import { useState, useEffect, useCallback } from 'react';
import {
  channelsApi,
  templatesApi,
  preferencesApi,
  inAppApi,
} from '../api';
import type {
  NotificationChannel,
  NotificationTemplate,
  NotificationTemplateCreateInput,
  NotificationPreference,
  NotificationPreferenceUpdateInput,
  InAppNotification,
  InAppNotificationsFilters,
} from '../types';

// ============================================================================
// Channels Hook
// ============================================================================

interface UseChannelsReturn {
  channels: NotificationChannel[];
  isLoading: boolean;
  error: Error | null;
  refresh: () => Promise<void>;
  getByCode: (code: string) => Promise<NotificationChannel>;
}

export function useChannels(): UseChannelsReturn {
  const [channels, setChannels] = useState<NotificationChannel[]>([]);
  const [isLoading, setIsLoading] = useState(true);
  const [error, setError] = useState<Error | null>(null);

  const fetchChannels = useCallback(async () => {
    setIsLoading(true);
    setError(null);
    try {
      const data = await channelsApi.getAll();
      setChannels(data);
    } catch (err) {
      setError(err instanceof Error ? err : new Error('Error fetching channels'));
    } finally {
      setIsLoading(false);
    }
  }, []);

  useEffect(() => {
    fetchChannels();
  }, [fetchChannels]);

  const getByCode = useCallback(async (code: string): Promise<NotificationChannel> => {
    return channelsApi.getByCode(code);
  }, []);

  return {
    channels,
    isLoading,
    error,
    refresh: fetchChannels,
    getByCode,
  };
}

// ============================================================================
// Templates Hook
// ============================================================================

interface UseTemplatesReturn {
  templates: NotificationTemplate[];
  isLoading: boolean;
  error: Error | null;
  refresh: () => Promise<void>;
  getByCode: (code: string) => Promise<NotificationTemplate>;
  create: (data: NotificationTemplateCreateInput) => Promise<NotificationTemplate>;
  update: (id: string, data: Partial<NotificationTemplateCreateInput>) => Promise<NotificationTemplate>;
  remove: (id: string) => Promise<void>;
}

export function useTemplates(): UseTemplatesReturn {
  const [templates, setTemplates] = useState<NotificationTemplate[]>([]);
  const [isLoading, setIsLoading] = useState(true);
  const [error, setError] = useState<Error | null>(null);

  const fetchTemplates = useCallback(async () => {
    setIsLoading(true);
    setError(null);
    try {
      const data = await templatesApi.getAll();
      setTemplates(data);
    } catch (err) {
      setError(err instanceof Error ? err : new Error('Error fetching templates'));
    } finally {
      setIsLoading(false);
    }
  }, []);

  useEffect(() => {
    fetchTemplates();
  }, [fetchTemplates]);

  const getByCode = useCallback(async (code: string): Promise<NotificationTemplate> => {
    return templatesApi.getByCode(code);
  }, []);

  const create = useCallback(async (data: NotificationTemplateCreateInput): Promise<NotificationTemplate> => {
    const result = await templatesApi.create(data);
    await fetchTemplates();
    return result;
  }, [fetchTemplates]);

  const update = useCallback(async (id: string, data: Partial<NotificationTemplateCreateInput>): Promise<NotificationTemplate> => {
    const result = await templatesApi.update(id, data);
    await fetchTemplates();
    return result;
  }, [fetchTemplates]);

  const remove = useCallback(async (id: string): Promise<void> => {
    await templatesApi.delete(id);
    await fetchTemplates();
  }, [fetchTemplates]);

  return {
    templates,
    isLoading,
    error,
    refresh: fetchTemplates,
    getByCode,
    create,
    update,
    remove,
  };
}

// ============================================================================
// Preferences Hook
// ============================================================================

interface UseNotificationPreferencesReturn {
  preferences: NotificationPreference | null;
  isLoading: boolean;
  isSaving: boolean;
  error: Error | null;
  refresh: () => Promise<void>;
  update: (data: NotificationPreferenceUpdateInput) => Promise<NotificationPreference>;
}

export function useNotificationPreferences(): UseNotificationPreferencesReturn {
  const [preferences, setPreferences] = useState<NotificationPreference | null>(null);
  const [isLoading, setIsLoading] = useState(true);
  const [isSaving, setIsSaving] = useState(false);
  const [error, setError] = useState<Error | null>(null);

  const fetchPreferences = useCallback(async () => {
    setIsLoading(true);
    setError(null);
    try {
      const data = await preferencesApi.get();
      setPreferences(data);
    } catch (err) {
      setError(err instanceof Error ? err : new Error('Error fetching preferences'));
    } finally {
      setIsLoading(false);
    }
  }, []);

  useEffect(() => {
    fetchPreferences();
  }, [fetchPreferences]);

  const update = useCallback(async (data: NotificationPreferenceUpdateInput): Promise<NotificationPreference> => {
    setIsSaving(true);
    setError(null);
    try {
      const result = await preferencesApi.update(data);
      setPreferences(result);
      return result;
    } catch (err) {
      const error = err instanceof Error ? err : new Error('Error updating preferences');
      setError(error);
      throw error;
    } finally {
      setIsSaving(false);
    }
  }, []);

  return {
    preferences,
    isLoading,
    isSaving,
    error,
    refresh: fetchPreferences,
    update,
  };
}

