// Import necessary modules for the application
const axios = require('axios'); // Axios is used to make HTTP requests to external APIs or services
const { exec } = require('child_process'); // exec is used to execute shell commands in a child process
const moment = require('moment'); // Moment.js is a library for parsing, validating, manipulating, and formatting dates
const fs = require('fs'); // File system module for interacting with the file system
const path = require('path'); // Path module for handling and transforming file paths
const Tail = require('tail').Tail; // Tail module is used for monitoring log files and reacting to new lines as they are added

// Configuration constants
const LOG_DIRECTORY = '/dockerData/logs'; // Directory where NGINX logs are stored
const BACKEND_URL = 'http://127.0.0.1:3001'; // URL for the backend process that handles log processing
const DISCORD_WEBHOOK_URL = 'WEBHOOKURL'; // URL of the Discord webhook for sending alerts and notifications

// Environment-dependent configuration
const DEBUG = process.env.DEBUG === 'true'; // Enable or disable debug logging based on environment variable
const LOG_BUFFER_LIMIT = 15; // Number of log lines to accumulate before sending them to the backend
const TIME_LIMIT = 10 * 60 * 1000; // Time interval (in milliseconds) to send logs even if buffer is not full (10 minutes)

let logBuffer = []; // Array to store log lines temporarily before sending to backend
let logTails = []; // Array to store active Tail instances for each log file being monitored
let isSendingLogs = false; // Flag to prevent multiple simultaneous log sending operations

// List of IP addresses to ignore in logs (e.g., trusted IPs, public DNS servers)
const ignoredIPs = ['1.1.1.1', '1.0.0.1', '8.8.8.8', '8.8.4.4'];

// List of IP subnets to ignore, commonly used to filter out traffic from known sources like Cloudflare
const ignoredSubnets = [
  '173.245.48.0/20', '103.21.244.0/22', '103.22.200.0/22', '103.31.4.0/22',
  '141.101.64.0/18', '108.162.192.0/18', '190.93.240.0/20', '188.114.96.0/20',
  '197.234.240.0/22', '198.41.128.0/17', '162.158.0.0/15', '104.16.0.0/13',
  '104.24.0.0/14', '172.64.0.0/13', '131.0.72.0/22'
];

// List of specific log files to ignore (e.g., specific proxy logs)
const ignoredFiles = ['proxy-host-149_access.log', 'proxy-host-2_access.log', 'proxy-host-99_access.log'];

// Function to get current timestamp in a formatted string (e.g., 'YYYY-MM-DD HH:mm:ss')
const getTimestamp = () => moment().format('YYYY-MM-DD HH:mm:ss');

// Logging functions for different log levels (INFO, WARN, ERROR, SUCCESS, DEBUG)
const log = {
  info: (message) => console.log(`[${getTimestamp()}] [INFO] ${message}`), // Log informational messages
  warn: (message) => console.log(`[${getTimestamp()}] [WARN] ${message}`), // Log warning messages
  error: (message) => console.log(`[${getTimestamp()}] [ERROR] ${message}`), // Log error messages
  success: (message) => console.log(`[${getTimestamp()}] [SUCCESS] ${message}`), // Log success messages
  debug: (message) => {
    if (DEBUG) { // Log debug messages only if DEBUG mode is enabled
      console.log(`[${getTimestamp()}] [DEBUG] ${message}`);
    }
  }
};

// Function to check if an IP address is in the ignored list or subnets
const isIgnoredIP = async (ip) => {
  if (ignoredIPs.includes(ip)) {
    return true; // Immediately return true if the IP is in the ignored IPs list
  }
  const { default: CIDR } = await import('ip-cidr'); // Dynamically import the ip-cidr module for CIDR range checking
  return ignoredSubnets.some((subnet) => new CIDR(subnet).contains(ip)); // Check if the IP is within any ignored subnets
};

// Function to read and monitor log files in the specified directory using the Tail module
const readLogs = () => {
  log.info('Initiating log reading process...');

  // Stop and clear any existing Tail instances
  logTails.forEach(tail => tail.unwatch());
  logTails = [];

  // Read the directory to get all log files
  fs.readdir(LOG_DIRECTORY, (err, files) => {
    if (err) {
      log.error(`Error reading directory: ${err}`); // Log an error if the directory cannot be read
      return;
    }

    // Filter log files, excluding those in the ignoredFiles list
    const logFiles = files.filter(file => file.endsWith('.log') && !ignoredFiles.includes(file));
    if (logFiles.length === 0) {
      log.warn(`No log files found in directory: ${LOG_DIRECTORY}`); // Warn if no log files are found
      return;
    }

    log.info(`Found ${logFiles.length} log files to tail.`); // Log the number of log files to be monitored

    // For each log file, start a new Tail instance to monitor the file
    logFiles.forEach(file => {
      const filePath = path.join(LOG_DIRECTORY, file); // Create the full path to the log file
      log.info(`Starting to read log from: ${filePath}`); // Log the start of monitoring for this file
      try {
        const tail = new Tail(filePath); // Create a new Tail instance for the log file

