From 0ae64c37deb99ad658bb4b90d32e09d138d071de Mon Sep 17 00:00:00 2001
From: Michelle Tilley <binarymuse@github.com>
Date: Mon, 18 Sep 2017 17:33:51 -0700
Subject: [PATCH] Add UrlHandlerRegistry

---
 spec/url-handler-registry-spec.js | 38 ++++++++++++
 src/url-handler-registry.js       | 99 +++++++++++++++++++++++++++++++
 2 files changed, 137 insertions(+)
 create mode 100644 spec/url-handler-registry-spec.js
 create mode 100644 src/url-handler-registry.js

diff --git a/spec/url-handler-registry-spec.js b/spec/url-handler-registry-spec.js
new file mode 100644
index 000000000..2845927ac
--- /dev/null
+++ b/spec/url-handler-registry-spec.js
@@ -0,0 +1,38 @@
+/** @babel */
+
+import {it} from './async-spec-helpers'
+
+import UrlHandlerRegistry from '../src/url-handler-registry'
+
+describe('UrlHandlerRegistry', () => {
+  let registry = new UrlHandlerRegistry()
+
+  it('handles URLs on a per-host basis', () => {
+    const testPackageSpy = jasmine.createSpy()
+    const otherPackageSpy = jasmine.createSpy()
+    registry.registerHostHandler('test-package', testPackageSpy)
+    registry.registerHostHandler('other-package', otherPackageSpy)
+
+    registry.handleUrl("atom://yet-another-package/path")
+    expect(testPackageSpy).not.toHaveBeenCalled()
+    expect(otherPackageSpy).not.toHaveBeenCalled()
+
+    registry.handleUrl("atom://test-package/path")
+    expect(testPackageSpy).toHaveBeenCalledWith("atom://test-package/path")
+    expect(otherPackageSpy).not.toHaveBeenCalled()
+
+    registry.handleUrl("atom://other-package/path")
+    expect(otherPackageSpy).toHaveBeenCalledWith("atom://other-package/path")
+  })
+
+  it('refuses to handle bad URLs', () => {
+    [
+      'atom:package/path',
+      'atom:8080://package/path',
+      'user:pass@atom://package/path',
+      'smth://package/path'
+    ].forEach(uri => {
+      expect(() => registry.handleUrl(uri)).toThrow()
+    })
+  })
+})
diff --git a/src/url-handler-registry.js b/src/url-handler-registry.js
new file mode 100644
index 000000000..19ab768de
--- /dev/null
+++ b/src/url-handler-registry.js
@@ -0,0 +1,99 @@
+const url = require('url')
+const {Disposable} = require('event-kit')
+
+// Public: Associates listener functions with URLs from outside the application.
+//
+// The global URL handler registry maps URLs to listener functions. URLs are mapped
+// based on the hostname of the URL; the format is atom://package/command?args.
+// The "core" package name is reserved for URLs handled by Atom core (it is not possible
+// to register a package with the name "core").
+//
+// Because URL handling can be triggered from outside the application (e.g. from
+// the user's browser), package authors should take great care to ensure that malicious
+// activities cannot be performed by an attacker. A good rule to follow is that
+// **URL handlers should not take action on behalf of the user**. For example, clicking
+// a link to open a pane item that prompts the user to install a package is okay;
+// automatically installing the package right away is not.
+//
+// Packages can register their desire to handle URLs via a special key in their
+// `package.json` called "urlHandlers". The value of this key should be an object
+// that contains, at minimum, a key named "method". This is the name of the method
+// on your package object that Atom will call when it receives a URL your package
+// is responsible for handling. It will pass the full URL as the only argument, and you
+// are free to do your own URL parsing to handle it.
+//
+// If your package can defer activation until a URL it needs to handle is triggered,
+// you can additionally specify the `"defer": true` option in your "urlHandlers" object.
+// When Atom receives a request for a URL in your package's namespace, it will activate your
+// pacakge and then call `methodName` on it as before.
+//
+// If your package specifies a deprecated `urlMain` property, you cannot register URL handlers
+// via the `urlHandlers` key.
+//
+// ## Example
+//
+// Here is a message that could open a specific panel in a package's view:
+//
+// `package.json`:
+//
+// ```javascript
+// {
+//   "name": "my-package",
+//   "main": "./lib/my-package.js",
+//   "urlHandlers": {
+//     "method": "handleUrl",
+//     "deferActivation": true,
+//   }
+// }
+// ```
+//
+// `lib/my-package.json`
+//
+// ```javascript
+// module.exports = {
+//   activate: function() {
+//     // code to activate your package
+//   }
+//
+//   handleUrl(url) {
+//     // parse and handle url
+//   }
+// }
+// ```
+//
+// In this example, when Atom handles `atom://my-package/something`, it will activate your
+// package and then call `handleUrl` passing in the string `"atom://my-package/something"`
+module.exports =
+class UrlHandlerRegistry {
+  constructor () {
+    this.registrations = new Map()
+  }
+
+  registerHostHandler (host, callback) {
+    if (typeof callback !== 'function') {
+      throw new Error('Cannot register a URL host handler with a non-function callback')
+    }
+
+    if (this.registrations.has(host)) {
+      throw new Error(`There is already a URL host handler for the host ${host}`)
+    } else {
+      this.registrations.set(host, callback)
+    }
+
+    return new Disposable(() => {
+      this.registrations.delete(host)
+    })
+  }
+
+  handleUrl (uri) {
+    const {protocol, slashes, auth, port, host} = url.parse(uri)
+    if (protocol !== 'atom:' || slashes !== true || auth || port) {
+      throw new Error(`UrlHandlerRegistry#handleUrl asked to handle an invalid URL: ${uri}`)
+    }
+
+    const registration = this.registrations.get(host)
+    if (registration) {
+      registration(uri)
+    }
+  }
+}