/*
 * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 1995 Alex Tatmanjants <alex@elvisti.kiev.ua>
 *              at Electronni Visti IA, Kiev, Ukraine.
 *                      All rights reserved.
 *
 * Copyright (c) 2011 The FreeBSD Foundation
 * All rights reserved.
 * Portions of this software were developed by David Chisnall
 * under sponsorship from the FreeBSD Foundation.
 *
 * 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.
 *
 * 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.
 *
 * Adapted to xlocale by John Marino <draco@marino.st>
 */

#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include "un-namespace.h"

#include "collate.h"
#include "setlocale.h"
#include "ldpart.h"
#include "libc_private.h"

struct xlocale_collate __xlocale_global_collate = {
        .header = {{0}, "C"},
        .__collate_load_error = 1
};

struct xlocale_collate __xlocale_C_collate = {
        .header = {{0}, "C"},
        .__collate_load_error = 1
};

static int
__collate_load_tables_l(const char *encoding, struct xlocale_collate *table);

static void
destruct_collate(void *t)
{
        struct xlocale_collate *table = t;
        if (table->map && (table->maplen > 0)) {
                (void) munmap(table->map, table->maplen);
        }
        free(t);
}

void *
__collate_load(const char *encoding, __unused locale_t unused)
{
        if (strcmp(encoding, "C") == 0 || strcmp(encoding, "POSIX") == 0) {
                return &__xlocale_C_collate;
        }
        struct xlocale_collate *table = calloc(sizeof(struct xlocale_collate), 1);
        table->header.header.destructor = destruct_collate;
        // FIXME: Make sure that _LDP_CACHE is never returned.  We should be doing
        // the caching outside of this section
        if (__collate_load_tables_l(encoding, table) != _LDP_LOADED) {
                xlocale_release(table);
                return NULL;
        }
        return table;
}

/**
 * Load the collation tables for the specified encoding into the global table.
 */
int
__collate_load_tables(const char *encoding)
{
        return (__collate_load_tables_l(encoding, &__xlocale_global_collate));
}

static int
__collate_load_tables_l(const char *encoding, struct xlocale_collate *table)
{
        int i, chains, z;
        char buf[PATH_MAX];
        char *TMP;
        char *map;
        collate_info_t *info;
        struct stat sbuf;
        int fd;

        table->__collate_load_error = 1;

        /* 'encoding' must be already checked. */
        if (strcmp(encoding, "C") == 0 || strcmp(encoding, "POSIX") == 0) {
                return (_LDP_CACHE);
        }

        (void) snprintf(buf, sizeof (buf), "%s/%s/LC_COLLATE",
            _PathLocale, encoding);

        if ((fd = _open(buf, O_RDONLY)) < 0)
                return (_LDP_ERROR);
        if (_fstat(fd, &sbuf) < 0) {
                (void) _close(fd);
                return (_LDP_ERROR);
        }
        if (sbuf.st_size < (COLLATE_STR_LEN + sizeof (info))) {
                (void) _close(fd);
                errno = EINVAL;
                return (_LDP_ERROR);
        }
        map = mmap(NULL, sbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
        (void) _close(fd);
        if ((TMP = map) == MAP_FAILED) {
                return (_LDP_ERROR);
        }

        if (strncmp(TMP, COLLATE_VERSION, COLLATE_STR_LEN) != 0) {
                (void) munmap(map, sbuf.st_size);
                errno = EINVAL;
                return (_LDP_ERROR);
        }
        TMP += COLLATE_STR_LEN;

        info = (void *)TMP;
        TMP += sizeof (*info);

        if ((info->directive_count < 1) ||
            (info->directive_count >= COLL_WEIGHTS_MAX) ||
            ((chains = info->chain_count) < 0)) {
                (void) munmap(map, sbuf.st_size);
                errno = EINVAL;
                return (_LDP_ERROR);
        }

        i = (sizeof (collate_char_t) * (UCHAR_MAX + 1)) +
            (sizeof (collate_chain_t) * chains) +
            (sizeof (collate_large_t) * info->large_count);
        for (z = 0; z < info->directive_count; z++) {
                i += sizeof (collate_subst_t) * info->subst_count[z];
        }
        if (i != (sbuf.st_size - (TMP - map))) {
                (void) munmap(map, sbuf.st_size);
                errno = EINVAL;
                return (_LDP_ERROR);
        }

        if (table->map && (table->maplen > 0)) {
                (void) munmap(table->map, table->maplen);
        }
        table->map = map;
        table->maplen = sbuf.st_size;
        table->info = info;
        table->char_pri_table = (void *)TMP;
        TMP += sizeof (collate_char_t) * (UCHAR_MAX + 1);