// ============================================================================
// In-App Notifications Hook
// ============================================================================

interface UseInAppNotificationsOptions {
  initialFilters?: InAppNotificationsFilters;
  autoLoad?: boolean;
  pollInterval?: number;
}

interface UseInAppNotificationsReturn {
  notifications: InAppNotification[];
  unreadCount: number;
  total: number;
  page: number;
  totalPages: number;
  isLoading: boolean;
  error: Error | null;
  filters: InAppNotificationsFilters;
  setFilters: (filters: InAppNotificationsFilters) => void;
  refresh: () => Promise<void>;
  markAsRead: (id: string) => Promise<void>;
  markAllAsRead: () => Promise<void>;
  archive: (id: string) => Promise<void>;
  remove: (id: string) => Promise<void>;
}

export function useInAppNotifications(
  options: UseInAppNotificationsOptions = {}
): UseInAppNotificationsReturn {
  const { initialFilters = {}, autoLoad = true, pollInterval } = options;

  const [notifications, setNotifications] = useState<InAppNotification[]>([]);
  const [unreadCount, setUnreadCount] = useState(0);
  const [total, setTotal] = useState(0);
  const [page, setPage] = useState(1);
  const [totalPages, setTotalPages] = useState(0);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<Error | null>(null);
  const [filters, setFilters] = useState<InAppNotificationsFilters>(initialFilters);

  const fetchNotifications = useCallback(async () => {
    setIsLoading(true);
    setError(null);
    try {
      const response = await inAppApi.getAll(filters);
      setNotifications(response.data);
      setUnreadCount(response.unreadCount);
      setTotal(response.total);
      setPage(response.page);
      setTotalPages(response.totalPages);
    } catch (err) {
      setError(err instanceof Error ? err : new Error('Error fetching notifications'));
    } finally {
      setIsLoading(false);
    }
  }, [filters]);

  const fetchUnreadCount = useCallback(async () => {
    try {
      const count = await inAppApi.getUnreadCount();
      setUnreadCount(count);
    } catch (err) {
      // Silently fail for unread count polling
    }
  }, []);

  useEffect(() => {
    if (autoLoad) {
      fetchNotifications();
    }
  }, [autoLoad, fetchNotifications]);

  // Poll for unread count
  useEffect(() => {
    if (!pollInterval) return;

    const interval = setInterval(fetchUnreadCount, pollInterval);
    return () => clearInterval(interval);
  }, [pollInterval, fetchUnreadCount]);

  const markAsRead = useCallback(async (id: string): Promise<void> => {
    await inAppApi.markAsRead(id);
    setNotifications(prev =>
      prev.map(n => n.id === id ? { ...n, isRead: true, readAt: new Date().toISOString() } : n)
    );
    setUnreadCount(prev => Math.max(0, prev - 1));
  }, []);

  const markAllAsRead = useCallback(async (): Promise<void> => {
    await inAppApi.markAllAsRead();
    setNotifications(prev =>
      prev.map(n => ({ ...n, isRead: true, readAt: new Date().toISOString() }))
    );
    setUnreadCount(0);
  }, []);

  const archive = useCallback(async (id: string): Promise<void> => {
    await inAppApi.archive(id);
    setNotifications(prev => prev.filter(n => n.id !== id));
  }, []);

  const remove = useCallback(async (id: string): Promise<void> => {
    await inAppApi.delete(id);
    setNotifications(prev => prev.filter(n => n.id !== id));
  }, []);

  return {
    notifications,
    unreadCount,
    total,
    page,
    totalPages,
    isLoading,
    error,
    filters,
    setFilters,
    refresh: fetchNotifications,
    markAsRead,
    markAllAsRead,
    archive,
    remove,
  };
}

// ============================================================================
// Notification Bell Hook (for header/navbar)
// ============================================================================

interface UseNotificationBellReturn {
  unreadCount: number;
  recentNotifications: InAppNotification[];
  isLoading: boolean;
  refresh: () => Promise<void>;
  markAsRead: (id: string) => Promise<void>;
  markAllAsRead: () => Promise<void>;
}

export function useNotificationBell(pollInterval = 30000): UseNotificationBellReturn {
  const {
    notifications: recentNotifications,
    unreadCount,
    isLoading,
    refresh,
    markAsRead,
    markAllAsRead,
  } = useInAppNotifications({
    initialFilters: { limit: 5, includeRead: false },
    pollInterval,
  });

  return {
    unreadCount,
    recentNotifications,
    isLoading,
    refresh,
    markAsRead,
    markAllAsRead,
  };
}