filerev.js

'use strict';
var crypto = require('crypto');
var path = require('path');
var fs = require('fs');
var chalk = require('chalk');
var eachAsync = require('each-async');
var convert = require('convert-source-map');

module.exports = function (grunt) {
  grunt.registerMultiTask('filerev', 'File revisioning based on content hashing', function () {
    var target = this.target;
    var filerev = grunt.filerev || {summary: {}};
    var options = this.options({
      algorithm: 'md5',
      length: 8,
      useQueryParam: false
    });

    eachAsync(this.files, function (el, i, next) {
      var move = true;

      // If dest is furnished it should indicate a directory
      if (el.dest) {
        // When globbing is used, el.dest contains basename, we remove it
        if (el.orig.expand) {
          el.dest = path.dirname(el.dest);
        }

        try {
          var stat = fs.lstatSync(el.dest);

          if (stat && !stat.isDirectory()) {
            grunt.fail.fatal('Destination ' + el.dest  + ' for target ' + target + ' is not a directory');
          }
        } catch (err) {
          grunt.verbose.writeln('Destination dir ' + el.dest + ' does not exists for target ' + target + ': creating');
          grunt.file.mkdir(el.dest);
        }
        // We need to copy file as we now have a dest different from the src
        move = false;
      }

      el.src.forEach(function (file) {
        if (grunt.file.isDir(file)) {
          return;
        }

        var dirname;
        var hash = crypto.createHash(options.algorithm).update(fs.readFileSync(file)).digest('hex');
        var suffix = hash.slice(0, options.length);
        var ext = path.extname(file);
        var newName;

        if (!options.useQueryParam) {
          if (typeof options.process === 'function') {
            newName = options.process(path.basename(file, ext), suffix, ext.slice(1));
          } else {
            if (options.process) {
              grunt.log.error('options.process must be a function; ignoring');
            }

            newName = [path.basename(file, ext), suffix, ext.slice(1)].join('.');
          }
        } else {
          // no renaming but the hash can be used to bust caches by appending it as a query parameter
          newName = [path.basename(file, ext), ext.slice(1)].join('.');
        }

        var resultPath;

        if (move) {
          dirname = path.dirname(file);
          resultPath = path.resolve(dirname, newName);
          fs.renameSync(file, resultPath);
        } else {
          dirname = el.dest;
          resultPath = path.resolve(dirname, newName);
          grunt.file.copy(file, resultPath);
        }

        // Source maps
        var sourceMap = false;

        if (ext === '.js' || ext === '.css') {
          var map = file + '.map';
          var resultPathMap = resultPath + '.map';

          if (grunt.file.exists(map)) {
            if (move) {
              fs.renameSync(map, resultPathMap);
            } else {
              grunt.file.copy(map, resultPathMap);
            }

            // rewrite the sourceMappingURL in files
            var fileContents = grunt.file.read(resultPath, {encoding: 'utf8'});
            // use regex that matches single-line and multi-line sourcemap urls
            // note: this will ignore inline base64-encoded sourcemaps
            var matches = convert.mapFileCommentRegex.exec(fileContents);

            if (matches) {
              var sourceMapFile = matches[1] || matches[2]; // 1st is single line, 2nd is multiline
              var newSrcMap = fileContents.replace(sourceMapFile, path.basename(resultPathMap));
              grunt.file.write(resultPath, newSrcMap, {encoding: 'utf8'});
              sourceMap = true;
            }
          }
        }

        filerev.summary[path.normalize(file)] = path.join(dirname, newName);
        // if using the useQueryParam method, append the queryString
        if (options.useQueryParam) {
          filerev.summary[path.normalize(file)] += '?rev=' + suffix;
        }
        grunt.verbose.writeln(chalk.green('✔ ') + file + chalk.gray(' changed to ') + newName);

        if (sourceMap) {
          filerev.summary[path.normalize(file + '.map')] = path.join(dirname, newName + '.map');
          grunt.verbose.writeln(chalk.green('✔ ') + file + '.map' + chalk.gray(' changed to ') + newName + '.map');
        }
      });

      grunt.log.writeln('Revved ' + chalk.cyan(el.src.length) + ' ' +
        (el.src.length === 1 ? 'file' : 'files')
      );

      next();
    }, this.async());

    grunt.filerev = filerev;
  });
};