import { AuthenticatedSession, SuperRole } from '../types';

export class TenantAuthService {
  private static SESSION_KEY = 'examforge_auth_session';
  private static TOKEN_KEY = 'local_user_token';

  /**
   * Safe getter for current active session
   */
  static getSession(): AuthenticatedSession | null {
    try {
      const val = localStorage.getItem(this.SESSION_KEY);
      if (!val) return null;
      const parsed = JSON.parse(val) as AuthenticatedSession;
      
      // Revoke if expired
      if (Date.now() > parsed.expiresAt) {
        this.clearSession();
        return null;
      }
      return parsed;
    } catch {
      return null;
    }
  }

  /**
   * Save active credentials locally
   */
  static saveSession(session: AuthenticatedSession) {
    try {
      localStorage.setItem(this.SESSION_KEY, JSON.stringify(session));
      localStorage.setItem(this.TOKEN_KEY, session.token);
    } catch (e) {
      console.warn("Storage failed to update session:", e);
    }
  }

  /**
   * Clear active trace credentials on logout
   */
  static clearSession() {
    localStorage.removeItem(this.SESSION_KEY);
    localStorage.removeItem(this.TOKEN_KEY);
    localStorage.removeItem('local_user_profile');
  }

  /**
   * Execute authentication using Tenant boundaries
   */
  static async loginTenant(payload: {
    idOrEmail: string;
    pinOrPass: string;
    schoolId: string;
  }): Promise<AuthenticatedSession> {
    const isEmail = payload.idOrEmail.includes('@');
    const endpoint = isEmail ? '/api/auth/login-email' : '/api/auth/login';
    
    const response = await fetch(endpoint, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'X-Tenant-School-ID': payload.schoolId, // Strict school boundary header
      },
      body: JSON.stringify({
        id: payload.idOrEmail,
        email: payload.idOrEmail,
        pin: payload.pinOrPass,
        password: payload.pinOrPass,
        schoolId: payload.schoolId
      }),
    });

    if (!response.ok) {
      const errorData = await response.json().catch(() => ({ error: 'Verification failed.' }));
      throw new Error(errorData.error || 'Failed to establish tenant session.');
    }

    const { user, customToken } = await response.json();
    
    const formedSession: AuthenticatedSession = {
      uid: user.id || user.uid,
      role: (user.role as SuperRole) || 'student',
      schoolId: payload.schoolId || user.schoolId || 'pilot-default-school',
      email: user.email,
      fullName: user.fullName || 'Anonymous Candidate',
      token: customToken || localStorage.getItem(this.TOKEN_KEY) || '',
      issuedAt: Date.now(),
      expiresAt: Date.now() + 24 * 60 * 60 * 1000, // 24 hours
    };

    this.saveSession(formedSession);
    return formedSession;
  }

  /**
   * Enforces role access verification dynamically in React routers or hooks
   */
  static authorizeRole(requiredRoles: SuperRole[]): boolean {
    const s = this.getSession();
    if (!s) return false;
    return requiredRoles.includes(s.role);
  }
}