line_image_lambda.js

console.log('Loading function');

const HEIGHT = 370;
const WIDTH = 320;
var fs = require('fs');
var gm = require('gm').subClass({ imageMagick: true });

var aws = require('aws-sdk');
var s3 = new aws.S3({ apiVersion: '2006-03-01' });

exports.handler = function(event, context) {
  console.log('Received event:', JSON.stringify(event, null, 2));
  var bucket = event.Records[0].s3.bucket.name;
  var key = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, ' '));
  var params = {
    Bucket: bucket,
	  Key: key
  };

  if (key.indexOf('-line.png') > -1) {
    context.done(null, '');
  }
  
  s3.getObject(params, function(err, data) {
    if (err) {
      console.log(err);
      var message = "Error getting object " + key + " from bucket " + bucket +
      ". Make sure they exist and your bucket is in the same region as this function.";
      console.log(message);
      context.fail(message);
    } else {
      console.log('CONTENT TYPE:', data.ContentType);
      var inputPath = "/tmp/input." + (event.outputExtension || 'JPG');
      var outputPath = "/tmp/output.png";
      require('fs').writeFileSync(inputPath, data.Body);
      var lineKey = key.split('.')[0] + '-line.png';
      gm(inputPath)
        .fuzz('20%')
        .trim()
        .resize(HEIGHT, WIDTH)
        .extent(HEIGHT, WIDTH)
	.fuzz('10%')
	.fill('#00000000')
	.setDraw('matte', 1, 1, 'floodfill')
        .setDraw('matte', 1, WIDTH - 1, 'floodfill')
        .setDraw('matte', HEIGHT - 1, 1, 'floodfill')
        .setDraw('matte', HEIGHT - 1, WIDTH - 1, 'floodfill')
	.write(outputPath, function (err) {
          if (!err) {
	    s3.putObject({
	      Bucket: bucket,
	      Key: lineKey,
	      Body: new Buffer(fs.readFileSync(outputPath))
	  }, function(err) {
	    if (err) {
	      console.log(err);
  	      context.done('error', 'error s3 put object' + err);
	    } else {
	      context.done(null, '');
	    }
	  });
        }
      });
    }
  });
};