import type { BrowserWindow } from "electron";
import { RuntimeError, mapCdpError, type CdpEventHandler, type CdpTransport } from "@rpa/core";

/**
 * 内置运行浏览器传输层（宿主适配层，任务 2.3）。
 *
 * 包装 Electron BrowserWindow.webContents.debugger，实现包内的 CdpTransport 接口；
 * CdpTransport / mapCdpError / ExternalTransport（外部浏览器）已迁入 @rpa/core。
 */
export class EmbeddedTransport implements CdpTransport {
  readonly kind = "embedded" as const;
  private wrappers = new Map<CdpEventHandler, (event: unknown, method: string, params?: Record<string, unknown>) => void>();

  constructor(private win: BrowserWindow) {}

  get closed(): boolean {
    return this.win.isDestroyed();
  }

  async send<T = unknown>(method: string, params: Record<string, unknown> = {}): Promise<T> {
    if (this.win.isDestroyed()) {
      throw new RuntimeError("tab_unavailable", "运行浏览器已关闭", { recommendation: "重新运行流程" });
    }
    try {
      if (!this.win.webContents.debugger.isAttached()) this.win.webContents.debugger.attach("1.3");
      return (await this.win.webContents.debugger.sendCommand(method, params)) as T;
    } catch (error) {
      throw mapCdpError(error, "embedded");
    }
  }

  on(method: string, handler: CdpEventHandler): void {
    if (this.win.isDestroyed()) return;
    const wrapper = (_event: unknown, evtMethod: string, evtParams?: Record<string, unknown>) => {
      if (evtMethod === method) handler(evtParams ?? {});
    };
    this.wrappers.set(handler, wrapper);
    this.win.webContents.debugger.on("message", wrapper as never);
  }

  off(method: string, handler: CdpEventHandler): void {
    const wrapper = this.wrappers.get(handler);
    if (wrapper) {
      this.win.webContents.debugger.removeListener("message", wrapper as never);
      this.wrappers.delete(handler);
    }
  }

  async close(): Promise<void> {
    if (!this.win.isDestroyed() && this.win.webContents.debugger.isAttached()) {
      try {
        this.win.webContents.debugger.detach();
      } catch {
        // 窗口关闭过程中 detach 可能失败，忽略
      }
    }
  }
}