var fs = require('fs');
var path = require('path');
var common = require('./common');

common.register('toEnd', _toEnd, {
  pipeOnly: true,
  wrapOutput: false,
});

//@
//@ ### ShellString.prototype.toEnd(file)
//@
//@ Examples:
//@
//@ ```javascript
//@ cat('input.txt').toEnd('output.txt');
//@ ```
//@
//@ Analogous to the redirect-and-append operator `>>` in Unix, but works with
//@ `ShellStrings` (such as those returned by `cat`, `grep`, etc.). Returns the
//@ same [ShellString](#shellstringstr) this operated on, to support chaining.
function _toEnd(options, file) {
  if (!file) common.error('wrong arguments');

  if (!fs.existsSync(path.dirname(file))) {
    common.error('no such file or directory: ' + path.dirname(file));
  }

  try {
    fs.appendFileSync(file, this.stdout || this.toString(), 'utf8');
    return this;
  } catch (e) {
    /* istanbul ignore next */
    common.error('could not append to file (code ' + e.code + '): ' + file, { continue: true });
  }
}
module.exports = _toEnd;
