#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/stat.h>
#include <sys/mman.h>

static const char *datafile = "cdda.raw";

/*
 * This number is 44100 * 2 * 2 / 75, that is,
 * bytes/frame = samples/sec * channels/sample * bytes/channel / frames/sec
 */
#define FRAMEBYTES 2352

#include "blocker.h"
#include "stringgetter.h"

static const char *cddir;
static unsigned char *play_data;
static unsigned int play_maplen;
static unsigned int play_start;
static unsigned int play_len;

static int play_prep(const char *cdname, int start, int length, FILE *errf)
{
 char *path;
 int fd;
 struct stat stb;
 int end;
 char *mmrv;

 end = start + length;
 if ( (start < 0) || (length < 0) || (end < 0) ||
      (end > 0x7fffffff/FRAMEBYTES) )
  { fprintf(errf,"start/length out of range\n");
    return(-1);
  }
 asprintf(&path,"%s/%s/%s",cddir,cdname,datafile);
 fd = open(path,O_RDONLY,0);
 if (fd < 0)
  { fprintf(errf,"%s open: %s\n",cdname,strerror(errno));
    return(-1);
  }
 if (fstat(fd,&stb) < 0)
  { fprintf(errf,"%s fstat: %s\n",cdname,strerror(errno));
    close(fd);
    return(-1);
  }
 play_maplen = stb.st_size;
 if (play_maplen != stb.st_size)
  { fprintf(errf,"%s: data file too big\n",cdname);
    close(fd);
    return(-1);
  }
 mmrv = mmap(0,play_maplen,PROT_READ,MAP_FILE|MAP_SHARED,fd,0);
 if (mmrv == MAP_FAILED)
  { fprintf(errf,"%s mmap: %s\n",cdname,strerror(errno));
    close(fd);
    return(-1);
  }
 play_data = mmrv;
 play_start = start * FRAMEBYTES;
 play_len = length * FRAMEBYTES;
 close(fd);
 return(0);
}

static void play_do(void)
{
 int w;

 fflush(stdout);
 while (play_len > 0)
  { w = write(1,play_data+play_start,play_len);
    if (w <= 0) exit(1);
    play_len -= w;
    play_start += w;
  }
 munmap(play_data,play_maplen);
}

int main(int, char **);
int main(int ac, char **av)
{
 FILE *b;
 STRINGGETTER *g;
 STRINGGOT line;
 char *cdname;
 int start;
 int length;

 int get(void *arg __attribute__((__unused__)))
  { return(getc(b));
  }

 if (ac != 2) exit(1);
 cddir = av[1];
 g = sg_init_pull(&get,&sg_term_nul,0);
 cdname = 0;
 while (1)
  { free(cdname);
    b = fwrap_r_blocked(stdin);
    line = sg_get(g);
    if (line.len < 0) break;
    cdname = strdup(line.str);
    line = sg_get(g);
    if (line.len < 0) break;
    start = atoi(line.str);
    line = sg_get(g);
    if (line.len < 0) break;
    length = atoi(line.str);
    if (getc(b) != EOF) break;
    fclose(b);
    b = fwrap_w_blocked(stdout);
    if (play_prep(cdname,start,length,b) < 0)
     { fprintf(b,"CD play failed.\n");
       fclose(b);
       continue;
     }
    fclose(b);
    play_do();
  }
 sg_done(g);
 return(0);
}