enhanced mailer

- added template system for dynamic re-registration of email templates
- permitted no-auth based smtp schemes (to support inbucket)
- added helper registration for dynamic components in the templates

services/mailer.js

@@ -4,7 +4,7 @@ const kue = require('./kue');
 const i18n = require('./i18n');
 const path = require('path');
 const fs = require('fs-extra');
-const _ = require('lodash');
+const { get, set, merge, template } = require('lodash');
 const { TEMPLATE_LOCALS } = require('../middleware/staticTemplate');
 
 const {
@@ -18,52 +18,76 @@ const {
 
 // load all the templates as strings
 const templates = {
-  data: {},
+  cache: {},
+  registered: {},
+};
+
+// Registers a template with the given filename and format.
+templates.register = async (filename, name, format) => {
+  // Check to see if this template was already registered.
+  if (get(templates.registered, [name, format], null) !== null) {
+    return;
+  }
+
+  const file = await fs.readFile(filename, 'utf8');
+  const view = template(file);
+
+  set(templates.registered, [name, format], view);
 };
 
 // load the templates per request during development
 templates.render = async (name, format = 'txt', context) => {
+  // Check to see if the template is a registered template (provided by a plugin
+  // ) and prefer that first.
+  let view = get(templates.registered, [name, format], null);
+  if (view !== null) {
+    return view(context);
+  }
+
   if (process.env.NODE_ENV === 'production') {
     // If we are in production mode, check the view cache.
-    const view = _.get(templates.data, [name, format], null);
+    const view = get(templates.cache, [name, format], null);
     if (view !== null) {
       return view(context);
     }
   }
 
+  // Template was not registered and was not cached. Let's try and find it!
   const filename = path.join(
     __dirname,
     'email',
     [name, format, 'ejs'].join('.')
   );
   const file = await fs.readFile(filename, 'utf8');
-  const view = _.template(file);
+  view = template(file);
 
   if (process.env.NODE_ENV === 'production') {
     // If we are in production mode, fill the view cache.
-    _.set(templates.data, [name, format], view);
+    set(templates.cache, [name, format], view);
   }
 
   return view(context);
 };
 
-const mailer = {};
+const mailer = { templates, helpers: {} };
 
 // enabled is true when the required configuration is available. When testing
 // is enabled, we will be simulating that emails are being sent, because in a
 // production system, emails should and would be sent.
 mailer.enabled =
-  Boolean(SMTP_HOST && SMTP_USERNAME && SMTP_PASSWORD && SMTP_FROM_ADDRESS) ||
-  process.env.NODE_ENV === 'test';
+  Boolean(SMTP_HOST && SMTP_FROM_ADDRESS) || process.env.NODE_ENV === 'test';
 
 if (mailer.enabled) {
   const options = {
     host: SMTP_HOST,
-    auth: {
+  };
+
+  if (SMTP_USERNAME && SMTP_PASSWORD) {
+    options.auth = {
       user: SMTP_USERNAME,
       pass: SMTP_PASSWORD,
-    },
-  };
+    };
+  }
 
   if (SMTP_PORT) {
     try {
@@ -85,6 +109,16 @@ mailer.task = new kue.Task({
   name: 'mailer',
 });
 
+/**
+ * registerHelpers will register the helpers on the mailer.
+ *
+ * @param {Object} helpers the helpers in object form that should be used by the
+ *                         mailer.
+ */
+mailer.registerHelpers = helpers => {
+  mailer.helpers = merge(mailer.helpers, helpers);
+};
+
 /**
  * send will create a new message and send it.
  */
@@ -99,12 +133,14 @@ mailer.send = async options => {
 
   // Create the new locals object and attach the static locals and the i18n
   // framework.
-  const locals = _.merge({}, options.locals, TEMPLATE_LOCALS, { t: i18n.t });
+  const locals = merge({}, mailer.helpers, options.locals, TEMPLATE_LOCALS, {
+    t: i18n.t,
+  });
 
   // Render the templates.
   const [html, text] = await Promise.all(
     ['html', 'txt'].map(fmt => {
-      return templates.render(options.template, fmt, locals);
+      return mailer.templates.render(options.template, fmt, locals);
     })
   );