import { Injectable, inject, signal } from '@angular/core';
import { RpcService } from './rpc.service';

export type UpdaterState = 'idle' | 'available' | 'downloading' | 'ready' | 'error';

/**
 * Drives the tab-bar update pill. The backend pushes updateStatus events
 * (available / downloading progress / error); "ready" is derived locally when
 * downloadUpdate resolves ok. Two-step UX: available -> download -> ready ->
 * apply (relaunch).
 */
@Injectable({ providedIn: 'root' })
export class UpdaterService {
  private rpc = inject(RpcService);

  readonly state = signal<UpdaterState>('idle');
  readonly version = signal('');
  readonly progress = signal(0);

  constructor() {
    if (!this.rpc.available) return;
    this.rpc.onUpdateStatus((s) => {
      if (s.phase === 'available') {
        this.version.set(s.version ?? '');
        this.state.set('available');
      } else if (s.phase === 'downloading') {
        this.state.set('downloading');
        this.progress.set(s.progress ?? 0);
      } else if (s.phase === 'error') {
        this.state.set('error');
      }
    });
  }

  async download(): Promise<void> {
    if (this.state() !== 'available') return;
    this.state.set('downloading');
    this.progress.set(0);
    const r = await this.rpc.request.downloadUpdate({});
    this.state.set(r?.ok ? 'ready' : 'error');
  }

  apply(): void {
    if (this.state() !== 'ready') return;
    void this.rpc.request.applyUpdate({}); // quits + relaunches
  }

  /** Manual re-check (menu item). */
  async check(): Promise<void> {
    if (!this.rpc.available) return;
    const r = await this.rpc.request.checkForUpdate({});
    if (r?.ok && r.updateAvailable) {
      this.version.set(r.version);
      this.state.set('available');
    }
  }
}