/**
 * 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 { CustomLoaderError } from "../../errors";
import type { ICdnMetadata } from "../../parsers/manifest";
import type {
  ILocalManifestInitSegmentLoader,
  ILocalManifestSegmentLoader,
} from "../../parsers/manifest/local";
import createCancellablePromise from "../../utils/create_cancellable_promise";
import isNullOrUndefined from "../../utils/is_null_or_undefined";
import type { CancellationSignal } from "../../utils/task_canceller";
import type {
  ISegmentContext,
  ISegmentLoaderCallbacks,
  ISegmentLoaderOptions,
  ISegmentLoaderResultSegmentLoaded,
} from "../types";

/**
 * @param {Function} customSegmentLoader
 * @param {Object} cancelSignal
 * @returns {Promise}
 */
function loadInitSegment(
  customSegmentLoader: ILocalManifestInitSegmentLoader,
  cancelSignal: CancellationSignal,
): Promise<ISegmentLoaderResultSegmentLoaded<ArrayBuffer | null>> {
  return createCancellablePromise(cancelSignal, (res, rej) => {
    /** `true` when the custom segmentLoader should not be active anymore. */
    let hasFinished = false;

    /**
     * Callback triggered when the custom segment loader has a response.
     * @param {Object} _args
     */
    const resolve = (_args: {
      data: ArrayBuffer | null;
      size?: number;
      duration?: number;
    }) => {
      if (hasFinished || cancelSignal.isCancelled()) {
        return;
      }
      hasFinished = true;
      res({
        resultType: "segment-loaded",
        resultData: {
          responseData: _args.data,
          size: _args.size,
          requestDuration: _args.duration,
        },
      });
    };

    /**
     * Callback triggered when the custom segment loader fails
     * @param {*} err - The corresponding error encountered
     */
    const reject = (err?: Error) => {
      if (hasFinished || cancelSignal.isCancelled()) {
        return;
      }
      hasFinished = true;
      rej(err);
    };

    const abort = customSegmentLoader({ resolve, reject });

    /** The logic to run when this loader is cancelled while pending. */
    return () => {
      if (hasFinished) {
        return;
      }
      hasFinished = true;
      if (typeof abort === "function") {
        abort();
      }
    };
  });
}

/**
 * @param {Object} segment
 * @param {Function} customSegmentLoader
 * @param {Object} cancelSignal
 * @returns {Promise.<Object>}
 */
function loadSegment(
  segment: { time: number; duration: number; timestampOffset?: number },
  customSegmentLoader: ILocalManifestSegmentLoader,
  cancelSignal: CancellationSignal,
): Promise<ISegmentLoaderResultSegmentLoaded<ArrayBuffer | null>> {
  return createCancellablePromise(cancelSignal, (res, rej) => {
    /** `true` when the custom segmentLoader should not be active anymore. */
    let hasFinished = false;

    /**
     * Callback triggered when the custom segment loader has a response.
     * @param {Object} _args
     */
    const resolve = (_args: {
      data: ArrayBuffer | null;
      size?: number;
      duration?: number;
    }) => {
      if (hasFinished || cancelSignal.isCancelled()) {
        return;
      }
      hasFinished = true;
      res({
        resultType: "segment-loaded",
        resultData: {
          responseData: _args.data,
          size: _args.size,
          requestDuration: _args.duration,
        },
      });
    };

    /**
     * Callback triggered when the custom segment loader fails
     * @param {*} err - The corresponding error encountered
     */
    const reject = (err?: Error) => {
      if (hasFinished || cancelSignal.isCancelled()) {
        return;
      }
      hasFinished = true;

      // Format error and send it
      const castedErr = err as
        | null
        | undefined
        | { message?: string; canRetry?: boolean; xhr?: XMLHttpRequest };
      const message =
        castedErr?.message ??
        "Unknown error when fetching a local segment through a " +
          "custom segmentLoader.";
      const emittedErr = new CustomLoaderError(
        message,
        castedErr?.canRetry ?? false,
        castedErr?.xhr,
      );
      rej(emittedErr);
    };

    const abort = customSegmentLoader(segment, { resolve, reject });

    /** The logic to run when this loader is cancelled while pending. */
    return () => {
      if (hasFinished) {
        return;
      }
      hasFinished = true;
      if (typeof abort === "function") {
        abort();
      }
    };
  });
}

/**
 * Generic segment loader for the local Manifest.
 * @param {string | null} _wantedCdn
 * @param {Object} content
 * @param {Object} cancelSignal
 * @param {Object} _callbacks
 * @returns {Promise}
 */
export default function segmentLoader(
  _wantedCdn: ICdnMetadata | null,
  content: ISegmentContext,
  _loaderOptions: ISegmentLoaderOptions, // TODO use timeout?
  cancelSignal: CancellationSignal,
  _callbacks: ISegmentLoaderCallbacks<ArrayBuffer | null>,
): Promise<ISegmentLoaderResultSegmentLoaded<ArrayBuffer | null>> {
  const { segment } = content;
  const privateInfos = segment.privateInfos;
  if (segment.isInit) {
    if (
      privateInfos === undefined ||
      isNullOrUndefined(privateInfos.localManifestInitSegment)
    ) {
      throw new Error("Segment is not a local Manifest segment");
    }
    return loadInitSegment(privateInfos.localManifestInitSegment.load, cancelSignal);
  }
  if (
    privateInfos === undefined ||
    isNullOrUndefined(privateInfos.localManifestSegment)
  ) {
    throw new Error("Segment is not an local Manifest segment");
  }
  return loadSegment(
    privateInfos.localManifestSegment.segment,
    privateInfos.localManifestSegment.load,
    cancelSignal,
  );
}