/*
 * Opentype font interfaces for the Uniscribe Script Processor (usp10.dll)
 *
 * Copyright 2012 CodeWeavers, Aric Stewart
 *
 * 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 <stdarg.h>
#include <stdlib.h>

#include "windef.h"
#include "winbase.h"
#include "wingdi.h"
#include "winuser.h"
#include "winnls.h"
#include "usp10.h"
#include "winternl.h"

#include "usp10_internal.h"

#include "wine/debug.h"

WINE_DEFAULT_DEBUG_CHANNEL(uniscribe);

#ifdef WORDS_BIGENDIAN
#define GET_BE_WORD(x) (x)
#define GET_BE_DWORD(x) (x)
#else
#define GET_BE_WORD(x) RtlUshortByteSwap(x)
#define GET_BE_DWORD(x) RtlUlongByteSwap(x)
#endif

/* These are all structures needed for the cmap format 12 table */
#define CMAP_TAG MS_MAKE_TAG('c', 'm', 'a', 'p')

typedef struct {
    WORD platformID;
    WORD encodingID;
    DWORD offset;
} CMAP_EncodingRecord;

typedef struct {
    WORD version;
    WORD numTables;
    CMAP_EncodingRecord tables[1];
} CMAP_Header;

typedef struct {
    DWORD startCharCode;
    DWORD endCharCode;
    DWORD startGlyphID;
} CMAP_SegmentedCoverage_group;

typedef struct {
    WORD format;
    WORD reserved;
    DWORD length;
    DWORD language;
    DWORD nGroups;
    CMAP_SegmentedCoverage_group groups[1];
} CMAP_SegmentedCoverage;

/* These are all structures needed for the GDEF table */
#define GDEF_TAG MS_MAKE_TAG('G', 'D', 'E', 'F')

enum {BaseGlyph=1, LigatureGlyph, MarkGlyph, ComponentGlyph};

typedef struct {
    DWORD Version;
    WORD GlyphClassDef;
    WORD AttachList;
    WORD LigCaretList;
    WORD MarkAttachClassDef;
} GDEF_Header;

typedef struct {
    WORD ClassFormat;
    WORD StartGlyph;
    WORD GlyphCount;
    WORD ClassValueArray[1];
} GDEF_ClassDefFormat1;

typedef struct {
    WORD Start;
    WORD End;
    WORD Class;
} GDEF_ClassRangeRecord;

typedef struct {
    WORD ClassFormat;
    WORD ClassRangeCount;
    GDEF_ClassRangeRecord ClassRangeRecord[1];
} GDEF_ClassDefFormat2;

/* These are all structures needed for the GSUB table */

typedef struct {
    DWORD version;
    WORD ScriptList;
    WORD FeatureList;
    WORD LookupList;
} GSUB_Header;

typedef struct {
    CHAR ScriptTag[4];
    WORD Script;
} GSUB_ScriptRecord;

typedef struct {
    WORD ScriptCount;
    GSUB_ScriptRecord ScriptRecord[1];
} GSUB_ScriptList;

typedef struct {
    CHAR LangSysTag[4];
    WORD LangSys;
} GSUB_LangSysRecord;

typedef struct {
    WORD DefaultLangSys;
    WORD LangSysCount;
    GSUB_LangSysRecord LangSysRecord[1];
} GSUB_Script;

typedef struct {
    WORD LookupOrder; /* Reserved */
    WORD ReqFeatureIndex;
    WORD FeatureCount;
    WORD FeatureIndex[1];
} GSUB_LangSys;

typedef struct {
    CHAR FeatureTag[4];
    WORD Feature;
} GSUB_FeatureRecord;

typedef struct {
    WORD FeatureCount;
    GSUB_FeatureRecord FeatureRecord[1];
} GSUB_FeatureList;

typedef struct {
    WORD FeatureParams; /* Reserved */
    WORD LookupCount;
    WORD LookupListIndex[1];
} GSUB_Feature;

typedef struct {
    WORD LookupCount;
    WORD Lookup[1];
} GSUB_LookupList;

typedef struct {
    WORD LookupType;
    WORD LookupFlag;
    WORD SubTableCount;
    WORD SubTable[1];
} GSUB_LookupTable;

typedef struct {
    WORD CoverageFormat;
    WORD GlyphCount;
    WORD GlyphArray[1];
} GSUB_CoverageFormat1;

typedef struct {
    WORD Start;
    WORD End;
    WORD StartCoverageIndex;
} GSUB_RangeRecord;

