import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';
import { HttpClient, HttpHeaders, HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs/internal/Observable';
import { tap } from 'rxjs/operators';
import { catchError } from 'rxjs/operators';
import { throwError } from 'rxjs';
@Injectable({
  providedIn: 'root'
})
export class AuthenticationService {
  private apiUrl = 'http://127.0.0.1:5000';  // Your backend URL
  private loggedInSubject = new BehaviorSubject<boolean>(this.isLoggedIn());  // BehaviorSubject to track login status

  constructor(private http: HttpClient) {
    // Change from 5 minutes to 30 seconds
    setInterval(() => this.checkAndRefreshToken(), 30 * 1000);  // Every 30 seconds

    // Periodically check for token expiry and refresh it if necessary
    //setInterval(() => this.checkAndRefreshToken(), 5 * 60 * 1000);  // Check every 5 minutes
  }
  



  // ✅ Login Method
  // ✅ Login Method (returns an Observable)
  login(username: string, password: string): Observable<any> {
    const loginData = { username, password };
    return this.http.post(`${this.apiUrl}/login`, loginData).pipe(
      tap((response: any) => {
        //const now = new Date();
        // Store tokens in localStorage
        localStorage.setItem('access_token', response.access_token);
        localStorage.setItem('refresh_token', response.refresh_token);

        
        // Optionally store expiry time of the access token (2 minutes)
        const accessTokenExpiry = Date.now() + 2 * 60 * 1000; // 2 minutes expiration for access token
        localStorage.setItem('access_token_expiry', accessTokenExpiry.toString());

        // Optionally store expiry time of the refresh token (5 minutes)
        const refreshTokenExpiry = Date.now() + 10 * 60 * 1000; // 5 minutes expiration for refresh token
        localStorage.setItem('refresh_token_expiry', refreshTokenExpiry.toString());

        this.loggedInSubject.next(true);

      }),
      catchError(error => {
        // Handle error (token expiry / invalid login)
        if (error.status === 401 && error.error.message === 'Token has expired') {
          //alert('Your session has expired, please log in again.');
        }
        return throwError(error);
      })
    );
  }








  logout(): Observable<any> {
    const token = this.getToken();
    console.log('🔑 Token at logout start:', token);

    this.removeToken(); // Remove token first
    this.loggedInSubject.next(false);

    if (!token) {
      console.warn('⚠️ No token found. Emitting success anyway.');
      return new Observable(observer => {
        observer.next(true);
        observer.complete();
      });
    }

    const headers = new HttpHeaders().set('Authorization', `Bearer ${token}`);
    console.log('📤 Sending logout request with headers:', headers);

    return this.http.post(`${this.apiUrl}/logout`, {}, { headers }).pipe(
      tap(() => {
        console.log('✅ Logout API request completed');  // This should now appear
      }),
      catchError((error) => {
        console.error('❌ Logout error in service:', error);
        return new Observable(observer => {
          observer.next(true); // Continue flow even on error
          observer.complete();
        });
      })
    );
  }






  // ✅ Get Token (to use for making authorized requests)
  getToken(): string | null {
    return localStorage.getItem('access_token');
  }

  // ✅ Store Token
  storeToken(token: string): void {
    localStorage.setItem('access_token', token);
    console.log('Token stored:', token);  // Log the token to confirm it's saved
    this.loggedInSubject.next(true);  // Update login status
  }
  // ✅ Remove Token
  removeToken(): void {
    localStorage.removeItem('access_token');
    localStorage.removeItem('refresh_token');
    localStorage.removeItem('access_token_expiry');
    this.loggedInSubject.next(false);  // Update login status
  }

  // ✅ Check if the user is logged in
  isLoggedIn(): boolean {
    return !!this.getToken();
  }
  // ✅ Observable to track login status
  get isLoggedIn$(): Observable<boolean> {
    return this.loggedInSubject.asObservable();
  }



  checkAndRefreshToken() {
    const accessTokenExpiry = localStorage.getItem('access_token_expiry');
    if (accessTokenExpiry && Date.now() >= (+accessTokenExpiry - 5000)) {
      // Refresh 5 seconds before expiry
      this.refreshAccessToken();
    }

    
  }

  // Check token every 5 minutes

  // ✅ Refresh Access Token Method
  // ✅ Refresh Access Token Method
  //refreshAccessToken() {
  //  const refreshToken = localStorage.getItem('refresh_token');
  //  if (refreshToken) {
  //    this.http.post(`${this.apiUrl}/refresh`, { refresh_token: refreshToken }).subscribe((response: any) => {
  //      // Store the new access token
  //      localStorage.setItem('access_token', response.access_token);

  //      // Optionally, update the expiry time of the new access token (2 minutes)
  //      const newAccessTokenExpiry = Date.now() + 2 * 60 * 1000; // 2 minutes
  //      localStorage.setItem('access_token_expiry', newAccessTokenExpiry.toString());
  //      alert('Your access token has been refreshed successfully!');
  //    }, error => {
  //      console.log("Error refreshing token", error);
  //      // Handle token refresh failure (e.g., log out the user)
  //      this.logout();
  //    });
  //  }
  //}
  refreshAccessToken() {
    const refreshToken = localStorage.getItem('refresh_token');

    if (refreshToken) {
      this.http.post(`${this.apiUrl}/refresh`, { refresh_token: refreshToken }).subscribe(
        (response: any) => {
          // Store the new access token
          localStorage.setItem('access_token', response.access_token);

          // Update expiry
          const newAccessTokenExpiry = Date.now() + 2 * 60 * 1000; // 2 minutes
          localStorage.setItem('access_token_expiry', newAccessTokenExpiry.toString());

          //alert('Your access token has been refreshed successfully!');
        },
        error => {
          console.log("Error refreshing token", error);

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

            // ✅ Remove tokens and redirect to login
            this.removeToken();
            this.loggedInSubject.next(false);
            window.location.href = '/authentication';  // Adjust this if your login route is different
          } else {
            // Other errors can be handled differently
            console.error("Unexpected error:", error);
          }
        }
      );
    }
  }


}