import { S3Client, GetObjectCommand, PutObjectCommand } from '@aws-sdk/client-s3';
import { createReadStream, createWriteStream } from 'fs';
import { pipeline } from 'stream/promises';

const createS3Client = () => {
  return new S3Client({
    region: process.env.S3_REGION || 'us-east-1',
    endpoint: process.env.S3_ENDPOINT,
    credentials: {
      accessKeyId: process.env.S3_ACCESS_KEY,
      secretAccessKey: process.env.S3_SECRET_KEY,
    },
    forcePathStyle: true,
  });
};

export const downloadFromS3 = async (bucket, key, localPath) => {
  const client = createS3Client();
  try {
    const response = await client.send(
      new GetObjectCommand({ Bucket: bucket, Key: key })
    );

    const writeStream = createWriteStream(localPath);
    await pipeline(response.Body, writeStream);
  } finally {
    client.destroy();
  }
};

export const uploadToS3 = async (bucket, key, localPath) => {
  const client = createS3Client();
  try {
    const readStream = createReadStream(localPath);
    await client.send(
      new PutObjectCommand({
        Bucket: bucket,
        Key: key,
        Body: readStream,
      })
    );
  } finally {
    client.destroy();
  }
};

// Multipart-aware streaming upload — used by the promotion worker to push
// large growing-file masters without buffering them entirely in memory.
export const uploadStreamToS3 = async (bucket, key, readable) => {
  const { Upload } = await import('@aws-sdk/lib-storage');
  const client = createS3Client();
  try {
    const upload = new Upload({
      client,
      params: { Bucket: bucket, Key: key, Body: readable },
      queueSize: 4,
      partSize: 8 * 1024 * 1024,
    });
    await upload.done();
  } finally {
    client.destroy();
  }
};