/*
 * WideCharToMultiByte implementation
 *
 * Copyright 2000 Alexandre Julliard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <string.h>

#include "wine/unicode.h"

/* search for a character in the unicode_compose_table; helper for compose() */
static inline int binary_search( WCHAR ch, int low, int high )
{
    extern const WCHAR unicode_compose_table[];
    while (low <= high)
    {
        int pos = (low + high) / 2;
        if (unicode_compose_table[2*pos] < ch)
        {
            low = pos + 1;
            continue;
        }
        if (unicode_compose_table[2*pos] > ch)
        {
            high = pos - 1;
            continue;
        }
        return pos;
    }
    return -1;
}

/* return the result of the composition of two Unicode chars, or 0 if none */
WCHAR compose( const WCHAR *str )
{
    extern const WCHAR unicode_compose_table[];
    extern const unsigned int unicode_compose_table_size;

    int idx = 1, low = 0, high = unicode_compose_table_size - 1;
    for (;;)
    {
        int pos = binary_search( str[idx], low, high );
        if (pos == -1) return 0;
        if (!idx--) return unicode_compose_table[2*pos+1];
        low = unicode_compose_table[2*pos+1];
        high = unicode_compose_table[2*pos+3] - 1;
    }
}


/****************************************************************/
/* sbcs support */

/* check if 'ch' is an acceptable sbcs mapping for 'wch' */
static inline int is_valid_sbcs_mapping( const struct sbcs_table *table, int flags,
                                         WCHAR wch, unsigned char ch )
{
    if ((flags & WC_NO_BEST_FIT_CHARS) || ch == (unsigned char)table->info.def_char)
        return (table->cp2uni[ch] == wch);
    return 1;
}

/* query necessary dst length for src string */
static int get_length_sbcs( const struct sbcs_table *table, int flags,
                            const WCHAR *src, unsigned int srclen, int *used )
{
    const unsigned char  * const uni2cp_low = table->uni2cp_low;
    const unsigned short * const uni2cp_high = table->uni2cp_high;
    int ret, tmp;
    WCHAR composed;

    if (!used) used = &tmp;  /* avoid checking on every char */
    *used = 0;

    for (ret = 0; srclen; ret++, src++, srclen--)
    {
        WCHAR wch = *src;
        unsigned char ch;

        if ((flags & WC_COMPOSITECHECK) && (srclen > 1) && (composed = compose(src)))
        {
            /* now check if we can use the composed char */
            ch = uni2cp_low[uni2cp_high[composed >> 8] + (composed & 0xff)];
            if (is_valid_sbcs_mapping( table, flags, composed, ch ))
            {
                /* we have a good mapping, use it */
                src++;
                srclen--;
                continue;
            }
            /* no mapping for the composed char, check the other flags */
            if (flags & WC_DEFAULTCHAR) /* use the default char instead */
            {
                *used = 1;
                src++;  /* skip the non-spacing char */
                srclen--;
                continue;
            }
            if (flags & WC_DISCARDNS) /* skip the second char of the composition */
            {
                src++;
                srclen--;
            }
            /* WC_SEPCHARS is the default */
        }
        if (!*used)
        {
            ch = uni2cp_low[uni2cp_high[wch >> 8] + (wch & 0xff)];
            *used = !is_valid_sbcs_mapping( table, flags, wch, ch );
        }
    }
    return ret;
}

/* wcstombs for single-byte code page */
static inline int wcstombs_sbcs( const struct sbcs_table *table,
                                 const WCHAR *src, unsigned int srclen,
                                 char *dst, unsigned int dstlen )
{
    const unsigned char  * const uni2cp_low = table->uni2cp_low;
    const unsigned short * const uni2cp_high = table->uni2cp_high;
    int ret = srclen;

    if (dstlen < srclen)
    {
        /* buffer too small: fill it up to dstlen and return error */
        srclen = dstlen;
        ret = -1;
    }

