import { Injectable, inject } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, Subscription } from 'rxjs';
import { signal } from '@angular/core';
import { Filament } from '../models/filament.model';

/**
 * API base URL — matches the Extrudex backend.
 * TODO: Move to environment config when environments are set up.
 */
const API_BASE_URL = '/api/filaments';

/**
 * Service for managing filament inventory data.
 *
 * Provides:
 * - A reactive `filaments` signal for components to bind to
 * - REST methods for GET, POST, DELETE endpoints
 * - Real-time updates via SignalR should be layered on top when the hub is ready
 */
@Injectable({ providedIn: 'root' })
export class FilamentService {
  private readonly http = inject(HttpClient);

  /** Reactive filament data — components read from this signal */
  readonly filaments = signal<Filament[]>([]);

  /** Fetch all filament spools and update the signal */
  getFilaments(): Observable<Filament[]> {
    const req = this.http.get<Filament[]>(API_BASE_URL);
    req.subscribe({
      next: (data) => this.filaments.set(data),
      error: (err) => console.error('Failed to load filaments:', err),
    });
    return req;
  }

  /** Fetch a single filament by ID */
  getFilament(id: string): Observable<Filament> {
    return this.http.get<Filament>(`${API_BASE_URL}/${id}`);
  }

  /** Set filament data directly — used by components or SignalR handlers */
  setFilaments(data: Filament[]): void {
    this.filaments.set(data);
  }

  /** Delete a filament spool by ID */
  deleteFilament(id: string): Observable<void> {
    return this.http.delete<void>(`${API_BASE_URL}/${id}`);
  }
}