Windows: register protocol handler for magnet links

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)
+  }
+}