import * as fs from 'fs';
import * as https from 'https'
import { S3Client, PutObjectCommand } from "@aws-sdk/client-s3";

export const handler = async(event) => {
    const url = event.queryStringParameters.url;

    try {
        const fileName = await transferFileFromUrlToS3(url, 'demo-lambda-codewhisperer');
        console.info(`Done.`);
        // get size of a file
        const stats = fs.statSync('/tmp/' + fileName);
        return {
            statusCode: 200,
            body: JSON.stringify(stats),
        };
            
    } catch (error) {
        console.log(JSON.stringify(error));
        return {
            statusCode: 500,
            body: JSON.stringify(error),
        };
    }
};


// Function for downloading a file from url parameter returning a promise
async function downloadFileFromUrl(url) {
    return new Promise((resolve, reject) => {
        https.get(url, (response) => {
            // get the name of the file from a url
            const fileName = url.substring(url.lastIndexOf('/') + 1);
            const file = fs.createWriteStream('/tmp/' + fileName);
            console.log(`Downloading ${url} to /tmp/${fileName}.`);
            response.pipe(file);
            file.on('finish', () => {
                file.close(() => {
                    resolve(fileName);
                });
            });
        }).on('error', (error) => {
            reject(error);
        });
    });
}

// function to upload a file to an s3 bucket piping the content
async function uploadFileToS3(bucketName, fileName) {
    const fileContent = fs.readFileSync('/tmp/' + fileName);
    const s3Client = new S3Client({ region: 'us-east-1' });
    const uploadResult = await s3Client.send(new PutObjectCommand({
        Bucket: bucketName,
        Key: fileName,
        Body: fileContent,
    }));
    return uploadResult;
}

async function transferFileFromUrlToS3(url, bucketName) {
    console.info(`Transferring ${url} to ${bucketName}.`);
    // download the file from the url
    const fileName = await downloadFileFromUrl(url);
    // upload the file to s3 bucket
    const response = await uploadFileToS3(bucketName, fileName);
    return fileName;
}