/**
 * 支付对外的相关接口
 * 
 */
import { EventTarget } from "cc"; 
import { PaymentApi } from "./PaymentApi";
import { PaymentOpenerFactory, type OpenStrategy } from "./PaymentOpener";
import { PendingOrderRepo } from "./PendingOrderRepo";
import PaymentPoller from "./PaymentPoller";
import type { CreateOrderReq, PaymentResult, PendingOrder, OrderStatus } from "./types";
import { ApiCode } from "../network/client/types";

export const PaymentEvents = {
  Started: "pay-started",     // { orderId }
  UrlOpened: "pay-url-opened",
  PollTick: "pay-poll-tick",  // { orderId, status }
  Finished: "pay-finished",   // PaymentResult
};

export class PaymentService {
  private static _I: PaymentService | null = null;
  static get I() { return this._I ?? (this._I = new PaymentService()); }
  private constructor() {}

  private bus = new EventTarget();

  on(event: string, cb: (...args: any[]) => void, target?: any) { 
    this.bus.on(event, cb, target); 
  }
  off(event: string, cb: (...args: any[]) => void, target?: any) { 
    this.bus.off(event, cb, target); 
  }

  /** 发起支付：创建订单→打开URL→回到App后开始轮询 */
  async startPayment(req: CreateOrderReq, open: OpenStrategy = "system"): Promise<PaymentResult> {
    // 下单
    const create = await PaymentApi.I.createOrder(req);
    if (create.code !== ApiCode.OK || !create.data) {
      return { orderId: "", status: "FAILED", message: create.msg || "create order failed" };
    }
    const { orderId, payUrl, expireAt } = create.data;
    this.bus.emit(PaymentEvents.Started, { orderId });

    // 存为未决订单（用于异常恢复）
    PendingOrderRepo.instance.add({ orderId, channel: req.channel, createdAt: Date.now(), expireAt, productId: req.productId });

    // 打开支付页
    await PaymentOpenerFactory.create(open).open(payUrl);
    this.bus.emit(PaymentEvents.UrlOpened, { orderId });

    //    等待回到前台（系统浏览器策略下）
    //    - 如果是 inapp/minigame，可在 WebView/回跳时立即开始轮询；
    //    - 这里给一个通用的“等待前台”方法（可用 Cocos 的 onShow/onHide 自行接入）
    await this.waitAppResumeIfNeeded(open);

    // 轮询
    const poller = new PaymentPoller();
    const data = await poller.poll(orderId, {
      maxDurationMs: 2 * 60 * 1000,
      startIntervalMs: 2000,
      maxIntervalMs: 10000,
      jitter: true,
    }, (d) => this.bus.emit(PaymentEvents.PollTick, { orderId, status: d.status }));

    // 产出结果
    let res: PaymentResult;
    if (!data) {
      res = { orderId, status: "EXPIRED", message: "poll timeout" };
    } else if (data.status === "SUCCESS") {
      res = { orderId, status: "SUCCESS" };
    } else {
      res = { orderId, status: data.status as OrderStatus, message: data.failureReason };
    }

    PendingOrderRepo.instance.remove(orderId);
    this.bus.emit(PaymentEvents.Finished, res);
    return res;
  }

  /** App 回到前台后恢复未完成订单的轮询（在 onShow 时调用） */
  async resumePending(): Promise<void> {
    const all = PendingOrderRepo.instance.all();
    for (const o of all) {
      // 可以做去重/只处理未过期的
      const r = await this.startPollingOnly(o.orderId);
      if (r && r.status !== "PENDING" && r.status !== "CREATED") {
        PendingOrderRepo.instance.remove(o.orderId);
        this.bus.emit(PaymentEvents.Finished, {
          orderId: o.orderId,
          status: r.status as OrderStatus,
          message: r.failureReason
        } as PaymentResult);
      }
    }
  }

  /** 仅轮询（用于 resumePending 或手动刷新） */
  private async startPollingOnly(orderId: string) {
    const poller = new PaymentPoller();
    return poller.poll(orderId, {
      maxDurationMs: 2 * 60 * 1000,
      startIntervalMs: 2000,
      maxIntervalMs: 8000,
      jitter: true,
    });
  }

  /** 等待“回到前台”的占位实现：实际请在 App 生命周期里调用 resumePending() */
  private async waitAppResumeIfNeeded(open: OpenStrategy) {
    // 如果是系统浏览器，我们通常等“App 回到前台”再开始轮询；
    // 这里简单 sleep 1s，实际项目请监听 Cocos 的 onShow/onHide 或平台回调。
    if (open === "system") {
      await new Promise(res => setTimeout(res, 1000));
    }
  }
}
export default PaymentService;