/**
 * 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 assert from "../../../../utils/assert";
import { insertInto, keepRangeIntersection } from "../../../../utils/ranges";

/**
 * Simulate TimeRanges as returned by SourceBuffer.prototype.buffered.
 * Add an "insert" and "remove" methods to manually update it.
 * @class ManualTimeRanges
 */
export default class ManualTimeRanges implements TimeRanges {
  public length: number;

  private _ranges: Array<{
    start: number;
    end: number;
  }>;

  constructor() {
    this._ranges = [];
    this.length = 0;
  }

  insert(start: number, end: number): void {
    if ((__ENVIRONMENT__.CURRENT_ENV as number) === (__ENVIRONMENT__.DEV as number)) {
      assert(start >= 0, "invalid start time");
      assert(end - start > 0, "invalid end time");
    }
    insertInto(this._ranges, { start, end });
    this.length = this._ranges.length;
  }

  remove(start: number, end: number): void {
    if ((__ENVIRONMENT__.CURRENT_ENV as number) === (__ENVIRONMENT__.DEV as number)) {
      assert(start >= 0, "invalid start time");
      assert(end - start > 0, "invalid end time");
    }
    const rangesToIntersect: Array<{ start: number; end: number }> = [];
    if (start > 0) {
      rangesToIntersect.push({ start: 0, end: start });
    }
    if (end < Infinity) {
      rangesToIntersect.push({ start: end, end: Infinity });
    }
    this._ranges = keepRangeIntersection(this._ranges, rangesToIntersect);
    this.length = this._ranges.length;
  }

  start(index: number): number {
    if (index >= this._ranges.length) {
      throw new Error("INDEX_SIZE_ERROR");
    }
    return this._ranges[index].start;
  }

  end(index: number): number {
    if (index >= this._ranges.length) {
      throw new Error("INDEX_SIZE_ERROR");
    }
    return this._ranges[index].end;
  }
}