YellowLabTools/lib/tools/redownload/brotliCompressor.js

var debug   = require('debug')('ylt:brotliCompressor');

var Q       = require('q');
var zlib    = require('zlib');

var gzipCompressor  = require('./gzipCompressor');


var GzipCompressor = function() {

    var BROTLI_COMPRESSION_LEVEL = 9;

    function compressFile(entry) {
        debug('Entering brotli compressor');
        return brotlifyFile(entry)

        .then(brotliOptimizedFile);
    }

    // Compress with Brotli files that were not compressed or not with brotli (with gzip or deflate)
    function brotlifyFile(entry) {
        var deferred = Q.defer();

        if (gzipCompressor.entryTypeCanBeCompressed(entry) && entry.weightCheck && entry.weightCheck.bodyBuffer) {

            if (!entry.weightCheck.isCompressed) {
                debug('File %s was not compressed at all, trying Brotli over it.', entry.url);
            } else if (entry.weightCheck.compressionTool !== 'brotli') {
                debug('File %s was compressed with %s. Trying with Brotli.', entry.url, entry.weightCheck.compressionTool);
            }

            zlib.brotliCompress(entry.weightCheck.bodyBuffer, {
                    params: {
                        [zlib.constants.BROTLI_PARAM_QUALITY]: 9
                    }
                }, function(err, buffer) {
                    if (err) {
                        debug('Could not compress uncompressed file with brotli');
                        debug(err);

                        deferred.reject(err);
                    } else {
                        var compressedSize = buffer.length;

                        if (!entry.weightCheck.isCompressed) {
                            debug('Brotli size is %d, was %d, this is %d% better.', compressedSize, entry.weightCheck.bodySize, Math.round((entry.weightCheck.bodySize - compressedSize) * 100 / entry.weightCheck.bodySize));
                        } else if (entry.weightCheck.compressionTool !== 'brotli') {
                            debug('Brotli size is %d, was %d with %s, this is %d% better.', compressedSize, entry.weightCheck.bodySize, entry.weightCheck.compressionTool, Math.round((entry.weightCheck.bodySize - compressedSize) * 100 / entry.weightCheck.bodySize));
                        }

                        entry.weightCheck.afterBrotliCompression = compressedSize;

                        deferred.resolve(entry);
                    }
                }
            );
        } else {
            debug('Compression not needed');
            deferred.resolve(entry);
        }

        return deferred.promise;
    }

    // Gzip a file after minification or optimization if this step was successful
    function brotliOptimizedFile(entry) {
        var deferred = Q.defer();

        if (gzipCompressor.entryTypeCanBeCompressed(entry) && entry.weightCheck && entry.weightCheck.isOptimized === false) {
            debug('Trying to brotlify file after minification: %s', entry.url);

            var uncompressedSize = entry.weightCheck.optimized;

            zlib.brotliCompress(Buffer.from(entry.weightCheck.bodyAfterOptimization, 'utf8'), {
                    params: {
                        [zlib.constants.BROTLI_PARAM_QUALITY]: 9
                    }
                }, function(err, buffer) {
                    if (err) {
                        debug('Could not compress minified file with brotli');
                        debug(err);

                        deferred.reject(err);
                    } else {
                        var compressedSize = buffer.length;

                        debug('Correctly brotlified the minified file, was %d and is now %d bytes', uncompressedSize, compressedSize);
                        entry.weightCheck.afterOptimizationAndBrotliCompression = compressedSize;

                        deferred.resolve(entry);
                    }
                }
            );
        } else {
            debug('Compressing optimized file not needed');
            deferred.resolve(entry);
        }

        return deferred.promise;
    }

    return {
        compressFile: compressFile
    };
};

module.exports = new GzipCompressor();