MyAiDesk/nomifun-tauri/ui/src/platform/bridge.ts

/**
 * @license
 * Copyright 2025-2026 NomiFun (nomifun.com)
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * In-house bridge: transport-agnostic pub/sub + request/response RPC.
 *
 * Replaces the bridge surface of the former third-party platform package.
 * The wire protocol is preserved byte-for-byte so the Rust backend
 * (`WebSocketMessage{name,data}`), the mobile client, and the desktop
 * adapters all keep working unchanged:
 *
 *  - invoke(name, data):
 *      emits event `"subscribe-" + name` with body `{ id, data }`,
 *      then awaits a one-shot `"subscribe.callback-" + name + id`.
 *  - subscribe(name, handler):
 *      listens on `"subscribe-" + name`, runs the handler, then emits
 *      `"subscribe.callback-" + name + body.id` with the result.
 *  - buildEmitter uses the bare event name (fire-and-forget, no callback).
 *
 * The id is concatenated to the name WITHOUT a delimiter — this matches the
 * original library and the consumers that hand-build the callback name
 * (mobile bridge.ts, useDirectorySelection.tsx). Do not change it.
 */
import EventEmitter from 'eventemitter3';

type AnyFn = (...args: any[]) => any;

interface Adapter {
  emit(name: string, data: any, ...args: any[]): void;
  on(emitter: { emit(name: string, ...args: any[]): void }): void;
}

interface InterceptParams {
  name: string;
  data: any;
}

// Internal event hub. The adapter plugs the real transport into `outbound`
// (how events leave this process) and feeds inbound events back via the
// emitter handed to `adapter.on`.
const hub = new EventEmitter();

let logOutput: ((...args: any[]) => void) | null = null;
const log = (...args: any[]) => {
  if (logOutput) logOutput(...args);
};

const interceptors: Array<(params: InterceptParams) => Promise<void>> = [];

// Default outbound: loopback (same-process). The adapter overrides this.
let outbound: (name: string, data: any, ...args: any[]) => void = (name, data, ...args) => {
  hub.emit(name, data, ...args);
};

/**
 * Register a listener. Callback-channel events (`subscribe(.callback)?-`)
 * bypass interceptors so RPC plumbing is never delayed by app-level guards.
 */
const on = (name: string, callback: AnyFn): (() => void) => {
  const wrapped = (...args: any[]) => {
    if (/^subscribe(\.callback)?-/.test(name) || interceptors.length === 0) {
      return callback(...args);
    }
    return Promise.all(interceptors.map((i) => i({ name, data: args[0] }))).then(() => callback(...args));
  };
  hub.on(name, wrapped);
  return () => hub.off(name, wrapped);
};

const off = (name: string, callback: AnyFn): void => {
  // Best-effort: matches the original loose contract. Listeners created via
  // `on()` return their own disposer; this removes direct hub listeners.
  hub.off(name, callback);
};

const emit = (name: string, data: any, ...args: any[]): void => {
  log('bridge.emit', name, data);
  outbound(name, data, ...args);
};

// Monotonic, collision-resistant id. Format is opaque; only uniqueness as a
// string matters (consumers concatenate it onto the callback event name).
let idCounter = 0;
const nextId = (prefix: string): string => `${prefix}_${idCounter++}_${randomSuffix()}`;
const randomSuffix = (): string => {
  // Avoid Math.random/Date in hot equality paths is unnecessary here; this is
  // a fresh id each call. Use performance-cheap entropy.
  let s = '';
  for (let i = 0; i < 6; i++) s += ((Math.random() * 36) | 0).toString(36);
  return s;
};

const subscribe = <Data = any, Result = any>(name: string, callback: (data: Data) => Promise<Result>): (() => void) => {
  return on('subscribe-' + name, (body: { id: string; data: Data }, ...rest: any[]) => {
    Promise.resolve(callback(body.data)).then((result) => {
      emit('subscribe.callback-' + name + body.id, result, ...rest);
    });
  });
};

const invoke = <Data = any>(name: string, data?: any): Promise<Data> => {
  const id = nextId(name);
  return new Promise<Data>((resolve) => {
    // Register the one-shot callback listener BEFORE emitting the request, so a
    // synchronous responder (loopback / same-process provider) cannot deliver
    // the result before we are listening. With an async transport the order is
    // immaterial; this is correct in both cases.
    const dispose = on('subscribe.callback-' + name + id, (result: Data) => {
      resolve(result);
      dispose();
    });
    emit('subscribe-' + name, { id, data });
  });
};

const create = <Data = any, Result = any>(key: string) => ({
  invoke: (data: Data) => invoke<Result>(key, data),
  subscribe: (handler: (data: Data) => Promise<Result>) => subscribe<Data, Result>(key, handler),
});

const buildProvider = <Data = any, Params = undefined>(key: string) => {
  const channel = create<Params, Data>(key);
  return {
    provider: (provider: Params extends undefined ? () => Promise<Data> : (params: Params) => Promise<Data>) => {
      channel.subscribe((params: Params) => (provider as (p: Params) => Promise<Data>)(params));
    },
    invoke: ((params?: Params) => channel.invoke(params as Params)) as Params extends undefined
      ? () => Promise<Data>
      : (params: Params) => Promise<Data>,
  };
};

const buildEmitter = <Params = undefined>(key: string) => ({
  on: (callback: Params extends undefined ? () => void : (params: Params) => void) => on(key, callback as AnyFn),
  emit: ((params?: Params) => emit(key, params)) as Params extends undefined ? () => void : (params: Params) => void,
});

const intercept = (callback: (params: InterceptParams) => Promise<void>): (() => void) => {
  interceptors.push(callback);
  return () => {
    const i = interceptors.indexOf(callback);
    if (i >= 0) interceptors.splice(i, 1);
  };
};

/**
 * Install the real transport. `emit` ships an outbound event; `on` is handed
 * an emitter whose `.emit(name, data)` feeds inbound events into the hub.
 */
const adapter = (config: Adapter): void => {
  outbound = (name, data, ...args) => config.emit(name, data, ...args);
  config.on({
    emit: (name: string, ...args: any[]) => {
      hub.emit(name, ...args);
    },
  });
};

const logger = (output: (...args: any[]) => void): void => {
  logOutput = output;
};

// Inert lifecycle hooks kept for API compatibility (no consumer relies on
// their behavior; they existed on the original surface).
const start = (): void => {};
const stop = (): void => {};
const status = (): boolean => true;
const debug = (_flag?: boolean): void => {};

export {
  adapter,
  buildProvider,
  buildEmitter,
  on,
  off,
  emit,
  subscribe,
  invoke,
  create,
  intercept,
  logger,
  start,
  stop,
  status,
  debug,
};