import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { BehaviorSubject, Observable, tap, catchError, throwError } from 'rxjs';
import { Router } from '@angular/router';

@Injectable({
  providedIn: 'root',
})
export class AuthService {
  private baseUrl = location.hostname.endsWith('hf.space')
  ? 'https://pykara-py-match-backend.hf.space/api'
  : 'http://localhost:5000/api';
  private isLoggedInSubject = new BehaviorSubject<boolean>(false);
  private currentUserId = new BehaviorSubject<number | null>(this.getUserIdFromStorage());
  private userIdSubject = new BehaviorSubject<number | null>(this.getUserIdFromStorage());

  constructor(private http: HttpClient, private router: Router) {
    // Check if user is already logged in (from session)
    this.initializeAuthState();
  }

  // Get user ID from storage with sessionStorage priority
  private getUserIdFromStorage(): number | null {
    const savedUserId = sessionStorage.getItem('user_id') || localStorage.getItem('user_id');
    return savedUserId ? Number(savedUserId) : null;
  }

  setUserId(userId: number): void {
    // Use sessionStorage as primary
    sessionStorage.setItem('user_id', userId.toString());
    // Update both BehaviorSubjects for consistency
    this.currentUserId.next(userId);
    this.userIdSubject.next(userId);
    this.isLoggedInSubject.next(true);
    console.log('🔐 AuthService - User ID set via setUserId:', userId);
  }

  getUserId(): number | null {
    // Prefer sessionStorage over localStorage
    const userId = sessionStorage.getItem('user_id') || localStorage.getItem('user_id');
    return userId ? parseInt(userId, 10) : null;
  }

  private initializeAuthState(): void {
    const savedUserId = this.getUserIdFromStorage();
    const savedUserData = sessionStorage.getItem('user_data') || localStorage.getItem('user_data');

    if (savedUserId && savedUserData) {
      this.isLoggedInSubject.next(true);
      this.currentUserId.next(savedUserId);
      this.userIdSubject.next(savedUserId);
      console.log('🔐 AuthService initialized with user:', savedUserId);
    } else {
      console.log('🔐 AuthService initialized - no user logged in');
    }
  }

  get isAuthenticated(): boolean {
    return this.isLoggedInSubject.value;
  }

  get userId(): number | null {
    return this.currentUserId.value;
  }

  get userId$(): Observable<number | null> {
    return this.currentUserId.asObservable();
  }

  /** SIGN UP */
  signUp(name: string, email: string, password: string): Observable<any> {
    return this.http.post(`${this.baseUrl}/signup`, { name, email, password }).pipe(
      tap((response: any) => {
        if (response.message && response.user_id) {
          this.setUserId(response.user_id);

          // Store user data in sessionStorage (primary)
          const userData = {
            user_id: response.user_id,
            name: name,
            email: email
          };

          sessionStorage.setItem('user_id', response.user_id.toString());
          sessionStorage.setItem('user_data', JSON.stringify(userData));

          // Keep localStorage as fallback only
          localStorage.setItem('user_id', response.user_id.toString());
          localStorage.setItem('user_name', name);

          console.log('✅ Signup successful, user auto-logged in:', response.user_id);
        }
      }),
      catchError((error) => {
        console.error('Signup error:', error);
        return throwError(() => error);
      })
    );
  }

  /** LOGIN */
  login(email: string, password: string): Observable<any> {
    return this.http.post(`${this.baseUrl}/login`, { email, password }).pipe(
      tap((response: any) => {
        if (response.message === 'Login successful.' && response.user_id) {
          this.setUserId(response.user_id);

          // Store user data in sessionStorage (primary)
          const userData = {
            user_id: response.user_id,
            name: response.name,
            email: response.email
          };

          sessionStorage.setItem('user_id', response.user_id.toString());
          sessionStorage.setItem('user_data', JSON.stringify(userData));

          // Keep localStorage as fallback only
          localStorage.setItem('user_id', response.user_id.toString());
          if (response.name) {
            localStorage.setItem('user_name', response.name);
            localStorage.setItem('userName', response.name);
            localStorage.setItem('name', response.name);
          }

          console.log('✅ Login successful, user ID:', response.user_id);
        }
      }),
      catchError((error) => {
        console.error('Login error:', error);
        return throwError(() => error);
      })
    );
  }

  /** LOGOUT - UPDATED: Remove page reload to preserve animations */
  logout(): void {
    console.log('🔐 AuthService - Logging out user:', this.currentUserId.value);

    // Update BehaviorSubjects first
    this.isLoggedInSubject.next(false);
    this.currentUserId.next(null);
    this.userIdSubject.next(null);

    // Clear session storage
    sessionStorage.clear(); // Clear all session storage to be safe

    // Clear specific localStorage items
    localStorage.removeItem('user_id');
    localStorage.removeItem('user_name');
    localStorage.removeItem('userName');
    localStorage.removeItem('name');
    localStorage.removeItem('auth_token');

    console.log('✅ Logout complete - all storage cleared');

    // Only navigate, don't reload - let the component handle the UI state
    this.router.navigate(['/']);
  }

  // Alternative logout method that doesn't navigate at all
  logoutSilent(): void {
    console.log('🔐 AuthService - Silent logout for user:', this.currentUserId.value);

    // Update BehaviorSubjects first
    this.isLoggedInSubject.next(false);
    this.currentUserId.next(null);
    this.userIdSubject.next(null);

    // Clear session storage
    sessionStorage.clear();

    // Clear specific localStorage items
    localStorage.removeItem('user_id');
    localStorage.removeItem('user_name');
    localStorage.removeItem('userName');
    localStorage.removeItem('name');
    localStorage.removeItem('auth_token');

    console.log('✅ Silent logout complete - storage cleared without navigation');
  }

  // Check if user is logged in (observable)
  get isLoggedIn$(): Observable<boolean> {
    return this.isLoggedInSubject.asObservable();
  }
}