expected to have a '.html.email' extension,
// and be called the same as plain-text body template.
//
// Other than standard node mailer options, you can specify a few additional
// options: ``options.template``, and ``options.data``. You don't need to 
// specify separate templates for plain-text and HTML templates. It is 
// assumed that the HTML template is called the same as plain-text one, but 
// with '.html.email' extension instead of just '.email'. Data is a JavaScript
// object that is passed to the template prior to rendering.
//
// Some of the node mailer options will be overriden by sendEmail function. 
// Notably, subject will be prefixed by ``config.email.subjectPrefix`` string
// if one is set, and sender will be overridden by ``config.email.sender`` 
// option. If sender option is not specified, ``config.email.mailer.user`` 
// will be used instead. Reply-to field will be discarded, and body, and html 
// fields will be set using the specified templates.
//
// @parm options, email options (same as those for node mailer)
// @param next, callback to be executed once the email is sent
exports.sendEmail = function(options, next) {
  var realOptions = {};
  
  realOptions.data = options.data || {};
  realOptions.template = options.template;

  if (!realOptions.template) {
    throw new MailerError('Cannot send email without template');
  }

  realOptions.subject = config.email.subjectPrefix + ' ' + options.subject;
  realOptions.sender = config.email.sender || config.email.mailer.user;
  realOptions.bcc = options.bcc;

  // Load plain-text template
  loadTemplate(realOptions.template, function(err, tmpl) {
    if (err) {
      throw new MailerError('Could not load template ' + realOptions.template);
    } else {
      realOptions.body = tmpl(realOptions.data);
      // Load HTML template
      loadTemplate(realOptions.template + '.html', function(err1, tmpl1) {
        if (!err1) {
          realOptions.html = tmpl1(realOptions.data);
        }
        // Send email
        nodemailer.send_mail(realOptions, next);
      });
    }
  });
};