typedef struct {
    WORD CoverageFormat;
    WORD RangeCount;
    GSUB_RangeRecord RangeRecord[1];
} GSUB_CoverageFormat2;

typedef struct {
    WORD SubstFormat; /* = 1 */
    WORD Coverage;
    WORD DeltaGlyphID;
} GSUB_SingleSubstFormat1;

typedef struct {
    WORD SubstFormat; /* = 2 */
    WORD Coverage;
    WORD GlyphCount;
    WORD Substitute[1];
}GSUB_SingleSubstFormat2;

typedef struct {
    WORD SubstFormat; /* = 1 */
    WORD Coverage;
    WORD SequenceCount;
    WORD Sequence[1];
}GSUB_MultipleSubstFormat1;

typedef struct {
    WORD GlyphCount;
    WORD Substitute[1];
}GSUB_Sequence;

typedef struct {
    WORD SubstFormat; /* = 1 */
    WORD Coverage;
    WORD LigSetCount;
    WORD LigatureSet[1];
}GSUB_LigatureSubstFormat1;

typedef struct {
    WORD LigatureCount;
    WORD Ligature[1];
}GSUB_LigatureSet;

typedef struct{
    WORD LigGlyph;
    WORD CompCount;
    WORD Component[1];
}GSUB_Ligature;

typedef struct{
    WORD SequenceIndex;
    WORD LookupListIndex;

}GSUB_SubstLookupRecord;

typedef struct{
    WORD SubstFormat; /* = 1 */
    WORD Coverage;
    WORD ChainSubRuleSetCount;
    WORD ChainSubRuleSet[1];
}GSUB_ChainContextSubstFormat1;

typedef struct {
    WORD SubstFormat; /* = 3 */
    WORD BacktrackGlyphCount;
    WORD Coverage[1];
}GSUB_ChainContextSubstFormat3_1;

typedef struct{
    WORD InputGlyphCount;
    WORD Coverage[1];
}GSUB_ChainContextSubstFormat3_2;

typedef struct{
    WORD LookaheadGlyphCount;
    WORD Coverage[1];
}GSUB_ChainContextSubstFormat3_3;

typedef struct{
    WORD SubstCount;
    GSUB_SubstLookupRecord SubstLookupRecord[1];
}GSUB_ChainContextSubstFormat3_4;

typedef struct {
    WORD SubstFormat; /* = 1 */
    WORD Coverage;
    WORD AlternateSetCount;
    WORD AlternateSet[1];
} GSUB_AlternateSubstFormat1;

typedef struct{
    WORD GlyphCount;
    WORD Alternate[1];
} GSUB_AlternateSet;

/**********
 * CMAP
 **********/

static VOID *load_CMAP_format12_table(HDC hdc, ScriptCache *psc)
{
    CMAP_Header *CMAP_Table = NULL;
    int length;
    int i;

    if (!psc->CMAP_Table)
    {
        length = GetFontData(hdc, CMAP_TAG , 0, NULL, 0);
        if (length != GDI_ERROR)
        {
            psc->CMAP_Table = HeapAlloc(GetProcessHeap(),0,length);
            GetFontData(hdc, CMAP_TAG , 0, psc->CMAP_Table, length);
            TRACE("Loaded cmap table of %i bytes\n",length);
        }
        else
            return NULL;
    }

    CMAP_Table = psc->CMAP_Table;

    for (i = 0; i < GET_BE_WORD(CMAP_Table->numTables); i++)
    {
        if ( (GET_BE_WORD(CMAP_Table->tables[i].platformID) == 3) &&
             (GET_BE_WORD(CMAP_Table->tables[i].encodingID) == 10) )
        {
            CMAP_SegmentedCoverage *format = (CMAP_SegmentedCoverage*)(((BYTE*)CMAP_Table) + GET_BE_DWORD(CMAP_Table->tables[i].offset));
            if (GET_BE_WORD(format->format) == 12)
                return format;
        }
    }
    return NULL;
}

static int compare_group(const void *a, const void* b)
{
    const DWORD *chr = a;
    const CMAP_SegmentedCoverage_group *group = b;

    if (*chr < GET_BE_DWORD(group->startCharCode))
        return -1;
    if (*chr > GET_BE_DWORD(group->endCharCode))
        return 1;
    return 0;
}

