/* shchars.c */

/* compile me: cc -o shchars -lcurses shchars.c */

#include <curses.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <term.h>

static unsigned char stoplist [256];

static void ruler (void);

#define Valid(p) ((p)!=NULL && (p)!=(char *)-1 && *(p))

static void ParseArgs (int *pargc, char ***pargv);

typedef struct SeqT {
    const char *name;
    const char *seq;
    const char *defval;
} SeqT;

static SeqT Seq[]= {
    {"enacs", NULL, "\x1b(B\x1b)0"},
                               /* G0 := default charset
                                  G1 := char-graph charset */
    {"smacs", NULL, "\x0e"},   /* SO (Shift Out) i.e. use G1 */
    {"rmacs", NULL, "\x0f"},   /* SI (Shift In)  i.e. use G0 */
    {"acsc",  NULL, "``aaffggjjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~"}
};
static int NSeq= (int)((sizeof Seq)/(sizeof Seq[0]));
#define enacs Seq[0].seq
#define smacs Seq[1].seq
#define rmacs Seq[2].seq
#define acsc  Seq[3].seq

int main (int argc, char **argv)
{
    const char *term;
    int err, rc, i, j, c, len;

    ParseArgs (&argc, &argv);

    term= getenv ("TERM");
    if (Valid (term)) {
        fprintf (stderr, "TERM=%s\n", term);
    } else {
        fprintf (stderr, "TERM variable not set, exiting\n");
        return 4;
    }
    rc= setupterm ((char *)term, 1, &err);
    if (rc!=OK) {
        fprintf (stderr, "setupterm(\"%s\") failed err=%d, using defaults\n", term, err);
        for (i=0; i<NSeq; ++i) {
            Seq[i].seq= Seq[i].defval;
        }
    } else {
        for (i=0; i<NSeq; ++i) {
            Seq[i].seq= tigetstr ((char *)Seq[i].name);
            if (!Valid(Seq[i].seq)) {
                fprintf (stderr, "tigetstr(%s) failed (retval=%p) using default\n",
                        Seq[i].name, Seq[i].seq);
                Seq[i].seq= Seq[i].defval;
            }
        }
    }

    printf ("%s", enacs);

    /* enable graphical characters */
    for (len= strlen (acsc), i=0; i<len-1; i+=2) {
        stoplist [(unsigned char)acsc[i+1]] &= ~2;
    }

    ruler ();
    for (i=0x00; i<=0xf0; i+=0x10) {
        printf ("%02x  ", i);
        for (j=0x0; j<=0xf; j++) {
	    c= i+j;
	    if (stoplist[c] & 1) printf (". ");
	    else                 printf ("%c ", c);
	}
	printf (" %02x  %s", i, smacs);
        for (j=0x0; j<=0xf; j++) {
	    c= i+j;
	    if (stoplist[c] & 2) printf (". ");
	    else                 printf ("%c ", c);
	}
	printf ("%s %02x\n", rmacs, i);
    }
    ruler ();
    return 0;
}

static void ruler (void)
{
    int j;
    
    printf ("    ");
    for (j=0; j<=0xf; ++j) {
        printf ("%x ", j);
    }
    printf ("     ");
    for (j=0; j<=0xf; ++j) {
        printf ("%x ", j);
    }
    printf ("\n");
}

/*  If the output of this program is broken,
 *  you may increase values of this table:
 *  1 means: dont show it as regular character,
 *  2 means: dont show it as graphic character,
 *  3 means: do not show it at all
 */
static unsigned char stoplist [256] = {
/*       0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* 00 */ 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
/* 10 */ 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
/* 20 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* 30 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* 40 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* 50 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* 60 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* 70 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,

/*       0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* 80 */ 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
/* 90 */ 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
/* a0 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* b0 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* c0 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* d0 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* e0 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/* f0 */ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
};

static void ParseArgs (int *pargc, char ***pargv)
{
    int argc;
    char **argv;
    int parse_arg;
    char *progname;

    argc = *pargc;
    argv = *pargv;
    parse_arg = 1;
    progname = argv[0];

    while (--argc && **++argv=='-' && parse_arg) {
	switch (argv[0][1]) {
	case 'e':case 'E':
	    if (strcasecmp (argv[0], "-enacs")==0) {
		break;

	    } else if (strcasecmp (argv[0], "-enacs-")==0) {
		break;

	    } else goto UNKOPT;

	case 'n':case 'N':
		if (strcasecmp (argv[0], "-no-enacs")==0) {
		    break;
		} else goto UNKOPT;

	case 0: case '-': parse_arg = 0; break;
	default:
UNKOPT:     fprintf (stderr, "Unknown option '%s'\n", *argv);
	    exit (4);
	}
    }
    ++argc;
    *--argv = progname;
    *pargc = argc;
    *pargv = argv;
}