#include "MidiBuffer.h"

//==============================================================================
/** A handy function to read un-aligned memory without a performance penalty or bus-error. */
template <typename Type>
inline Type readUnaligned (const void* srcPtr) noexcept
{
    Type value;
    memcpy(&value, srcPtr, sizeof(Type));
    return value;
}

/** A handy function to write un-aligned memory without a performance penalty or bus-error. */
template <typename Type>
inline void writeUnaligned (void* dstPtr, Type value) noexcept
{
    memcpy(dstPtr, &value, sizeof (Type));
}

namespace MidiBufferHelpers
{
    inline int getEventTime (const void* d) noexcept
    {
        return readUnaligned<int32>(d);
    }

    inline uint16 getEventDataSize (const void* d) noexcept
    {
        return readUnaligned<uint16> (static_cast<const char*> (d) + sizeof (int32));
    }

    inline uint16 getEventTotalSize (const void* d) noexcept
    {
        return (uint16) (getEventDataSize (d) + sizeof (int32) + sizeof (uint16));
    }

    static int findActualEventLength (const uint8* data, int maxBytes) noexcept
    {
        auto byte = (unsigned int)*data;

        if (byte == 0xf0 || byte == 0xf7)
        {
            int i = 1;

            while (i < maxBytes)
                if (data[i++] == 0xf7)
                    break;

            return i;
        }

        if (byte == 0xff)
        {
            if (maxBytes == 1)
                return 1;

            const auto var = FMidiMessage::readVariableLengthValue (data + 1, maxBytes - 1);
            return FMath::Min(maxBytes, var.value + 2 + var.bytesUsed);
        }

        if (byte >= 0x80)
            return FMath::Min(maxBytes, FMidiMessage::getMessageLengthFromFirstByte ((uint8) byte));

        return 0;
    }

    static uint8* findEventAfter (uint8* d, uint8* endData, int samplePosition) noexcept
    {
        while (d < endData && getEventTime(d) <= samplePosition)
            d += getEventTotalSize(d);

        return d;
    }
}

//==============================================================================
MidiBufferIterator& MidiBufferIterator::operator++() noexcept
{
    data += sizeof (int32) + sizeof (uint16) + size_t (MidiBufferHelpers::getEventDataSize (data));
    return *this;
}

MidiBufferIterator MidiBufferIterator::operator++ (int) noexcept
{
    auto copy = *this;
    ++(*this);
    return copy;
}

MidiBufferIterator::reference MidiBufferIterator::operator*() const noexcept
{
    return { data + sizeof (int32) + sizeof (uint16),
             MidiBufferHelpers::getEventDataSize (data),
             MidiBufferHelpers::getEventTime (data) };
}

//==============================================================================
FMidiBuffer::FMidiBuffer(const FMidiMessage& message) noexcept
{
    addEvent(message, 0);
}

void FMidiBuffer::swapWith (FMidiBuffer& other) noexcept      { Swap(data, other.data); }
void FMidiBuffer::clear() noexcept                           { data.Reset(); }
void FMidiBuffer::ensureSize (size_t minimumNumBytes)        { ensure(data.GetAllocatedSize() >= (int) minimumNumBytes); }
bool FMidiBuffer::isEmpty() const noexcept                   { return data.IsEmpty(); }

void FMidiBuffer::clear (int startSample, int numSamples)
{
    auto start = MidiBufferHelpers::findEventAfter (data.GetData(), data.GetData() + data.Num(), startSample - 1);
    auto end   = MidiBufferHelpers::findEventAfter (start,          data.GetData() + data.Num(), startSample + numSamples - 1);

    data.RemoveAt(static_cast<int>(start - data.GetData()), static_cast<int>(end - start));
}

bool FMidiBuffer::addEvent (const FMidiMessage& m, int sampleNumber)
{
    return addEvent (m.getRawData(), m.getRawDataSize(), sampleNumber);
}

bool FMidiBuffer::addEvent (const void* newData, int maxBytes, int sampleNumber)
{
    auto numBytes = MidiBufferHelpers::findActualEventLength (static_cast<const uint8*> (newData), maxBytes);

    if (numBytes <= 0)
        return true;

    if (std::numeric_limits<uint16>::max() < numBytes)
    {
        // This method only supports messages smaller than (1 << 16) bytes
        return false;
    }

    auto newItemSize = (size_t)numBytes + sizeof (int32) + sizeof (uint16);
    auto offset = (int)(MidiBufferHelpers::findEventAfter(data.GetData(), data.GetData() + data.Num(), sampleNumber) - data.GetData());

    // data.insertMultiple(offset, 0, (int)newItemSize);

    for (int i = 0; i < (int)newItemSize; ++i)
        data.Insert(0, offset);
    
    auto* d = data.GetData() + offset;
    writeUnaligned<int32>  (d, sampleNumber);
    d += sizeof (int32);
    writeUnaligned<uint16> (d, static_cast<uint16> (numBytes));
    d += sizeof (uint16);
    memcpy (d, newData, (size_t) numBytes);

    return true;
}

void FMidiBuffer::addEvents (const FMidiBuffer& otherBuffer,
                            int startSample, int numSamples, int sampleDeltaToAdd)
{
    for (auto i = otherBuffer.findNextSamplePosition (startSample); i != otherBuffer.cend(); ++i)
    {
        const auto metadata = *i;

        if (metadata.samplePosition >= startSample + numSamples && numSamples >= 0)
            break;

        addEvent (metadata.data, metadata.numBytes, metadata.samplePosition + sampleDeltaToAdd);
    }
}

int FMidiBuffer::getNumEvents() noexcept
{
    int n = 0;
        
    for (int i = 0; i < data.Num(); ++i, ++n)
    {
        i += MidiBufferHelpers::getEventTotalSize(&data[i]);
    }

    return n;
}

int FMidiBuffer::getFirstEventTime() const noexcept
{
    return data.Num() > 0 ? MidiBufferHelpers::getEventTime(data.GetData()) : 0;
}

int FMidiBuffer::getLastEventTime() const noexcept
{
    if (data.Num() == 0)
        return 0;

    // auto endData = data.end();

    // for (auto d = data.begin();;)
    // {
    //     auto nextOne = d + MidiBufferHelpers::getEventTotalSize(d);
    //
    //     if (nextOne >= endData)
    //         return MidiBufferHelpers::getEventTime (d);
    //
    //     d = nextOne;
    // }

    for (int i = 0; i < data.Num(); ++i)
    {
        const int32 nextOne = i + MidiBufferHelpers::getEventTotalSize(&data[i]);

        if (nextOne >= data.Num())
            return MidiBufferHelpers::getEventTime(&data[i]);

        i = nextOne;
    }
    return 0;
}

MidiBufferIterator FMidiBuffer::findNextSamplePosition (int samplePosition) const noexcept
{
    return std::find_if (cbegin(), cend(), [&] (const MidiMessageMetadata& metadata) noexcept
    {
        return metadata.samplePosition >= samplePosition;
    });
}