const mysql = require("mysql2/promise");
const { Client } = require("ssh2");
const dotenv = require("dotenv");
const path = require("path");
const { outputProgress, formatElapsedTime, estimateRemaining, calculateRate } = require('../metrics/utils/progress');

dotenv.config({ path: path.join(__dirname, "../../.env") });

// SSH configuration
const sshConfig = {
  host: process.env.PROD_SSH_HOST,
  port: process.env.PROD_SSH_PORT || 22,
  username: process.env.PROD_SSH_USER,
  privateKey: process.env.PROD_SSH_KEY_PATH
    ? require("fs").readFileSync(process.env.PROD_SSH_KEY_PATH)
    : undefined,
};

// Production database configuration
const prodDbConfig = {
  host: process.env.PROD_DB_HOST || "localhost",
  user: process.env.PROD_DB_USER,
  password: process.env.PROD_DB_PASSWORD,
  database: process.env.PROD_DB_NAME,
  port: process.env.PROD_DB_PORT || 3306,
};

// Local database configuration
const localDbConfig = {
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_NAME,
  multipleStatements: true,
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0,
  namedPlaceholders: true,
};

// Constants
const BATCH_SIZE = 1000;
const PROGRESS_INTERVAL = 1000; // Update progress every second

async function setupSshTunnel() {
  return new Promise((resolve, reject) => {
    const ssh = new Client();

    ssh.on('error', (err) => {
      console.error('SSH connection error:', err);
      // Don't reject here, just log the error
    });

    ssh.on('end', () => {
      console.log('SSH connection ended normally');
    });

    ssh.on('close', () => {
      console.log('SSH connection closed');
    });

    ssh
      .on("ready", () => {
        ssh.forwardOut(
          "127.0.0.1",
          0,
          prodDbConfig.host,
          prodDbConfig.port,
          async (err, stream) => {
            if (err) reject(err);
            resolve({ ssh, stream });
          }
        );
      })
      .connect(sshConfig);
  });
}

// Helper function to update progress with time estimate
function updateProgress(current, total, operation, startTime) {
    outputProgress({
        status: 'running',
        operation,
        current,
        total,
        rate: calculateRate(startTime, current),
        elapsed: formatElapsedTime(startTime),
        remaining: estimateRemaining(startTime, current, total),
        percentage: ((current / total) * 100).toFixed(1)
    });
}

module.exports = {
  setupSshTunnel,
  updateProgress,
  prodDbConfig,
  localDbConfig,
  BATCH_SIZE,
  PROGRESS_INTERVAL,
  outputProgress,
  formatElapsedTime
};