'use strict';

var ERR_INVALID_OPT_VALUE = require('readable-stream/errors').codes.ERR_INVALID_OPT_VALUE;

function highWaterMarkFrom(options, isDuplex, duplexKey) {
  return options.highWaterMark != null ? options.highWaterMark : isDuplex ? options[duplexKey] : null;
}

function getHighWaterMark(state, options, duplexKey, isDuplex) {
  var hwm = highWaterMarkFrom(options, isDuplex, duplexKey);

  if (hwm != null) {
    if (!(isFinite(hwm) && Math.floor(hwm) === hwm) || hwm < 0) {
      var name = isDuplex ? duplexKey : 'highWaterMark';
      throw new ERR_INVALID_OPT_VALUE(name, hwm);
    }

    return Math.floor(hwm);
  } // Default value


  return state.objectMode ? 16 : 16 * 1024;
}

module.exports = {
  getHighWaterMark: getHighWaterMark
};