import { ActorDebugAdapter, DebugMessage } from "../src/debugger";

export class DebugHarness {
  readonly adapter: ActorDebugAdapter;
  readonly messages: DebugMessage[] = [];
  private seq = 0;
  private readonly listeners = new Set<() => void>();

  constructor(create: (send: (message: DebugMessage) => void) => ActorDebugAdapter) {
    this.adapter = create((message) => {
      this.messages.push(message);
      for (const listener of this.listeners) listener();
    });
  }

  async request<T = unknown>(command: string, args?: Record<string, unknown>): Promise<T> {
    const seq = ++this.seq;
    const response = this.wait((message) => message.request_seq === seq);
    this.adapter.handleMessage({ seq, type: "request", command, arguments: args });
    const message = await response;
    if (!message.success) throw new Error(message.message);
    return message.body as T;
  }

  wait(predicate: (message: DebugMessage) => boolean, since = 0): Promise<DebugMessage> {
    return new Promise((resolve, reject) => {
      const check = () => {
        const found = this.messages.slice(since).find(predicate);
        if (!found) return;
        clearTimeout(timer);
        this.listeners.delete(check);
        resolve(found);
      };
      const timer = setTimeout(() => {
        this.listeners.delete(check);
        reject(new Error("Timed out waiting for DAP message"));
      }, 5000);
      this.listeners.add(check);
      check();
    });
  }

  async attach(): Promise<void> {
    await this.request("initialize");
    await this.request("attach");
    await this.wait((message) => message.event === "initialized");
    await this.request("configurationDone");
    await this.wait((message) => message.event === "stopped");
  }
}