add magnet link support to transmission web

web/assets/css/transmission-app.scss

@@ -785,6 +785,7 @@ $popup-top: 61px; // TODO: ugly that this is hardcoded
 
   .blocklist-size-label,
   .blocklist-update-button,
+  .register-handler-button,
   .port-status {
     grid-column: 2 / 3;
   }

web/src/open-dialog.js

@@ -8,13 +8,13 @@ import { Formatter } from './formatter.js';
 import { createDialogContainer, makeUUID } from './utils.js';
 
 export class OpenDialog extends EventTarget {
-  constructor(controller, remote) {
+  constructor(controller, remote, url = '') {
     super();
 
     this.controller = controller;
     this.remote = remote;
 
-    this.elements = this._create();
+    this.elements = this._create(url);
     this.elements.dismiss.addEventListener('click', () => this._onDismiss());
     this.elements.confirm.addEventListener('click', () => this._onConfirm());
     this._updateFreeSpaceInAddDialog();
@@ -43,8 +43,10 @@ export class OpenDialog extends EventTarget {
   _updateFreeSpaceInAddDialog() {
     const path = this.elements.folder_input.value;
     this.remote.getFreeSpace(path, (dir, bytes) => {
-      const string = bytes > 0 ? `${Formatter.size(bytes)} Free` : '';
-      this.elements.freespace.textContent = string;
+      if (!this.closed) {
+        const string = bytes > 0 ? `${Formatter.size(bytes)} Free` : '';
+        this.elements.freespace.textContent = string;
+      }
     });
   }
 
@@ -114,7 +116,7 @@ export class OpenDialog extends EventTarget {
     this._onDismiss();
   }
 
-  _create() {
+  _create(url) {
     const elements = createDialogContainer();
     const { confirm, root, heading, workarea } = elements;
 
@@ -145,6 +147,7 @@ export class OpenDialog extends EventTarget {
     input = document.createElement('input');
     input.type = 'url';
     input.id = input_id;
+    input.value = url;
     workarea.append(input);
     elements.url_input = input;
     input.addEventListener('keyup', ({ key }) => {

web/src/prefs-dialog.js

@@ -196,6 +196,53 @@ export class PrefsDialog extends EventTarget {
     callback();
   }
 
+  static _getProtocolHandlerRegistered() {
+    return localStorage.getItem('protocol-handler-registered') === 'true';
+  }
+
+  static _updateProtocolHandlerButton(button) {
+    button.removeAttribute('disabled');
+    button.removeAttribute('title');
+
+    if (PrefsDialog._getProtocolHandlerRegistered()) {
+      button.textContent = 'Remove Browser Handler';
+      if (!('unregisterProtocolHandler' in navigator)) {
+        button.setAttribute(
+          'title',
+          'Your browser does not support removing protocol handlers. This button only allows you to re-register a handler.'
+        );
+      }
+    } else {
+      button.textContent = 'Add Browser Handler';
+      button.removeAttribute('title');
+      if (!('registerProtocolHandler' in navigator)) {
+        button.setAttribute('disabled', true);
+        button.setAttribute(
+          'title',
+          'Your browser does not support protocol handlers'
+        );
+      }
+    }
+  }
+
+  static _toggleProtocolHandler(button) {
+    const handlerUrl = new URL(window.location.href);
+    handlerUrl.search = 'addtorrent=%s';
+    if (this._getProtocolHandlerRegistered()) {
+      navigator.unregisterProtocolHandler?.('magnet', handlerUrl.toString());
+      localStorage.removeItem('protocol-handler-registered');
+      PrefsDialog._updateProtocolHandlerButton(button);
+    } else {
+      navigator.registerProtocolHandler(
+        'magnet',
+        handlerUrl.toString(),
+        'Transmission Web'
+      );
+      localStorage.setItem('protocol-handler-registered', 'true');
+      PrefsDialog._updateProtocolHandlerButton(button);
+    }
+  }
+
   static _createTorrentsPage() {
     const root = document.createElement('div');
     root.classList.add('prefs-torrents-page');
@@ -302,13 +349,25 @@ export class PrefsDialog extends EventTarget {
     PrefsDialog._enableIfChecked(input, cal.check);
     const stop_idle_input = input;
 
+    label = document.createElement('div');
+    label.textContent = 'Magnet Protocol Handler';
+    label.classList.add('section-label');
+    root.append(label);
+
+    const button = document.createElement('button');
+    button.classList.add('register-handler-button');
+    PrefsDialog._updateProtocolHandlerButton(button);
+    root.append(button);
+    const register_handler_button = button;
+
     return {
       autostart_check,
       download_dir,
       download_queue_check,
       download_queue_input,
       incomplete_dir_check,
       incomplete_dir_input,
+      register_handler_button,
       root,
       stop_idle_check,
       stop_idle_input,
@@ -723,6 +782,12 @@ export class PrefsDialog extends EventTarget {
         this._setBlocklistButtonEnabled(false);
       }
     );
+    this.elements.torrents.register_handler_button.addEventListener(
+      'click',
+      (event_) => {
+        PrefsDialog._toggleProtocolHandler(event_.currentTarget);
+      }
+    );
     this.outside = new OutsideClickListener(this.elements.root);
     this.outside.addEventListener('click', () => this.close());
 

web/src/transmission.js

@@ -260,9 +260,24 @@ export class Transmission extends EventTarget {
     }
   }
 
+  _openTorrentFromUrl() {
+    setTimeout(() => {
+      const addTorrent = new URLSearchParams(window.location.search).get(
+        'addtorrent'
+      );
+      if (addTorrent) {
+        this.setCurrentPopup(new OpenDialog(this, this.remote, addTorrent));
+        const newUrl = new URL(window.location);
+        newUrl.search = '';
+        window.history.pushState('', '', newUrl.toString());
+      }
+    }, 0);
+  }
+
   loadDaemonPrefs() {
     this.remote.loadDaemonPrefs((data) => {
       this.session_properties = data.arguments;
+      this._openTorrentFromUrl();
     });
   }