/*
	Simple C interface for XAudio2
	Author: Hans-Kristian Arntzen
	License: Public Domain
*/

#include "xaudio-c.h"
#include "xaudio2.hpp"
#include <stdint.h>
#include <algorithm>

struct xaudio2 : public IXAudio2VoiceCallback
{
   xaudio2(unsigned samplerate, unsigned channels, unsigned size) : 
      buf(0), pXAudio2(0), pMasterVoice(0), pSourceVoice(0),
      buffers(0), bufptr(0)
   {
      CoInitializeEx(0, COINIT_MULTITHREADED);
      if (FAILED(XAudio2Create(&pXAudio2, 0)))
         throw -1;
      if (FAILED(pXAudio2->CreateMasteringVoice(
                  &pMasterVoice, channels, samplerate, 0, 0, 0)))
         throw -1;

      WAVEFORMATEX wfx;
      wfx.wFormatTag = WAVE_FORMAT_IEEE_FLOAT;
      wfx.nChannels = channels;
      wfx.nSamplesPerSec = samplerate;
      wfx.nBlockAlign = channels * sizeof(float);
      wfx.wBitsPerSample = sizeof(float) * 8;
      wfx.nAvgBytesPerSec = wfx.nSamplesPerSec * wfx.nBlockAlign;
      wfx.cbSize = 0;
      if (FAILED(pXAudio2->CreateSourceVoice(
                  &pSourceVoice, &wfx, XAUDIO2_VOICE_NOSRC, XAUDIO2_DEFAULT_FREQ_RATIO, this, 0, 0)))
         throw -1;

      hEvent = CreateEvent(0, FALSE, FALSE, 0);
      if (!hEvent)
         throw -1;

      pSourceVoice->Start(0);

      bufsize = size / max_buffers;
      buf = new uint8_t[bufsize * max_buffers];
      write_buffer = 0;
   }

   virtual ~xaudio2()
   {
      if (pSourceVoice)
      {
         pSourceVoice->Stop(0);
         pSourceVoice->DestroyVoice();
      }

      if (pMasterVoice)
         pMasterVoice->DestroyVoice();

      if (pXAudio2)
         pXAudio2->Release();

      if (hEvent)
         CloseHandle(hEvent);

      if (buf)
         delete[] buf;
   }

   size_t write_avail() const
   {
      return bufsize * (max_buffers - buffers - 1);
   }

   size_t write(const void *buffer_, size_t bytes_)
   {
      unsigned bytes = bytes_;
      const uint8_t *buffer = reinterpret_cast<const uint8_t*>(buffer_);
      while (bytes > 0)
      {
         unsigned need = std::min(bytes, bufsize - bufptr);
         memcpy(buf + write_buffer * bufsize + bufptr,
               buffer, need);

         bufptr += need;
         buffer += need;
         bytes -= need;

         if (bufptr == bufsize)
         {
            WaitForSingleObject(hEvent, 0); // Clear out ready state.
            while (buffers == max_buffers - 1)
               WaitForSingleObject(hEvent, INFINITE);

            XAUDIO2_BUFFER xa2buffer = {0};
            xa2buffer.AudioBytes = bufsize;
            xa2buffer.pAudioData = buf + write_buffer * bufsize;
            xa2buffer.pContext = 0;
            if (FAILED(pSourceVoice->SubmitSourceBuffer(&xa2buffer)))
               return 0;

            InterlockedIncrement(&buffers);
            bufptr = 0;
            write_buffer = (write_buffer + 1) & (max_buffers_mask);
         }
      }

      return bytes_;
   }

   enum { max_buffers = 16, max_buffers_mask = max_buffers - 1 };

   STDMETHOD_(void, OnBufferStart) (void *) {}
   STDMETHOD_(void, OnBufferEnd) (void *) 
   {
      InterlockedDecrement(&buffers);
      SetEvent(hEvent);
   }
   STDMETHOD_(void, OnLoopEnd) (void *) {}
   STDMETHOD_(void, OnStreamEnd) () {}
   STDMETHOD_(void, OnVoiceError) (void *, HRESULT) {}
   STDMETHOD_(void, OnVoiceProcessingPassEnd) () {}
   STDMETHOD_(void, OnVoiceProcessingPassStart) (UINT32) {}

   uint8_t *buf;
   IXAudio2 *pXAudio2;
   IXAudio2MasteringVoice *pMasterVoice;
   IXAudio2SourceVoice *pSourceVoice;
   HANDLE hEvent;

   volatile long buffers;
   unsigned bufsize;
   unsigned bufptr;
   unsigned write_buffer;
};

xaudio2_t *xaudio2_new(unsigned samplerate, unsigned channels, size_t size)
{
   xaudio2 *handle = 0;
   try {
      handle = new xaudio2(samplerate, channels, size);
   } catch(...) { delete handle; return 0; }

   return handle;
}

size_t xaudio2_write_avail(xaudio2_t *handle)
{
   try {
      return handle->write_avail();
   } catch(...) { return 0; }
}

size_t xaudio2_write(xaudio2_t *handle, const void *buf, size_t bytes)
{
   try {
      return handle->write(buf, bytes);
   } catch(...) { return 0; }
}

void xaudio2_free(xaudio2_t *handle)
{
   delete handle;
}