/**
 * API модуль для чата
 */

import apiClient from '@/lib/api-client';

export interface Chat {
  id: number;
  uuid?: string;
  participants?: number[];
  participant_name?: string;
  avatar_url?: string | null;
  other_user_id?: number | null;
  other_is_online?: boolean;
  other_last_activity?: string | null;
  last_message?: string;
  last_message_time?: string;
  unread_count?: number;
  created_at?: string;
  // расширенные поля из бэка (для удобного маппинга)
  my_participant?: { unread_count?: number; is_muted?: boolean; is_pinned?: boolean };
  other_participant?: {
    full_name?: string;
    first_name?: string;
    last_name?: string;
    avatar?: string | null;
    avatar_url?: string | null;
    role?: string;
  };
  last_message_obj?: any;
}

export interface Message {
  id: number;
  uuid?: string;
  chat: number;
  // у системных сообщений может быть строка/NULL
  sender: any;
  sender_id?: number | null;
  sender_name?: string;
  content: string;
  file?: string;
  file_type?: string;
  created_at?: string;
  is_read?: boolean;
}

export interface PaginatedResponse<T> {
  count: number;
  next: string | null;
  previous: string | null;
  results: T[];
}

/**
 * Получить список чатов (conversations)
 */
export async function getConversations(params?: {
  page?: number;
  page_size?: number;
}): Promise<PaginatedResponse<Chat>> {
  const response = await apiClient.get<Chat[] | PaginatedResponse<Chat>>('/chat/chats/', {
    params,
  });
  const data: any = response.data;
  if (Array.isArray(data)) {
    return { count: data.length, next: null, previous: null, results: data };
  }
  return {
    count: data?.count ?? (data?.results?.length ?? 0),
    next: data?.next ?? null,
    previous: data?.previous ?? null,
    results: data?.results ?? [],
  };
}

/**
 * Получить чат по UUID (detail=true в DRF)
 */
export async function getChatById(uuid: string): Promise<Chat> {
  const response = await apiClient.get<Chat>(`/chat/chats/${uuid}/`);
  return response.data;
}

/**
 * Создать чат
 */
export async function createChat(participantId: number): Promise<Chat> {
  const response = await apiClient.post<Chat>('/chat/chats/', {
    participants: [participantId],
  });
  return response.data;
}

/**
 * Получить сообщения чата
 */
export async function getMessages(
  chatId: number,
  params?: { page?: number; page_size?: number }
): Promise<PaginatedResponse<Message>> {
  // fallback: если нет uuid — используем общий endpoint
  const response = await apiClient.get<PaginatedResponse<Message>>('/chat/messages/', {
    params: { ...params, chat: chatId },
  });
  return response.data;
}

export async function getChatMessagesByUuid(
  chatUuid: string,
  params?: { page?: number; page_size?: number }
): Promise<PaginatedResponse<Message>> {
  const response = await apiClient.get<PaginatedResponse<Message>>(
    `/chat/chats/${chatUuid}/messages/`,
    { params }
  );
  return response.data;
}

/**
 * Отправить сообщение
 */
export async function sendMessage(
  chatId: number,
  content: string,
  file?: File
): Promise<Message> {
  const formData = new FormData();
  formData.append('chat', chatId.toString());
  formData.append('content', content);
  if (file) {
    formData.append('file', file);
  }

  const response = await apiClient.post<any>('/chat/messages/', formData, {
    headers: {
      'Content-Type': 'multipart/form-data',
    },
  });
  const data: any = response.data;
  // backend может возвращать { success: true, data: {...} }
  if (data && typeof data === 'object' && 'data' in data) {
    return data.data as Message;
  }
  return data as Message;
}

/**
 * Отметить сообщения как прочитанные
 */
export async function markMessagesAsRead(chatUuid: string, messageUuids?: string[]): Promise<void> {
  await apiClient.post(`/chat/chats/${chatUuid}/mark_read/`, messageUuids ? { message_uuids: messageUuids } : {});
}

/**
 * Получить или создать чат для урока
 */
export async function getOrCreateLessonChat(lessonId: number): Promise<Chat> {
  const res = await apiClient.get<{ success: boolean; data: Chat } | Chat>(
    `/chat/chats/lesson_chat/?lesson_id=${lessonId}`
  );
  const data = res.data;
  if (data && typeof data === 'object' && 'success' in data && 'data' in data) {
    return (data as { success: boolean; data: Chat }).data;
  }
  return data as Chat;
}