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

   This file is part of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found at: www.gnu.org/licenses

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

   ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.

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

MPESynthesiser::MPESynthesiser()
{
}

MPESynthesiser::MPESynthesiser (MPEInstrument* instrument)  : MPESynthesiserBase (instrument)
{
}

MPESynthesiser::~MPESynthesiser()
{
}

//==============================================================================
void MPESynthesiser::startVoice (MPESynthesiserVoice* voice, MPENote noteToStart)
{
    jassert (voice != nullptr);
    voice->currentlyPlayingNote = noteToStart;
    voice->noteStarted();
}

void MPESynthesiser::stopVoice (MPESynthesiserVoice* voice, MPENote noteToStop, bool allowTailOff)
{
    jassert (voice != nullptr);
    voice->currentlyPlayingNote = noteToStop;
    voice->noteStopped (allowTailOff);
}

//==============================================================================
void MPESynthesiser::noteAdded (MPENote newNote)
{
    const ScopedLock sl (voicesLock);

    if (MPESynthesiserVoice* voice = findFreeVoice (newNote, shouldStealVoices))
        startVoice (voice, newNote);
}

void MPESynthesiser::notePressureChanged (MPENote changedNote)
{
    const ScopedLock sl (voicesLock);

    for (int i = 0; i < voices.size(); ++i)
    {
        MPESynthesiserVoice* voice = voices.getUnchecked (i);

        if (voice->isCurrentlyPlayingNote (changedNote))
        {
            voice->currentlyPlayingNote = changedNote;
            voice->notePressureChanged();
        }
    }
}

void MPESynthesiser::notePitchbendChanged (MPENote changedNote)
{
    const ScopedLock sl (voicesLock);

    for (int i = 0; i < voices.size(); ++i)
    {
        MPESynthesiserVoice* voice = voices.getUnchecked (i);

        if (voice->isCurrentlyPlayingNote (changedNote))
        {
            voice->currentlyPlayingNote = changedNote;
            voice->notePitchbendChanged();
        }
    }
}

void MPESynthesiser::noteTimbreChanged (MPENote changedNote)
{
    const ScopedLock sl (voicesLock);

    for (int i = 0; i < voices.size(); ++i)
    {
        MPESynthesiserVoice* voice = voices.getUnchecked (i);

        if (voice->isCurrentlyPlayingNote (changedNote))
        {
            voice->currentlyPlayingNote = changedNote;
            voice->noteTimbreChanged();
        }
    }
}

void MPESynthesiser::noteKeyStateChanged (MPENote changedNote)
{
    const ScopedLock sl (voicesLock);

    for (int i = 0; i < voices.size(); ++i)
    {
        MPESynthesiserVoice* voice = voices.getUnchecked (i);

        if (voice->isCurrentlyPlayingNote (changedNote))
        {
            voice->currentlyPlayingNote = changedNote;
            voice->noteKeyStateChanged();
        }
    }
}

void MPESynthesiser::noteReleased (MPENote finishedNote)
{
    const ScopedLock sl (voicesLock);

    for (int i = voices.size(); --i >= 0;)
    {
        MPESynthesiserVoice* const voice = voices.getUnchecked (i);

        if (voice->isCurrentlyPlayingNote(finishedNote))
            stopVoice (voice, finishedNote, true);
    }
}

void MPESynthesiser::setCurrentPlaybackSampleRate (const double newRate)
{
    MPESynthesiserBase::setCurrentPlaybackSampleRate (newRate);

    const ScopedLock sl (voicesLock);

    turnOffAllVoices (false);

    for (int i = voices.size(); --i >= 0;)
        voices.getUnchecked (i)->setCurrentSampleRate (newRate);
}

void MPESynthesiser::handleMidiEvent (const MidiMessage& m)
{
    if (m.isController())
        handleController (m.getChannel(), m.getControllerNumber(), m.getControllerValue());
    else if (m.isProgramChange())
        handleProgramChange (m.getChannel(), m.getProgramChangeNumber());

    MPESynthesiserBase::handleMidiEvent (m);
}

MPESynthesiserVoice* MPESynthesiser::findFreeVoice (MPENote noteToFindVoiceFor, bool stealIfNoneAvailable) const
{
    const ScopedLock sl (voicesLock);

    for (int i = 0; i < voices.size(); ++i)
    {
        MPESynthesiserVoice* const voice = voices.getUnchecked (i);

        if (! voice->isActive())
            return voice;
    }

    if (stealIfNoneAvailable)
        return findVoiceToSteal (noteToFindVoiceFor);

    return nullptr;
}

struct MPEVoiceAgeSorter
{
    static int compareElements (MPESynthesiserVoice* v1, MPESynthesiserVoice* v2) noexcept
    {
        return v1->wasStartedBefore (*v2) ? -1 : (v2->wasStartedBefore (*v1) ? 1 : 0);
    }
};

MPESynthesiserVoice* MPESynthesiser::findVoiceToSteal (MPENote noteToStealVoiceFor) const
{
    // This voice-stealing algorithm applies the following heuristics:
    // - Re-use the oldest notes first
    // - Protect the lowest & topmost notes, even if sustained, but not if they've been released.


