text: // Copyright (c) 2015 Uber Technologies, Inc.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  
  'use strict';
  
  var crypto = require('crypto');
  var readDirFiles = require('read-dir-files').read;
  var traverse = require('traverse');
  var fileFilter = require('./common').fileFilter;
  
  module.exports.sha1 = sha1;
  module.exports.shasumFiles = shasumFiles;
  
  function sha1(content) {
      var hash = crypto.createHash('sha1');
      hash.update(content);
      return hash.digest('hex');
  }
  
  function relPath(dir) {
      return '.' + dir.substr(dir.lastIndexOf('/idl/'), dir.length);
  }
  
  function shasumFiles(dir, callback) {
      readDirFiles(dir, 'utf8', onFiles);
  
      function onFiles(err, files) {
          if (err) {
              if (err.code === 'ENOENT') {
                  err.message = 'Directory not found: ' + relPath(dir);
                  err.path = relPath(dir);
              }
              return callback(err);
          }
  
          var filteredFiles = {};
  
          traverse(files).forEach(function filter(value) {
              if (!this.isLeaf) {
                  return;
              }
              if (this.key && fileFilter(this.key)) {
                  filteredFiles[this.path.join('/')] = value;
              }
          });
  
          var shasums = Object.keys(filteredFiles).reduce(hashFile, {});
  
          callback(null, shasums);
  
          function hashFile(memo, filename) {
              memo[filename] = sha1(filteredFiles[filename]);
              return memo;
          }
      }
  }
  