util.js

'use strict';
var path = require('path');
var fs = require('fs');

function rewrite (args) {
  var re = new RegExp(args.reg);
  if (re.test(args.haystack)) {
    return args.haystack;
  }

  var lines = args.haystack.split('\n');
  var otherwiseLineIndex = 0;
  lines.forEach(function (line, i) {
    if (line.indexOf(args.needle) !== -1) {
      otherwiseLineIndex = i;
    }
  });

  var spaces = 0;
  while (lines[otherwiseLineIndex - 2].charAt(spaces) === ' ') {
    spaces += 1;
  }
  var spaceStr = '';
  while ((spaces -= 1) >= 0) {
    spaceStr += ' ';
  }

  lines.splice(otherwiseLineIndex, 0, args.splicable.map(function (line) {
    return spaceStr + line;
  }).join('\n'));

  return lines.join('\n');
}

function rewriteFile (args) {
  args.path = args.path || process.cwd();
  var fullPath = path.join(args.path, args.file);

  args.haystack = fs.readFileSync(fullPath, 'utf8');
  var body = rewrite(args);

  fs.writeFileSync(fullPath, body);
}

module.exports = {
  rewriteFile: rewriteFile,
  rewrite: rewrite
};