// ============================================
// Telegram Bot API Helpers
// ============================================

export class TelegramError extends Error {
  constructor(
    message: string,
    public readonly code?: number,
    public readonly description?: string
  ) {
    super(message);
    this.name = 'TelegramError';
  }
}

export interface InlineKeyboardButton {
  text: string;
  url?: string;
  callback_data?: string;
  web_app?: { url: string };
}

async function callTelegramAPI(
  token: string,
  method: string,
  body: Record<string, unknown>
): Promise<Response> {
  const response = await fetch(
    `https://api.telegram.org/bot${token}/${method}`,
    {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(body),
    }
  );

  if (!response.ok) {
    let description = '';
    try {
      const errorData = await response.json() as { description?: string };
      description = errorData.description || '';
    } catch {
      // JSON parse failure ignored
    }
    throw new TelegramError(
      `Telegram API ${method} failed: ${response.status}`,
      response.status,
      description
    );
  }

  return response;
}

function wrapTelegramCall(method: string, fn: () => Promise<Response>): Promise<void> {
  return fn().then(() => undefined).catch((error: unknown) => {
    if (error instanceof TelegramError) throw error;
    throw new TelegramError(
      `Network error in ${method}`,
      undefined,
      error instanceof Error ? error.message : String(error)
    );
  });
}

export async function sendMessage(
  token: string,
  chatId: number,
  text: string,
  options?: {
    parse_mode?: 'HTML' | 'Markdown' | 'MarkdownV2';
    reply_to_message_id?: number;
    disable_notification?: boolean;
  }
): Promise<void> {
  return wrapTelegramCall('sendMessage', () =>
    callTelegramAPI(token, 'sendMessage', {
      chat_id: chatId,
      text,
      parse_mode: options?.parse_mode || 'HTML',
      reply_to_message_id: options?.reply_to_message_id,
      disable_notification: options?.disable_notification,
    })
  );
}

export async function sendMessageWithKeyboard(
  token: string,
  chatId: number,
  text: string,
  keyboard: InlineKeyboardButton[][],
  options?: {
    parse_mode?: 'HTML' | 'Markdown' | 'MarkdownV2';
  }
): Promise<void> {
  return wrapTelegramCall('sendMessageWithKeyboard', () =>
    callTelegramAPI(token, 'sendMessage', {
      chat_id: chatId,
      text,
      parse_mode: options?.parse_mode || 'HTML',
      reply_markup: { inline_keyboard: keyboard },
    })
  );
}

export async function sendChatAction(
  token: string,
  chatId: number,
  action: 'typing' | 'upload_photo' | 'upload_document' = 'typing'
): Promise<void> {
  return wrapTelegramCall('sendChatAction', () =>
    callTelegramAPI(token, 'sendChatAction', {
      chat_id: chatId,
      action,
    })
  );
}

export async function answerCallbackQuery(
  token: string,
  callbackQueryId: string,
  options?: {
    text?: string;
    show_alert?: boolean;
  }
): Promise<void> {
  return wrapTelegramCall('answerCallbackQuery', () =>
    callTelegramAPI(token, 'answerCallbackQuery', {
      callback_query_id: callbackQueryId,
      text: options?.text,
      show_alert: options?.show_alert,
    })
  );
}

export async function editMessageText(
  token: string,
  chatId: number,
  messageId: number,
  text: string,
  options?: {
    parse_mode?: 'HTML' | 'Markdown' | 'MarkdownV2';
    reply_markup?: { inline_keyboard: InlineKeyboardButton[][] };
  }
): Promise<void> {
  return wrapTelegramCall('editMessageText', () =>
    callTelegramAPI(token, 'editMessageText', {
      chat_id: chatId,
      message_id: messageId,
      text,
      parse_mode: options?.parse_mode || 'HTML',
      reply_markup: options?.reply_markup,
    })
  );
}

export async function sendPhoto(
  token: string,
  chatId: number,
  photo: ArrayBuffer,
  options?: {
    caption?: string;
    parse_mode?: 'HTML' | 'Markdown' | 'MarkdownV2';
    reply_to_message_id?: number;
  }
): Promise<void> {
  const formData = new FormData();
  formData.append('chat_id', String(chatId));
  formData.append('photo', new Blob([photo], { type: 'image/png' }), 'diagram.png');
  if (options?.caption) {
    formData.append('caption', options.caption);
    formData.append('parse_mode', options.parse_mode || 'HTML');
  }
  if (options?.reply_to_message_id) {
    formData.append('reply_to_message_id', String(options.reply_to_message_id));
  }

  try {
    const response = await fetch(
      `https://api.telegram.org/bot${token}/sendPhoto`,
      { method: 'POST', body: formData }
    );

    if (!response.ok) {
      let description = '';
      try {
        const errorData = await response.json() as { description?: string };
        description = errorData.description || '';
      } catch {
        // JSON parse failure ignored
      }
      throw new TelegramError(
        `Telegram API sendPhoto failed: ${response.status}`,
        response.status,
        description
      );
    }
  } catch (error) {
    if (error instanceof TelegramError) throw error;
    throw new TelegramError(
      'Network error in sendPhoto',
      undefined,
      error instanceof Error ? error.message : String(error)
    );
  }
}

export async function setWebhook(
  token: string,
  webhookUrl: string,
  secretToken: string
): Promise<{ ok: boolean; description?: string }> {
  const response = await fetch(
    `https://api.telegram.org/bot${token}/setWebhook`,
    {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        url: webhookUrl,
        secret_token: secretToken,
        allowed_updates: ['message', 'callback_query'],
        drop_pending_updates: true,
      }),
    }
  );

  return response.json() as Promise<{ ok: boolean; description?: string }>;
}

export async function getWebhookInfo(token: string): Promise<unknown> {
  const response = await fetch(
    `https://api.telegram.org/bot${token}/getWebhookInfo`
  );
  return response.json();
}