feat(custom-routes): create an option to define AMP pages

Add routeAliases support

docs/api/options.md

@@ -9,6 +9,7 @@ General options of amp module
 |  tags   | `{}`    | Object of tag options  | Define new tags or modify current tags, for instance if you want to use `amp-mustache` version 0.1, tags value must be `{ 'amp-mustache': { version: '0.1' } }` |
 | origin  | `` | Any String | Main domain of website. Using this AMP modules tries to add missing canonical link for pages. |
 | mode    | `hybrid` | `only\|hybrid\|false` | Default behaviour of amp module. (`only` all pages serve in AMP mode by default, `hybrid` pages serves in both normal and AMP mode, `false` pages does not serve AMP by default ) |
+| routeAliases    | `auto` | `auto\|Array` | Allows to limit route aliases to only AMP pages. With `auto` the module will create aliases for every route. If your app uses AMP only on a few routes you can provide those routes into an Array. Routes are absolute, without '/amp' prefix, eg. `['/story', '/page2']`  |
 
 
 ## Page Options

lib/module.js

@@ -18,6 +18,7 @@ module.exports = function (moduleOptions) {
     origin: '',
     mode: 'hybrid',
     tags: {},
+    routeAliases: 'auto',
     ...this.options.amp,
     ...moduleOptions
   }
@@ -31,10 +32,10 @@ module.exports = function (moduleOptions) {
     registerValidator.call(this, options)
   }
 
-  processRoutes.call(this)
+  processRoutes.call(this, options)
 }
 
-function processRoutes () {
+function processRoutes (options) {
   this.extendRoutes((routes) => {
     for (const route of routes) {
       route.meta = route.meta || {}
@@ -45,7 +46,7 @@ function processRoutes () {
 
       if (route.path === '/amp' || route.path.indexOf('/amp/') === 0) {
         route.meta.amp = true
-      } else {
+      } else if (!Array.isArray(options.routeAliases) || options.routeAliases.includes(route.path)) {
         route.alias.push('/amp' + route.path)
       }
     }