const TELEGRAM_API_BASE = 'https://api.telegram.org';

function getToken(account: string): string {
  const envKey = `TELEGRAM_${account.toUpperCase()}_BOT_TOKEN`;
  return process.env[envKey] ?? '';
}

async function telegramRequest(
  token: string,
  method: string,
  params?: Record<string, unknown>
) {
  const url = `${TELEGRAM_API_BASE}/bot${token}/${method}`;
  const res = await fetch(url, {
    method: params ? 'POST' : 'GET',
    headers: params ? { 'Content-Type': 'application/json' } : undefined,
    body: params ? JSON.stringify(params) : undefined,
    signal: AbortSignal.timeout(15000),
  });

  const data = await res.json();
  if (!data.ok) {
    throw new Error(`Telegram API error: ${data.description ?? 'Unknown error'}`);
  }
  return data.result;
}

export async function getMe(args: { account?: string }): Promise<{
  id: number;
  first_name: string;
  username: string;
  is_bot: boolean;
}> {
  const token = getToken(args.account ?? 'default');
  if (!token) {
    throw new Error('Missing Telegram credentials. Set TELEGRAM_{ACCOUNT}_BOT_TOKEN');
  }
  return telegramRequest(token, 'getMe');
}

export async function sendMessage(args: {
  chat_id: string | number;
  text: string;
  parse_mode?: 'HTML' | 'Markdown' | 'MarkdownV2';
  account?: string;
}): Promise<{ message_id: number; chat_id: string | number }> {
  const token = getToken(args.account ?? 'default');
  if (!token) {
    throw new Error('Missing Telegram credentials. Set TELEGRAM_{ACCOUNT}_BOT_TOKEN');
  }

  const result = await telegramRequest(token, 'sendMessage', {
    chat_id: args.chat_id,
    text: args.text,
    parse_mode: args.parse_mode,
  });

  return {
    message_id: result.message_id,
    chat_id: result.chat.id,
  };
}

export async function sendPhoto(args: {
  chat_id: string | number;
  photo: string;
  caption?: string;
  account?: string;
}): Promise<{ message_id: number; chat_id: string | number }> {
  const token = getToken(args.account ?? 'default');
  if (!token) {
    throw new Error('Missing Telegram credentials. Set TELEGRAM_{ACCOUNT}_BOT_TOKEN');
  }

  const result = await telegramRequest(token, 'sendPhoto', {
    chat_id: args.chat_id,
    photo: args.photo,
    caption: args.caption,
  });

  return {
    message_id: result.message_id,
    chat_id: result.chat.id,
  };
}

export async function getUpdates(args: {
  limit?: number;
  account?: string;
}): Promise<Array<{
  update_id: number;
  message?: {
    message_id: number;
    from?: { id: number; first_name: string; username?: string };
    chat: { id: number; type: string; title?: string };
    date: number;
    text?: string;
  };
}>> {
  const token = getToken(args.account ?? 'default');
  if (!token) {
    throw new Error('Missing Telegram credentials. Set TELEGRAM_{ACCOUNT}_BOT_TOKEN');
  }

  return telegramRequest(token, 'getUpdates', {
    limit: args.limit ?? 10,
  });
}

export async function getChat(args: {
  chat_id: string | number;
  account?: string;
}): Promise<{
  id: number;
  type: string;
  title?: string;
  username?: string;
  description?: string;
  member_count?: number;
}> {
  const token = getToken(args.account ?? 'default');
  if (!token) {
    throw new Error('Missing Telegram credentials. Set TELEGRAM_{ACCOUNT}_BOT_TOKEN');
  }

  return telegramRequest(token, 'getChat', {
    chat_id: args.chat_id,
  });
}