/*
 *      bsfilt.c - a colcrt-like processor for cawf(1)
 */

/*
 *      Copyright (c) 1991 Purdue University Research Foundation,
 *      West Lafayette, Indiana 47907.  All rights reserved.
 *
 *      Written by Victor A. Abell <abe@mace.cc.purdue.edu>,  Purdue
 *      University Computing Center.  Not derived from licensed software;
 *      derived from awf(1) by Henry Spencer of the University of Toronto.
 *
 *      Permission is granted to anyone to use this software for any
 *      purpose on any computer system, and to alter it and redistribute
 *      it freely, subject to the following restrictions:
 *
 *      1. The author is not responsible for any consequences of use of
 *         this software, even if they arise from flaws in it.
 *
 *      2. The origin of this software must not be misrepresented, either
 *         by explicit claim or by omission.  Credits must appear in the
 *         documentation.
 *
 *      3. Altered versions must be plainly marked as such, and must not
 *         be misrepresented as being the original software.  Credits must
 *         appear in the documentation.
 *
 *      4. This notice may not be removed or altered.
 */

#include <stdio.h>
#ifdef UNIX
#ifdef USG
#include <string.h>
#else
#include <strings.h>
#endif  
#else
#include <string.h>
#endif

#define MAXLL   2048                    /* ridiculous maximum line length */

int Dash = 1;                           /* underline with dashes */
int Dp = 0;                             /* dash pending */
int Lc = 0;                             /* line count */
char *Pname;                            /* program name */
char Ulb[MAXLL];                        /* underline buffer */
int Ulx = 0;                            /* underline buffer index */

void Putchar();
#ifndef STDDEF
char *strrchr();
#endif

main(argc, argv)
        int argc;
        char *argv[];
{
        int ax = 1;                     /* argument index */
        int c;                          /* character buffer */
        FILE *fs;                       /* file stream */
        int nf = 0;                     /* number of files processed */
        char pc;                        /* previous character */
        int under = 0;                  /* underline */
/*
 * Save program name.
 */
        if ((Pname = strrchr(argv[0], '/')) != NULL)
                Pname++;
        else if ((Pname = strrchr(argv[0], '\\')) != NULL)
                Pname++;
        else
                Pname = argv[0];
/*
 * Process options.
 */
        if (argc > 1 && argv[1][0] == '-') {
                switch (argv[1][1]) {
        /*
         * "-U" - underline with dashes.
         */
                case 'U':
                        Dash = 0;
                        under = 1;
                        break;
        /*
         * "-" - do no  underlining at all.
         */
                case '\0':
                        Dash = under = 0;
                        break;
                default:
                        (void) fprintf(stderr,
                                "%s usage: [-] [-U] [file]\n", Pname);
                        exit(1);
                }
                ax++;
        }
/*
 * Process files.  Read standard input if no files names.
 */

        while (ax < argc || nf == 0) {
                if (ax >= argc)
                        fs = stdin;
                else {
#ifdef  UNIX
                        if ((fs = fopen(argv[ax], "r")) == NULL)
#else
                        if ((fs = fopen(argv[ax], "rt")) == NULL)
#endif
                        {
                                (void) fprintf(stderr, "%s: can't open %s\n",
                                        Pname, argv[ax]);
                                exit(1);
                        }
                        ax++;
                }
                nf++;
        /*
         * Read input a character at a time.
         */
                for (pc = '\0'; (c = fgetc(fs)) != EOF;) {
                        switch(c) {

                        case '\n':
                                if (pc)
                                        Putchar(pc);
                                Putchar('\n');
                                pc = '\0';
                                break;

                        case '\b':
                                if (pc == '_') {
                                        if (under) {
                                                putchar(pc);
                                                putchar('\b');
                                        } else if (Dash)
                                                Dp = 1;
                                }
                                pc = '\0';
                                break;

                        default:
                                if (pc)
                                        Putchar(pc);
                                pc = c;
                        }
                }
                if (pc) {
                        Putchar(pc);
                        Putchar('\n');
                }
        }
        exit(0);
}


/*
 * Putchar(ch) - put a character with possible underlining
 */

void
Putchar(ch)
        char ch;
{
        int i;                                  /* temporary index */

        if (ch == '\n') {
/*
 * Handle end of line.
 */
                putchar('\n');
                if (Ulx) {
                        while (Ulx && Ulb[Ulx-1] == ' ')
                                Ulx--;
                        if (Ulx) {
                                for (i = 0; i < Ulx; i++)
                                        putchar(Ulb[i]);
                                putchar('\n');
                        }
                }
                Dp = Ulx = 0;
                Lc++;
                return;
        }
/*
 * Put "normal" character.
 */
        putchar(ch);
        if (Dash) {

        /*
         * Handle dash-type underlining.
         */
                if (Ulx >= MAXLL) {
                        (void) fprintf(stderr,
                                "%s: underline for line %d > %d characters\n",
                                Pname, Lc, MAXLL);
                        exit(1);
                }
                Ulb[Ulx++] = Dp ? '-' : ' ';
                Dp = 0;
        }
}