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path: root/packages/meshbay-android/app/src/main/assets/bridge/meshbay-bridge.js
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/**
 * The bridge, and the whole of it — the Android counterpart of
 * meshbay-client/src/preload.js, with the same shape wherever it offers
 * something at all.
 *
 * Injected at document start into documents of the packaged origin, before any
 * page script. It takes the native port the listener injected, hides the
 * global, and exposes `window.meshbay` frozen. There is no context isolation
 * on Android: page script runs in the same world, so what this buys is that
 * nothing can reach the raw port by name, not that this file is out of reach.
 * The confinement that matters is native — the listener answers the packaged
 * origin's top-level document only, and checks every argument.
 *
 * What the desktop offers and this build does not is ABSENT, not a function
 * that refuses: `platform.js` decides what to show from whether an object
 * exists (`platform.node.available`, `platform.folder.available`, …).
 *
 * `HUB_BASE` is prepended by the shell when it injects this file: the
 * interface asks for it while its modules load, before anything can await.
 */
(function () {
  'use strict';
  const port = window.meshbayNative;
  try { delete window.meshbayNative; } catch (e) { /* already gone */ }
  // A same-origin child frame gets the port too; it gets no bridge, and native
  // refuses whatever it sends anyway.
  if (!port || window.top !== window) return;

  const pending = new Map();
  let seq = 0;
  port.onmessage = (event) => {
    let reply;
    try { reply = JSON.parse(event.data); } catch (e) { return; }
    const waiter = pending.get(reply.id);
    if (!waiter) return;
    pending.delete(reply.id);
    if (reply.ok) waiter.resolve(reply.value);
    else waiter.reject(new Error(reply.error));
  };
  const call = (channel, ...args) => new Promise((resolve, reject) => {
    const id = ++seq;
    pending.set(id, { resolve, reject });
    port.postMessage(JSON.stringify({ id, ch: channel, args }));
  });

  const meshbay = {
    hubBase: () => HUB_BASE,
    setHubBase: (base) => call('hub:set', base),

    capabilities: {
      nodeAdmin: false,      // no node runs on a phone (§11.3)
      localFolders: false,
      nativeSave: false,     // phase 2
      lanCast: false,        // phase 3
      tray: false,
    },

    setLocale: (code) => call('ui:locale', code),

    // The page's origin is refused by the hub's absent CORS, and is not a
    // credential anyway: native goes, to the signed-in hub only.
    fetch: (url, init) => call('hub:fetch', url, init),

    resolveStun: (urls) => call('ice:resolve-stun', urls),
  };

  const freeze = (o) => {
    Object.freeze(o);
    for (const v of Object.values(o)) if (v && typeof v === 'object' && !Object.isFrozen(v)) freeze(v);
    return o;
  };
  Object.defineProperty(window, 'meshbay', {
    value: freeze(meshbay), writable: false, configurable: false, enumerable: false,
  });

  // The WebView exposes File System Access and cannot back it with anything a
  // person can see. Left in place, `downloads.SUPPORTED` reads true and a
  // download could take a path that fails — or reach the blob floor silently.
  for (const name of ['showDirectoryPicker', 'showSaveFilePicker', 'showOpenFilePicker']) {
    try {
      Object.defineProperty(window, name, { value: undefined, writable: false, configurable: false });
    } catch (e) { /* not definable: leave it, native save comes first anyway */ }
  }
})();