Windows: register protocol handler for magnet links

main/index.js

@@ -1,10 +1,12 @@
 var electron = require('electron')
+
+var app = electron.app
+
 var ipc = require('./ipc')
 var menu = require('./menu')
 var shortcuts = require('./shortcuts')
 var windows = require('./windows')
-
-var app = electron.app
+var registerProtocolHandler = require('./register-protocol-handler')
 
 app.on('open-file', onOpen)
 app.on('open-url', onOpen)
@@ -16,6 +18,7 @@ app.on('ready', function () {
   menu.init()
   windows.createMainWindow()
   shortcuts.init()
+  registerProtocolHandler()
 })
 
 app.on('before-quit', function () {

main/register-protocol-handler.js

@@ -0,0 +1,26 @@
+module.exports = function () {
+  if (process.platform === 'win32') {
+    registerProtocolHandler('magnet', 'URL:BitTorrent Magnet URL', 'WebTorrent.exe')
+  }
+}
+
+function registerProtocolHandler (protocol, name, command) {
+  var Registry = require('winreg')
+
+  var protocolKey = new Registry({
+    hive: Registry.HKCR, // HKEY_CLASSES_ROOT
+    key: '\\' + protocol
+  })
+  protocolKey.set('', Registry.REG_SZ, name, callback)
+  protocolKey.set('URL Protocol', Registry.REG_SZ, '', callback)
+
+  var commandKey = new Registry({
+    hive: Registry.HKCR,
+    key: '\\' + protocol + '\\shell\\open\\command'
+  })
+  commandKey.set('', Registry.REG_SZ, '"' + command + '" "%1"', callback)
+
+  function callback (err) {
+    if (err) console.error(err.message || err)
+  }
+}

package.json

@@ -25,7 +25,8 @@
     "prettier-bytes": "^1.0.1",
     "upload-element": "^1.0.1",
     "virtual-dom": "^2.1.1",
-    "webtorrent": "^0.86.0"
+    "webtorrent": "^0.86.0",
+    "winreg": "^1.0.1"
   },
   "devDependencies": {
     "electron-packager": "^5.0.0",