        // Event listener for new lines added to the log file
        tail.on('line', async (line) => {
          if (line.includes('git.ssh.surf')) {
            log.debug(`Ignoring line involving git.ssh.surf: ${line}`); // Ignore lines related to specific domains
            return;
          }

          log.debug(`Read line: ${line}`); // Debug log for each line read
          const ipMatch = line.match(/\[Client (\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\]/); // Regex to extract client IP from the log line
          if (ipMatch) {
            const ip = ipMatch[1];
            const isIgnored = await isIgnoredIP(ip); // Check if the IP should be ignored
            if (isIgnored) {
              log.debug(`Ignored line with IP: ${ip}`); // Debug log for ignored IPs
              return;
            }
          }

          // Add the line to the log buffer
          logBuffer.push(line);
          // If buffer reaches the limit, send logs to the backend
          if (logBuffer.length >= LOG_BUFFER_LIMIT) {
            await sendLogsToBackend();
          }
        });

        // Event listener for errors in Tail instance
        tail.on('error', (error) => {
          log.error(`Tail error: ${error}`); // Log errors that occur while tailing the file
        });

        tail.watch(); // Start watching the log file for new lines

        log.debug(`Started tailing file: ${filePath}`); // Debug log indicating the file is being monitored
        logTails.push(tail); // Add the Tail instance to the list of active Tails
      } catch (ex) {
        log.error(`Failed to tail file ${filePath}: ${ex}`); // Log any exceptions that occur while starting the Tail
      }
    });
  });
};

// Function to count the number of tokens in a message using llama-tokenizer-js
async function countLlamaTokens(messages) {
  const llamaTokenizer = await import('llama-tokenizer-js'); // Dynamically import the tokenizer module
  let totalTokens = 0; // Initialize token counter
  for (const message of messages) {
    if (message.role === 'user' || message.role === 'assistant') {
      const encodedTokens = llamaTokenizer.default.encode(message.content); // Encode message content to count tokens
      totalTokens += encodedTokens.length; // Accumulate the total number of tokens
    }
  }
  return totalTokens; // Return the total token count
}

// Function to trim conversation history to fit within token limits
async function trimConversationHistory(messages, maxLength, tolerance) {
  let tokenLength = await countLlamaTokens(messages); // Get the current token length
  if (tokenLength > maxLength + tolerance) {
    const diff = tokenLength - (maxLength + tolerance); // Calculate how many tokens need to be removed
    let removedTokens = 0;

    // Iterate over the messages in reverse order to remove older messages first
    for (let i = messages.length - 1; i >= 0; i--) {
      const message = messages[i];
      const messageTokens = await countLlamaTokens([message]); // Count tokens in the current message

      if (removedTokens + messageTokens <= diff) {
        messages.splice(i, 1); // Remove the message if it helps reduce the token count sufficiently
        removedTokens += messageTokens;
        console.log(`${getTimestamp()} [CLEANUP] ${removedTokens} removed | After Resize: ${await countLlamaTokens(messages)}`);
      } else {
        const messagesToRemove = Math.floor(diff / messageTokens); // Determine how many messages need to be removed
        for (let j = 0; j < messagesToRemove; j++) {
          messages.splice(i, 1); // Remove the determined number of messages
          removedTokens += messageTokens;
        }
        break; // Exit the loop once enough tokens have been removed
      }
    }
  }
}

// Function to send accumulated log buffer to the backend server
const sendLogsToBackend = async () => {
  if (logBuffer.length === 0) {
    log.info('Log buffer is empty, skipping sending to backend'); // Log if there are no logs to send
    return;
  }

  if (isSendingLogs) {
    log.info('Log sending is already in progress, skipping...'); // Prevent concurrent log sending operations
    return;
  }

  isSendingLogs = true; // Set the flag to indicate logs are being sent
  log.info('Sending logs to backend...'); // Log the start of the log sending process
  try {
    const messages = [{ role: 'user', content: logBuffer.join('\n') }]; // Combine the log buffer into a single message
    await trimConversationHistory(messages, 2000, 100); // Trim the message if it exceeds token limits
    const response = await axios.post(BACKEND_URL, { message: messages.map(msg => msg.content).join('\n') }); // Send the logs to the backend

    // Check the response for any alerts, actions, or reports
    if (response.data.content.includes('ALERT') || response.data.content.includes('ACTION') || response.data.content.includes('REPORT')) {
      log.warn('ALERT detected in response'); // Log if an alert is detected
      const ips = extractIPsFromAlert(response.data.content); // Extract IP addresses from the alert message
      if (ips.length > 0) {
        const nonIgnoredIPs = [];
        for (const ip of ips) {
          if (await isIgnoredIP(ip)) {
            log.debug(`Skipping banning for ignored IP: ${ip}`); // Skip banning if the IP is in the ignored list
            continue;
          }
          log.info(`Detected IP for banning: ${ip}`); // Log the IP address that will be banned
          await banIP(ip); // Execute the ban command for the IP
          await delay(3000); // Add a 3-second delay between bans to avoid overloading the system
          nonIgnoredIPs.push(ip); // Keep track of banned IPs that are not ignored
        }
        await sendAlertToDiscord(response.data.content, nonIgnoredIPs); // Send the alert message to Discord
      } else {
        log.warn('No IPs detected for banning.'); // Log if no IPs were found for banning
        await sendAlertToDiscord(response.data.content, []); // Still send the alert to Discord, even without IPs
      }
    } else if (response.data.content.includes('GENERAL')) {
      await sendGeneralToDiscord(response.data.content); // Send general information to Discord if present
    } else {
      log.info('No alerts detected in response'); // Log if no significant alerts are found
      log.info(`Response:\n ${response.data.content}`); // Log the response content for review
    }

