/**
 * 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 { extractCompleteChunks } from "../../parsers/containers/isobmff";
import { concat } from "../../utils/byte_parsing";
import type { IFetchedDataObject } from "../../utils/request/fetch";
import fetchRequest from "../../utils/request/fetch";
import type { CancellationSignal } from "../../utils/task_canceller";
import type {
  ISegmentLoaderCallbacks,
  ISegmentLoaderResultChunkedComplete,
} from "../types";

/**
 * Load segments through a "chunk" mode (decodable chunk by decodable chunk).
 *
 * This method is particularly adapted to low-latency streams.
 *
 * @param {string} url - URL of the segment to download.
 * @param {Object} requestOptions
 * @param {Object|undefined} requestOptions.headers - Headers for the
 * low-latency request
 * @param {number|undefined} requestOptions.timeout - Request timeout for the
 * low-latency request.
 * @param {number|undefined} requestOptions.connectionTimeout - HTTP connection
 * timeout for the low-latency request.
 * @param {Object} callbacks
 * @param {CancellationSignal} cancelSignal
 * @returns {Promise}
 */
export default async function loadChunkedSegmentData(
  url: string,
  requestOptions: {
    headers: Record<string, string> | undefined;
    timeout: number | undefined;
    connectionTimeout: number | undefined;
  },
  callbacks: ISegmentLoaderCallbacks<Uint8Array<ArrayBuffer>>,
  cancelSignal: CancellationSignal,
): Promise<ISegmentLoaderResultChunkedComplete> {
  let partialChunk: Uint8Array | null = null;

  /**
   * Called each time `fetch` has new data available.
   * @param {Object} info
   */
  function onData(info: IFetchedDataObject): void {
    const chunk = new Uint8Array(info.chunk);
    const concatenated = partialChunk !== null ? concat(partialChunk, chunk) : chunk;
    const res = extractCompleteChunks(concatenated);
    const completeChunks = res[0];
    partialChunk = res[1];
    if (completeChunks !== null) {
      completeChunks.forEach((completedChunk) => {
        callbacks.onNewChunk(completedChunk);
      });
      if (cancelSignal.isCancelled()) {
        return;
      }
    }
    callbacks.onProgress({
      duration: info.duration,
      size: info.size,
      totalSize: info.totalSize,
    });
    if (cancelSignal.isCancelled()) {
      return;
    }
  }

  const res = await fetchRequest({
    url,
    headers: requestOptions.headers,
    onData,
    timeout: requestOptions.timeout,
    connectionTimeout: requestOptions.connectionTimeout,
    cancelSignal,
  });
  return {
    resultType: "chunk-complete" as const,
    resultData: res,
  };
}