/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
/**
    An AudioSource which takes another source as input, and buffers it using a thread.

    Create this as a wrapper around another thread, and it will read-ahead with
    a background thread to smooth out playback. You can either create one of these
    directly, or use it indirectly using an AudioTransportSource.

    @see PositionableAudioSource, AudioTransportSource

    @tags{Audio}
*/
class JUCE_API  BufferingAudioSource  : public PositionableAudioSource,
                                        private TimeSliceClient
{
public:
    //==============================================================================
    /** Creates a BufferingAudioSource.

        @param source                       the input source to read from
        @param backgroundThread             a background thread that will be used for the
                                            background read-ahead. This object must not be deleted
                                            until after any BufferingAudioSources that are using it
                                            have been deleted!
        @param deleteSourceWhenDeleted      if true, then the input source object will
                                            be deleted when this object is deleted
        @param numberOfSamplesToBuffer      the size of buffer to use for reading ahead
        @param numberOfChannels             the number of channels that will be played
        @param prefillBufferOnPrepareToPlay if true, then calling prepareToPlay on this object will
                                            block until the buffer has been filled
    */
    BufferingAudioSource (PositionableAudioSource* source,
                          TimeSliceThread& backgroundThread,
                          bool deleteSourceWhenDeleted,
                          int numberOfSamplesToBuffer,
                          int numberOfChannels = 2,
                          bool prefillBufferOnPrepareToPlay = true);

    /** Destructor.

        The input source may be deleted depending on whether the deleteSourceWhenDeleted
        flag was set in the constructor.
    */
    ~BufferingAudioSource() override;

    //==============================================================================
    /** Implementation of the AudioSource method. */
    void prepareToPlay (int samplesPerBlockExpected, double sampleRate) override;

    /** Implementation of the AudioSource method. */
    void releaseResources() override;

    /** Implementation of the AudioSource method. */
    void getNextAudioBlock (const AudioSourceChannelInfo&) override;

    //==============================================================================
    /** Implements the PositionableAudioSource method. */
    void setNextReadPosition (int64 newPosition) override;

    /** Implements the PositionableAudioSource method. */
    int64 getNextReadPosition() const override;

    /** Implements the PositionableAudioSource method. */
    int64 getTotalLength() const override       { return source->getTotalLength(); }

    /** Implements the PositionableAudioSource method. */
    bool isLooping() const override             { return source->isLooping(); }

    /** A useful function to block until the next the buffer info can be filled.

        This is useful for offline rendering.
    */
    bool waitForNextAudioBlockReady (const AudioSourceChannelInfo& info, uint32 timeout);

private:
    //==============================================================================
    Range<int> getValidBufferRange (int numSamples) const;
    bool readNextBufferChunk();
    void readBufferSection (int64 start, int length, int bufferOffset);
    int useTimeSlice() override;

    //==============================================================================
    OptionalScopedPointer<PositionableAudioSource> source;
    TimeSliceThread& backgroundThread;
    int numberOfSamplesToBuffer, numberOfChannels;
    AudioBuffer<float> buffer;
    CriticalSection callbackLock, bufferRangeLock;
    WaitableEvent bufferReadyEvent;
    int64 bufferValidStart = 0, bufferValidEnd = 0;
    std::atomic<int64> nextPlayPos { 0 };
    double sampleRate = 0;
    bool wasSourceLooping = false, isPrepared = false;
    const bool prefillBuffer;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (BufferingAudioSource)
};

} // namespace juce