DWORD OpenType_CMAP_GetGlyphIndex(HDC hdc, ScriptCache *psc, DWORD utf32c, LPWORD pgi, DWORD flags)
{
    /* BMP: use gdi32 for ease */
    if (utf32c < 0x10000)
    {
        WCHAR ch = utf32c;
        return GetGlyphIndicesW(hdc,&ch, 1, pgi, flags);
    }

    if (!psc->CMAP_format12_Table)
        psc->CMAP_format12_Table = load_CMAP_format12_table(hdc, psc);

    if (flags & GGI_MARK_NONEXISTING_GLYPHS)
        *pgi = 0xffff;
    else
        *pgi = 0;

    if (psc->CMAP_format12_Table)
    {
        CMAP_SegmentedCoverage *format = NULL;
        CMAP_SegmentedCoverage_group *group = NULL;

        format = (CMAP_SegmentedCoverage *)psc->CMAP_format12_Table;

        group = bsearch(&utf32c, format->groups, GET_BE_DWORD(format->nGroups),
                        sizeof(CMAP_SegmentedCoverage_group), compare_group);

        if (group)
        {
            DWORD offset = utf32c - GET_BE_DWORD(group->startCharCode);
            *pgi = GET_BE_DWORD(group->startGlyphID) + offset;
            return 0;
        }
    }
    return 0;
}

/**********
 * GDEF
 **********/

static WORD GDEF_get_glyph_class(const GDEF_Header *header, WORD glyph)
{
    int offset;
    WORD class = 0;
    const GDEF_ClassDefFormat1 *cf1;

    if (!header)
        return 0;

    offset = GET_BE_WORD(header->GlyphClassDef);
    if (!offset)
        return 0;

    cf1 = (GDEF_ClassDefFormat1*)(((BYTE*)header)+offset);
    if (GET_BE_WORD(cf1->ClassFormat) == 1)
    {
        if (glyph >= GET_BE_WORD(cf1->StartGlyph))
        {
            int index = glyph - GET_BE_WORD(cf1->StartGlyph);
            if (index < GET_BE_WORD(cf1->GlyphCount))
                class = GET_BE_WORD(cf1->ClassValueArray[index]);
        }
    }
    else if (GET_BE_WORD(cf1->ClassFormat) == 2)
    {
        const GDEF_ClassDefFormat2 *cf2 = (GDEF_ClassDefFormat2*)cf1;
        int i, top;
        top = GET_BE_WORD(cf2->ClassRangeCount);
        for (i = 0; i < top; i++)
        {
            if (glyph >= GET_BE_WORD(cf2->ClassRangeRecord[i].Start) &&
                glyph <= GET_BE_WORD(cf2->ClassRangeRecord[i].End))
            {
                class = GET_BE_WORD(cf2->ClassRangeRecord[i].Class);
                break;
            }
        }
    }
    else
        ERR("Unknown Class Format %i\n",GET_BE_WORD(cf1->ClassFormat));

    return class;
}

static VOID *load_gdef_table(HDC hdc)
{
    VOID* GDEF_Table = NULL;
    int length = GetFontData(hdc, GDEF_TAG , 0, NULL, 0);
    if (length != GDI_ERROR)
    {
        GDEF_Table = HeapAlloc(GetProcessHeap(),0,length);
        GetFontData(hdc, GDEF_TAG , 0, GDEF_Table, length);
        TRACE("Loaded GDEF table of %i bytes\n",length);
    }
    return GDEF_Table;
}

void OpenType_GDEF_UpdateGlyphProps(HDC hdc, ScriptCache *psc, const WORD *pwGlyphs, const WORD cGlyphs, WORD* pwLogClust, const WORD cChars, SCRIPT_GLYPHPROP *pGlyphProp)
{
    int i;

    if (!psc->GDEF_Table)
        psc->GDEF_Table = load_gdef_table(hdc);

    for (i = 0; i < cGlyphs; i++)
    {
        WORD class;
        int char_count = 0;
        int k;

        k = USP10_FindGlyphInLogClust(pwLogClust, cChars, i);
        if (k >= 0)
        {
            for (; k < cChars && pwLogClust[k] == i; k++)
                char_count++;
        }

        class = GDEF_get_glyph_class(psc->GDEF_Table, pwGlyphs[i]);