    while (srclen >= 16)
    {
        dst[0]  = uni2cp_low[uni2cp_high[src[0]  >> 8] + (src[0]  & 0xff)];
        dst[1]  = uni2cp_low[uni2cp_high[src[1]  >> 8] + (src[1]  & 0xff)];
        dst[2]  = uni2cp_low[uni2cp_high[src[2]  >> 8] + (src[2]  & 0xff)];
        dst[3]  = uni2cp_low[uni2cp_high[src[3]  >> 8] + (src[3]  & 0xff)];
        dst[4]  = uni2cp_low[uni2cp_high[src[4]  >> 8] + (src[4]  & 0xff)];
        dst[5]  = uni2cp_low[uni2cp_high[src[5]  >> 8] + (src[5]  & 0xff)];
        dst[6]  = uni2cp_low[uni2cp_high[src[6]  >> 8] + (src[6]  & 0xff)];
        dst[7]  = uni2cp_low[uni2cp_high[src[7]  >> 8] + (src[7]  & 0xff)];
        dst[8]  = uni2cp_low[uni2cp_high[src[8]  >> 8] + (src[8]  & 0xff)];
        dst[9]  = uni2cp_low[uni2cp_high[src[9]  >> 8] + (src[9]  & 0xff)];
        dst[10] = uni2cp_low[uni2cp_high[src[10] >> 8] + (src[10] & 0xff)];
        dst[11] = uni2cp_low[uni2cp_high[src[11] >> 8] + (src[11] & 0xff)];
        dst[12] = uni2cp_low[uni2cp_high[src[12] >> 8] + (src[12] & 0xff)];
        dst[13] = uni2cp_low[uni2cp_high[src[13] >> 8] + (src[13] & 0xff)];
        dst[14] = uni2cp_low[uni2cp_high[src[14] >> 8] + (src[14] & 0xff)];
        dst[15] = uni2cp_low[uni2cp_high[src[15] >> 8] + (src[15] & 0xff)];
        src += 16;
        dst += 16;
        srclen -= 16;
    }

    /* now handle remaining characters */
    src += srclen;
    dst += srclen;
    switch(srclen)
    {
    case 15: dst[-15] = uni2cp_low[uni2cp_high[src[-15] >> 8] + (src[-15] & 0xff)];
    case 14: dst[-14] = uni2cp_low[uni2cp_high[src[-14] >> 8] + (src[-14] & 0xff)];
    case 13: dst[-13] = uni2cp_low[uni2cp_high[src[-13] >> 8] + (src[-13] & 0xff)];
    case 12: dst[-12] = uni2cp_low[uni2cp_high[src[-12] >> 8] + (src[-12] & 0xff)];
    case 11: dst[-11] = uni2cp_low[uni2cp_high[src[-11] >> 8] + (src[-11] & 0xff)];
    case 10: dst[-10] = uni2cp_low[uni2cp_high[src[-10] >> 8] + (src[-10] & 0xff)];
    case 9:  dst[-9]  = uni2cp_low[uni2cp_high[src[-9]  >> 8] + (src[-9]  & 0xff)];
    case 8:  dst[-8]  = uni2cp_low[uni2cp_high[src[-8]  >> 8] + (src[-8]  & 0xff)];
    case 7:  dst[-7]  = uni2cp_low[uni2cp_high[src[-7]  >> 8] + (src[-7]  & 0xff)];
    case 6:  dst[-6]  = uni2cp_low[uni2cp_high[src[-6]  >> 8] + (src[-6]  & 0xff)];
    case 5:  dst[-5]  = uni2cp_low[uni2cp_high[src[-5]  >> 8] + (src[-5]  & 0xff)];
    case 4:  dst[-4]  = uni2cp_low[uni2cp_high[src[-4]  >> 8] + (src[-4]  & 0xff)];
    case 3:  dst[-3]  = uni2cp_low[uni2cp_high[src[-3]  >> 8] + (src[-3]  & 0xff)];
    case 2:  dst[-2]  = uni2cp_low[uni2cp_high[src[-2]  >> 8] + (src[-2]  & 0xff)];
    case 1:  dst[-1]  = uni2cp_low[uni2cp_high[src[-1]  >> 8] + (src[-1]  & 0xff)];
    case 0: break;
    }
    return ret;
}

/* slow version of wcstombs_sbcs that handles the various flags */
static int wcstombs_sbcs_slow( const struct sbcs_table *table, int flags,
                               const WCHAR *src, unsigned int srclen,
                               char *dst, unsigned int dstlen,
                               const char *defchar, int *used )
{
    const unsigned char  * const uni2cp_low = table->uni2cp_low;
    const unsigned short * const uni2cp_high = table->uni2cp_high;
    unsigned char def;
    unsigned int len;
    int tmp;
    WCHAR composed;

    if (!defchar)
        def = table->info.def_char & 0xff;
    else
        def = *defchar;

    if (!used) used = &tmp;  /* avoid checking on every char */
    *used = 0;

    for (len = dstlen; srclen && len; dst++, len--, src++, srclen--)
    {
        WCHAR wch = *src;

