text: var common = require('./common');
  var fs = require('fs');
  
  // add c spaces to the left of str
  function lpad(c, str) {
    var res = '' + str;
    if (res.length < c) {
      res = Array((c - res.length) + 1).join(' ') + res;
    }
    return res;
  }
  
  common.register('uniq', _uniq, {
    canReceivePipe: true,
    cmdOptions: {
      'i': 'ignoreCase',
      'c': 'count',
      'd': 'duplicates',
    },
  });
  
  //@
  //@ ### uniq([options,] [input, [output]])
  //@
  //@ Available options:
  //@
  //@ + `-i`: Ignore case while comparing
  //@ + `-c`: Prefix lines by the number of occurrences
  //@ + `-d`: Only print duplicate lines, one for each group of identical lines
  //@
  //@ Examples:
  //@
  //@ ```javascript
  //@ uniq('foo.txt');
  //@ uniq('-i', 'foo.txt');
  //@ uniq('-cd', 'foo.txt', 'bar.txt');
  //@ ```
  //@
  //@ Filter adjacent matching lines from `input`. Returns a
  //@ [ShellString](#shellstringstr).
  function _uniq(options, input, output) {
    // Check if this is coming from a pipe
    var pipe = common.readFromPipe();
  
    if (!pipe) {
      if (!input) common.error('no input given');
  
      if (!fs.existsSync(input)) {
        common.error(input + ': No such file or directory');
      } else if (common.statFollowLinks(input).isDirectory()) {
        common.error("error reading '" + input + "'");
      }
    }
    if (output && fs.existsSync(output) && common.statFollowLinks(output).isDirectory()) {
      common.error(output + ': Is a directory');
    }
  
    var lines = (input ? fs.readFileSync(input, 'utf8') : pipe)
                .trimRight()
                .split('\n');
  
    var compare = function (a, b) {
      return options.ignoreCase ?
             a.toLocaleLowerCase().localeCompare(b.toLocaleLowerCase()) :
             a.localeCompare(b);
    };
    var uniqed = lines.reduceRight(function (res, e) {
      // Perform uniq -c on the input
      if (res.length === 0) {
        return [{ count: 1, ln: e }];
      } else if (compare(res[0].ln, e) === 0) {
        return [{ count: res[0].count + 1, ln: e }].concat(res.slice(1));
      } else {
        return [{ count: 1, ln: e }].concat(res);
      }
    }, []).filter(function (obj) {
                   // Do we want only duplicated objects?
      return options.duplicates ? obj.count > 1 : true;
    }).map(function (obj) {
                   // Are we tracking the counts of each line?
      return (options.count ? (lpad(7, obj.count) + ' ') : '') + obj.ln;
    }).join('\n') + '\n';
  
    if (output) {
      (new common.ShellString(uniqed)).to(output);
      // if uniq writes to output, nothing is passed to the next command in the pipeline (if any)
      return '';
    } else {
      return uniqed;
    }
  }
  
  module.exports = _uniq;
  