        switch (class)
        {
            case 0:
            case BaseGlyph:
                pGlyphProp[i].sva.fClusterStart = 1;
                pGlyphProp[i].sva.fDiacritic = 0;
                pGlyphProp[i].sva.fZeroWidth = 0;
                break;
            case LigatureGlyph:
                pGlyphProp[i].sva.fClusterStart = 1;
                pGlyphProp[i].sva.fDiacritic = 0;
                pGlyphProp[i].sva.fZeroWidth = 0;
                break;
            case MarkGlyph:
                pGlyphProp[i].sva.fClusterStart = 0;
                pGlyphProp[i].sva.fDiacritic = 1;
                pGlyphProp[i].sva.fZeroWidth = 1;
                break;
            case ComponentGlyph:
                pGlyphProp[i].sva.fClusterStart = 0;
                pGlyphProp[i].sva.fDiacritic = 0;
                pGlyphProp[i].sva.fZeroWidth = 0;
                break;
            default:
                ERR("Unknown glyph class %i\n",class);
                pGlyphProp[i].sva.fClusterStart = 1;
                pGlyphProp[i].sva.fDiacritic = 0;
                pGlyphProp[i].sva.fZeroWidth = 0;
        }

        if (char_count == 0)
            pGlyphProp[i].sva.fClusterStart = 0;
    }
}

/**********
 * GSUB
 **********/
static INT GSUB_apply_lookup(const GSUB_LookupList* lookup, INT lookup_index, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count);

static INT GSUB_is_glyph_covered(LPCVOID table , UINT glyph)
{
    const GSUB_CoverageFormat1* cf1;

    cf1 = table;

    if (GET_BE_WORD(cf1->CoverageFormat) == 1)
    {
        int count = GET_BE_WORD(cf1->GlyphCount);
        int i;
        TRACE("Coverage Format 1, %i glyphs\n",count);
        for (i = 0; i < count; i++)
            if (glyph == GET_BE_WORD(cf1->GlyphArray[i]))
                return i;
        return -1;
    }
    else if (GET_BE_WORD(cf1->CoverageFormat) == 2)
    {
        const GSUB_CoverageFormat2* cf2;
        int i;
        int count;
        cf2 = (const GSUB_CoverageFormat2*)cf1;

        count = GET_BE_WORD(cf2->RangeCount);
        TRACE("Coverage Format 2, %i ranges\n",count);
        for (i = 0; i < count; i++)
        {
            if (glyph < GET_BE_WORD(cf2->RangeRecord[i].Start))
                return -1;
            if ((glyph >= GET_BE_WORD(cf2->RangeRecord[i].Start)) &&
                (glyph <= GET_BE_WORD(cf2->RangeRecord[i].End)))
            {
                return (GET_BE_WORD(cf2->RangeRecord[i].StartCoverageIndex) +
                    glyph - GET_BE_WORD(cf2->RangeRecord[i].Start));
            }
        }
        return -1;
    }
    else
        ERR("Unknown CoverageFormat %i\n",GET_BE_WORD(cf1->CoverageFormat));

    return -1;
}

static INT GSUB_apply_SingleSubst(const GSUB_LookupTable *look, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    int j;
    TRACE("Single Substitution Subtable\n");

    for (j = 0; j < GET_BE_WORD(look->SubTableCount); j++)
    {
        int offset;
        const GSUB_SingleSubstFormat1 *ssf1;
        offset = GET_BE_WORD(look->SubTable[j]);
        ssf1 = (const GSUB_SingleSubstFormat1*)((const BYTE*)look+offset);
        if (GET_BE_WORD(ssf1->SubstFormat) == 1)
        {
            int offset = GET_BE_WORD(ssf1->Coverage);
            TRACE("  subtype 1, delta %i\n", GET_BE_WORD(ssf1->DeltaGlyphID));
            if (GSUB_is_glyph_covered((const BYTE*)ssf1+offset, glyphs[glyph_index]) != -1)
            {
                TRACE("  Glyph 0x%x ->",glyphs[glyph_index]);
                glyphs[glyph_index] = glyphs[glyph_index] + GET_BE_WORD(ssf1->DeltaGlyphID);
                TRACE(" 0x%x\n",glyphs[glyph_index]);
                return glyph_index + write_dir;
            }
        }
        else
        {
            const GSUB_SingleSubstFormat2 *ssf2;
            INT index;
            INT offset;

            ssf2 = (const GSUB_SingleSubstFormat2 *)ssf1;
            offset = GET_BE_WORD(ssf1->Coverage);
            TRACE("  subtype 2,  glyph count %i\n", GET_BE_WORD(ssf2->GlyphCount));
            index = GSUB_is_glyph_covered((const BYTE*)ssf2+offset, glyphs[glyph_index]);
            TRACE("  Coverage index %i\n",index);
            if (index != -1)
            {
                if (glyphs[glyph_index] == GET_BE_WORD(ssf2->Substitute[index]))
                    return GSUB_E_NOGLYPH;

