Fix fetch module definition for Fastboot

Define fetch module with a setupFastboot method export to set host and
protocol for every instance.

Rename public/fastboot-fetch.js to public/fetch-fastboot.js to avoid
lower version ember-fetch overwrite this file.

Overrides treeForPublic in index.js to only include public asset if top
level addon to avoid any future rename.

README.md

@@ -49,6 +49,7 @@ export default DS.RESTAdapter.extend(AdapterFetch, {
 ```
 
 ### Use with Fastboot
+#### ajax-service
 Currently, Fastboot supplies its own server-side ajax functionality, and including `ember-fetch` and the `adapter-fetch` mixin in a Fastboot app will not work without some modifications. To allow the `node-fetch` polyfill that is included with this addon to make your API calls, you must add an initializer to the consuming app's `fastboot` directory that overrides the one Fastboot utilizes to inject its own ajax.
 
 Example:
@@ -65,6 +66,17 @@ export default {
 }
 ```
 
+#### relative url
+`ember-fetch` uses `node-fetch` in Fastboot, which [doesn't allow relative URL](https://github.com/bitinn/node-fetch/tree/v2.3.0#fetchurl-options).
+
+> `url` should be an absolute url, such as `https://example.com/`.
+> A path-relative URL (`/file/under/root`) or protocol-relative URL (`//can-be-http-or-https.com/`)
+> will result in a rejected promise.
+
+However, `ember-fetch` grabs the `protocol` and `host` info from fastboot request after the `instance-initializes`.
+This allows you to make a relative URL request unless the app is not initialized, e.g. `initializers` and `app.js`.
+
+#### top-level addon
 For addon authors, if the addon supports Fastboot mode, `ember-fetch` should also be listed as a [peer dependency](https://docs.npmjs.com/files/package.json#peerdependencies).
 This is because Fastboot only invokes top-level addon's `updateFastBootManifest` ([detail](https://github.com/ember-fastboot/ember-cli-fastboot/issues/597)), thus `ember-fetch` has to be a top-level addon installed by the host app.
 

fastboot/instance-initializers/setup-fetch.js

@@ -1,16 +1,16 @@
-import setupFetch from 'fetch/setup';
+import { setupFastboot } from 'fetch';
 
 /**
  * To allow relative URLs for Fastboot mode, we need the per request information
- * from the fastboot service. Then we re-define the `fetch` amd module.
+ * from the fastboot service. Then we set the protocol and host to fetch module.
  */
 function patchFetchForRelativeURLs(instance) {
   const fastboot = instance.lookup('service:fastboot');
   const request = fastboot.get('request');
   // Prember is not sending protocol
   const protocol = request.protocol === 'undefined:' ? 'http:' : request.protocol;
   // host is cp
-  setupFetch(protocol, request.get('host'))();
+  setupFastboot(protocol, request.get('host'));
 }
 
 export default {

index.js

@@ -97,7 +97,7 @@ module.exports = {
    * in a FastBoot build or not. Based on that, we return a tree that contains
    * the correct version of the polyfill at the `vendor/ember-fetch.js` path.
    */
-  treeForVendor: function() {
+  treeForVendor() {
     let babelAddon = this.addons.find(addon => addon.name === 'ember-cli-babel');
 
     let browserTree = this.treeForBrowserFetch();
@@ -121,9 +121,22 @@ module.exports = {
     }`), 'wrapped');
   },
 
-  //add node version of fetch.js into fastboot package.json manifest vendorFiles array
-  updateFastBootManifest: function(manifest) {
-    manifest.vendorFiles.push('ember-fetch/fastboot-fetch.js');
+  // Only include public/fetch-fastboot.js if top level addon
+  treeForPublic() {
+    return !this.parent.parent ? this._super.treeForPublic.apply(this, arguments) : null;
+  },
+
+  cacheKeyForTree(treeType) {
+    if (treeType === 'public') {
+      return require('calculate-cache-key-for-tree')('public', this, [!this.parent.parent]);
+    } else {
+      return this._super.cacheKeyForTree.call(this, treeType);
+    }
+  },
+
+  // Add node version of fetch.js into fastboot package.json manifest vendorFiles array
+  updateFastBootManifest(manifest) {
+    manifest.vendorFiles.push('ember-fetch/fetch-fastboot.js');
     return manifest;
   },
 

