/**
 * Authentication Store
 * Manages user authentication state, login/logout, and token persistence
 */

import { defineStore } from 'pinia';
import { ref, computed } from 'vue';
import { authAPI } from '@/api';
import type { User, LoginRequest, RegisterRequest } from '@/types';

const AUTH_TOKEN_KEY = 'auth_token';
const AUTH_USER_KEY = 'auth_user';
const AUTO_REFRESH_INTERVAL = 60 * 1000; // 60 seconds

export const useAuthStore = defineStore('auth', () => {
  // ==================== State ====================

  const user = ref<User | null>(null);
  const token = ref<string | null>(null);
  let refreshIntervalId: ReturnType<typeof setInterval> | null = null;

  // ==================== Computed ====================

  const isAuthenticated = computed(() => {
    return !!token.value && !!user.value;
  });

  const isAdmin = computed(() => {
    return user.value?.role === 'admin';
  });

  // ==================== Actions ====================

  /**
   * Initialize auth state from localStorage
   * Call this on app startup to restore session
   * Also starts auto-refresh and immediately fetches latest user data
   */
  function checkAuth(): void {
    const savedToken = localStorage.getItem(AUTH_TOKEN_KEY);
    const savedUser = localStorage.getItem(AUTH_USER_KEY);

    if (savedToken && savedUser) {
      try {
        token.value = savedToken;
        user.value = JSON.parse(savedUser);

        // Immediately refresh user data from backend (async, don't block)
        refreshUser().catch((error) => {
          console.error('Failed to refresh user on init:', error);
        });

        // Start auto-refresh interval
        startAutoRefresh();
      } catch (error) {
        console.error('Failed to parse saved user data:', error);
        clearAuth();
      }
    }
  }

  /**
   * Start auto-refresh interval for user data
   * Refreshes user data every 60 seconds
   */
  function startAutoRefresh(): void {
    // Clear existing interval if any
    stopAutoRefresh();

    refreshIntervalId = setInterval(() => {
      if (token.value) {
        refreshUser().catch((error) => {
          console.error('Auto-refresh user failed:', error);
        });
      }
    }, AUTO_REFRESH_INTERVAL);
  }

  /**
   * Stop auto-refresh interval
   */
  function stopAutoRefresh(): void {
    if (refreshIntervalId) {
      clearInterval(refreshIntervalId);
      refreshIntervalId = null;
    }
  }

  /**
   * User login
   * @param credentials - Login credentials (username and password)
   * @returns Promise resolving to the authenticated user
   * @throws Error if login fails
   */
  async function login(credentials: LoginRequest): Promise<User> {
    try {
      const response = await authAPI.login(credentials);

      // Store token and user
      token.value = response.access_token;
      user.value = response.user;

      // Persist to localStorage
      localStorage.setItem(AUTH_TOKEN_KEY, response.access_token);
      localStorage.setItem(AUTH_USER_KEY, JSON.stringify(response.user));

      // Start auto-refresh interval
      startAutoRefresh();

      return response.user;
    } catch (error) {
      // Clear any partial state on error
      clearAuth();
      throw error;
    }
  }

  /**
   * User registration
   * @param userData - Registration data (username, email, password)
   * @returns Promise resolving to the newly registered and authenticated user
   * @throws Error if registration fails
   */
  async function register(userData: RegisterRequest): Promise<User> {
    try {
      const response = await authAPI.register(userData);

      // Store token and user
      token.value = response.access_token;
      user.value = response.user;

      // Persist to localStorage
      localStorage.setItem(AUTH_TOKEN_KEY, response.access_token);
      localStorage.setItem(AUTH_USER_KEY, JSON.stringify(response.user));

      // Start auto-refresh interval
      startAutoRefresh();

      return response.user;
    } catch (error) {
      // Clear any partial state on error
      clearAuth();
      throw error;
    }
  }

  /**
   * User logout
   * Clears all authentication state and persisted data
   */
  function logout(): void {
    // Call API logout (client-side cleanup)
    authAPI.logout();

    // Clear state
    clearAuth();
  }

  /**
   * Refresh current user data
   * Fetches latest user info from the server
   * @returns Promise resolving to the updated user
   * @throws Error if not authenticated or request fails
   */
  async function refreshUser(): Promise<User> {
    if (!token.value) {
      throw new Error('Not authenticated');
    }

    try {
      const updatedUser = await authAPI.getCurrentUser();
      user.value = updatedUser;
      
      // Update localStorage
      localStorage.setItem(AUTH_USER_KEY, JSON.stringify(updatedUser));

      return updatedUser;
    } catch (error) {
      // If refresh fails with 401, clear auth state
      if ((error as { status?: number }).status === 401) {
        clearAuth();
      }
      throw error;
    }
  }

  /**
   * Clear all authentication state
   * Internal helper function
   */
  function clearAuth(): void {
    // Stop auto-refresh
    stopAutoRefresh();

    token.value = null;
    user.value = null;
    localStorage.removeItem(AUTH_TOKEN_KEY);
    localStorage.removeItem(AUTH_USER_KEY);
  }

  // ==================== Return Store API ====================

  return {
    // State
    user,
    token,

    // Computed
    isAuthenticated,
    isAdmin,

    // Actions
    login,
    register,
    logout,
    checkAuth,
    refreshUser,
  };
});