        if ((flags & WC_COMPOSITECHECK) && (srclen > 1) && (composed = compose(src)))
        {
            /* now check if we can use the composed char */
            *dst = uni2cp_low[uni2cp_high[composed >> 8] + (composed & 0xff)];
            if (is_valid_sbcs_mapping( table, flags, composed, *dst ))
            {
                /* we have a good mapping, use it */
                src++;
                srclen--;
                continue;
            }
            /* no mapping for the composed char, check the other flags */
            if (flags & WC_DEFAULTCHAR) /* use the default char instead */
            {
                *dst = def;
                *used = 1;
                src++;  /* skip the non-spacing char */
                srclen--;
                continue;
            }
            if (flags & WC_DISCARDNS) /* skip the second char of the composition */
            {
                src++;
                srclen--;
            }
            /* WC_SEPCHARS is the default */
        }

        *dst = uni2cp_low[uni2cp_high[wch >> 8] + (wch & 0xff)];
        if (!is_valid_sbcs_mapping( table, flags, wch, *dst ))
        {
            *dst = def;
            *used = 1;
        }
    }
    if (srclen) return -1;  /* overflow */
    return dstlen - len;
}


/****************************************************************/
/* dbcs support */

/* check if 'ch' is an acceptable dbcs mapping for 'wch' */
static inline int is_valid_dbcs_mapping( const struct dbcs_table *table, int flags,
                                         WCHAR wch, unsigned short ch )
{
    if ((flags & WC_NO_BEST_FIT_CHARS) || ch == table->info.def_char)
    {
        /* check if char maps back to the same Unicode value */
        if (ch & 0xff00)
        {
            unsigned char off = table->cp2uni_leadbytes[ch >> 8];
            return (table->cp2uni[(off << 8) + (ch & 0xff)] == wch);
        }
        return (table->cp2uni[ch & 0xff] == wch);
    }
    return 1;
}

/* compute the default char for the dbcs case */
static inline WCHAR get_defchar_dbcs( const struct dbcs_table *table, const char *defchar )
{
    if (!defchar) return table->info.def_char;
    if (!defchar[1]) return (unsigned char)defchar[0];
    return ((unsigned char)defchar[0] << 8) | (unsigned char)defchar[1];
}

/* query necessary dst length for src string */
static int get_length_dbcs( const struct dbcs_table *table, int flags,
                            const WCHAR *src, unsigned int srclen,
                            const char *defchar, int *used )
{
    const unsigned short * const uni2cp_low = table->uni2cp_low;
    const unsigned short * const uni2cp_high = table->uni2cp_high;
    WCHAR defchar_value, composed;
    int len, tmp;

    if (!defchar && !used && !(flags & WC_COMPOSITECHECK))
    {
        for (len = 0; srclen; srclen--, src++, len++)
        {
            if (uni2cp_low[uni2cp_high[*src >> 8] + (*src & 0xff)] & 0xff00) len++;
        }
        return len;
    }

    defchar_value = get_defchar_dbcs( table, defchar );
    if (!used) used = &tmp;  /* avoid checking on every char */
    *used = 0;
    for (len = 0; srclen; len++, srclen--, src++)
    {
        unsigned short res;
        WCHAR wch = *src;

        if ((flags & WC_COMPOSITECHECK) && (srclen > 1) && (composed = compose(src)))
        {
            /* now check if we can use the composed char */
            res = uni2cp_low[uni2cp_high[composed >> 8] + (composed & 0xff)];

            if (is_valid_dbcs_mapping( table, flags, composed, res ))
            {
                /* we have a good mapping for the composed char, use it */
                if (res & 0xff00) len++;
                src++;
                srclen--;
                continue;
            }
            /* no mapping for the composed char, check the other flags */
            if (flags & WC_DEFAULTCHAR) /* use the default char instead */
            {
                if (defchar_value & 0xff00) len++;
                *used = 1;
                src++;  /* skip the non-spacing char */
                srclen--;
                continue;
            }
            if (flags & WC_DISCARDNS) /* skip the second char of the composition */
            {
                src++;
                srclen--;
            }
            /* WC_SEPCHARS is the default */
        }

        res = uni2cp_low[uni2cp_high[wch >> 8] + (wch & 0xff)];
        if (!is_valid_dbcs_mapping( table, flags, wch, res ))
        {
            res = defchar_value;
            *used = 1;
        }
        if (res & 0xff00) len++;
    }
    return len;
}

