/**
 * 平台服务入口（架构设计第 2 节）。
 *
 * 组装：应用服务 + HTTP / SSE 入口。控制面（core）与引擎适配（agent）在后续阶段接入。
 */
import { randomUUID } from 'node:crypto';
import type { Server } from 'node:http';
import type { AddressInfo } from 'node:net';

import type { AgentRuntime } from './agent/runtime.js';
import { ApplicationService } from './app/service.js';
import { createHttpServer } from './entry/http.js';

export { ApplicationService } from './app/service.js';
export type { Subject } from './app/subject.js';
export { createHttpServer } from './entry/http.js';

export interface StartOptions {
  host?: string;
  port?: number;
  version?: string;
  /** 引擎实现：默认假引擎；A3.3 起可换成 Pi 子进程，测试也可注入脚本化假引擎 */
  runtime?: AgentRuntime;
}

export interface RunningServer {
  url: string;
  port: number;
  service: ApplicationService;
  /** 引擎工具回调的内部令牌：由平台生成，启动引擎子进程时注入（A3.11） */
  internalToken: string;
  close(): Promise<void>;
}

export async function startServer(options: StartOptions = {}): Promise<RunningServer> {
  const host = options.host ?? '127.0.0.1';
  const port = options.port ?? 5199;
  const service = new ApplicationService({
    ...(options.version === undefined ? {} : { version: options.version }),
    ...(options.runtime === undefined ? {} : { runtime: options.runtime }),
  });
  // 开发期可选：APS_DEV_PROVIDER=1 时注册假 Provider，用于本地联调与演示（默认不注册，能力清单为空）
  if (process.env.APS_DEV_PROVIDER === '1') {
    const { createFakeProvider } = await import('@aps/provider-sdk/testing');
    await service.registerProvider(createFakeProvider());
  }

  const internalToken = randomUUID();
  const server: Server = createHttpServer(service, internalToken);

  await new Promise<void>((resolve, reject) => {
    server.once('error', reject);
    server.listen(port, host, () => resolve());
  });

  const address = server.address() as AddressInfo | null;
  const actualPort = address ? address.port : port;

  return {
    url: `http://${host}:${actualPort}`,
    port: actualPort,
    service,
    internalToken,
    close: () =>
      new Promise<void>((resolve, reject) => {
        server.close((error) => (error ? reject(error) : resolve()));
        // 事件流是长连接，关停时必须主动断开，否则 close 会一直等它们
        // 客户端断线后按 Last-Event-ID 重连，不会丢事件（协议文档第 5 节）
        server.closeAllConnections();
      }),
  };
}