/*      $NetBSD: citrus_csmapper.c,v 1.13 2025/12/16 12:39:01 nia Exp $ */

/*-
 * Copyright (c)2003 Citrus Project,
 * All rights reserved.
 *
 * 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 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 AUTHOR 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: citrus_csmapper.c,v 1.13 2025/12/16 12:39:01 nia Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include "reentrant.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <paths.h>
#include <sys/types.h>
#include <sys/endian.h>
#include <sys/queue.h>

#include "citrus_namespace.h"
#include "citrus_types.h"
#include "citrus_bcs.h"
#include "citrus_region.h"
#include "citrus_memstream.h"
#include "citrus_mmap.h"
#include "citrus_module.h"
#include "citrus_hash.h"
#include "citrus_mapper.h"
#include "citrus_csmapper.h"
#include "citrus_pivot_file.h"
#include "citrus_db.h"
#include "citrus_db_hash.h"
#include "citrus_lookup.h"

#ifdef _REENTRANT
static rwlock_t lock = RWLOCK_INITIALIZER;
#endif
static struct _citrus_mapper_area *maparea = NULL;

#define CS_ALIAS        _PATH_CSMAPPER "/charset.alias"
#define CS_PIVOT        _PATH_CSMAPPER "/charset.pivot"


/* ---------------------------------------------------------------------- */

static int
get32(struct _region *r, uint32_t *rval)
{
        if (_region_size(r) != 4)
                return EFTYPE;

        memcpy(rval, _region_head(r), (size_t)4);
        *rval = be32toh(*rval);

        return 0;
}

static int
open_subdb(struct _citrus_db **subdb, struct _citrus_db *db, const char *src)
{
        int ret;
        struct _region r;

        ret = _db_lookup_by_s(db, src, &r, NULL);
        if (ret)
                return ret;
        ret = _db_open(subdb, &r, _CITRUS_PIVOT_SUB_MAGIC, _db_hash_std, NULL);
        if (ret)
                return ret;

        return 0;
}


#define NO_SUCH_FILE    EOPNOTSUPP
static int
find_best_pivot_pvdb(const char *src, const char *dst, char *pivot,
                     size_t pvlen, unsigned long *rnorm)
{
        int ret, num, i;
        struct _region fr, r1, r2;
        struct _citrus_db *db1, *db2, *db3;
        char buf[LINE_MAX];
        unsigned long norm;
        uint32_t val32;

        ret = _map_file(&fr, CS_PIVOT ".pvdb");
        if (ret) {
                if (ret == ENOENT)
                        ret = NO_SUCH_FILE;
                return ret;
        }
        ret = _db_open(&db1, &fr, _CITRUS_PIVOT_MAGIC, _db_hash_std, NULL);
        if (ret)
                goto quit1;
        ret = open_subdb(&db2, db1, src);
        if (ret)
                goto quit2;

        num = _db_get_num_entries(db2);
        *rnorm = ULONG_MAX;
        for (i = 0; i < num; i++) {
                /* iterate each pivot */
                ret = _db_get_entry(db2, i, &r1, &r2);
                if (ret)
                        goto quit3;
                /* r1:pivot name, r2:norm among src and pivot */
                ret = get32(&r2, &val32);
                if (ret)
                        goto quit3;
                norm = val32;
                snprintf(buf, sizeof(buf), "%.*s",
                         (int)_region_size(&r1), (char *)_region_head(&r1));
                /* buf: pivot name */
                ret = open_subdb(&db3, db1, buf);
                if (ret)
                        goto quit3;
                if (_db_lookup_by_s(db3, dst, &r2, NULL) != 0)
                        /* don't break the loop, test all src/dst pairs. */
                        goto quit4;
                /* r2: norm among pivot and dst */
                ret = get32(&r2, &val32);
                if (ret)
                        goto quit4;
                norm += val32;
                /* judge minimum norm */
                if (norm < *rnorm) {
                        *rnorm = norm;
                        strlcpy(pivot, buf, pvlen);
                }
quit4:
                _db_close(db3);
                if (ret)
                        goto quit3;
        }
quit3:
        _db_close(db2);
quit2:
        _db_close(db1);
quit1:
        _unmap_file(&fr);
        if (ret)
                return ret;

        if (*rnorm == ULONG_MAX)
                return ENOENT;

        return 0;
}

/* ---------------------------------------------------------------------- */

struct zone {
        const char *begin, *end;
};

struct parse_arg {
        char dst[PATH_MAX];
        unsigned long norm;
};

static int
parse_line(struct parse_arg *pa, struct _region *r)
{
        char buf[20];
        struct zone z1, z2;
        size_t len;

        len = _region_size(r);
        z1.begin = _bcs_skip_ws_len(_region_head(r), &len);
        if (len == 0)
                return EFTYPE;
        z1.end = _bcs_skip_nonws_len(z1.begin, &len);
        if (len == 0)
                return EFTYPE;
        z2.begin = _bcs_skip_ws_len(z1.end, &len);
        if (len == 0)
                return EFTYPE;
        z2.end = _bcs_skip_nonws_len(z2.begin, &len);

