/*
 Copyright (C) 2009 Jonathon Fowler <jf@jonof.id.au>

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program 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.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 */

/**
 * libSDL output driver for MultiVoc
 */

#define _NEED_SDLMIXER
#include "compat.h"
#include "sdl_inc.h"
#include "driver_sdl.h"
#include "multivoc.h"

#ifdef __ANDROID__
#include "duke3d.h"
#include "android.h"
#endif

enum {
   SDLErr_Warning = -2,
   SDLErr_Error   = -1,
   SDLErr_Ok      = 0,
   SDLErr_Uninitialised,
   SDLErr_InitSubSystem,
   SDLErr_OpenAudio
};

static int32_t ErrorCode = SDLErr_Ok;
static int32_t Initialised = 0;
static int32_t Playing = 0;
static int32_t StartedSDL = -1;

static char *MixBuffer = 0;
static int32_t MixBufferSize = 0;
static int32_t MixBufferCount = 0;
static int32_t MixBufferCurrent = 0;
static int32_t MixBufferUsed = 0;
static void ( *MixCallBack )( void ) = 0;

static Mix_Chunk *DummyChunk = NULL;
static uint8_t *DummyBuffer = NULL;
static int32_t InterruptsDisabled = 0;
static SDL_mutex *EffectFence;

static void fillData(int chan, void *ptr, int remaining, void *udata)
{
	int32_t len;
	char *sptr;

    UNREFERENCED_PARAMETER(chan);
    UNREFERENCED_PARAMETER(udata);

    if (!MixBuffer || !MixCallBack)
      return;

    SDL_LockMutex(EffectFence);

	while (remaining > 0) {
		if (MixBufferUsed == MixBufferSize) {
			MixCallBack();

			MixBufferUsed = 0;
			MixBufferCurrent++;
			if (MixBufferCurrent >= MixBufferCount) {
				MixBufferCurrent -= MixBufferCount;
			}
		}

		while (remaining > 0 && MixBufferUsed < MixBufferSize) {
			sptr = MixBuffer + (MixBufferCurrent * MixBufferSize) + MixBufferUsed;

			len = MixBufferSize - MixBufferUsed;
			if (remaining < len) {
				len = remaining;
			}

			memcpy(ptr, sptr, len);

			ptr = (void *)((uintptr_t)(ptr) + len);
			MixBufferUsed += len;
			remaining -= len;
		}
	}

    SDL_UnlockMutex(EffectFence);
}


int32_t SDLDrv_GetError(void)
{
    return ErrorCode;
}

const char *SDLDrv_ErrorString( int32_t ErrorNumber )
{
    const char *ErrorString;

    switch( ErrorNumber ) {
        case SDLErr_Warning :
        case SDLErr_Error :
            ErrorString = SDLDrv_ErrorString( ErrorCode );
            break;

        case SDLErr_Ok :
            ErrorString = "SDL Audio ok.";
            break;

        case SDLErr_Uninitialised:
            ErrorString = "SDL Audio uninitialised.";
            break;

        case SDLErr_InitSubSystem:
            ErrorString = "SDL Audio: error in Init or InitSubSystem.";
            break;

        case SDLErr_OpenAudio:
            ErrorString = "SDL Audio: error in OpenAudio.";
            break;

        default:
            ErrorString = "Unknown SDL Audio error code.";
            break;
    }

    return ErrorString;
}

int32_t SDLDrv_PCM_Init(int32_t *mixrate, int32_t *numchannels, void * initdata)
{
    uint32_t inited;
    int32_t err = 0;
    int32_t chunksize;
    uint16_t fmt;

    UNREFERENCED_PARAMETER(numchannels);
    UNREFERENCED_PARAMETER(initdata);

    if (Initialised) {
        SDLDrv_PCM_Shutdown();
    }

    inited = SDL_WasInit(SDL_INIT_EVERYTHING);

    if (inited == 0) {
        // nothing was initialised
        err = SDL_Init(SDL_INIT_AUDIO);
        StartedSDL = 0;
    } else if (!(inited & SDL_INIT_AUDIO)) {
        err = SDL_InitSubSystem(SDL_INIT_AUDIO);
        StartedSDL = 1;
    }

    if (err < 0) {
        ErrorCode = SDLErr_InitSubSystem;
        return SDLErr_Error;
    }

    chunksize = 512;
#ifdef __ANDROID__
    chunksize = droidinfo.audio_buffer_size;
#endif

    if (*mixrate >= 16000) chunksize *= 2;
    if (*mixrate >= 32000) chunksize *= 2;

    err = Mix_OpenAudio(*mixrate, AUDIO_S16SYS, *numchannels, chunksize);

    if (err < 0) {
        ErrorCode = SDLErr_OpenAudio;
        return SDLErr_Error;
    }


    int intmixrate = *mixrate;
    int intnumchannels = *numchannels;
    if (Mix_QuerySpec(&intmixrate, &fmt, &intnumchannels))
    {
        if (fmt == AUDIO_U8 || fmt == AUDIO_S8)
        {
            ErrorCode = SDLErr_OpenAudio;
            return SDLErr_Error;
        }
    }
    *mixrate = intmixrate;
    *numchannels = intnumchannels;

    //Mix_SetPostMix(fillData, NULL);

    EffectFence = SDL_CreateMutex();

    // channel 0 and 1 are actual sounds
    // dummy channel 2 runs our fillData() callback as an effect
    Mix_RegisterEffect(2, fillData, NULL, NULL);

    DummyBuffer = (uint8_t *) calloc(1, chunksize);

    DummyChunk = Mix_QuickLoad_RAW(DummyBuffer, chunksize);

    Mix_PlayChannel(2, DummyChunk, -1);

    Initialised = 1;

    return SDLErr_Ok;
}

void SDLDrv_PCM_Shutdown(void)
{
    if (!Initialised)
        return;
    else Mix_HaltChannel(-1);

    if (DummyChunk != NULL)
    {
        Mix_FreeChunk(DummyChunk);
        DummyChunk = NULL;
    }

    DO_FREE_AND_NULL(DummyBuffer);

    Mix_CloseAudio();

    SDL_DestroyMutex(EffectFence);

    if (StartedSDL > 0) {
        SDL_QuitSubSystem(SDL_INIT_AUDIO);
    } else if (StartedSDL == 0) {
        SDL_Quit();
    }

    StartedSDL = -1;
    Initialised = 0;
}

int32_t SDLDrv_PCM_BeginPlayback(char *BufferStart, int32_t BufferSize,
						int32_t NumDivisions, void ( *CallBackFunc )( void ) )
{
	if (!Initialised) {
		ErrorCode = SDLErr_Uninitialised;
		return SDLErr_Error;
	}

	if (Playing) {
		SDLDrv_PCM_StopPlayback();
	}

	MixBuffer = BufferStart;
	MixBufferSize = BufferSize;
	MixBufferCount = NumDivisions;
	MixBufferCurrent = 0;
	MixBufferUsed = 0;
	MixCallBack = CallBackFunc;

	// prime the buffer
	MixCallBack();

	Mix_Resume(-1);

    Playing = 1;

	return SDLErr_Ok;
}

void SDLDrv_PCM_StopPlayback(void)
{
	if (!Initialised || !Playing) {
		return;
	}

    Mix_Pause(-1);

	Playing = 0;
}

void SDLDrv_PCM_Lock(void)
{
    if (InterruptsDisabled++)
        return;

    SDL_LockMutex(EffectFence);
}

void SDLDrv_PCM_Unlock(void)
{
    if (--InterruptsDisabled)
        return;

    SDL_UnlockMutex(EffectFence);
}