/**
 * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS-IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
'use strict';

const {AMP_CACHE_HOST, appendRuntimeVersion} = require('./AmpConstants.js');

function calculateHost({
  ampUrlPrefix = AMP_CACHE_HOST,
  ampRuntimeVersion,
  lts = false,
  rtv = false,
}) {
  if (lts && rtv) {
    throw new Error('lts flag is not compatible with runtime version parameter');
  }
  ampUrlPrefix = ampUrlPrefix.replace(/\/$/, '');
  if (ampRuntimeVersion && rtv) {
    ampUrlPrefix = appendRuntimeVersion(ampUrlPrefix, ampRuntimeVersion);
  } else if (lts) {
    ampUrlPrefix += '/lts';
  }
  return ampUrlPrefix;
}

module.exports = {
  calculateHost,
};