/*
 * Copyright (C) 2022 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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.
 */

#pragma once

#if ENABLE(MEDIA_SOURCE)

#include "MediaDescription.h"
#include "MediaSample.h"
#include "PlatformTimeRanges.h"
#include "SampleMap.h"
#include <wtf/Logger.h>
#include <wtf/LoggerHelper.h>
#include <wtf/MediaTime.h>
#include <wtf/TZoneMalloc.h>
#include <wtf/UniqueRef.h>

namespace WebCore {

class TrackBuffer final
#if !RELEASE_LOG_DISABLED
    : public LoggerHelper
#endif
{
    WTF_MAKE_TZONE_ALLOCATED(TrackBuffer);
public:
    // Returns true if the timestamp gap between `fromTime` and `toTime`
    // is acceptable per the gap-skipping policy. Used both with DTS gaps
    // (between adjacent samples in nextSample) and with PTS gaps
    // (between a seek target and the next available sample in
    // reenqueueMediaForTime). Only consulted when the gap exceeds
    // PlatformTimeRanges::timeFudgeFactor() — gaps below that threshold
    // are treated as contiguous (matching how the buffered range itself
    // is reported to clients) and never reach the lambda.
    using IsAcceptableEnqueueGapFn = Function<bool(const MediaTime& fromTime, const MediaTime& toTime)>;

    static UniqueRef<TrackBuffer> create(RefPtr<MediaDescription>&&, IsAcceptableEnqueueGapFn&& = nullptr);

    MediaTime NODELETE maximumBufferedTime() const;
    void addBufferedRange(const MediaTime& start, const MediaTime& end, AddTimeRangeOption = AddTimeRangeOption::None);
    void addSample(MediaSample&);
    // Replace an already-buffered sample with a copy whose presentation and
    // decode timestamps are shifted forward by `offset` (duration shrinks
    // accordingly; presentationEndTime is preserved). Updates both the
    // SampleMap and m_decodeQueue, and adjusts m_buffered to match.
    void adjustSampleStartTime(MediaSample& original, const MediaTime& offset);

    bool reenqueueMediaForTime(const MediaTime&, bool isEnded = false);
    MediaTime findSeekTimeForTargetTime(const MediaTime& targetTime, const MediaTime& negativeThreshold, const MediaTime& positiveThreshold);
    int64_t removeCodedFrames(const MediaTime& start, const MediaTime& end, const MediaTime& currentTime);
    PlatformTimeRanges removeSamples(const DecodeOrderSampleMap::MapType&, ASCIILiteral);
    int64_t codedFramesIntervalSize(const MediaTime& start, const MediaTime& end);

    RefPtr<MediaSample> nextSample();
    size_t remainingSamples() const { return decodeQueue().size(); }

    void NODELETE resetTimestampOffset();
    void NODELETE reset();
    void clearSamples();

    const MediaTime& lastDecodeTimestamp() const LIFETIME_BOUND { return m_lastDecodeTimestamp; }
    void setLastDecodeTimestamp(MediaTime timestamp) { m_lastDecodeTimestamp = WTF::move(timestamp); }

    const MediaTime& greatestFrameDuration() const LIFETIME_BOUND { return m_greatestFrameDuration; }
    void setGreatestFrameDuration(MediaTime duration) { m_greatestFrameDuration = WTF::move(duration); }
    const MediaTime& lastFrameDuration() const LIFETIME_BOUND { return m_lastFrameDuration; }
    void setLastFrameDuration(MediaTime duration) { m_lastFrameDuration = WTF::move(duration); }

    const MediaTime& highestPresentationTimestamp() const LIFETIME_BOUND { return m_highestPresentationTimestamp; }
    void setHighestPresentationTimestamp(MediaTime timestamp) { m_highestPresentationTimestamp = WTF::move(timestamp); }

    const MediaTime& highestEnqueuedPresentationTime() const LIFETIME_BOUND { return m_highestEnqueuedPresentationTime; }
    void setHighestEnqueuedPresentationTime(MediaTime timestamp) { m_highestEnqueuedPresentationTime = WTF::move(timestamp); }
    const MediaTime& minimumEnqueuedPresentationTime() const LIFETIME_BOUND { return m_minimumEnqueuedPresentationTime; }

    // Raises the tracked reorder depth. Call once per init segment with the
    // codec-declared max_num_reorder_frames / sps_max_num_reorder_pics when
    // available. The running observation in addSample() can only grow it further.
    void setInitialReorderDepth(size_t depth) { m_maxObservedReorderDepth = std::max(m_maxObservedReorderDepth, depth); }

    const DecodeOrderSampleMap::KeyType& lastEnqueuedDecodeKey() const LIFETIME_BOUND { return m_lastEnqueuedDecodeKey; }
    void setLastEnqueuedDecodeKey(DecodeOrderSampleMap::KeyType key) { m_lastEnqueuedDecodeKey = WTF::move(key); }

    const MediaTime& enqueueDiscontinuityBoundary() const LIFETIME_BOUND { return m_enqueueDiscontinuityBoundary; }
    void setEnqueueDiscontinuityBoundary(MediaTime boundary) { m_enqueueDiscontinuityBoundary = WTF::move(boundary); }

    const MediaTime& roundedTimestampOffset() const LIFETIME_BOUND { return m_roundedTimestampOffset; }
    void setRoundedTimestampOffset(MediaTime offset) { m_roundedTimestampOffset = WTF::move(offset); }
    void setRoundedTimestampOffset(const MediaTime&, uint32_t, const MediaTime&);

