import { Injectable } from '@angular/core';

interface RegisterResponse {
  id: string;
  token: string;
}

@Injectable({ providedIn: 'root' })
export class TournamentAuthService {
  private readonly inflight = new Map<string, Promise<string>>();

  async getToken(serverUrl: string): Promise<string> {
    const key = this.cacheKey(serverUrl);
    const cached = localStorage.getItem(key);
    if (cached) return cached;

    const existing = this.inflight.get(key);
    if (existing) return existing;

    const promise = this.register(serverUrl)
      .then(token => {
        localStorage.setItem(key, token);
        this.inflight.delete(key);
        return token;
      })
      .catch(err => {
        this.inflight.delete(key);
        throw err;
      });

    this.inflight.set(key, promise);
    return promise;
  }

  clearToken(serverUrl: string): void {
    localStorage.removeItem(this.cacheKey(serverUrl));
  }

  private async register(serverUrl: string): Promise<string> {
    const base = serverUrl.replace(/\/+$/, '');
    const localName = localStorage.getItem('username') ?? 'viewer';
    const res = await fetch(`${base}/api/auth/register`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ name: `${localName}-watch`, isBot: false })
    });
    if (!res.ok) throw new Error(`tournament-server register failed: ${res.status}`);
    const body = (await res.json()) as RegisterResponse;
    return body.token;
  }

  private cacheKey(serverUrl: string): string {
    return `tournament-token:${serverUrl.replace(/\/+$/, '')}`;
  }
}