/**
 * 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 type {
  IManifest,
  IAdaptation,
  ISegment,
  IPeriod,
  IRepresentation,
} from "../../../manifest";
import isNullOrUndefined from "../../../utils/is_null_or_undefined";
import objectValues from "../../../utils/object_values";

/**
 * Store information about pending requests, like information about:
 *   - for which segments they are
 *   - how the request's progress goes
 * @class PendingRequestsStore
 */
export default class PendingRequestsStore {
  private _currentRequests: Partial<Record<string, IRequestInfo>>;

  constructor() {
    this._currentRequests = {};
  }

  /**
   * Add information about a new pending request.
   * @param {Object} payload
   */
  public add(payload: IPendingRequestStoreBegin): void {
    const { id, requestTimestamp, content } = payload;
    this._currentRequests[id] = { requestTimestamp, progress: [], content };
  }

  /**
   * Notify of the progress of a currently pending request.
   * @param {Object} progress
   */
  public addProgress(progress: IPendingRequestStoreProgress): void {
    const request = this._currentRequests[progress.id];
    if (isNullOrUndefined(request)) {
      if ((__ENVIRONMENT__.CURRENT_ENV as number) === (__ENVIRONMENT__.DEV as number)) {
        throw new Error("ABR: progress for a request not added");
      }
      log.warn("ABR: progress for a request not added");
      return;
    }
    request.progress.push(progress);
  }

  /**
   * Remove a request previously set as pending.
   * @param {string} id
   */
  public remove(id: string): void {
    if (isNullOrUndefined(this._currentRequests[id])) {
      if ((__ENVIRONMENT__.CURRENT_ENV as number) === (__ENVIRONMENT__.DEV as number)) {
        throw new Error("ABR: can't remove unknown request");
      }
      log.warn("ABR: can't remove unknown request");
    }
    delete this._currentRequests[id];
  }

  /**
   * Returns information about all pending requests, in segment's chronological
   * order.
   * @returns {Array.<Object>}
   */
  public getRequests(): IRequestInfo[] {
    return objectValues(this._currentRequests)
      .filter((x): x is IRequestInfo => !isNullOrUndefined(x))
      .sort((reqA, reqB) => reqA.content.segment.time - reqB.content.segment.time);
  }
}

/**
 * Payload needed to add progress information for a request to the
 * PendingRequestsStore.
 */
export interface IPendingRequestStoreProgress {
  /** Amount of time since the request has started, in seconds. */
  duration: number;
  /**
   * Same `id` value used to identify that request at the time the corresponding
   * `IABRRequestBeginEventValue` was sent.
   */
  id: string;
  /** Current downloaded size, in bytes. */
  size: number;
  /**
  /**
   * Monotonically-raising timestamp (common to the RxPlayer) corresponding to
   * the time at which this progress report was processed.
   */
  timestamp: number;
  /**
   * Total size of the segment to download (including already-loaded data),
   * in bytes.
   */
  totalSize: number;
}

/** Payload needed to add a request to the PendingRequestsStore. */
export interface IPendingRequestStoreBegin {
  /**
   * String identifying this request.
   *
   * Only one request communicated to the current `RepresentationEstimator`
   * should have this `id` at the same time.
   */
  id: string;
  /**
   * Value of the monotonically-raising timestamp used by the RxPlayer at the
   * time the request began.
   */
  requestTimestamp: number;
  /** Context associated to the segment. */
  content: IRequestInfoContent;
}

/** Information linked to a segment request, stored in the PendingRequestsStore. */
export interface IRequestInfo {
  /** Information on the current progress made by this request. */
  progress: IPendingRequestStoreProgress[];
  /**
   * Value of the monotonically-raising timestamp used by the RxPlayer at the
   * time the request began.
   */
  requestTimestamp: number;
  /** Context associated to the segment. */
  content: IRequestInfoContent;
}

/** Content linked to a segment request. */
export interface IRequestInfoContent {
  manifest: IManifest;
  period: IPeriod;
  adaptation: IAdaptation;
  representation: IRepresentation;
  segment: ISegment;
}