package.json

@@ -29,6 +29,7 @@
     "broccoli-rollup": "^2.1.1",
     "broccoli-stew": "^2.0.0",
     "broccoli-templater": "^2.0.1",
+    "calculate-cache-key-for-tree": "^1.1.0",
     "ember-cli-babel": "^6.8.2",
     "node-fetch": "^2.3.0",
     "whatwg-fetch": "^3.0.0"

public/fetch-fastboot.js

@@ -0,0 +1,75 @@
+/* globals define FastBoot */
+define('fetch', ['exports'], function(exports) {
+  var httpRegex = /^https?:\/\//;
+  var protocolRelativeRegex = /^\/\//;
+
+  var AbortControllerPolyfill = FastBoot.require(
+    'abortcontroller-polyfill/dist/cjs-ponyfill'
+  );
+  var nodeFetch = FastBoot.require('node-fetch');
+
+  /**
+   * Build the absolute url if it's not, can handle:
+   * - protocol-relative URL (//can-be-http-or-https.com/)
+   * - path-relative URL (/file/under/root)
+   *
+   * @param {string} url
+   * @param {string} protocol
+   * @param {string} host
+   * @returns {string}
+   */
+  function buildAbsoluteUrl(url, protocol, host) {
+    if (protocolRelativeRegex.test(url)) {
+      url = host + url;
+    } else if (!httpRegex.test(url)) {
+      if (!host) {
+        throw new Error(
+          'You are using using fetch with a path-relative URL, but host is missing from Fastboot request. Please set the hostWhitelist property in your environment.js.'
+        );
+      }
+      url = protocol + '//' + host + url;
+    }
+    return url;
+  }
+
+  var FastbootHost, FastbootProtocol;
+
+  /**
+   * Isomorphic `fetch` API for both browser and fastboot
+   *
+   * node-fetch doesn't allow relative URLs, we patch it with Fastboot runtime info.
+   * Before instance-initializers Absolute URL is still not allowed, in this case
+   * node-fetch will throw error.
+   * `FastbootProtocol` and `FastbootHost` are re-set for every instance during its
+   * initializers through calling `setupFastboot`.
+   *
+   * @param {String|Object} input
+   * @param {Object} [options]
+   */
+  exports.default = function fetch(input, options) {
+    if (typeof input === 'object') {
+      input.url = buildAbsoluteUrl(input.url, FastbootProtocol, FastbootHost);
+    } else {
+      input = buildAbsoluteUrl(input, FastbootProtocol, FastbootHost);
+    }
+    return nodeFetch(input, options);
+  };
+  /**
+   * Assign the local protocol and host being used for building absolute URLs
+   * @private
+   */
+  exports.setupFastboot = function setupFastboot(protocol, host) {
+    FastbootProtocol = protocol;
+    FastbootHost = host;
+  }
+  exports.Request = nodeFetch.Request;
+  exports.Headers = nodeFetch.Headers;
+  exports.Response = nodeFetch.Response;
+  exports.AbortController = AbortControllerPolyfill.AbortController;
+});
+
+define('fetch/ajax', ['exports'], function() {
+  throw new Error(
+    'You included `fetch/ajax` but it was renamed to `ember-fetch/ajax`'
+  );
+});

test/fastboot-build-test.js

@@ -28,7 +28,7 @@ describe('it builds with ember-cli-fastboot', function() {
   it('builds into dist/ember-fetch/fetch-fastboot.js', function() {
     return app.runEmberCommand('build').then(function() {
       expect(app.filePath('dist/index.html')).to.be.a.file();
-      expect(app.filePath('dist/ember-fetch/fastboot-fetch.js')).to.be.a.file();
+      expect(app.filePath('dist/ember-fetch/fetch-fastboot.js')).to.be.a.file();
       expect(app.filePath('dist/assets/dummy-fastboot.js')).to.be.a.file();
     });
   });