// s3.js
require('dotenv').config();
const { S3Client, PutObjectCommand } = require('@aws-sdk/client-s3');
const { stringify } = require('csv-stringify/sync');

const s3 = new S3Client({
    region: process.env.AWS_REGION
});

/**
 * Uploads a CSV to s3://<bucket>/trends/<key>.csv with public-read ACL.
 * @param {string} key     Date key like '20250423'
 * @param {Array<Object>} rows  Array of DB rows to stringify into CSV
 * @returns {string} Public URL of the uploaded CSV
 */
async function uploadTrendsCsv(key, rows) {
    // Convert rows to CSV string (includes header)
    const csv = stringify(rows, { header: true });
    const cmd = new PutObjectCommand({
        Bucket: process.env.S3_BUCKET_NAME,
        Key: `trends/${key}.csv`,
        Body: csv,
        ContentType: 'text/csv',
        ACL: 'public-read'
    });
    await s3.send(cmd);
    return `${process.env.S3_BASE_URL}/${key}.csv`;
}

module.exports = { uploadTrendsCsv };