// Notification System Composable
// Provides consistent toast, alert, and confirmation patterns

import { ref, reactive, readonly } from 'vue';
import { useDesignSystem } from './useDesignSystem';

// Global notification state
const notifications = ref([]);
const nextId = ref(1);

export const useNotifications = () => {
  const { statusColors, utils } = useDesignSystem();

  // Generate unique ID for notifications
  const generateId = () => nextId.value++;

  // Notification types
  const types = {
    SUCCESS: 'success',
    ERROR: 'error',
    WARNING: 'warning',
    INFO: 'info'
  };

  // Default configuration
  const defaultConfig = {
    duration: 5000,
    persistent: false,
    position: 'top-right',
    showIcon: true,
    showClose: true,
    allowHtml: false,
    maxNotifications: 5
  };

  // Add notification to queue
  const addNotification = (notification) => {
    const id = generateId();
    const config = { ...defaultConfig, ...notification, id };
    
    // Limit number of notifications
    if (notifications.value.length >= defaultConfig.maxNotifications) {
      notifications.value.shift();
    }
    
    notifications.value.push(config);
    
    // Auto-remove if not persistent
    if (!config.persistent && config.duration > 0) {
      setTimeout(() => {
        removeNotification(id);
      }, config.duration);
    }
    
    return id;
  };

  // Remove notification by ID
  const removeNotification = (id) => {
    const index = notifications.value.findIndex(n => n.id === id);
    if (index > -1) {
      notifications.value.splice(index, 1);
    }
  };

  // Clear all notifications
  const clearAll = () => {
    notifications.value = [];
  };

  // Success notification
  const success = (message, options = {}) => {
    return addNotification({
      type: types.SUCCESS,
      title: options.title || 'Success',
      message,
      icon: 'mdi:check-circle',
      ...options
    });
  };

  // Error notification
  const error = (message, options = {}) => {
    return addNotification({
      type: types.ERROR,
      title: options.title || 'Error',
      message,
      icon: 'mdi:alert-circle',
      persistent: options.persistent !== undefined ? options.persistent : true,
      ...options
    });
  };

  // Warning notification
  const warning = (message, options = {}) => {
    return addNotification({
      type: types.WARNING,
      title: options.title || 'Warning',
      message,
      icon: 'mdi:alert',
      duration: options.duration || 7000,
      ...options
    });
  };

  // Info notification
  const info = (message, options = {}) => {
    return addNotification({
      type: types.INFO,
      title: options.title || 'Information',
      message,
      icon: 'mdi:information',
      ...options
    });
  };

  // Confirmation dialog
  const confirm = (options = {}) => {
    return new Promise((resolve) => {
      const id = addNotification({
        type: 'confirm',
        title: options.title || 'Confirm Action',
        message: options.message || 'Are you sure you want to proceed?',
        icon: options.icon || 'mdi:help-circle',
        persistent: true,
        showClose: false,
        actions: [
          {
            label: options.cancelLabel || 'Cancel',
            variant: 'secondary-outline',
            action: () => {
              removeNotification(id);
              resolve(false);
            }
          },
          {
            label: options.confirmLabel || 'Confirm',
            variant: options.dangerous ? 'danger' : 'primary',
            action: () => {
              removeNotification(id);
              resolve(true);
            }
          }
        ],
        ...options
      });
    });
  };

  // Loading notification with promise
  const loading = (promise, options = {}) => {
    const id = addNotification({
      type: 'loading',
      title: options.title || 'Loading...',
      message: options.message || 'Please wait...',
      icon: 'mdi:loading',
      persistent: true,
      showClose: false,
      ...options
    });

    return promise
      .then((result) => {
        removeNotification(id);
        if (options.successMessage) {
          success(options.successMessage);
        }
        return result;
      })
      .catch((err) => {
        removeNotification(id);
        if (options.errorMessage) {
          error(options.errorMessage);
        } else {
          error(err.message || 'An error occurred');
        }
        throw err;
      });
  };

  // DMS-specific notifications
  const dms = {
    // Document operations
    documentUploaded: (filename, count = 1) => {
      const message = count === 1 
        ? `Document "${filename}" uploaded successfully`
        : `${count} documents uploaded successfully`;
      return success(message, { title: 'Upload Complete' });
    },

    documentDeleted: (filename) => {
      return success(`Document "${filename}" deleted successfully`, {
        title: 'Document Deleted'
      });
    },

    documentShared: (filename, users) => {
      const userCount = Array.isArray(users) ? users.length : 1;
      const message = `Document "${filename}" shared with ${userCount} user${userCount > 1 ? 's' : ''}`;
      return success(message, { title: 'Document Shared' });
    },

    // Permission changes
    accessGranted: (resource) => {
      return success(`Access granted to ${resource}`, {
        title: 'Access Granted'
      });
    },

    accessRevoked: (resource) => {
      return warning(`Access revoked for ${resource}`, {
        title: 'Access Revoked'
      });
    },

    // Sync operations
    syncStarted: () => {
      return info('Synchronization started', {
        title: 'Sync in Progress',
        duration: 3000
      });
    },

    syncCompleted: (itemCount) => {
      return success(`Synchronization completed. ${itemCount} items updated.`, {
        title: 'Sync Complete'
      });
    },

    syncFailed: (error) => {
      return error(`Synchronization failed: ${error}`, {
        title: 'Sync Error'
      });
    },

    // Version control
    newVersionCreated: (filename, version) => {
      return success(`Version ${version} created for "${filename}"`, {
        title: 'New Version'
      });
    },

    versionRestored: (filename, version) => {
      return success(`Document "${filename}" restored to version ${version}`, {
        title: 'Version Restored'
      });
    },

    // Audit & Security
    unauthorizedAccess: (resource) => {
      return error(`Unauthorized access attempt to ${resource}`, {
        title: 'Security Alert',
        persistent: true
      });
    },

    sessionExpiring: (minutes) => {
      return warning(`Your session will expire in ${minutes} minutes`, {
        title: 'Session Warning',
        duration: 10000
      });
    }
  };

  // Bulk operations helper
  const bulk = {
    success: (operations) => {
      const count = operations.length;
      const message = `${count} operation${count > 1 ? 's' : ''} completed successfully`;
      return success(message, { title: 'Bulk Operation Complete' });
    },

    partialSuccess: (successful, failed) => {
      const message = `${successful} operation(s) completed, ${failed} failed`;
      return warning(message, { title: 'Partial Success' });
    },

    failed: (count, error) => {
      const message = `${count} operation(s) failed: ${error}`;
      return error(message, { title: 'Bulk Operation Failed' });
    }
  };

  return {
    // State
    notifications: readonly(notifications),
    
    // Core methods
    success,
    error,
    warning,
    info,
    confirm,
    loading,
    
    // Management
    removeNotification,
    clearAll,
    
    // DMS-specific
    dms,
    bulk,
    
    // Utilities
    types,
    defaultConfig
  };
};

// Global instance for app-wide usage
let globalInstance = null;

export const setupNotifications = () => {
  if (!globalInstance) {
    globalInstance = useNotifications();
  }
  return globalInstance;
};

export const useGlobalNotifications = () => {
  if (!globalInstance) {
    throw new Error('Notifications not initialized. Call setupNotifications() first.');
  }
  return globalInstance;
};