/**
 * 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 isNullOrUndefined from "../../../../utils/is_null_or_undefined";
import type { IPeriodIntermediateRepresentation } from "../node_parser_types";

/** Time information from a Period. */
interface IPeriodTimeInformation {
  /** Time in seconds at which the Period starts. */
  periodStart: number;
  /** Difference in seconds between the Period's end and its start. */
  periodDuration?: number | undefined;
  /** Time in seconds at which the Period ends. */
  periodEnd?: number | undefined;
}

/** Additionnal context needed to retrieve the period time information. */
export interface IParsedPeriodsContext {
  /** Value of MPD@availabilityStartTime. */
  availabilityStartTime: number;
  /** Value of MPD@mediaPresentationDuration. */
  duration?: number | undefined;
  /** `true` if MPD@type is equal to "dynamic". */
  isDynamic: boolean;
}

/**
 * Get periods time information from current, next and previous
 * periods.
 * @param {Array.<Object>} periodsIR
 * @param {Object} manifestInfos
 * @return {Array.<Object>}
 */
export default function getPeriodsTimeInformation(
  periodsIR: IPeriodIntermediateRepresentation[],
  manifestInfos: IParsedPeriodsContext,
): IPeriodTimeInformation[] {
  const periodsTimeInformation: IPeriodTimeInformation[] = [];
  periodsIR.forEach((currentPeriod, i) => {
    let periodStart: number;
    if (!isNullOrUndefined(currentPeriod.attributes.start)) {
      periodStart = currentPeriod.attributes.start;
    } else {
      if (i === 0) {
        periodStart =
          !manifestInfos.isDynamic ||
          isNullOrUndefined(manifestInfos.availabilityStartTime)
            ? 0
            : manifestInfos.availabilityStartTime;
      } else {
        // take time information from previous period
        const prevPeriodInfos = periodsTimeInformation[periodsTimeInformation.length - 1];
        if (
          !isNullOrUndefined(prevPeriodInfos) &&
          !isNullOrUndefined(prevPeriodInfos.periodEnd)
        ) {
          periodStart = prevPeriodInfos.periodEnd;
        } else {
          throw new Error("Missing start time when parsing periods.");
        }
      }
    }

    let periodDuration: number | undefined;
    const nextPeriod = periodsIR[i + 1];
    if (!isNullOrUndefined(currentPeriod.attributes.duration)) {
      periodDuration = currentPeriod.attributes.duration;
    } else if (i === periodsIR.length - 1) {
      periodDuration = manifestInfos.duration;
    } else if (!isNullOrUndefined(nextPeriod.attributes.start)) {
      periodDuration = nextPeriod.attributes.start - periodStart;
    }

    const periodEnd = !isNullOrUndefined(periodDuration)
      ? periodStart + periodDuration
      : undefined;
    periodsTimeInformation.push({ periodStart, periodDuration, periodEnd });
  });
  return periodsTimeInformation;
}