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



@Injectable({
  providedIn: 'root'
})

export class AuthService {
  private apiUrl = location.hostname.endsWith('hf.space')
    ? 'https://pykara-py-learn-backend.hf.space'
    : 'http://localhost:5000'; // Your Flask API base URL
  private loggedInSubject = new BehaviorSubject<boolean>(false);  // Shared state
  public isLoggedIn$ = this.loggedInSubject.asObservable();
  private refreshIntervalId: any;
  constructor(private http: HttpClient, private router: Router) { }

  // ✅ Called to check current status
  isLoggedIn(): boolean {
    return this.loggedInSubject.value;
  }

  // ✅ Set login status manually
  setLoggedIn(status: boolean): void {
    this.loggedInSubject.next(status);
  }
  // ✅ Login Method


  login(username: string, password: string): Observable<any> {
  return this.http.post(`${this.apiUrl}/login`, { username, password }, { withCredentials: true });
  }


  startAutoRefresh(): void {
    if (this.refreshIntervalId) return;
    this.refreshIntervalId = setInterval(() => {
      this.refreshAccessToken();
    }, 12 * 60 * 1000);
  }

  clearAutoRefresh(): void {
    clearInterval(this.refreshIntervalId);
    this.refreshIntervalId = null;
  }

  refreshAccessToken(): void {
    this.http.post(`${this.apiUrl}/refresh`, {}, { withCredentials: true }).subscribe(
      (response: any) => {
        console.log("✅ Access token refreshed:", response.access_token);
        //alert("🔄 Access token has been refreshed!");
      },
      (error) => {
        console.error("❌ Refresh failed:", error);

        if (
          error.status === 401 &&
          error.error &&
          (error.error.message === 'Refresh token has expired' || error.error.message === 'Invalid refresh token')
        ) {
          //alert("⚠️ Your session has expired. Please log in again.");

          // Clear cookies manually (if needed)
          this.clearTokens();

          // Redirect to login
          this.router.navigate(['/auth']);
        }
      }
    );
  }


  

  logout(): Observable<any> {
    console.log("🔧 Sending logout request with credentials");

    return this.http.post(`${this.apiUrl}/logout`, {}, { withCredentials: true }).pipe(
      tap(response => {
        console.log('🔙 Response from backend:', response);
        this.clearTokens();
        this.clearAutoRefresh();  // ✅ Stop auto-refresh
        this.setLoggedIn(false);  // ✅ Reflect logout in UI
      }),
      catchError(error => {
        console.error('❌ Error from backend:', error);
        // Still ensure local state reflects logout
        this.clearTokens();
        this.clearAutoRefresh();
        this.setLoggedIn(false);
        return throwError(() => error);
      })
    );
  }



 



  clearTokens(): void {
    document.cookie = 'access_token=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/;';
    document.cookie = 'refresh_token=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/;';
    this.clearAutoRefresh();  // ✅
  }


  //// ✅ Check if user is logged in (check for presence of cookies)
  //isLoggedIn(): boolean {
  //  // Check cookies directly (this will happen automatically when the browser sends cookies)
  //  // Check if the cookies are present (you can do it manually using a service or via backend)
  //  return document.cookie.includes('access_token');
  //}

  // ✅ Get access token (using cookies)
  getAccessToken(): string | null {
    const cookies = document.cookie.split('; ');
    for (let cookie of cookies) {
      if (cookie.startsWith('access_token=')) {
        return cookie.split('=')[1];
      }
    }
    return null;
  }

  // ✅ Save tokens (Not necessary, as tokens are managed via cookies)
  saveTokens(accessToken: string, refreshToken: string): void {
    // No need for this if you're using cookies, but if you want to persist in localStorage, use:
    localStorage.setItem('access_token', accessToken);
    localStorage.setItem('refresh_token', refreshToken);
  }

  //checkSession(): Observable<boolean> {
  //  return this.http.get(`${this.apiUrl}/check-auth`, { withCredentials: true }).pipe(
  //    tap((res: any) => {
  //      console.log('✅ Session valid:', res);
  //      this.setLoggedIn(true);
  //    }),
  //    catchError((err) => {
  //      console.warn('❌ Session check failed:', err);
  //      this.setLoggedIn(false);
  //      return [false]; // Return false on error
  //    })
  //  );
  //}

  checkSession(): Observable<boolean> {
    return this.http.get(`${this.apiUrl}/check-auth`, { withCredentials: true }).pipe(
      tap((res: any) => {
        console.log('✅ Session valid:', res);
        this.setLoggedIn(true);
        this.startAutoRefresh();
        return true; // ✅ Important!
      }),
      catchError((err) => {
        if (err.status === 401) {
          // Access token may be expired. Try refresh
          console.warn('🔄 Access token expired. Trying to refresh...');

          return this.http.post(`${this.apiUrl}/refresh`, {}, { withCredentials: true }).pipe(
            tap((refreshRes: any) => {
              console.log("✅ Token refreshed during checkSession.");
              //alert("✅ Token refreshed during checkSession.");
              this.setLoggedIn(true);
              this.startAutoRefresh();
            }),
            catchError((refreshErr) => {
              console.error("❌ Refresh token failed during checkSession.", refreshErr);
              this.setLoggedIn(false);
              return of(false);
            })
          );
        } else {
          console.error("❌ Unknown error during checkSession", err);
          this.setLoggedIn(false);
          return of(false);
        }
      })
    );
  }




 



}