# Source: streaming/PreBufferSink.js

    /**
     * The copyright in this software is being made available under the BSD License,
     * included below. This software may be subject to other third party and contributor
     * rights, including patent rights, and no such rights are granted under this license.
     *
     * Copyright (c) 2013, Dash Industry Forum.
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without modification,
     * are permitted provided that the following conditions are met:
     *  * Redistributions of source code must retain the above copyright notice, this
     *  list of conditions and the following disclaimer.
     *  * Redistributions in binary form must reproduce the above copyright notice,
     *  this list of conditions and the following disclaimer in the documentation and/or
     *  other materials provided with the distribution.
     *  * Neither the name of Dash Industry Forum nor the names of its
     *  contributors may be used to endorse or promote products derived from this software
     *  without specific prior written permission.
     *
     *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY
     *  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     *  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
     *  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     *  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     *  POSSIBILITY OF SUCH DAMAGE.
     */
    import Debug from '../core/Debug';
    import FactoryMaker from '../core/FactoryMaker';

    /**
     * This is a sink that is used to temporarily hold onto media chunks before a video element is added.
     * The discharge() function is used to get the chunks out of the PreBuffer for adding to a real SourceBuffer.
     *
     * @class PreBufferSink
     * @ignore
     * @implements FragmentSink
     */
    function PreBufferSink(onAppendedCallback) {
        const context = this.context;

        let instance,
            logger,
            outstandingInit;
        let chunks = [];
        let onAppended = onAppendedCallback;

        function setup() {
            logger = Debug(context).getInstance().getLogger(instance);
        }

        function reset() {
            chunks = [];
            outstandingInit = null;
            onAppended = null;
        }

        function append(chunk) {
            if (chunk.segmentType !== 'InitializationSegment') { //Init segments are stored in the initCache.
                chunks.push(chunk);
                chunks.sort(function (a, b) {
                    return a.start - b.start;
                });
                outstandingInit = null;
            } else {//We need to hold an init chunk for when a corresponding media segment is being downloaded when the discharge happens.
                outstandingInit = chunk;
            }

            logger.debug('PreBufferSink appended chunk s: ' + chunk.start + '; e: ' + chunk.end);
            if (onAppended) {
                onAppended({
                    chunk: chunk
                });
            }
            return Promise.resolve();
        }

        function remove(start, end) {
            chunks = chunks.filter(a => !((isNaN(end) || a.start < end) && (isNaN(start) || a.end > start))); //The opposite of the getChunks predicate.
            return Promise.resolve();
        }

        //Nothing async, nothing to abort.
        function abort() {
            return Promise.resolve();
        }

        function getAllBufferRanges() {
            let ranges = [];

            for (let i = 0; i < chunks.length; i++) {
                let chunk = chunks[i];
                if (ranges.length === 0 || chunk.start > ranges[ranges.length - 1].end) {
                    ranges.push({start: chunk.start, end: chunk.end});
                } else {
                    ranges[ranges.length - 1].end = chunk.end;
                }
            }

            //Implements TimeRanges interface. So acts just like sourceBuffer.buffered.
            const timeranges = {
                start: function (n) {
                    return ranges[n].start;
                },
                end: function (n) {
                    return ranges[n].end;
                }
            };

            Object.defineProperty(timeranges, 'length', {
                get: function () {
                    return ranges.length;
                }
            });

            return timeranges;
        }

        function updateTimestampOffset() {
            return Promise.resolve();
        }

        function getBuffer() {
            return this;
        }

        /**
         * Return the all chunks in the buffer the lie between times start and end.
         * Because a chunk cannot be split, this returns the full chunk if any part of its time lies in the requested range.
         * Chunks are removed from the buffer when they are discharged.
         * @function PreBufferSink#discharge
         * @param {?Number} start The start time from which to discharge from the buffer. If NaN, it is regarded as unbounded.
         * @param {?Number} end The end time from which to discharge from the buffer. If NaN, it is regarded as unbounded.
         * @returns {Array} The set of chunks from the buffer within the time ranges.
         */
        function discharge(start, end) {
            const result = getChunksAt(start, end);
            if (outstandingInit) {
                result.push(outstandingInit);
                outstandingInit = null;
            }

            remove(start, end);

            return result;
        }

        function getChunksAt(start, end) {
            return chunks.filter(a => ((isNaN(end) || a.start < end) && (isNaN(start) || a.end > start)));
        }

        function waitForUpdateEnd(callback) {
            callback();
        }

        instance = {
            getAllBufferRanges,
            append,
            remove,
            abort,
            discharge,
            reset,
            updateTimestampOffset,
            waitForUpdateEnd,
            getBuffer
        };

        setup();

        return instance;
    }

    PreBufferSink.__dashjs_factory_name = 'PreBufferSink';
    const factory = FactoryMaker.getClassFactory(PreBufferSink);
    export default factory;

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