import { HttpHandlerFn, HttpInterceptorFn, HttpRequest } from '@angular/common/http';
import { inject } from '@angular/core';
import { throwError } from 'rxjs';
import { catchError, filter, switchMap, take } from 'rxjs/operators';
import { AuthService } from './auth.service';

export const AuthInterceptor: HttpInterceptorFn = (req: HttpRequest<unknown>, next: HttpHandlerFn) => {
    const authService = inject(AuthService);

    const attachHeaders = (token: string | null) => {
        const activeRole = authService.getActiveRole();
        return req.clone({
            setHeaders: {
                authorization: token ?? '',
                'active-role': activeRole?.code ?? ''
            }
        });
    };

    /**
     * Ejecuta el refresh del token y reintenta la petición original.
     * Si hay un refresh en curso, encola la petición hasta que el nuevo
     * token esté disponible.
     */
    const refreshAndRetry = () => {
        if (authService.isRefreshing) {
            return authService.refreshTokenSubject.pipe(
                filter((token): token is string => token !== null),
                take(1),
                switchMap(token => next(attachHeaders(token)))
            );
        }

        authService.isRefreshing = true;
        authService.refreshTokenSubject.next(null);

        return authService.refreshAccessToken().pipe(
            switchMap(newToken => {
                authService.isRefreshing = false;
                return next(attachHeaders(newToken));
            }),
            catchError(error => {
                authService.isRefreshing = false;
                return throwError(() => error);
            })
        );
    };

    const token = authService.getToken();

    // Refresh proactivo: el token existe pero ya expiró
    if (token && authService.isTokenExpired() && authService.getRefreshToken()) {
        return refreshAndRetry();
    }

    // Flujo normal + fallback 401 por si el servidor rechaza el token
    return next(attachHeaders(token)).pipe(
        catchError(error => {
            if (error.status === 401 && authService.getRefreshToken()) {
                return refreshAndRetry();
            }
            return throwError(() => error);
        })
    );
};