import 'dotenv/config';
import { getDb } from '../lib/database.js';
import { NntpPool } from '../lib/NntpPool.js';
import { YencFile } from '../lib/YencFile.js';
import fs from 'fs/promises';
import log4js from '../lib/logger.js';

const logger = log4js.getLogger('download');

async function downloadAndProcessPart(pool, partNumber, segment, yencFile) {
  let conn;
  try {
    conn = await pool.acquire();
    await conn.group('alt.binaries.test');
    logger.debug(`Downloading part ${partNumber} with message ID: ${segment.id}`);
    const bodyBuffer = (await conn.body(`<${segment.id}>`)).data;
    yencFile.processPart(bodyBuffer);
  } catch (error) {
    if (error.code === 430) {
      logger.error(`Article not found for part ${partNumber} (Message ID: ${segment.id})`);
    } else {
      throw error;
    }
  } finally {
    if (conn) {
      pool.release(conn);
    }
  }
}

async function downloadFile(fileId, numConnections) {
  const pool = new NntpPool(numConnections);
  const yencFile = new YencFile();

  const db = await getDb();
  const file = await db.get('SELECT * FROM files WHERE id = ?', fileId);

  if (!file) {
    logger.error(`File with ID ${fileId} not found.`);
    return;
  }

  logger.info(`Downloading file: ${file.filename} with ${numConnections} connections.`);

  const messageIds = JSON.parse(file.message_ids);
  const sortedParts = Object.entries(messageIds).sort(([a], [b]) => parseInt(a, 10) - parseInt(b, 10));

  const downloadPromises = sortedParts.map(([partNumber, segment]) =>
    downloadAndProcessPart(pool, partNumber, segment, yencFile)
  );

  await Promise.all(downloadPromises);

  const completeFile = yencFile.getBuffer();
  if (completeFile) {
    await fs.writeFile(file.filename, completeFile);
    logger.info(`File "${file.filename}" downloaded successfully.`);
  } else {
    logger.error('Could not download all parts of the file.');
  }

  await pool.shutdown();
}

const args = process.argv.slice(2);
const fileIdArg = args.find(arg => !arg.startsWith('--'));
const connectionsArg = args.find(arg => arg.startsWith('--connections='));

const fileId = fileIdArg ? parseInt(fileIdArg, 10) : null;
const numConnections = connectionsArg ? parseInt(connectionsArg.split('=')[1], 10) : 10;

if (!fileId || isNaN(fileId)) {
  logger.error('Please provide a valid file ID as a command-line argument.');
  process.exit(1);
}

downloadFile(fileId, numConnections);