FEATURE: add email query param to login, signup, and password-reset URLs to prefill form

app/assets/javascripts/discourse/controllers/forgot-password.js.es6

@@ -7,6 +7,12 @@ export default Ember.Controller.extend(ModalFunctionality, {
     return Ember.isEmpty((this.get('accountEmailOrUsername') || '').trim()) || this.get('disabled');
   }.property('accountEmailOrUsername', 'disabled'),
 
+  onShow: function() {
+    if ($.cookie('email')) {
+      this.set('accountEmailOrUsername', $.cookie('email'));
+    }
+  },
+
   actions: {
     submit: function() {
       var self = this;

app/assets/javascripts/discourse/views/create-account.js.es6

@@ -6,9 +6,14 @@ export default ModalBodyView.extend({
   classNames: ['create-account'],
 
   _setup: function() {
-    // allows the submission the form when pressing 'ENTER' on *any* text input field
-    // but only when the submit button is enabled
+    // Allows submitting the form when pressing 'ENTER' on *any* text input field
+    // but only when the submit button is enabled.
     const createAccountController = this.get('controller');
+
+    if ($.cookie('email')) {
+      createAccountController.set('accountEmail', $.cookie('email'));
+    }
+
     Em.run.schedule('afterRender', function() {
       $("input[type='text'], input[type='password']").keydown(function(e) {
         if (createAccountController.get('submitDisabled') === false && e.keyCode === 13) {

app/assets/javascripts/discourse/views/login.js.es6

@@ -15,8 +15,13 @@ export default ModalBodyView.extend({
 
     // Get username and password from the browser's password manager,
     // if it filled the hidden static login form:
-    loginController.set('loginName', $('#hidden-login-form input[name=username]').val());
-    loginController.set('loginPassword', $('#hidden-login-form input[name=password]').val());
+    var prefillUsername = $('#hidden-login-form input[name=username]').val();
+    if (prefillUsername) {
+      loginController.set('loginName', prefillUsername);
+      loginController.set('loginPassword', $('#hidden-login-form input[name=password]').val());
+    } else if ($.cookie('email')) {
+      loginController.set('loginName', $.cookie('email'));
+    }
 
     Em.run.schedule('afterRender', function() {
       $('#login-account-password, #login-account-name').keydown(function(e) {

app/controllers/static_controller.rb

@@ -6,8 +6,10 @@ class StaticController < ApplicationController
   skip_before_filter :check_xhr, :redirect_to_login_if_required
   skip_before_filter :verify_authenticity_token, only: [:cdn_asset, :enter, :favicon]
 
+  PAGES_WITH_EMAIL_PARAM = ['login', 'password_reset', 'signup']
+
   def show
-    return redirect_to(path '/') if current_user && params[:id] == 'login'
+    return redirect_to(path '/') if current_user && (params[:id] == 'login' || params[:id] == 'signup')
 
     map = {
       "faq" => {redirect: "faq_url", topic_id: "guidelines_topic_id"},
@@ -44,6 +46,10 @@ class StaticController < ApplicationController
       return
     end
 
+    if PAGES_WITH_EMAIL_PARAM.include?(@page) && params[:email]
+      cookies[:email] = { value: params[:email], expires: 1.day.from_now }
+    end
+
     file = "static/#{@page}.#{I18n.locale}"
     file = "static/#{@page}.en" if lookup_context.find_all("#{file}.html").empty?
     file = "static/#{@page}"    if lookup_context.find_all("#{file}.html").empty?

config/routes.rb

@@ -255,7 +255,7 @@ Discourse::Application.routes.draw do
   get "guidelines" => "static#show", id: "guidelines", as: 'guidelines'
   get "tos" => "static#show", id: "tos", as: 'tos'
   get "privacy" => "static#show", id: "privacy", as: 'privacy'
-  get "signup" => "list#latest"
+  get "signup" => "static#show", id: "signup"
   get "login-preferences" => "static#show", id: "login"
 
   get "users/admin-login" => "users#admin_login"