        /* z1 : dst name, z2 : norm */
        snprintf(pa->dst, sizeof(pa->dst),
                 "%.*s", (int)(z1.end-z1.begin), z1.begin);
        snprintf(buf, sizeof(buf),
                 "%.*s", (int)(z2.end-z2.begin), z2.begin);
        pa->norm = _bcs_strtoul(buf, NULL, 0);

        return 0;
}

static int
find_dst(struct parse_arg *pasrc, const char *dst)
{
        int ret;
        struct parse_arg padst;
        struct _lookup *cl;
        struct _region data;

        ret = _lookup_seq_open(&cl, CS_PIVOT, _LOOKUP_CASE_IGNORE);
        if (ret)
                return ret;

        ret = _lookup_seq_lookup(cl, pasrc->dst, &data);
        while (ret == 0) {
                ret = parse_line(&padst, &data);
                if (ret)
                        break;
                if (strcmp(dst, padst.dst) == 0) {
                        pasrc->norm += padst.norm;
                        break;
                }
                ret = _lookup_seq_next(cl, NULL, &data);
        }
        _lookup_seq_close(cl);

        return ret;
}

static int
find_best_pivot_lookup(const char *src, const char *dst, char *pivot,
                       size_t pvlen, unsigned long *rnorm)
{
        int ret;
        struct _lookup *cl;
        struct _region data;
        struct parse_arg pa;
        unsigned long norm_min;
        char pivot_min[PATH_MAX];

        ret = _lookup_seq_open(&cl, CS_PIVOT, _LOOKUP_CASE_IGNORE);
        if (ret)
                return ret;

        norm_min = ULONG_MAX;

        /* find pivot code */
        ret = _lookup_seq_lookup(cl, src, &data);
        while (ret == 0) {
                ret = parse_line(&pa, &data);
                if (ret)
                        break;
                ret = find_dst(&pa, dst);
                if (ret)
                        break;
                if (pa.norm < norm_min) {
                        norm_min = pa.norm;
                        strlcpy(pivot_min, pa.dst, sizeof(pivot_min));
                }
                ret = _lookup_seq_next(cl, NULL, &data);
        }
        _lookup_seq_close(cl);

        if (ret != ENOENT)
                return ret;
        if (norm_min == ULONG_MAX)
                return ENOENT;
        strlcpy(pivot, pivot_min, pvlen);
        if (rnorm)
                *rnorm = norm_min;

        return 0;
}

static int
find_best_pivot(const char *src, const char *dst, char *pivot, size_t pvlen,
                unsigned long *rnorm)
{
        int ret;

        ret = find_best_pivot_pvdb(src, dst, pivot, pvlen, rnorm);
        if (ret == NO_SUCH_FILE)
                ret = find_best_pivot_lookup(src, dst, pivot, pvlen, rnorm);

        return ret;
}

static __inline int
open_serial_mapper(struct _citrus_mapper_area *__restrict ma,
                   struct _citrus_mapper * __restrict * __restrict rcm,
                   const char *src, const char *pivot, const char *dst)
{
        char buf[4 * PATH_MAX];

        snprintf(buf, sizeof(buf), "%s/%s,%s/%s", src, pivot, pivot, dst);

        return _mapper_open_direct(ma, rcm, "mapper_serial", buf);
}

static struct _citrus_csmapper *csm_none = NULL;
static int
get_none(struct _citrus_mapper_area *__restrict ma,
         struct _citrus_csmapper *__restrict *__restrict rcsm)
{
        int ret;

        rwlock_wrlock(&lock);
        if (csm_none) {
                *rcsm = csm_none;
                ret = 0;
                goto quit;
        }

        ret = _mapper_open_direct(ma, &csm_none, "mapper_none", "");
        if (ret)
                goto quit;
        _mapper_set_persistent(csm_none);

        *rcsm = csm_none;
        ret = 0;
quit:
        rwlock_unlock(&lock);
        return ret;
}

int
_citrus_csmapper_open(struct _citrus_csmapper * __restrict * __restrict rcsm,
                      const char * __restrict src, const char * __restrict dst,
                      uint32_t flags, unsigned long *rnorm)
{
        int ret;
        char buf1[PATH_MAX], buf2[PATH_MAX], key[PATH_MAX], pivot[PATH_MAX];
        const char *realsrc, *realdst;
        unsigned long norm;

        norm = 0;       /* XXX gcc */

        ret = _citrus_mapper_create_area(&maparea, _PATH_CSMAPPER);
        if (ret)
                return ret;

        realsrc = _lookup_alias(CS_ALIAS, src, buf1, sizeof(buf1),
                                _LOOKUP_CASE_IGNORE);
        realdst = _lookup_alias(CS_ALIAS, dst, buf2, sizeof(buf2),
                                _LOOKUP_CASE_IGNORE);
        if (!strcmp(realsrc, realdst)) {
                ret = get_none(maparea, rcsm);
                if (ret == 0 && rnorm != NULL)
                        *rnorm = 0;
                return ret;
        }

        snprintf(key, sizeof(key), "%s/%s", realsrc, realdst);

        ret = _mapper_open(maparea, rcsm, key);
        if (ret == 0) {
                if (rnorm != NULL)
                        *rnorm = 0;
                return 0;
        }
        if (ret != ENOENT || (flags & _CSMAPPER_F_PREVENT_PIVOT)!=0)
                return ret;

        ret = find_best_pivot(realsrc, realdst, pivot, sizeof(pivot), &norm);
        if (ret)
                return ret;

        ret = open_serial_mapper(maparea, rcsm, realsrc, pivot, realdst);
        if (ret == 0 && rnorm != NULL)
                *rnorm = norm;

        return ret;
}