/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 of the License, or (at your option) any later version.

    This library 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

    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public

    License along with this library; if not, write to the Free Software

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

/* Allow access to an ESD network stream mixing buffer */

#ifdef ESD_SUPPORT

#include <errno.h>

#include <esd.h>

#include "SDL_timer.h"

#include "SDL_audio.h"

#include "SDL_esdaudio.h"

#include "SDL_name.h"

#include "SDL_loadso.h"

#else

#define SDL_NAME(X)	X

#endif

/* The tag name used by ESD audio */

#define ESD_DRIVER_NAME		"esd"

/* Audio driver functions */

static int ESD_OpenAudio(_THIS, SDL_AudioSpec *spec);

static void ESD_WaitAudio(_THIS);

static void ESD_PlayAudio(_THIS);

static Uint8 *ESD_GetAudioBuf(_THIS);

static void ESD_CloseAudio(_THIS);

static void *esd_handle = NULL;

static int esd_loaded = 0;

static int (*SDL_NAME(esd_open_sound))( const char *host );

static int (*SDL_NAME(esd_close))( int esd );

static int (*SDL_NAME(esd_play_stream))( esd_format_t format, int rate,

                                         const char *host, const char *name );

static struct {

	const char *name;

	void **func;

} esd_functions[] = {

	{ "esd_open_sound",	(void **)&SDL_NAME(esd_open_sound)	},

	{ "esd_close",		(void **)&SDL_NAME(esd_close)		},

	{ "esd_play_stream",	(void **)&SDL_NAME(esd_play_stream)	},

};

static void UnloadESDLibrary()

{

	if ( esd_loaded ) {

		SDL_UnloadObject(esd_handle);

		esd_handle = NULL;

		esd_loaded = 0;

	}

}

static int LoadESDLibrary(void)

{

	int i, retval = -1;

	esd_handle = SDL_LoadObject(esd_library);

	if ( esd_handle ) {

		esd_loaded = 1;

		retval = 0;

		for ( i=0; i<SDL_TABLESIZE(esd_functions); ++i ) {

			*esd_functions[i].func = SDL_LoadFunction(esd_handle, esd_functions[i].name);

			if ( !*esd_functions[i].func ) {

				retval = -1;

				UnloadESDLibrary();

				break;

			}

		}

	}

	return retval;

}

#else

static void UnloadESDLibrary()

{

	return;

}

static int LoadESDLibrary(void)

{

	return 0;

}

/* Audio driver bootstrap functions */

static int Audio_Available(void)

{

	int connection;

	int available;

	available = 0;

	if ( LoadESDLibrary() < 0 ) {

		return available;

	}

	connection = SDL_NAME(esd_open_sound)(NULL);

	if ( connection >= 0 ) {

		available = 1;

		SDL_NAME(esd_close)(connection);

	}

	UnloadESDLibrary();

	return(available);

}

static void Audio_DeleteDevice(SDL_AudioDevice *device)

{

	SDL_free(device->hidden);

	SDL_free(device);

	UnloadESDLibrary();

}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)

{

	SDL_AudioDevice *this;

	/* Initialize all variables that we clean on shutdown */

	LoadESDLibrary();

	this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));

	if ( this ) {

		SDL_memset(this, 0, (sizeof *this));

		this->hidden = (struct SDL_PrivateAudioData *)

				SDL_malloc((sizeof *this->hidden));

	}

	if ( (this == NULL) || (this->hidden == NULL) ) {

		SDL_OutOfMemory();

		if ( this ) {

			SDL_free(this);

		}

		return(0);

	}

	SDL_memset(this->hidden, 0, (sizeof *this->hidden));

	audio_fd = -1;

	/* Set the function pointers */

	this->OpenAudio = ESD_OpenAudio;

	this->WaitAudio = ESD_WaitAudio;

	this->PlayAudio = ESD_PlayAudio;

	this->GetAudioBuf = ESD_GetAudioBuf;

	this->CloseAudio = ESD_CloseAudio;

	this->free = Audio_DeleteDevice;

	return this;

}

AudioBootStrap ESD_bootstrap = {

	ESD_DRIVER_NAME, "Enlightened Sound Daemon",

	Audio_Available, Audio_CreateDevice

};

/* This function waits until it is possible to write a full sound buffer */

static void ESD_WaitAudio(_THIS)

{

	Sint32 ticks;

	/* Check to see if the thread-parent process is still alive */

	{ static int cnt = 0;

		/* Note that this only works with thread implementations 

		   that use a different process id for each thread.