        for (z = 0; z < info->directive_count; z++) {
                if (info->subst_count[z] > 0) {
                        table->subst_table[z] = (void *)TMP;
                        TMP += info->subst_count[z] * sizeof (collate_subst_t);
                } else {
                        table->subst_table[z] = NULL;
                }
        }

        if (chains > 0) {
                table->chain_pri_table = (void *)TMP;
                TMP += chains * sizeof (collate_chain_t);
        } else
                table->chain_pri_table = NULL;
        if (info->large_count > 0)
                table->large_pri_table = (void *)TMP;
        else
                table->large_pri_table = NULL;

        table->__collate_load_error = 0;
        return (_LDP_LOADED);
}

static const int32_t *
substsearch(struct xlocale_collate *table, const wchar_t key, int pass)
{
        const collate_subst_t *p;
        int n = table->info->subst_count[pass];

        if (n == 0)
                return (NULL);

        if (pass >= table->info->directive_count)
                return (NULL);

        if (!(key & COLLATE_SUBST_PRIORITY))
                return (NULL);

        p = table->subst_table[pass] + (key & ~COLLATE_SUBST_PRIORITY);
        assert(p->key == key);
        return (p->pri);
}

static collate_chain_t *
chainsearch(struct xlocale_collate *table, const wchar_t *key, int *len)
{
        int low = 0;
        int high = table->info->chain_count - 1;;
        int next, compar, l;
        collate_chain_t *p;
        collate_chain_t *tab = table->chain_pri_table;

        if (high < 0)
                return (NULL);

        while (low <= high) {
                next = (low + high) / 2;
                p = tab + next;
                compar = *key - *p->str;
                if (compar == 0) {
                        l = wcsnlen(p->str, COLLATE_STR_LEN);
                        compar = wcsncmp(key, p->str, l);
                        if (compar == 0) {
                                *len = l;
                                return (p);
                        }
                }
                if (compar > 0)
                        low = next + 1;
                else
                        high = next - 1;
        }
        return (NULL);
}

static collate_large_t *
largesearch(struct xlocale_collate *table, const wchar_t key)
{
        int low = 0;
        int high = table->info->large_count - 1;
        int next, compar;
        collate_large_t *p;
        collate_large_t *tab = table->large_pri_table;

        if (high < 0)
                return (NULL);

        while (low <= high) {
                next = (low + high) / 2;
                p = tab + next;
                compar = key - p->val;
                if (compar == 0)
                        return (p);
                if (compar > 0)
                        low = next + 1;
                else
                        high = next - 1;
        }
        return (NULL);
}

void
_collate_lookup(struct xlocale_collate *table, const wchar_t *t, int *len,
    int *pri, int which, const int **state)
{
        collate_chain_t *p2;
        collate_large_t *match;
        int p, l;
        const int *sptr;

        /*
         * If this is the "last" pass for the UNDEFINED, then
         * we just return the priority itself.
         */
        if (which >= table->info->directive_count) {
                *pri = *t;
                *len = 1;
                *state = NULL;
                return;
        }

        /*
         * If we have remaining substitution data from a previous
         * call, consume it first.
         */
        if ((sptr = *state) != NULL) {
                *pri = *sptr;
                sptr++;
                if ((sptr == *state) || (sptr == NULL))
                        *state = NULL;
                else
                        *state = sptr;
                *len = 0;
                return;
        }

        /* No active substitutions */
        *len = 1;

        /*
         * Check for composites such as diphthongs that collate as a
         * single element (aka chains or collating-elements).
         */
        if (((p2 = chainsearch(table, t, &l)) != NULL) &&
            ((p = p2->pri[which]) >= 0)) {

                *len = l;
                *pri = p;

        } else if (*t <= UCHAR_MAX) {

                /*
                 * Character is a small (8-bit) character.
                 * We just look these up directly for speed.
                 */
                *pri = table->char_pri_table[*t].pri[which];

        } else if ((table->info->large_count > 0) &&
            ((match = largesearch(table, *t)) != NULL)) {

                /*
                 * Character was found in the extended table.
                 */
                *pri = match->pri.pri[which];

        } else {
                /*
                 * Character lacks a specific definition.
                 */
                if (table->info->directive[which] & DIRECTIVE_UNDEFINED) {
                        /* Mask off sign bit to prevent ordering confusion. */
                        *pri = (*t & COLLATE_MAX_PRIORITY);
                } else {
                        *pri = table->info->undef_pri[which];
                }
                /* No substitutions for undefined characters! */
                return;
        }

