import ky from "ky";
import logger from "../utils/logger.js";
import FormData from "form-data";
import fs from "fs";
import path from "path";

// Function to escape special characters for MarkdownV2
const escapeMarkdown = (text) => {
  return text.replace(/([_*\[\]()~`>#+=|{}.!\\-])/g, '\\$1');
};

// Function to preserve markdown formatting while escaping other special characters
const preserveMarkdown = (text) => {
  // First, temporarily replace valid markdown
  text = text
    .replace(/\*\*(.*?)\*\*/g, '%%%BOLD%%%$1%%%BOLD%%%')
    .replace(/__(.*?)__/g, '%%%ITALIC%%%$1%%%ITALIC%%%')
    .replace(/`(.*?)`/g, '%%%CODE%%%$1%%%CODE%%%')
    .replace(/\[(.*?)\]\((.*?)\)/g, '%%%LINK_TEXT%%%$1%%%LINK_URL%%%$2%%%LINK%%%');

  // Escape all special characters
  text = escapeMarkdown(text);

  // Restore markdown formatting
  return text
    .replace(/%%%BOLD%%%(.*?)%%%BOLD%%%/g, '*$1*')
    .replace(/%%%ITALIC%%%(.*?)%%%ITALIC%%%/g, '_$1_')
    .replace(/%%%CODE%%%(.*?)%%%CODE%%%/g, '`$1`')
    .replace(/%%%LINK_TEXT%%%(.*?)%%%LINK_URL%%%(.*?)%%%LINK%%%/g, '[$1]($2)');
};

/**
 * Sends a message via a Telegram bot.
 * @param {string} telegramToken - The bot's API token.
 * @param {number} chatId - The recipient's Telegram chat ID.
 * @param {string} message - The message text.
 * @param {string} [photoPath] - Optional path to photo file.
 * @returns {Promise<boolean>} - Returns `true` if the message is sent successfully, otherwise `false`.
 */
export const sendTelegramMessage = async (telegramToken, chatId, message, photoPath = null) => {
  try {
    // Process message text if it exists
    const processedMessage = message?.trim() ? preserveMarkdown(message) : '';

    if (photoPath) {
      const formData = new FormData();
      formData.append('chat_id', chatId);

      // Debug information before reading file
      logger.info('Attempting to read file:', {
        photoPath,
        exists: fs.existsSync(photoPath),
        stats: fs.existsSync(photoPath) ? fs.statSync(photoPath) : null,
        dirname: path.dirname(photoPath),
        basename: path.basename(photoPath)
      });

      try {
        // Ensure the file exists before reading
        if (!fs.existsSync(photoPath)) {
          throw new Error(`File does not exist at path: ${photoPath}`);
        }

        // Create read stream and append to FormData
        const photoStream = fs.createReadStream(photoPath);
        formData.append('photo', photoStream);

        if (processedMessage) {
          formData.append('caption', processedMessage);
          formData.append('parse_mode', 'MarkdownV2');
        }

        // Debug the FormData contents
        logger.info('FormData created:', {
          boundaryUsed: formData.getBoundary?.() || 'No boundary found',
          headers: formData.getHeaders?.() || 'No headers available',
          messageLength: processedMessage.length
        });

        // Wait for the entire request to complete
        await new Promise((resolve, reject) => {
          formData.submit({
            host: 'api.telegram.org',
            path: `/bot${telegramToken}/sendPhoto`,
            protocol: 'https:',
          }, (err, res) => {
            if (err) {
              reject(err);
              return;
            }

            let data = '';
            res.on('data', chunk => {
              data += chunk;
            });

            res.on('end', () => {
              try {
                const response = JSON.parse(data);
                if (!response.ok) {
                  reject(new Error(response.description || 'Failed to send photo'));
                } else {
                  resolve(response);
                }
              } catch (e) {
                reject(new Error('Failed to parse Telegram response'));
              }
            });
          });
        });

      } catch (error) {
        // Log detailed error information
        logger.error(`❌ Telegram API Error for chat ${chatId}:`, {
          error: error.message,
          response: error.response ? await error.response.json().catch(() => ({})) : undefined,
          photoPath,
          messageLength: processedMessage.length,
          fileExists: fs.existsSync(photoPath),
          fileStats: fs.existsSync(photoPath) ? fs.statSync(photoPath) : null
        });
        throw error;
      }
    } else {
      try {
        await ky.post(`https://api.telegram.org/bot${telegramToken}/sendMessage`, {
          json: {
            chat_id: chatId,
            text: processedMessage,
            parse_mode: "MarkdownV2",
          },
          timeout: 5000,
        });
      } catch (error) {
        // Log detailed error information
        logger.error(`❌ Telegram API Error for chat ${chatId}:`, {
          error: error.message,
          response: await error.response?.json().catch(() => ({})),
          messageLength: processedMessage.length
        });
        throw error;
      }
    }

    logger.info(`✅ Telegram message sent to ${chatId}`);
    return true;
  } catch (error) {
    logger.error(`❌ Failed to send Telegram message to ${chatId}: ${error.message}`);
    return false;
  }
};

/**
 * Sends messages in bulk while respecting Telegram's rate limits.
 * @param {string} telegramToken - The bot's API token.
 * @param {Array<number>} chatIds - An array of chat IDs to send to.
 * @param {string} message - The message text.
 * @param {string} [photoPath] - Optional path to photo file.
 * @returns {Promise<void>}
 */
export const sendBulkTelegramMessages = async (telegramToken, chatIds, message, photoPath = null) => {
  for (let i = 0; i < chatIds.length; i++) {
    const chatId = chatIds[i];
    await sendTelegramMessage(telegramToken, chatId, message, photoPath);

    if ((i + 1) % 30 === 0) {
      logger.info(`⏳ Rate limit pause (sent ${i + 1} messages)...`);
      await new Promise((resolve) => setTimeout(resolve, 1000));
    }
  }
};