/*
 * gh.c:
 * GREP with hilighting.
 *
 * Copyright (c) 2002 Chris Lightfoot. All rights reserved.
 * Email: chris@ex-parrot.com; WWW: http://www.ex-parrot.com/~chris/
 *
 */

static const char rcsid[] = "$Id: gh.c,v 1.3 2003/01/18 17:02:29 chris Exp $";

#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <regex.h>

void usage(FILE *fp) {
    fprintf(fp,
"gh - grep with hilight\n"
"\n"
"Usage: gh [options] pattern [file] ...\n"
"\n"
"Options: -h    display this message\n"
"         -i    case-insensitive pattern match\n"
"         -n    print line numbers\n"
"         -p    pass-through; print all lines, whether or not they match\n"
"\n"
        );
}

int print_line_number, print_file_name, pass_through;
regex_t R;

int grep_line(const char *line, const char *name, const int n) {
    int a;
    regmatch_t match;
    if ((a = regexec(&R, line, 1, &match, 0)) == 0 || pass_through) {
        if (print_file_name) printf("%s:", name);
        if (print_line_number) printf("%d:", n);
        if (a == 0) {
            printf("%.*s\x1b[7m%.*s\x1b[0m%s\n",
                    match.rm_so, line,
                    match.rm_eo - match.rm_so, line + match.rm_so,
                    line + match.rm_eo);
            return 1;
        } else
            printf("%s\n", line);
    }
    return 0;
}

int grep_stream(FILE *fp, const char *name) {
    static char *buf;
    static size_t blen;
    int i, c, res = 0, n;

    if (!buf)
        buf = malloc(blen = 1024);

    i = 0;
    n = 1;
    while ((c = fgetc(fp)) != EOF) {
        if (c != '\n')
            buf[i++] = (char)c;
        else {
            buf[i] = 0;
            if (grep_line(buf, name, n))
                res = 1;
            i = 0;
            ++n;
        }

        if (i == blen)
            buf = realloc(buf, blen *= 2);
    }

    if (ferror(fp))
        perror(name);
    else if (i > 0) {
        /* grep partial last line... */
        buf[i] = 0;
        if (grep_line(buf, name, n))
            res = 1;
    }

    return res;
}

char optstr[] = "+hinp";

int main(int argc, char *argv[]) {
    int c, err, ret = 1;
    int Rflags = REG_EXTENDED;

    opterr = 0;
    while ((c = getopt(argc, argv, optstr)) != EOF) {
        switch (c) {
            case 'h':
                usage(stdout);
                return 0;

            case 'i':
                Rflags |= REG_ICASE;
                break;

            case 'n':
                print_line_number = 1;
                break;

            case 'p':
                pass_through = 1;
                break;

            case '?':
            default:
                fprintf(stderr, "bad option -%c\n", optopt);
                usage(stderr);
                return 1;
        }
    }

    if (!argv[optind]) {
        usage(stderr);
        return -1;
    }

    if ((err = regcomp(&R, argv[optind], Rflags))) {
        char e[1024];
        regerror(err, &R, e, sizeof e);
        fprintf(stderr, "gh: %s: %s\n", argv[1], e);
        return -1;
    }

    ++optind;

    if (!argv[optind]) {
        grep_stream(stdin, "standard input");
    } else {
        if (argc - optind > 1)
            print_file_name = 1;
        while (argv[optind]) {
            FILE *fp;
            if (!(fp = fopen(argv[optind], "rt")))
                perror(argv[optind]);
            else {
                if (grep_stream(fp, argv[optind])) ret = 0;
                fclose(fp);
            }
            ++optind;
        }
    }

    return ret;
}