		*/

		if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */

			if ( kill(parent, 0) < 0 ) {

				this->enabled = 0;

			}

		}

	}

	/* Use timer for general audio synchronization */

	ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;

	if ( ticks > 0 ) {

		SDL_Delay(ticks);

	}

}

static void ESD_PlayAudio(_THIS)

{

	int written;

	/* Write the audio data, checking for EAGAIN on broken audio drivers */

	do {

		written = write(audio_fd, mixbuf, mixlen);

		if ( (written < 0) && ((errno == 0) || (errno == EAGAIN)) ) {

			SDL_Delay(1);	/* Let a little CPU time go by */

		}

	} while ( (written < 0) && 

	          ((errno == 0) || (errno == EAGAIN) || (errno == EINTR)) );

	/* Set the next write frame */

	next_frame += frame_ticks;

	/* If we couldn't write, assume fatal error for now */

	if ( written < 0 ) {

		this->enabled = 0;

	}

}

static Uint8 *ESD_GetAudioBuf(_THIS)

{

	return(mixbuf);

}

static void ESD_CloseAudio(_THIS)

{

	if ( mixbuf != NULL ) {

		SDL_FreeAudioMem(mixbuf);

		mixbuf = NULL;

	}

	if ( audio_fd >= 0 ) {

		SDL_NAME(esd_close)(audio_fd);

		audio_fd = -1;

	}

}

/* Try to get the name of the program */

static char *get_progname(void)

{

	char *progname = NULL;

#ifdef linux

	FILE *fp;

	static char temp[BUFSIZ];

	SDL_snprintf(temp, SDL_arraysize(temp), "/proc/%d/cmdline", getpid());

	fp = fopen(temp, "r");

	if ( fp != NULL ) {

		if ( fgets(temp, sizeof(temp)-1, fp) ) {

			progname = SDL_strrchr(temp, '/');

			if ( progname == NULL ) {

				progname = temp;

			} else {

				progname = progname+1;

			}

		}

		fclose(fp);

	}

#endif

	return(progname);

}

static int ESD_OpenAudio(_THIS, SDL_AudioSpec *spec)

{

	esd_format_t format;

	/* Convert audio spec to the ESD audio format */

	format = (ESD_STREAM | ESD_PLAY);

	switch ( spec->format & 0xFF ) {

		case 8:

			format |= ESD_BITS8;

			break;

		case 16:

			format |= ESD_BITS16;

			break;

		default:

			SDL_SetError("Unsupported ESD audio format");

			return(-1);

	}

	if ( spec->channels == 1 ) {

		format |= ESD_MONO;

	} else {

		format |= ESD_STEREO;

	}

#if 0

	spec->samples = ESD_BUF_SIZE;	/* Darn, no way to change this yet */

#endif

	/* Open a connection to the ESD audio server */

	audio_fd = SDL_NAME(esd_play_stream)(format, spec->freq, NULL, get_progname());

	if ( audio_fd < 0 ) {

		SDL_SetError("Couldn't open ESD connection");

		return(-1);

	}

	/* Calculate the final parameters for this audio specification */

	SDL_CalculateAudioSpec(spec);

	frame_ticks = (float)(spec->samples*1000)/spec->freq;

	next_frame = SDL_GetTicks()+frame_ticks;

	/* Allocate mixing buffer */

	mixlen = spec->size;

	mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);

	if ( mixbuf == NULL ) {

		return(-1);

	}

	SDL_memset(mixbuf, spec->silence, spec->size);

	/* Get the parent process id (we're the parent of the audio thread) */

	parent = getpid();

	/* We're ready to rock and roll. :-) */

	return(0);

}

#endif /* ESD_SUPPORT */