/// <reference lib="webworker" />
// Toàn bộ phần nặng chạy trong worker này: nạp model, suy luận WebGPU, vòng lặp agent, tool và shell.

import type { WorkerEvent, WorkerRequest } from '../shared/protocol';
import type { WorkspaceState } from '../shared/types';
import { Agent } from './agent';
import { MiniCpmEngine } from './engine';
import { isModelCached } from './modelCache';
import { Workspace } from './workspace';

const post = (event: WorkerEvent) => (self as DedicatedWorkerGlobalScope).postMessage(event);

// ───────────────────────── Lưu trạng thái trong IndexedDB ─────────────────────────

interface Store {
  load(): Promise<WorkspaceState | undefined>;
  save(state: WorkspaceState): Promise<void>;
}

async function openStore(): Promise<Store> {
  const db = await new Promise<IDBDatabase>((resolve, reject) => {
    const req = indexedDB.open('minicpm5-pi-react-workspace', 1);
    req.onupgradeneeded = () => req.result.createObjectStore('state');
    req.onsuccess = () => resolve(req.result);
    req.onerror = () => reject(req.error);
  });
  return {
    load: () =>
      new Promise((resolve, reject) => {
        const req = db.transaction('state').objectStore('state').get('current');
        req.onsuccess = () => resolve(req.result as WorkspaceState | undefined);
        req.onerror = () => reject(req.error);
      }),
    save: (state) =>
      new Promise((resolve, reject) => {
        const tx = db.transaction('state', 'readwrite');
        tx.objectStore('state').put(state, 'current');
        tx.oncomplete = () => resolve();
        tx.onerror = () => reject(tx.error);
        tx.onabort = () => reject(tx.error);
      }),
  };
}

// ───────────────────────── Khởi tạo ─────────────────────────

const engine = new MiniCpmEngine();
let store: Store | undefined;
let workspace: Workspace;
let agent: Agent;
let busy = false;
let controller: AbortController | undefined;

async function currentState(): Promise<WorkspaceState> {
  return {
    version: 1,
    files: await workspace.snapshot(),
    entries: await workspace.serialize(),
    messages: agent.messages,
  };
}

async function persist(): Promise<WorkspaceState> {
  const state = await currentState();
  try {
    await store?.save(state);
  } catch (err) {
    post({ type: 'persistence_error', error: 'Changes are in memory, but browser storage failed: ' + (err as Error).message });
  }
  post({ type: 'workspace', files: state.files });
  return state;
}

const initialized = (async () => {
  let saved: WorkspaceState | undefined;
  try {
    store = await openStore();
    saved = await store.load();
  } catch (err) {
    post({ type: 'persistence_error', error: 'Workspace saving is unavailable: ' + (err as Error).message });
  }
  workspace = new Workspace(saved?.entries, saved?.files);
  await workspace.ready;
  agent = new Agent({ engine, workspace, emit: post, persist: async () => void (await persist()) }, saved?.messages ?? []);

  const state = await currentState();
  if (!saved) {
    try {
      await store?.save(state);
    } catch (err) {
      post({ type: 'persistence_error', error: 'Changes are in memory, but browser storage failed: ' + (err as Error).message });
    }
  }
  post({ type: 'initialized', ...state });
})();

// ───────────────────────── Xử lý lệnh ─────────────────────────

self.onmessage = async ({ data }: MessageEvent<WorkerRequest>) => {
  const { id, action } = data;
  const args = (data.args ?? {}) as Record<string, any>;
  const reply = (value?: unknown) => post({ type: 'reply', id, value });

  try {
    await initialized;

    if (action === 'stop') {
      controller?.abort();
      engine.stop();
      return reply(true);
    }
    if (action === 'snapshot') return reply(await currentState());
    if (action === 'cache_status') return reply(await isModelCached());

    if (busy) throw new Error('Wait for the current operation or stop it first.');
    busy = true;
    controller = new AbortController();
    post({ type: 'busy', action, cachedOnly: args.cachedOnly === true });

    try {
      let value: unknown;
      switch (action) {
        case 'load':
          value = await engine.load({ cachedOnly: args.cachedOnly === true }, controller.signal, post);
          break;
        case 'prompt':
          await agent.prompt(args.text, controller.signal);
          value = await currentState();
          break;
        case 'shell':
          value = await workspace.exec(args.command, controller.signal);
          await persist();
          break;
        case 'write':
          await workspace.write(args.path, args.content);
          value = await persist();
          break;
        case 'new_chat':
          agent.reset();
          value = await persist();
          break;
        case 'read':
          value = await workspace.read(args.path);
          break;
        default:
          throw new Error('Unknown action: ' + action);
      }
      reply(value);
    } finally {
      busy = false;
      controller = undefined;
      post({ type: 'idle' });
    }
  } catch (err) {
    const e = err as Error & { code?: string };
    post({
      type: 'reply',
      id,
      error: e?.name === 'AbortError' ? 'Stopped.' : String(e?.message ?? e),
      errorName: e?.name,
      errorCode: e?.code,
    });
  }
};