        /*
         * Try substituting (expanding) the character.  We are
         * currently doing this *after* the chain compression.  I
         * think it should not matter, but this way might be slightly
         * faster.
         *
         * We do this after the priority search, as this will help us
         * to identify a single key value.  In order for this to work,
         * its important that the priority assigned to a given element
         * to be substituted be unique for that level.  The localedef
         * code ensures this for us.
         */
        if ((sptr = substsearch(table, *pri, which)) != NULL) {
                if ((*pri = *sptr) > 0) {
                        sptr++;
                        *state = *sptr ? sptr : NULL;
                }
        }

}

/*
 * This is the meaty part of wcsxfrm & strxfrm.  Note that it does
 * NOT NULL terminate.  That is left to the caller.
 */
size_t
_collate_wxfrm(struct xlocale_collate *table, const wchar_t *src, wchar_t *xf,
    size_t room)
{
        int             pri;
        int             len;
        const wchar_t   *t;
        wchar_t         *tr = NULL;
        int             direc;
        int             pass;
        const int32_t   *state;
        size_t          want = 0;
        size_t          need = 0;
        int             ndir = table->info->directive_count;

        assert(src);

        for (pass = 0; pass <= ndir; pass++) {

                state = NULL;

                if (pass != 0) {
                        /* insert level separator from the previous pass */
                        if (room) {
                                *xf++ = 1;
                                room--;
                        }
                        want++;
                }

                /* special pass for undefined */
                if (pass == ndir) {
                        direc = DIRECTIVE_FORWARD | DIRECTIVE_UNDEFINED;
                } else {
                        direc = table->info->directive[pass];
                }

                t = src;

                if (direc & DIRECTIVE_BACKWARD) {
                        wchar_t *bp, *fp, c;
                        if (tr)
                                free(tr);
                        if ((tr = wcsdup(t)) == NULL) {
                                errno = ENOMEM;
                                goto fail;
                        }
                        bp = tr;
                        fp = tr + wcslen(tr) - 1;
                        while (bp < fp) {
                                c = *bp;
                                *bp++ = *fp;
                                *fp-- = c;
                        }
                        t = (const wchar_t *)tr;
                }

                if (direc & DIRECTIVE_POSITION) {
                        while (*t || state) {
                                _collate_lookup(table, t, &len, &pri, pass, &state);
                                t += len;
                                if (pri <= 0) {
                                        if (pri < 0) {
                                                errno = EINVAL;
                                                goto fail;
                                        }
                                        state = NULL;
                                        pri = COLLATE_MAX_PRIORITY;
                                }
                                if (room) {
                                        *xf++ = pri;
                                        room--;
                                }
                                want++;
                                need = want;
                        }
                } else {
                        while (*t || state) {
                                _collate_lookup(table, t, &len, &pri, pass, &state);
                                t += len;
                                if (pri <= 0) {
                                        if (pri < 0) {
                                                errno = EINVAL;
                                                goto fail;
                                        }
                                        state = NULL;
                                        continue;
                                }
                                if (room) {
                                        *xf++ = pri;
                                        room--;
                                }
                                want++;
                                need = want;
                        }
                }
        }
        free(tr);
        return (need);

fail:
        free(tr);
        return ((size_t)(-1));
}

/*
 * In the non-POSIX case, we transform each character into a string of
 * characters representing the character's priority.  Since char is usually
 * signed, we are limited by 7 bits per byte.  To avoid zero, we need to add
 * XFRM_OFFSET, so we can't use a full 7 bits.  For simplicity, we choose 6
 * bits per byte.
 *
 * It turns out that we sometimes have real priorities that are
 * 31-bits wide.  (But: be careful using priorities where the high
 * order bit is set -- i.e. the priority is negative.  The sort order
 * may be surprising!)
 *
 * TODO: This would be a good area to optimize somewhat.  It turns out
 * that real prioririties *except for the last UNDEFINED pass* are generally
 * very small.  We need the localedef code to precalculate the max
 * priority for us, and ideally also give us a mask, and then we could
 * severely limit what we expand to.
 */
#define XFRM_BYTES      6
#define XFRM_OFFSET     ('0')   /* make all printable characters */
#define XFRM_SHIFT      6
#define XFRM_MASK       ((1 << XFRM_SHIFT) - 1)
#define XFRM_SEP        ('.')   /* chosen to be less than XFRM_OFFSET */

static int
xfrm(struct xlocale_collate *table, unsigned char *p, int pri, int pass)
{
        /* we use unsigned to ensure zero fill on right shift */
        uint32_t val = (uint32_t)table->info->pri_count[pass];
        int nc = 0;

