/**
 * Copyright 2015 CANAL+ Group
 *
 * 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.
 */

import log from "../../../../../../log";
import isNullOrUndefined from "../../../../../../utils/is_null_or_undefined";
import type { IIndexSegment } from "../../../../utils/index_helpers";

/**
 * Translate parsed `S` node into Segment compatible with this index:
 * Find out the start, repeatCount and duration of each of these.
 *
 * @param {Object} item - parsed `S` node
 * @param {Object|null} previousItem - the previously parsed Segment (related
 * to the `S` node coming just before). If `null`, we're talking about the first
 * segment.
 * @param {Object|null} nextItem - the `S` node coming next. If `null`, we're
 * talking about the last segment.
 * @returns {Object|null}
 */
export default function convertElementsToIndexSegment(
  item: { start?: number; repeatCount?: number; duration?: number },
  previousItem: IIndexSegment | null,
  nextItem: { start?: number; repeatCount?: number; duration?: number } | null,
): IIndexSegment | null {
  let start = item.start;
  let duration = item.duration;
  const repeatCount = item.repeatCount;
  if (start === undefined) {
    if (previousItem === null) {
      start = 0;
    } else if (!isNullOrUndefined(previousItem.duration)) {
      start = previousItem.start + previousItem.duration * (previousItem.repeatCount + 1);
    }
  }
  if (
    (duration === undefined || isNaN(duration)) &&
    nextItem !== null &&
    nextItem.start !== undefined &&
    !isNaN(nextItem.start) &&
    start !== undefined &&
    !isNaN(start)
  ) {
    duration = nextItem.start - start;
  }
  if (
    start !== undefined &&
    !isNaN(start) &&
    duration !== undefined &&
    !isNaN(duration) &&
    (repeatCount === undefined || !isNaN(repeatCount))
  ) {
    return {
      start,
      duration,
      repeatCount: repeatCount === undefined ? 0 : repeatCount,
    };
  }
  log.warn('DASH: A "S" Element could not have been parsed.');
  return null;
}