/* wcstombs for double-byte code page */
static inline int wcstombs_dbcs( const struct dbcs_table *table,
                                 const WCHAR *src, unsigned int srclen,
                                 char *dst, unsigned int dstlen )
{
    const unsigned short * const uni2cp_low = table->uni2cp_low;
    const unsigned short * const uni2cp_high = table->uni2cp_high;
    int len;

    for (len = dstlen; srclen && len; len--, srclen--, src++)
    {
        unsigned short res = uni2cp_low[uni2cp_high[*src >> 8] + (*src & 0xff)];
        if (res & 0xff00)
        {
            if (len == 1) break;  /* do not output a partial char */
            len--;
            *dst++ = res >> 8;
        }
        *dst++ = (char)res;
    }
    if (srclen) return -1;  /* overflow */
    return dstlen - len;
}

/* slow version of wcstombs_dbcs that handles the various flags */
static int wcstombs_dbcs_slow( const struct dbcs_table *table, int flags,
                               const WCHAR *src, unsigned int srclen,
                               char *dst, unsigned int dstlen,
                               const char *defchar, int *used )
{
    const unsigned short * const uni2cp_low = table->uni2cp_low;
    const unsigned short * const uni2cp_high = table->uni2cp_high;
    WCHAR defchar_value = get_defchar_dbcs( table, defchar );
    WCHAR composed;
    int len, tmp;

    if (!used) used = &tmp;  /* avoid checking on every char */
    *used = 0;

    for (len = dstlen; srclen && len; len--, srclen--, src++)
    {
        unsigned short res;
        WCHAR wch = *src;

        if ((flags & WC_COMPOSITECHECK) && (srclen > 1) && (composed = compose(src)))
        {
            /* now check if we can use the composed char */
            res = uni2cp_low[uni2cp_high[composed >> 8] + (composed & 0xff)];

            if (is_valid_dbcs_mapping( table, flags, composed, res ))
            {
                /* we have a good mapping for the composed char, use it */
                src++;
                srclen--;
                goto output_char;
            }
            /* no mapping for the composed char, check the other flags */
            if (flags & WC_DEFAULTCHAR) /* use the default char instead */
            {
                res = defchar_value;
                *used = 1;
                src++;  /* skip the non-spacing char */
                srclen--;
                goto output_char;
            }
            if (flags & WC_DISCARDNS) /* skip the second char of the composition */
            {
                src++;
                srclen--;
            }
            /* WC_SEPCHARS is the default */
        }

        res = uni2cp_low[uni2cp_high[wch >> 8] + (wch & 0xff)];
        if (!is_valid_dbcs_mapping( table, flags, wch, res ))
        {
            res = defchar_value;
            *used = 1;
        }

    output_char:
        if (res & 0xff00)
        {
            if (len == 1) break;  /* do not output a partial char */
            len--;
            *dst++ = res >> 8;
        }
        *dst++ = (char)res;
    }
    if (srclen) return -1;  /* overflow */
    return dstlen - len;
}

/* wide char to multi byte string conversion */
/* return -1 on dst buffer overflow */
int wine_cp_wcstombs( const union cptable *table, int flags,
                      const WCHAR *src, int srclen,
                      char *dst, int dstlen, const char *defchar, int *used )
{
    if (table->info.char_size == 1)
    {
        if (flags || defchar || used)
        {
            if (!dstlen) return get_length_sbcs( &table->sbcs, flags, src, srclen, used );
            return wcstombs_sbcs_slow( &table->sbcs, flags, src, srclen,
                                       dst, dstlen, defchar, used );
        }
        if (!dstlen) return srclen;
        return wcstombs_sbcs( &table->sbcs, src, srclen, dst, dstlen );
    }
    else /* mbcs */
    {
        if (!dstlen) return get_length_dbcs( &table->dbcs, flags, src, srclen, defchar, used );
        if (flags || defchar || used)
            return wcstombs_dbcs_slow( &table->dbcs, flags, src, srclen,
                                       dst, dstlen, defchar, used );
        return wcstombs_dbcs( &table->dbcs, src, srclen, dst, dstlen );
    }
}

/* CP_SYMBOL implementation */
/* return -1 on dst buffer overflow, -2 on invalid character */
int wine_cpsymbol_wcstombs( const WCHAR *src, int srclen, char *dst, int dstlen)
{
    int len, i;
    if( dstlen == 0) return srclen;
    len = dstlen > srclen ? srclen : dstlen;
    for( i = 0; i < len; i++)
    {
        WCHAR w = src [ i ];
        if( w < 0x20 )
            dst[i] = w;
        else if( w >= 0xf020 && w < 0xf100)
            dst[i] = w - 0xf000;
        else
            return -2;
    }
    if( srclen > len) return -1;
    return len;
}