Ayesh / grunt-guetzli

'use strict';

module.exports = function(grunt) {

  var path = require('path');

  var async = require('async');

  var fs = require('fs');

  grunt.registerMultiTask('guetzli', "Compresses JPG and PNG images according to Google's Guetzli algorithm", function() {

    /**

     * Retrieves defined options.

     */

    var options = this.options();

    grunt.verbose.writeflags(options, 'Options');

    var done = this.async();

    var guetzli_bin = 'guetzli';

    if (options.binpath) {

        guetzli_bin = options.binpath;

    }

    var source_total = 0;

    var dest_total = 0;

    var oversize_total = 0;

    // Iterate over all src-dest file pairs.

    async.eachSeries(this.files, function(f, next) {

      /**

       * Create folder for the dest file

       */

      grunt.file.mkdir(path.dirname(f.dest));

      var args = [];

       /**

       * Quality scale: Minimum allowed is 84.

       */

      if (options.quality) {

          if (options.quality < 84) {

              grunt.fail.warn('Guetzli: Quality must be >= 84 to avoid noticeable artifacts.');

          }

          args.push('--quality');

          args.push(options.quality);

      }

      /**

       * Outputs the rules that have been matched.

       */

      if (options.verbose) {

        args.push('--verbose');

      }

      args.push(f.src);

      args.push(f.dest);

      /**

       * Outputs the file that is being analysed.

       */

      grunt.log.subhead('Compressing: ' + f.dest);

      var child = grunt.util.spawn({

        cmd: guetzli_bin,

        args: args

      }, function(error, result, code) {

        //grunt.log.writeln(code+''+result);

        if (code !== 0) {

          return grunt.warn(String(code));

        }

        else{

            var source = fs.statSync(f.src[0])['size'];

            var dest = fs.statSync(f.dest)['size'];

            var diff = ((source - dest) / source) * 100;

            diff = Number((diff).toFixed(2));

            source_total += source;

            if (diff < 0) {

                oversize_total++;

                source_total += source;

                diff = diff * -1;

                if (options.deleteLarger) {

                    grunt.file.delete(f.dest);

                    grunt.log.writeln('Deleted: '['yellow'] + diff + '% larger than its source.');

                }

                else {

                    dest_total += dest;

                    grunt.log.writeln('Warning: '['yellow'] + diff + '% larger than its source. Left undeleted.');

                }

            }

            else {

                dest_total += dest;

                grunt.log.oklns('Done: '['green'] + diff + '% smaller | ' + diff + '%: ' + source + ' -> ' + dest);

            }

        }

      });

      /**

       * displays the output and error streams via the parent process.

       */

      child.stdout.pipe(process.stdout);

      child.stderr.pipe(process.stderr);

        var total_diff = (source_total - dest_total) / source_total;

        var total_diff_perentage = Number((total_diff * 100).toFixed(2));

        grunt.log.subhead('Operation statistics:');

        grunt.log.oklns(source_total + ' -> ' + dest_total);

        grunt.log.oklns(total_diff_perentage +'% saved.');

        if (oversize_total !== 0) {

            if (options.deleteLarger) {

                grunt.log.oklns('Deleted ' + oversize_total + ' file(s) due to larger output.');

            }

            else {

                grunt.log.oklns('Warning: ' + 'Contains ' + oversize_total + ' file(s) larger than their sources.');

            }

        }

        done();

    });

  });

};