/*
 * Copyright (c) 1984,1985,1989,1994  Mark Nudelman
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice in the documentation and/or other materials provided with 
 *    the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN 
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


/*
 * Functions to define the character set
 * and do things specific to the character set.
 */

#include "less.h"

/*
 * Predefined character sets,
 * selected by the LESSCHARSET environment variable.
 */
struct charset {
	char *name;
	char *desc;
} charsets[] = {
	{ "ascii",	"8bcccbcc18b95.b"		},
	{ "latin1",	"8bcccbcc18b95.33b."		},
	{ "dos",	"8bcccbcc12bc5b95.98b.b"	},
	{ NULL }
};

#define	IS_BINARY_CHAR	01
#define	IS_CONTROL_CHAR	02

static char chardef[256];
static char *binfmt = NULL;
public int binattr = AT_BLINK;


/*
 * Define a charset, given a description string.
 * The string consists of 256 letters,
 * one for each character in the charset.
 * If the string is shorter than 256 letters, missing letters
 * are taken to be identical to the last one.
 * A decimal number followed by a letter is taken to be a 
 * repetition of the letter.
 *
 * Each letter is one of:
 *	. normal character
 *	b binary character
 *	c control character
 */
	static void
ichardef(s)
	char *s;
{
	register char *cp;
	register int n;
	register char v;

	n = 0;
	v = 0;
	cp = chardef;
	while (*s != '\0')
	{
		switch (*s++)
		{
		case '.':
			v = 0;
			break;
		case 'c':
			v = IS_CONTROL_CHAR;
			break;
		case 'b':
			v = IS_BINARY_CHAR|IS_CONTROL_CHAR;
			break;

		case '0': case '1': case '2': case '3': case '4':
		case '5': case '6': case '7': case '8': case '9':
			n = (10 * n) + (s[-1] - '0');
			continue;

		default:
			error("invalid chardef", NULL_PARG);
			quit(1);
			/*NOTREACHED*/
		}

		do
		{
			if (cp >= chardef + sizeof(chardef))
			{
				error("chardef longer than 256", NULL_PARG);
				quit(1);
				/*NOTREACHED*/
			}
			*cp++ = v;
		} while (--n > 0);
		n = 0;
	}

	while (cp < chardef + sizeof(chardef))
		*cp++ = v;
}

/*
 * Define a charset, given a charset name.
 * The valid charset names are listed in the "charsets" array.
 */
	static int
icharset(name)
	register char *name;
{
	register struct charset *p;

	if (name == NULL || *name == '\0')
		return (0);

	for (p = charsets;  p->name != NULL;  p++)
	{
		if (strcmp(name, p->name) == 0)
		{
			ichardef(p->desc);
			return (1);
		}
	}

	error("invalid charset name", NULL_PARG);
	quit(1);
	/*NOTREACHED*/
}

/*
 * Define the printing format for control chars.
 */
   	public void
setbinfmt(s)
	char *s;
{
	if (s == NULL || *s == '\0')
		s = "*k<%X>";
	/*
	 * Select the attributes if it starts with "*".
	 */
	if (*s == '*')
	{
		switch (s[1])
		{
		case 'd':  binattr = AT_BOLD;      break;
		case 'k':  binattr = AT_BLINK;     break;
		case 'u':  binattr = AT_UNDERLINE; break;
		default:   binattr = AT_NORMAL;    break;
		}
		s += 2;
	}
	if (*s == '\0')
		binfmt = "<%X>";
	else
		binfmt = s;
}

/*
 * Initialize charset data structures.
 */
	public void
init_charset()
{
	register char *s;

	s = getenv("LESSBINFMT");
	setbinfmt(s);
	
	/*
	 * See if environment variable LESSCHARSET is defined.
	 */
	s = getenv("LESSCHARSET");
	if (icharset(s))
		return;
	/*
	 * LESSCHARSET is not defined: try LESSCHARDEF.
	 */
	s = getenv("LESSCHARDEF");
	if (s != NULL && *s != '\0')
	{
		ichardef(s);
		return;
	}
	/*
	 * LESSCHARDEF is not defined either: default to "ascii".
	 */
	(void) icharset("ascii");

}

/*
 * Is a given character a "binary" character?
 */
	public int
binary_char(c)
	int c;
{
	c &= 0377;
	return (chardef[c] & IS_BINARY_CHAR);
}

/*
 * Is a given character a "control" character?
 */
	public int
control_char(c)
	int c;
{
	c &= 0377;
	return (chardef[c] & IS_CONTROL_CHAR);
}

/*
 * Return the printable form of a character.
 * For example, in the "ascii" charset '\3' is printed as "^C".
 */
	public char *
prchar(c)
	int c;
{
	static char buf[8];

	c &= 0377;
	if (c == ESC)
		sprintf(buf, "ESC");
	else if (!control_char(c))
		sprintf(buf, "%c", c);
	else if (!control_char(c ^ 0100))
		sprintf(buf, "^%c", c ^ 0100);
	else
		sprintf(buf, binfmt, c);
	return (buf);
}
