#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <strings.h>

#include "ul.h"

static int ofd;
static FILE *of;
static char *line;
static int len;
static int cursor;
static unsigned int initflags;
static const char *disp[256];
static int displen[256];
static int wantbeep;
static struct sigvec contsv;
static struct sigvec oldcont;

static void ul_cont(int sig __attribute__((__unused__)))
{
 char *s;
 int olen;
 int curs;

 if ( (oldcont.sv_handler != SIG_IGN) &&
      (oldcont.sv_handler != SIG_DFL) )
  { sigvec(SIGCONT,&oldcont,0);
    kill(getpid(),SIGCONT);
    sigpause(sigblock(0)&~sigmask(SIGCONT));
    sigvec(SIGCONT,&contsv,&oldcont);
  }
 write(ofd,"\r\n",2);
 s = line;
 line = malloc(1);
 olen = len;
 curs = cursor;
 len = 0;
 cursor = 0;
 ul_update(s,olen,curs);
}

void ul_init(int fd, unsigned int flags)
{
 int i;
 static char db[400];
 int j;

 ofd = dup(fd);
 of = fdopen(ofd,"w");
 initflags = flags;
 line = 0;
 len = 0;
 cursor = 0;
 wantbeep = 0;
 j = 0;
#define SET() do { disp[i] = &db[j]; } while (0)
#define CHAR(c) (db[j++]=(c))
#define TERM() (displen[i] = &db[j] - disp[i])
 for (i=0;i<32;i++)
  { SET();
    CHAR('^');
    CHAR(i^64);
    TERM();
  }
 for (;i<127;i++)
  { SET();
    CHAR(i);
    TERM();
  }
 SET();
 CHAR('^');
 CHAR('?');
 TERM();
 i ++;
 for (;i<0xa0;i++)
  { SET();
    CHAR('\\');
    CHAR('0'+(i>>6));
    CHAR('0'+((i>>3)&7));
    CHAR('0'+(i&7));
    TERM();
  }
 for (;i<256;i++)
  { SET();
    CHAR(i);
    TERM();
  }
 if (j > sizeof(db)) abort();
#undef SET
#undef CHAR
#undef TERM
 if (! (initflags & UL_NO_CONT))
  { contsv.sv_handler = ul_cont;
    contsv.sv_mask = 0;
    contsv.sv_flags = 0;
    sigvec(SIGCONT,&contsv,&oldcont);
  }
}

extern void ul_new(void)
{
 write(ofd,"\r\n",2);
 len = 0;
 cursor = 0;
}

extern void ul_beep(void)
{
 wantbeep = 1;
}

static void cursorto(int x)
{
 for (;cursor>x;cursor--) putc('\b',of);
 for (;cursor<x;cursor++) putc(line[cursor],of);
}

extern void ul_update(const char *newstr, int argl, int cpos)
#define ns ((const unsigned char *)newstr)
{
 char *oldline;
 char *newline;
 int newlen;
 int i;
 int j;
 int c;
 int mapped_cpos;

 newlen = 0;
 for (i=0;i<argl;i++) newlen += displen[ns[i]];
 newline = malloc(newlen);
 i = 0;
 j = 0;
 mapped_cpos = 0;
 while (i < argl)
  { c = ns[i];
    bcopy(disp[c],newline+j,displen[c]);
    i ++;
    j += displen[c];
    if (cpos == i) mapped_cpos = j;
  }
 j = (newlen < len) ? newlen : len;
 for (i=0;(i<j)&&(newline[i]==line[i]);i++) ;
 if ((i < j) || (newlen != len))
  { cursorto(i);
    oldline = line;
    line = newline;
    if (newlen == len)
     { for (j=len-1;oldline[j]==newline[j];j--) ;
       cursorto(j+1);
     }
    else
     { cursorto(newlen);
       if (newlen < len)
	{ for (j=newlen;j<len;j++) putc(' ',of);
	  for (j=newlen;j<len;j++) putc('\b',of);
	}
       len = newlen;
     }
    free(oldline);
  }
 else
  { free(newline);
  }
 cursorto(mapped_cpos);
 if (wantbeep) putc('\7',of);
 wantbeep = 0;
 fflush(of);
}
#undef ns

extern void ul_end(void)
{
 free(line);
 fclose(of);
 if (! (initflags & UL_NO_CONT)) sigvec(SIGCONT,&oldcont,0);
}