    // Clear the log buffer after successful sending
    logBuffer = [];
    log.info('Log buffer cleared');

    // Reset the conversation history on the backend to start fresh
    await resetConversationHistory();
  } catch (error) {
    log.error(`Error sending logs to backend: ${error.message}`); // Log any errors that occur during the process
  } finally {
    isSendingLogs = false; // Reset the flag to allow new log sending operations
  }
};

// Function to extract IP addresses from the alert message using a regular expression
const extractIPsFromAlert = (message) => {
  const ipPattern = /\|\|(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\|\|/g; // Regex to find IPs wrapped in ||...||
  let matches;
  const uniqueIPs = new Set(); // Use a Set to store unique IP addresses

  while ((matches = ipPattern.exec(message)) !== null) {
    uniqueIPs.add(matches[1]); // Add each found IP to the Set
  }

  return Array.from(uniqueIPs); // Convert the Set to an array of unique IPs
};

// Function to ban an IP address using a shell command
const banIP = (ip) => {
  return new Promise((resolve, reject) => {
    log.info(`Banning IP address: ${ip}`); // Log the IP address being banned
    exec(`/usr/bin/banIP ${ip}`, (error, stdout, stderr) => {
      if (error) {
        log.error(`Error banning IP address: ${error.message}`); // Log any errors that occur during the ban
        reject(error); // Reject the promise if an error occurs
        return;
      }
      if (stderr) {
        log.warn(`stderr: ${stderr}`); // Log any warnings or errors from the command's stderr
      }
      log.success(`IP address ${ip} has been banned`); // Log a success message if the ban was successful
      resolve(); // Resolve the promise to indicate success
    });
  });
};

// Function to send alert messages to a Discord channel via webhook
const sendAlertToDiscord = async (alertMessage, ips) => {
  log.info('Sending alert to Discord...'); // Log the start of the Discord alert sending process
  try {
    await axios.post(DISCORD_WEBHOOK_URL, {
      embeds: [
        {
          title: 'Alert Detected', // Title for the Discord embed
          description: alertMessage, // The alert message content
          color: 15158332, // Red color for alerts
          fields: ips.filter(ip => !ignoredIPs.includes(ip)).map(ip => ({
            name: 'Banned IP', // Field name in the Discord embed
            value: ip, // The banned IP address
            inline: true // Display fields inline for better readability
          })),
          timestamp: new Date() // Timestamp for when the alert was sent
        }
      ]
    });
    log.success('Alert sent to Discord'); // Log a success message if the alert was successfully sent
  } catch (error) {
    log.error(`Error sending alert to Discord: ${error.message}`); // Log any errors that occur during the Discord alert sending process
  }
};

// Function to send general information messages to a Discord channel via webhook
const sendGeneralToDiscord = async (generalMessage) => {
  log.info('Sending general information to Discord...'); // Log the start of the general information sending process
  try {
    await axios.post(DISCORD_WEBHOOK_URL, {
      embeds: [
        {
          title: 'General Information', // Title for the Discord embed
          description: generalMessage, // The general information content
          color: 3066993, // Blue color for general information
          timestamp: new Date() // Timestamp for when the information was sent
        }
      ]
    });
    log.success('General information sent to Discord'); // Log a success message if the general information was successfully sent
  } catch (error) {
    log.error(`Error sending general information to Discord: ${error.message}`); // Log any errors that occur during the Discord general information sending process
  }
};

// Function to reset the conversation history in the backend
const resetConversationHistory = async () => {
  log.info('Resetting conversation history...'); // Log the start of the conversation history reset process
  try {
    await axios.post(`${BACKEND_URL.replace('/api/v1/chat', '')}/api/v1/reset-conversation`); // Send a request to reset the conversation history
    log.success('Conversation history reset'); // Log a success message if the reset was successful
  } catch (error) {
    log.error(`Error resetting conversation history: ${error.message}`); // Log any errors that occur during the conversation history reset process
  }
};

// Utility function to introduce a delay between operations, useful for rate limiting
const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms)); // Create a promise that resolves after the specified delay

// Start reading logs continuously from the specified directory
readLogs();

// Set up an interval to send logs to the backend if buffer limit is reached or every 10 minutes
setInterval(sendLogsToBackend, TIME_LIMIT);