/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * 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, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#include <stdlib.h>
#include "shell.h"
#include "output.h"
#include "error.h"
#include "memalloc.h"
#include "mystring.h"
#include "alias.h"
#include "options.h"
#include "builtins.h"

#define ATABSIZE 39

static struct alias *atab[ATABSIZE];
static int aliases;

static void setalias(const char *, const char *);
static int unalias(const char *);
static size_t hashalias(const char *);

static
void
setalias(const char *name, const char *val)
{
        struct alias *ap, **app;

        unalias(name);
        app = &atab[hashalias(name)];
        INTOFF;
        ap = ckmalloc(sizeof (struct alias));
        ap->name = savestr(name);
        ap->val = savestr(val);
        ap->flag = 0;
        ap->next = *app;
        *app = ap;
        aliases++;
        INTON;
}

static void
freealias(struct alias *ap)
{
        ckfree(ap->name);
        ckfree(ap->val);
        ckfree(ap);
}

static int
unalias(const char *name)
{
        struct alias *ap, **app;

        app = &atab[hashalias(name)];

        for (ap = *app; ap; app = &(ap->next), ap = ap->next) {
                if (equal(name, ap->name)) {
                        /*
                         * if the alias is currently in use (i.e. its
                         * buffer is being used by the input routine) we
                         * just null out the name instead of freeing it.
                         * We could clear it out later, but this situation
                         * is so rare that it hardly seems worth it.
                         */
                        if (ap->flag & ALIASINUSE)
                                *ap->name = '\0';
                        else {
                                INTOFF;
                                *app = ap->next;
                                freealias(ap);
                                INTON;
                        }
                        aliases--;
                        return (0);
                }
        }

        return (1);
}

static void
rmaliases(void)
{
        struct alias *ap, **app;
        int i;

        INTOFF;
        for (i = 0; i < ATABSIZE; i++) {
                app = &atab[i];
                while (*app) {
                        ap = *app;
                        if (ap->flag & ALIASINUSE) {
                                *ap->name = '\0';
                                app = &(*app)->next;
                        } else {
                                *app = ap->next;
                                freealias(ap);
                        }
                }
        }
        aliases = 0;
        INTON;
}

struct alias *
lookupalias(const char *name, int check)
{
        struct alias *ap;

        if (aliases == 0)
                return (NULL);
        for (ap = atab[hashalias(name)]; ap; ap = ap->next) {
                if (equal(name, ap->name)) {
                        if (check && (ap->flag & ALIASINUSE))
                                return (NULL);
                        return (ap);
                }
        }

        return (NULL);
}

static int
comparealiases(const void *p1, const void *p2)
{
        const struct alias *const *a1 = p1;
        const struct alias *const *a2 = p2;

        return strcmp((*a1)->name, (*a2)->name);
}

static void
printalias(const struct alias *a)
{
        out1fmt("%s=", a->name);
        out1qstr(a->val);
        out1c('\n');
}

static void
printaliases(void)
{
        int i, j;
        struct alias **sorted, *ap;

        INTOFF;
        sorted = ckmalloc(aliases * sizeof(*sorted));
        j = 0;
        for (i = 0; i < ATABSIZE; i++)
                for (ap = atab[i]; ap; ap = ap->next)
                        if (*ap->name != '\0')
                                sorted[j++] = ap;
        qsort(sorted, aliases, sizeof(*sorted), comparealiases);
        for (i = 0; i < aliases; i++) {
                printalias(sorted[i]);
                if (int_pending())
                        break;
        }
        ckfree(sorted);
        INTON;
}

int
aliascmd(int argc __unused, char **argv __unused)
{
        char *n, *v;
        int ret = 0;
        struct alias *ap;

        nextopt("");

        if (*argptr == NULL) {
                printaliases();
                return (0);
        }
        while ((n = *argptr++) != NULL) {
                if (n[0] == '\0') {
                        warning("'': not found");
                        ret = 1;
                        continue;
                }
                if ((v = strchr(n+1, '=')) == NULL) /* n+1: funny ksh stuff */
                        if ((ap = lookupalias(n, 0)) == NULL) {
                                warning("%s: not found", n);
                                ret = 1;
                        } else
                                printalias(ap);
                else {
                        *v++ = '\0';
                        setalias(n, v);
                }
        }

        return (ret);
}

int
unaliascmd(int argc __unused, char **argv __unused)
{
        int i;

        while ((i = nextopt("a")) != '\0') {
                if (i == 'a') {
                        rmaliases();
                        return (0);
                }
        }
        for (i = 0; *argptr; argptr++)
                i |= unalias(*argptr);

        return (i);
}

static size_t
hashalias(const char *p)
{
        unsigned int hashval;

        hashval = (unsigned char)*p << 4;
        while (*p)
                hashval+= *p++;
        return (hashval % ATABSIZE);
}

const struct alias *
iteralias(const struct alias *index)
{
        size_t i = 0;

        if (index != NULL) {
                if (index->next != NULL)
                        return (index->next);
                i = hashalias(index->name) + 1;
        }
        for (; i < ATABSIZE; i++)
                if (atab[i] != NULL)
                        return (atab[i]);

        return (NULL);
}