        while (val) {
                *p = (pri & XFRM_MASK) + XFRM_OFFSET;
                pri >>= XFRM_SHIFT;
                val >>= XFRM_SHIFT;
                p++;
                nc++;
        }
        return (nc);
}

size_t
_collate_sxfrm(struct xlocale_collate *table, const wchar_t *src, char *xf,
    size_t room)
{
        int             pri;
        int             len;
        const wchar_t   *t;
        wchar_t         *tr = NULL;
        int             direc;
        int             pass;
        const int32_t   *state;
        size_t          want = 0;
        size_t          need = 0;
        int             b;
        uint8_t         buf[XFRM_BYTES];
        int             ndir = table->info->directive_count;

        assert(src);

        for (pass = 0; pass <= ndir; pass++) {

                state = NULL;

                if (pass != 0) {
                        /* insert level separator from the previous pass */
                        if (room) {
                                *xf++ = XFRM_SEP;
                                room--;
                        }
                        want++;
                }

                /* special pass for undefined */
                if (pass == ndir) {
                        direc = DIRECTIVE_FORWARD | DIRECTIVE_UNDEFINED;
                } else {
                        direc = table->info->directive[pass];
                }

                t = src;

                if (direc & DIRECTIVE_BACKWARD) {
                        wchar_t *bp, *fp, c;
                        if (tr)
                                free(tr);
                        if ((tr = wcsdup(t)) == NULL) {
                                errno = ENOMEM;
                                goto fail;
                        }
                        bp = tr;
                        fp = tr + wcslen(tr) - 1;
                        while (bp < fp) {
                                c = *bp;
                                *bp++ = *fp;
                                *fp-- = c;
                        }
                        t = (const wchar_t *)tr;
                }

                if (direc & DIRECTIVE_POSITION) {
                        while (*t || state) {

                                _collate_lookup(table, t, &len, &pri, pass, &state);
                                t += len;
                                if (pri <= 0) {
                                        if (pri < 0) {
                                                errno = EINVAL;
                                                goto fail;
                                        }
                                        state = NULL;
                                        pri = COLLATE_MAX_PRIORITY;
                                }

                                b = xfrm(table, buf, pri, pass);
                                want += b;
                                if (room) {
                                        while (b) {
                                                b--;
                                                if (room) {
                                                        *xf++ = buf[b];
                                                        room--;
                                                }
                                        }
                                }
                                need = want;
                        }
                } else {
                        while (*t || state) {
                                _collate_lookup(table, t, &len, &pri, pass, &state);
                                t += len;
                                if (pri <= 0) {
                                        if (pri < 0) {
                                                errno = EINVAL;
                                                goto fail;
                                        }
                                        state = NULL;
                                        continue;
                                }

                                b = xfrm(table, buf, pri, pass);
                                want += b;
                                if (room) {

                                        while (b) {
                                                b--;
                                                if (room) {
                                                        *xf++ = buf[b];
                                                        room--;
                                                }
                                        }
                                }
                                need = want;
                        }
                }
        }
        free(tr);
        return (need);

fail:
        free(tr);
        return ((size_t)(-1));
}

/*
 * __collate_equiv_value returns the primary collation value for the given
 * collating symbol specified by str and len.  Zero or negative is returned
 * if the collating symbol was not found.  This function is used by bracket
 * code in the TRE regex library.
 */
int
__collate_equiv_value(locale_t locale, const wchar_t *str, size_t len)
{
        int32_t e;

        if (len < 1 || len >= COLLATE_STR_LEN)
                return (-1);

        FIX_LOCALE(locale);
        struct xlocale_collate *table =
                (struct xlocale_collate*)locale->components[XLC_COLLATE];

        if (table->__collate_load_error)
                return ((len == 1 && *str <= UCHAR_MAX) ? *str : -1);

        if (len == 1) {
                e = -1;
                if (*str <= UCHAR_MAX)
                        e = table->char_pri_table[*str].pri[0];
                else if (table->info->large_count > 0) {
                        collate_large_t *match_large;
                        match_large = largesearch(table, *str);
                        if (match_large)
                                e = match_large->pri.pri[0];
                }
                if (e == 0)
                        return (1);
                return (e > 0 ? e : 0);
        }
        if (table->info->chain_count > 0) {
                wchar_t name[COLLATE_STR_LEN];
                collate_chain_t *match_chain;
                int clen;

                wcsncpy (name, str, len);
                name[len] = 0;
                match_chain = chainsearch(table, name, &clen);
                if (match_chain) {
                        e = match_chain->pri[0];
                        if (e == 0)
                                return (1);
                        return (e < 0 ? -e : e);
                }
        }
        return (0);
}