    // apparently you are trying to render audio without having any voices...
    jassert (voices.size() > 0);

    // These are the voices we want to protect (ie: only steal if unavoidable)
    MPESynthesiserVoice* low = nullptr; // Lowest sounding note, might be sustained, but NOT in release phase
    MPESynthesiserVoice* top = nullptr; // Highest sounding note, might be sustained, but NOT in release phase

    // this is a list of voices we can steal, sorted by how long they've been running
    Array<MPESynthesiserVoice*> usableVoices;
    usableVoices.ensureStorageAllocated (voices.size());

    for (int i = 0; i < voices.size(); ++i)
    {
        MPESynthesiserVoice* const voice = voices.getUnchecked (i);
        jassert (voice->isActive()); // We wouldn't be here otherwise

        MPEVoiceAgeSorter sorter;
        usableVoices.addSorted (sorter, voice);

        if (! voice->isPlayingButReleased()) // Don't protect released notes
        {
            const int noteNumber = voice->getCurrentlyPlayingNote().initialNote;

            if (low == nullptr || noteNumber < low->getCurrentlyPlayingNote().initialNote)
                low = voice;

            if (top == nullptr || noteNumber > top->getCurrentlyPlayingNote().initialNote)
                top = voice;
        }
    }

    // Eliminate pathological cases (ie: only 1 note playing): we always give precedence to the lowest note(s)
    if (top == low)
        top = nullptr;

    const int numUsableVoices = usableVoices.size();

    // If we want to re-use the voice to trigger a new note,
    // then The oldest note that's playing the same note number is ideal.
    if (noteToStealVoiceFor.isValid())
    {
        for (int i = 0; i < numUsableVoices; ++i)
        {
            MPESynthesiserVoice* const voice = usableVoices.getUnchecked (i);

            if (voice->getCurrentlyPlayingNote().initialNote == noteToStealVoiceFor.initialNote)
                return voice;
        }
    }

    // Oldest voice that has been released (no finger on it and not held by sustain pedal)
    for (int i = 0; i < numUsableVoices; ++i)
    {
        MPESynthesiserVoice* const voice = usableVoices.getUnchecked (i);

        if (voice != low && voice != top && voice->isPlayingButReleased())
            return voice;
    }

    // Oldest voice that doesn't have a finger on it:
    for (int i = 0; i < numUsableVoices; ++i)
    {
        MPESynthesiserVoice* const voice = usableVoices.getUnchecked (i);

        if (voice != low && voice != top
             && voice->getCurrentlyPlayingNote().keyState != MPENote::keyDown
             && voice->getCurrentlyPlayingNote().keyState != MPENote::keyDownAndSustained)
            return voice;
    }

    // Oldest voice that isn't protected
    for (int i = 0; i < numUsableVoices; ++i)
    {
        MPESynthesiserVoice* const voice = usableVoices.getUnchecked (i);

        if (voice != low && voice != top)
            return voice;
    }

    // We've only got "protected" voices now: lowest note takes priority
    jassert (low != nullptr);

    // Duophonic synth: give priority to the bass note:
    if (top != nullptr)
        return top;

    return low;
}

//==============================================================================
void MPESynthesiser::addVoice (MPESynthesiserVoice* const newVoice)
{
    const ScopedLock sl (voicesLock);
    newVoice->setCurrentSampleRate (getSampleRate());
    voices.add (newVoice);
}

void MPESynthesiser::clearVoices()
{
    const ScopedLock sl (voicesLock);
    voices.clear();
}

MPESynthesiserVoice* MPESynthesiser::getVoice (const int index) const
{
    const ScopedLock sl (voicesLock);
    return voices [index];
}

void MPESynthesiser::removeVoice (const int index)
{
    const ScopedLock sl (voicesLock);
    voices.remove (index);
}

void MPESynthesiser::reduceNumVoices (const int newNumVoices)
{
    // we can't possibly get to a negative number of voices...
    jassert (newNumVoices >= 0);

    const ScopedLock sl (voicesLock);

    while (voices.size() > newNumVoices)
    {
        if (MPESynthesiserVoice* voice = findFreeVoice (MPENote(), true))
            voices.removeObject (voice);
        else
            voices.remove (0); // if there's no voice to steal, kill the oldest voice
    }
}

void MPESynthesiser::turnOffAllVoices (bool allowTailOff)
{
    // first turn off all voices (it's more efficient to do this immediately
    // rather than to go through the MPEInstrument for this).
    for (int i = voices.size(); --i >= 0;)
        voices.getUnchecked (i)->noteStopped (allowTailOff);

    // finally make sure the MPE Instrument also doesn't have any notes anymore.
    instrument->releaseAllNotes();
}

//==============================================================================
void MPESynthesiser::renderNextSubBlock (AudioBuffer<float>& buffer, int startSample, int numSamples)
{
    for (int i = voices.size(); --i >= 0;)
    {
        MPESynthesiserVoice* voice = voices.getUnchecked (i);

        if (voice->isActive())
            voice->renderNextBlock (buffer, startSample, numSamples);
    }
}

void MPESynthesiser::renderNextSubBlock (AudioBuffer<double>& buffer, int startSample, int numSamples)
{
    for (int i = voices.size(); --i >= 0;)
    {
        MPESynthesiserVoice* voice = voices.getUnchecked (i);

        if (voice->isActive())
            voice->renderNextBlock (buffer, startSample, numSamples);
    }
}
