/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <regex.h>
#include <locale.h>
#include <langinfo.h>
#include <limits.h>
#include <errno.h>
#include "getresponse.h"

/* defaults - C locale values for yesstr, nostr, yesexpr (LC_MESSAGES) */
#define DEFAULT_YESSTR  "yes"
#define DEFAULT_NOSTR   "no"
#define DEFAULT_YESEXPR "^[yY]"
#define DEFAULT_NOEXPR  "^[nN]"

#define FREE_MEM        \
                free(yesstr);   \
                free(nostr);    \
                free(yesexpr);  \
                free(noexpr)

#define SET_DEFAULT_STRS \
        yesstr = DEFAULT_YESSTR; \
        nostr = DEFAULT_NOSTR; \
        yesexpr = DEFAULT_YESEXPR; \
        noexpr = DEFAULT_NOEXPR;

/* variables used by getresponse functions */
char    *yesstr = NULL;
char    *nostr = NULL;

/* for regcomp()/regexec() yesexpr and noexpr */
static regex_t preg_yes, preg_no;

/*
 * This function compiles a regular expression that is used to match an
 * affirmative response from the user, and also assigns the strings used
 * in the prompts that request affirmative or negative responses.  The
 * locale's values for YESEXPR, NOEXPR, YESSTR and NOSTR are used.
 *
 * If there are any problems using the locale's YESEXPR, NOEXPR, YESSTR or NOSTR
 * values, default values of YESEXPR, YESSTR and NOSTR will be used
 * as a fallback.  The default values are the same as the C locale values.
 */
int
init_yes(void)
{
        int     fallback = 0;
        char    *yesexpr;
        char    *noexpr;

        /* get yes expression and strings for yes/no prompts */
        yesstr  = strdup(nl_langinfo(YESSTR));
        nostr   = strdup(nl_langinfo(NOSTR));
        yesexpr = strdup(nl_langinfo(YESEXPR));
        noexpr  = strdup(nl_langinfo(NOEXPR));

        if (yesstr == NULL || nostr == NULL ||
            yesexpr == NULL || noexpr == NULL) {
                FREE_MEM;
                errno = ENOMEM;
                return (-1);
        }

        /* if problem with locale strings, use default values */
        if (*yesstr == '\0' || *nostr == '\0' ||
            *yesexpr == '\0' || *noexpr == '\0') {
                FREE_MEM;
                SET_DEFAULT_STRS;
                fallback = 1;
        }
        /* Compile the yes and no expressions */
        while (regcomp(&preg_yes, yesexpr, REG_EXTENDED | REG_NOSUB) != 0 ||
            regcomp(&preg_no, noexpr, REG_EXTENDED | REG_NOSUB) != 0) {
                if (fallback == 1) {
                        /* The fallback yesexpr failed, so exit */
                        errno = EINVAL;
                        return (-1);
                }
                /* The locale's yesexpr or noexpr failed so use fallback */
                FREE_MEM;
                SET_DEFAULT_STRS;
                fallback = 1;
        }
        if (fallback == 0) {
                free(yesexpr);
                free(noexpr);
        }
        return (0);
}

void
fini_yes(void)
{
        free(yesstr);
        free(nostr);
        yesstr = DEFAULT_YESSTR;
        nostr = DEFAULT_NOSTR;
        regfree(&preg_yes);
        regfree(&preg_no);
}

static int
yes_no(int (*func)(char *))
{
        int     i, b;
        char    ans[LINE_MAX + 1];

        /* Get user's answer */
        i = 0;
        for (;;) {
                b = getchar();
                if (b == '\n' || b == '\0' || b == EOF)
                        break;
                if (i < LINE_MAX)
                        ans[i] = b;
                i++;
        }
        if (i >= LINE_MAX)
                ans[LINE_MAX] = '\0';
        else
                ans[i] = '\0';

        return (func(ans));
}

static int
yes_no_check(char *ans, regex_t *reg1, regex_t *reg2)
{
        if (regexec(reg1, ans, 0, NULL, 0) == 0) {
                if (regexec(reg2, ans, 0, NULL, 0) == 0) {
                        /* Both Expressions Match (reg2 conservative) */
                        return (0);
                }
                /* Match */
                return (1);
        }
        return (0);
}

/*
 * yes_check() returns 1 if the input string is matched by yesexpr and is
 * not matched by noexpr;  otherwise yes_check() returns 0.
 */
int
yes_check(char *ans)
{
        return (yes_no_check(ans, &preg_yes, &preg_no));
}

/*
 * no_check() returns 1 if the input string is matched by noexpr and is
 * not matched by yesexpr;  otherwise no_check() returns 0.
 */
int
no_check(char *ans)
{
        return (yes_no_check(ans, &preg_no, &preg_yes));
}

int
yes(void)
{
        return (yes_no(yes_check));
}

int
no(void)
{
        return (yes_no(no_check));
}