/**
 * 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`, `BINARY` and `CAST` are prepended by the shell when it injects
 * this file: the interface asks for the hub while its modules load, before
 * anything can await; BINARY says whether the WebView carries ArrayBuffer
 * messages; CAST whether this device can cast at all.
 */
(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 }));
  });

  // A write is a binary message: "MBB1" | id | channel | 0 | handle | bytes,
  // big-endian — one copy, no JSON, no base64 (spike S-3: 136 MB/s awaited
  // per 48 KB chunk). Without ArrayBuffer messages, base64 over JSON.
  const SAVE_WRITE = 1;
  const CAST_PUSH = 2;
  const bytesOf = (chunk) => (chunk instanceof Uint8Array ? chunk
    : ArrayBuffer.isView(chunk) ? new Uint8Array(chunk.buffer, chunk.byteOffset, chunk.byteLength)
      : new Uint8Array(chunk));
  const base64Of = (bytes) => {
    let s = '';
    for (let i = 0; i < bytes.length; i += 0x8000) s += String.fromCharCode.apply(null, bytes.subarray(i, i + 0x8000));
    return btoa(s);
  };
  const sendBinary = (channel, handle, bytes) => new Promise((resolve, reject) => {
    const id = ++seq;
    pending.set(id, { resolve, reject });
    const frame = new ArrayBuffer(16 + bytes.length);
    const head = new DataView(frame);
    head.setUint32(0, 0x4d424231);   // "MBB1"
    head.setUint32(4, id);
    head.setUint16(8, channel);
    head.setUint32(12, handle);
    new Uint8Array(frame, 16).set(bytes);
    port.postMessage(frame);
  });
  const writeChunk = (handle, chunk) => {
    const bytes = bytesOf(chunk);
    return BINARY ? sendBinary(SAVE_WRITE, handle, bytes) : call('save:write', handle, base64Of(bytes));
  };
  const pushSegment = (chunk) => {
    const bytes = bytesOf(chunk);
    return BINARY ? sendBinary(CAST_PUSH, 0, bytes) : call('cast:push', base64Of(bytes));
  };

  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: true,
      lanCast: CAST,         // false where the vendor's play services are absent
      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),

    // The device's hub key: generated, held and used natively. The page asks
    // for a signature and never sees a key — it parses hostile input.
    device: {
      ensure: () => call('device:ensure'),
      publicKey: () => call('device:public'),
      sign: (username) => call('device:sign', username),
      forget: () => call('device:forget'),
    },

    // The bundle key and the identity on every node, held natively: the page
    // is told public keys and handed signatures and agreements. A signature is
    // asked for by kind and fields, never by bytes.
    keys: {
      available: () => call('keys:available'),
      deriveSession: (o) => call('keys:derive-session', o),
      commitPending: (u) => call('keys:commit-pending', u),
      dropPending: (u) => call('keys:drop-pending', u),
      hasSession: (u) => call('keys:has-session', u),
      forgetSession: (u) => call('keys:forget-session', u),
      identity: (u, n) => call('keys:identity', u, n),
      openBundle: (u, n, o) => call('keys:open-bundle', u, n, o),
      mint: (u, n) => call('keys:mint', u, n),
      sealBundle: (u, n, o) => call('keys:seal-bundle', u, n, o),
      sealRecovery: (u, n, m, name) => call('keys:seal-recovery', u, n, m, name),
      markSealed: (u, n, fp) => call('keys:mark-sealed', u, n, fp),
      fingerprint: (u) => call('keys:fingerprint', u),
      sign: (u, n, kind, fields) => call('keys:sign', u, n, kind, fields),
      shared: (u, n, peer) => call('keys:shared', u, n, peer),
      playlistKey: (u) => call('keys:playlist-key', u),
      browserAccess: (u) => call('keys:browser-access', u),
      setBrowserAccess: (u, on) => call('keys:set-browser-access', u, on),
      createdHere: (u) => call('keys:created-here', u),
    },

    // Whether the OS protects what is stored. The store itself is not
    // reachable from here.
    secrets: {
      backend: () => call('secrets:backend'),
    },

    // LAN cast relay: the page feeds it decrypted segments, a receiver on the
    // same Wi-Fi plays from the URL. Present only where casting can work —
    // `platform.cast.available` is whether this object exists.
    ...(CAST ? { cast: {
      start: (opts) => {
        const o = Object.assign({}, opts || {});
        if (o.initSegment) o.initSegment = base64Of(bytesOf(o.initSegment));
        return call('cast:start', o);
      },
      push: (data) => pushSegment(data),
      stop: () => call('cast:stop'),
      subtitle: (sub) => call('cast:subtitle', sub),
      finish: () => call('cast:finish'),
      status: () => call('cast:status'),
      scan: () => call('cast:scan'),
      devices: () => call('cast:devices'),
      chromecastConnect: (opts) => call('cast:chromecast:connect', opts),
      chromecastReload: (opts) => call('cast:chromecast:reload', opts),
      chromecastDisconnect: () => call('cast:chromecast:disconnect'),
    } } : {}),

    // Where downloads go, chosen once. A display name comes back, never a URI.
    folder: {
      choose: () => call('folder:choose'),
      get: () => call('folder:get'),
      forget: () => call('folder:forget'),
    },

    // A sink that writes to disk as chunks arrive, never a buffer handed over
    // at the end. The page holds an id. `open` exists only where the target
    // says the file may be opened — a type that runs nothing.
    saveFile: async (suggestedName, opts) => {
      const handle = await call('save:begin', suggestedName, opts);
      if (!handle) return null;
      const sink = {
        name: handle.name,
        write: (chunk) => writeChunk(handle.id, chunk),
        close: () => call('save:end', handle.id),
        abort: () => call('save:abort', handle.id),
      };
      if (handle.openable) sink.open = () => call('save:open', handle.id);
      return sink;
    },
  };

  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 */ }
  }
})();