text: 'use strict';
  
  const fs = require('fs');
  
  const args = process.argv.slice(2);
  if (args[0] === 'production') {
      // set up for build process
      fs.renameSync('app/index.html', 'app/index-dev.html');
      var contents = fs.readFileSync('app/index-dev.html').toString().split('\n');
      var shared = 0, inDev = 1, inProd = 2;
      var state = shared;
      var newContents = [];
      for (var i = 0; i < contents.length; i++) {
          switch (contents[i].trim()) {
              case '<!-- production -->':
                  state = inProd;
                  break;
              case '<!-- dev -->':
                  state = inDev;
                  break;
              case '<!-- endproduction -->':
              case '<!-- enddev -->':
                  state = shared;
                  break;
              default:
                  if (state === shared) {
                      newContents.push(contents[i]);
                  } else if (state === inProd) {
                      newContents.push(contents[i].replace('<!--', '').replace('-->',''));
                  }
          }
      }
      fs.writeFileSync('app/index.html', newContents.join('\n'));
  } else if (args[0] === 'development') {
      // reset to the one we use for dev
      fs.renameSync('app/index-dev.html', 'app/index.html');
  }
  
  process.exit(0);