var AWS = require('aws-sdk');

var S3 = new AWS.S3();

var Sharp = require('sharp');

var BUCKET = process.env.BUCKET;

var URL = process.env.URL;

exports.handler = function(event, context) {

var key = event.queryStringParameters.key;

var match = key.match(/(\d+)x(\d+)\/(.*)/);

var width = parseInt(match[1], 10);

var height = parseInt(match[2], 10);

var originalKey = match[3];

S3.getObject({Bucket: BUCKET, Key: originalKey}).promise()

.then((data) => Sharp(data.Body)

.resize(width, height)

.max()

.toFormat('png')

.toBuffer()

)

.then((buffer) => S3.putObject({

Body: buffer,

Bucket: BUCKET,

ContentType: 'image/png',

Key: key

}).promise()

)

.then(() => context.succeed({

statusCode: '301',

headers: {'location': `${URL}/${key}`},

body: ''

})

)

.catch((err) => context.fail(err))

}