'use strict';

var AWS = require('aws-sdk');
var exec = require('child_process').exec;
var fs = require('fs');

process.env['PATH'] = process.env['PATH'] + ':' + process.env['LAMBDA_TASK_ROOT'];

var s3 = new AWS.S3();

function saveMetadataToS3(body, bucket, key, callback){
    console.log('Saving metadata to s3');

    s3.putObject({
        Bucket: bucket,
        Key: key,
        Body: body
    }, function(error, data){
        if (error){
          callback(error);
        }
    });
}

function extractMetadata(sourceBucket, sourceKey, localFilename, callback){
    console.log('Extracting metadata');

    var cmd = 'bin/ffprobe -v quiet -print_format json -show_format "/tmp/' + localFilename + '"';

    exec(cmd, function(error, stdout, stderr){
        if (error === null){
            var metadataKey = sourceKey.split('.')[0] + '.json';
            saveMetadataToS3(stdout, sourceBucket, metadataKey, callback);
        } else {
            console.log(stderr);
            callback(error);
        }
    });
}

function saveFileToFilesystem(sourceBucket, sourceKey, callback){
    console.log('Saving to filesystem');

    var localFilename = sourceKey.split('/').pop();
    var file = fs.createWriteStream('/tmp/' + localFilename);

    var stream = s3.getObject({Bucket: sourceBucket, Key: sourceKey}).createReadStream().pipe(file);

    stream.on('error', function(error){
        callback(error);
    });

    //This will become easier with async waterfall
    stream.on('close', function(){
        extractMetadata(sourceBucket, sourceKey, localFilename, callback);
    });
}

exports.handler = function(event, context, callback){
    var message = JSON.parse(event.Records[0].Sns.Message);

    var sourceBucket = message.Records[0].s3.bucket.name;
    var sourceKey = decodeURIComponent(message.Records[0].s3.object.key.replace(/\+/g, ' '));

    saveFileToFilesystem(sourceBucket, sourceKey, callback);
};