#include "asterisk.h"
#include "asterisk/logger.h"

#include <stdlib.h>
#include <stdio.h>

#include "mpg123.h"
#include "mpglib.h"


void InitMP3Constants(void)
{
	init_layer3_const();
	make_decode_tables_const();
	
}


BOOL InitMP3(struct mpstr *mp, long outscale) 
{
	/* quiet 4096 med 8192 */

	memset(mp,0,sizeof(struct mpstr));

	mp->framesize = 0;
	mp->fsizeold = -1;
	mp->bsize = 0;
	mp->head = mp->tail = NULL;
	mp->fr.single = 3; /* force mono */
	mp->bsnum = 0;
	mp->synth_bo = 1;
	mp->outsamplerate = 8000;

	make_decode_tables_scale(mp, outscale);

	init_layer3_sample_limits(mp, SBLIMIT);

	return !0;
}

void ExitMP3(struct mpstr *mp)
{
	struct buf *b,*bn;
	
	b = mp->tail;
	while(b) {
		free(b->pnt);
		bn = b->next;
		free(b);
		b = bn;
	}
}

static struct buf *addbuf(struct mpstr *mp,char *buf,int size)
{
	struct buf *nbuf;

	nbuf = malloc( sizeof(struct buf) );
	if(!nbuf) {
		ast_log(LOG_WARNING,"Out of memory!\n");
		return NULL;
	}
	nbuf->pnt = malloc(size);
	if(!nbuf->pnt) {
		free(nbuf);
		return NULL;
	}
	nbuf->size = size;
	memcpy(nbuf->pnt,buf,size);
	nbuf->next = NULL;
	nbuf->prev = mp->head;
	nbuf->pos = 0;

	if(!mp->tail) {
		mp->tail = nbuf;
	}
	else {
	  mp->head->next = nbuf;
	}

	mp->head = nbuf;
	mp->bsize += size;

	return nbuf;
}

static void remove_buf(struct mpstr *mp)
{
  struct buf *buf = mp->tail;
  
  mp->tail = buf->next;
  if(mp->tail)
    mp->tail->prev = NULL;
  else {
    mp->tail = mp->head = NULL;
  }
  
  free(buf->pnt);
  free(buf);

}

static int read_buf_byte(int *error, struct mpstr *mp)
{
	unsigned int b;int pos;

	pos = mp->tail->pos;
	while(pos >= mp->tail->size) {
		remove_buf(mp);
		pos = mp->tail->pos;
		if(!mp->tail) {
			/* We may pick up this error a few times*/
			/* But things have gone pear shaped */
			ast_log(LOG_WARNING,"Fatal Buffer error!\n");
			*error = 1;
			return (0);		
		}
	}

	b = mp->tail->pnt[pos];
	mp->bsize--;
	mp->tail->pos++;
	

	return b;
}

static int  read_head(struct mpstr *mp)
{
	unsigned long head;
	int error=0;
	

	head = read_buf_byte(&error, mp);
	head <<= 8;
	head |= read_buf_byte(&error, mp);
	head <<= 8;
	head |= read_buf_byte(&error, mp);
	head <<= 8;
	head |= read_buf_byte(&error, mp);

	mp->header = head;

	if(error){
		return (1);
	}else
		return (0);
		
}

static int head_check(unsigned long head)
{
    if( (head & 0xffe00000) != 0xffe00000)
	return FALSE;
    if(!((head>>17)&3))
	return FALSE;
    if( ((head>>12)&0xf) == 0xf || ((head>>12)&0xf) == 0)
	return FALSE;
    if( ((head>>10)&0x3) == 0x3 )
	return FALSE;
    if ((head & 0xffff0000) == 0xfffe0000)
      return FALSE;

    return TRUE;
}

static int head_shift(struct mpstr *mp)
{
	unsigned long head;
	int error = 0;
	
	head = mp->header;
	
	head <<= 8;
	head |= read_buf_byte(&error, mp);
	
	mp->header = head;

	if (error){
		return (1);
	}else
		return (0);
	
}


int decodeMP3(struct mpstr *mp,char *in,int isize,char *out,
		int osize,int *done)
{
	int len;
	long n,m;
	int down_sample_sblimit;

	if(osize < 4608) {
		ast_log(LOG_WARNING,"To less out space\n");
		return MP3_ERR;
	}

	if(in) {
		if(addbuf(mp,in,isize) == NULL) {
			return MP3_ERR;
		}
	}

	/* First decode header */
	if(mp->framesize == 0) {
		if(mp->bsize < 4) {
			return MP3_NEED_MORE;
		}
		if (read_head(mp))
			return MP3_ERR;
		
		if(!head_check(mp->header) ) {
			int i;

			ast_log(LOG_WARNING,"Junk at the beginning of frame %08lx\n",mp->header);
			
			/* step in byte steps through next 64K */
			for(i=0;i<65536;i++) {
				if(!mp->bsize)
					return MP3_NEED_MORE;
				
				if(head_shift(mp))
					return MP3_ERR;
				
				if(head_check(mp->header))
					break;
			}
			if(i == 65536) {
				ast_log(LOG_WARNING,"Giving up searching valid MPEG header\n");
				return MP3_ERR;
			}
		}

		decode_header(&mp->fr,mp->header);
		mp->framesize = mp->fr.framesize;

		if (!mp->initmp3){
			mp->initmp3 = 1;
			
			n = freqs[mp->fr.sampling_frequency];
			if (mp->outsamplerate) {
				m = mp->outsamplerate;
			}
			else {
				m =n;
			}
		
			if (synth_ntom_set_step(n,m))
				return MP3_ERR;
			
			
			if(n>m) {
				down_sample_sblimit = SBLIMIT * m;
				down_sample_sblimit /= n;
			}
			else {
				down_sample_sblimit = SBLIMIT;
			}
			
			init_layer3_sample_limits(mp, down_sample_sblimit);
	
		}
	}
	

	if(mp->fr.framesize > mp->bsize)
		return MP3_NEED_MORE;

	(mp->worksample).wordpointer = mp->bsspace[mp->bsnum] + 512;
	mp->bsnum = (mp->bsnum + 1) & 0x1;
	(mp->worksample).bitindex = 0;

	len = 0;
	while(len < mp->framesize) {
		int nlen;
		int blen = mp->tail->size - mp->tail->pos;
		if( (mp->framesize - len) <= blen) {
                  nlen = mp->framesize-len;
		}
		else {
                  nlen = blen;
                }
		memcpy((mp->worksample).wordpointer+len,mp->tail->pnt+mp->tail->pos,nlen);
                len += nlen;
                mp->tail->pos += nlen;
		mp->bsize -= nlen;
                if(mp->tail->pos == mp->tail->size) {
                   remove_buf(mp);
                }
	}

	*done = 0;
	if(mp->fr.error_protection)
           getbits(mp, 16);
	
	if (do_layer3(mp,(unsigned char *) out,done))
		return MP3_ERR;

	mp->fsizeold = mp->framesize;
	mp->framesize = 0;

	return MP3_OK;
}

int set_pointer(struct mpstr *mp, long backstep)
{
  unsigned char *bsbufold;
  if(mp->fsizeold < 0 && backstep > 0) {
    ast_log(LOG_WARNING,"Can't step back %ld!\n",backstep);
    return MP3_ERR;
  }
  bsbufold = mp->bsspace[mp->bsnum] + 512;
  (mp->worksample).wordpointer -= backstep;
  if (backstep)
    memcpy((mp->worksample).wordpointer,bsbufold+mp->fsizeold-backstep,backstep);
  (mp->worksample).bitindex = 0;
  return MP3_OK;
}