    uint32_t lastFrameTimescale() const { return m_lastFrameTimescale; }
    void setLastFrameTimescale(uint32_t timescale) { m_lastFrameTimescale = timescale; }
    bool needRandomAccessFlag() const { return m_needRandomAccessFlag; }
    void setNeedRandomAccessFlag(bool flag) { m_needRandomAccessFlag = flag; }
    bool enabled() const { return m_enabled; }
    void setEnabled(bool enabled) { m_enabled = enabled; }
    bool needsReenqueueing() const { return m_needsReenqueueing; }
    void setNeedsReenqueueing(bool flag) { m_needsReenqueueing = flag; }

    const SampleMap& samples() const LIFETIME_BOUND { return m_samples; }
    SampleMap& samples() LIFETIME_BOUND { return m_samples; }
    const RefPtr<MediaDescription>& description() const { return m_description; }
    const PlatformTimeRanges& buffered() const LIFETIME_BOUND { return m_buffered; }
    PlatformTimeRanges& buffered() LIFETIME_BOUND { return m_buffered; }

#if !RELEASE_LOG_DISABLED
    void setLogger(const Logger&, uint64_t);
    const Logger& logger() const final { ASSERT(m_logger); return *m_logger.get(); }
    uint64_t logIdentifier() const final { return m_logIdentifier; }
    ASCIILiteral logClassName() const final { return "TrackBuffer"_s; }
    WTFLogChannel& logChannel() const final;
#endif

private:
    friend UniqueRef<TrackBuffer> WTF::makeUniqueRefWithoutFastMallocCheck<TrackBuffer>(RefPtr<WebCore::MediaDescription>&&, IsAcceptableEnqueueGapFn&&);
    TrackBuffer(RefPtr<MediaDescription>&&, IsAcceptableEnqueueGapFn&&);

    // Returns true if the DTS gap from `fromTime` to `toTime` is small
    // enough to enqueue across. Gaps within
    // PlatformTimeRanges::timeFudgeFactor() are always accepted (the
    // buffered range itself would be reported as contiguous); larger
    // gaps consult the constructor-supplied callback (when set —
    // currently MSE only).
    bool isAcceptableEnqueueGap(const MediaTime& fromTime, const MediaTime& toTime) const;

    const DecodeOrderSampleMap::MapType& decodeQueue() const LIFETIME_BOUND { return m_decodeQueue; }
    DecodeOrderSampleMap::MapType& decodeQueue() LIFETIME_BOUND { return m_decodeQueue; }
    void updateMinimumUpcomingPresentationTime();
    void clearDecodeQueue();

    // Result of attempting to split the sample whose presentation range contains a given time.
    struct DivideResult {
        // Presentation timestamp of the "after" piece (the piece whose range starts at the split
        // point). Invalid if no split happened (no containing sample, not divisible, or
        // MediaSample::divide returned null halves).
        MediaTime afterSplitPresentationTime { MediaTime::invalidTime() };
        // Byte sizes of the pieces produced by the split, valid only when
        // afterSplitPresentationTime is valid.
        int64_t beforeSplitSize { 0 };
        int64_t afterSplitSize { 0 };
    };
    enum class ApplyDivide : bool { No, Yes };
    DivideResult tryDivideSampleAtTime(const MediaTime&, ApplyDivide);

    SampleMap m_samples;
    DecodeOrderSampleMap::MapType m_decodeQueue;
    RefPtr<MediaDescription> m_description;
    PlatformTimeRanges m_buffered;

    MediaTime m_lastDecodeTimestamp { MediaTime::invalidTime() };

    MediaTime m_greatestFrameDuration { MediaTime::invalidTime() };
    MediaTime m_lastFrameDuration { MediaTime::invalidTime() };

    MediaTime m_highestPresentationTimestamp { MediaTime::invalidTime() };

    MediaTime m_highestEnqueuedPresentationTime { MediaTime::invalidTime() };
    MediaTime m_minimumEnqueuedPresentationTime { MediaTime::invalidTime() };

    // Running observation of decode-order reorder depth. Seeded by
    // setInitialReorderDepth; grown when a deeper reorder is seen. Gates
    // publication of m_minimumEnqueuedPresentationTime so a yet-to-arrive
    // B-frame can't invalidate the value handed to the renderer.
    MediaTime m_maxPresentationTimeSeenInDecodeOrder { MediaTime::invalidTime() };
    size_t m_samplesSinceMaxPresentationTime { 0 };
    size_t m_maxObservedReorderDepth { 3 };

    DecodeOrderSampleMap::KeyType m_lastEnqueuedDecodeKey { MediaTime::invalidTime(), MediaTime::invalidTime() };

    MediaTime m_enqueueDiscontinuityBoundary;
    MediaTime m_lastEnqueueDecodeEnd;
    IsAcceptableEnqueueGapFn m_isAcceptableEnqueueGap;

    MediaTime m_roundedTimestampOffset { MediaTime::invalidTime() };

#if !RELEASE_LOG_DISABLED
    RefPtr<const Logger> m_logger;
    uint64_t m_logIdentifier { 0 };
#endif

    uint32_t m_lastFrameTimescale { 0 };
    bool m_needRandomAccessFlag { true };
    bool m_enabled { false };
    bool m_needsReenqueueing { false };
    bool m_hasOutOfOrderFrames { false };
};

} // namespace WebCore

#endif // ENABLE(MEDIA_SOURCE)
