/**
 * useAuth Composable
 *
 * Manages authentication state including login, logout, token storage, and user info
 */

import { ref, computed, watch } from 'vue';
import { apiClient } from '../utilities/api-client.js';

// Shared state
const token = ref(localStorage.getItem('auth_token') || null);
const user = ref(null);
const isLoading = ref(false);
const error = ref(null);

// Compute derived states
const isAuthenticated = computed(() => !!token.value && !!user.value);
const isAdmin = computed(() => user.value?.isAdmin || false);

/**
 * Load and verify stored token on app startup
 */
async function initializeAuth() {
  const storedToken = localStorage.getItem('auth_token');

  if (!storedToken) {
    token.value = null;
    user.value = null;
    return;
  }

  try {
    const response = await apiClient.post('/api/auth/verify', {
      token: storedToken
    });
    token.value = storedToken;
    user.value = response.user;
  } catch (err) {
    // Token is invalid, clear it
    localStorage.removeItem('auth_token');
    token.value = null;
    user.value = null;
  }
}

/**
 * Login with password
 * @param {string} password - Admin password
 * @returns {Promise<Object>} Response with token and user info
 * @throws {Error} If login fails
 */
async function login(password) {
  isLoading.value = true;
  error.value = null;

  try {
    if (!password) {
      throw new Error('Password is required');
    }

    const response = await apiClient.post('/api/auth/login', { password });

    // Store token
    token.value = response.token;
    user.value = response.user;
    localStorage.setItem('auth_token', response.token);

    return response;
  } catch (err) {
    error.value = err.message;
    token.value = null;
    user.value = null;
    throw err;
  } finally {
    isLoading.value = false;
  }
}

/**
 * Logout and clear authentication
 */
async function logout() {
  isLoading.value = true;

  try {
    await apiClient.post('/api/auth/logout', {});
  } catch (err) {
    console.error('Logout error:', err);
  } finally {
    // Clear token regardless of API response
    token.value = null;
    user.value = null;
    localStorage.removeItem('auth_token');
    isLoading.value = false;
  }
}

/**
 * Refresh the current token
 * @returns {Promise<Object>} Response with new token
 * @throws {Error} If refresh fails
 */
async function refreshToken() {
  if (!token.value) {
    throw new Error('No token to refresh');
  }

  try {
    const response = await apiClient.post('/api/auth/refresh', {
      token: token.value
    });
    token.value = response.token;
    localStorage.setItem('auth_token', response.token);
    return response;
  } catch (err) {
    // If refresh fails, logout
    await logout();
    throw err;
  }
}

/**
 * Get current user info
 * @returns {Promise<Object>} User info
 */
async function getUserInfo() {
  try {
    const response = await apiClient.get('/api/auth/user', {
      headers: {
        Authorization: `Bearer ${token.value}`
      }
    });
    user.value = response.user;
    return response.user;
  } catch (err) {
    // If getting user info fails, logout
    await logout();
    throw err;
  }
}

/**
 * Check if user has a specific permission
 * @param {string|string[]} permissions - Permission or array of permissions
 * @returns {boolean} True if user has permission
 */
function hasPermission(permissions) {
  if (!user.value) return false;

  const perms = Array.isArray(permissions) ? permissions : [permissions];
  return perms.some(perm => user.value.permissions?.includes(perm));
}

/**
 * Add auth token to API client headers
 */
export function setupAuthInterceptor() {
  if (token.value) {
    apiClient.setDefaultHeader('Authorization', `Bearer ${token.value}`);
  }

  // Watch for token changes and update header
  watch(token, newToken => {
    if (newToken) {
      apiClient.setDefaultHeader('Authorization', `Bearer ${newToken}`);
    } else {
      apiClient.removeDefaultHeader('Authorization');
    }
  });
}

export function useAuth() {
  return {
    // State
    token: computed(() => token.value),
    user: computed(() => user.value),
    isLoading: computed(() => isLoading.value),
    error: computed(() => error.value),

    // Computed
    isAuthenticated,
    isAdmin,

    // Methods
    initializeAuth,
    login,
    logout,
    refreshToken,
    getUserInfo,
    hasPermission,
    setupAuthInterceptor
  };
}