                TRACE("    Glyph is 0x%x ->",glyphs[glyph_index]);
                glyphs[glyph_index] = GET_BE_WORD(ssf2->Substitute[index]);
                TRACE("0x%x\n",glyphs[glyph_index]);
                return glyph_index + write_dir;
            }
        }
    }
    return GSUB_E_NOGLYPH;
}

static INT GSUB_apply_MultipleSubst(const GSUB_LookupTable *look, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    int j;
    TRACE("Multiple Substitution Subtable\n");

    for (j = 0; j < GET_BE_WORD(look->SubTableCount); j++)
    {
        int offset, index;
        const GSUB_MultipleSubstFormat1 *msf1;
        offset = GET_BE_WORD(look->SubTable[j]);
        msf1 = (const GSUB_MultipleSubstFormat1*)((const BYTE*)look+offset);

        offset = GET_BE_WORD(msf1->Coverage);
        index = GSUB_is_glyph_covered((const BYTE*)msf1+offset, glyphs[glyph_index]);
        if (index != -1)
        {
            const GSUB_Sequence *seq;
            int sub_count;
            int j;
            offset = GET_BE_WORD(msf1->Sequence[index]);
            seq = (const GSUB_Sequence*)((const BYTE*)msf1+offset);
            sub_count = GET_BE_WORD(seq->GlyphCount);
            TRACE("  Glyph 0x%x (+%i)->",glyphs[glyph_index],(sub_count-1));

            for (j = (*glyph_count)+(sub_count-1); j > glyph_index; j--)
                    glyphs[j] =glyphs[j-(sub_count-1)];

            for (j = 0; j < sub_count; j++)
                    if (write_dir < 0)
                        glyphs[glyph_index + (sub_count-1) - j] = GET_BE_WORD(seq->Substitute[j]);
                    else
                        glyphs[glyph_index + j] = GET_BE_WORD(seq->Substitute[j]);

            *glyph_count = *glyph_count + (sub_count - 1);

            if (TRACE_ON(uniscribe))
            {
                for (j = 0; j < sub_count; j++)
                    TRACE(" 0x%x",glyphs[glyph_index+j]);
                TRACE("\n");
            }

            return glyph_index + (sub_count * write_dir);
        }
    }
    return GSUB_E_NOGLYPH;
}

static INT GSUB_apply_AlternateSubst(const GSUB_LookupTable *look, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    int j;
    TRACE("Alternate Substitution Subtable\n");

    for (j = 0; j < GET_BE_WORD(look->SubTableCount); j++)
    {
        int offset;
        const GSUB_AlternateSubstFormat1 *asf1;
        INT index;

        offset = GET_BE_WORD(look->SubTable[j]);
        asf1 = (const GSUB_AlternateSubstFormat1*)((const BYTE*)look+offset);
        offset = GET_BE_WORD(asf1->Coverage);

        index = GSUB_is_glyph_covered((const BYTE*)asf1+offset, glyphs[glyph_index]);
        if (index != -1)
        {
            const GSUB_AlternateSet *as;
            offset =  GET_BE_WORD(asf1->AlternateSet[index]);
            as = (const GSUB_AlternateSet*)((const BYTE*)asf1+offset);
            FIXME("%i alternates, picking index 0\n",GET_BE_WORD(as->GlyphCount));
            if (glyphs[glyph_index] == GET_BE_WORD(as->Alternate[0]))
                return GSUB_E_NOGLYPH;

            TRACE("  Glyph 0x%x ->",glyphs[glyph_index]);
            glyphs[glyph_index] = GET_BE_WORD(as->Alternate[0]);
            TRACE(" 0x%x\n",glyphs[glyph_index]);
            return glyph_index + write_dir;
        }
    }
    return GSUB_E_NOGLYPH;
}

static INT GSUB_apply_LigatureSubst(const GSUB_LookupTable *look, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    int j;

    TRACE("Ligature Substitution Subtable\n");
    for (j = 0; j < GET_BE_WORD(look->SubTableCount); j++)
    {
        const GSUB_LigatureSubstFormat1 *lsf1;
        int offset,index;

        offset = GET_BE_WORD(look->SubTable[j]);
        lsf1 = (const GSUB_LigatureSubstFormat1*)((const BYTE*)look+offset);
        offset = GET_BE_WORD(lsf1->Coverage);
        index = GSUB_is_glyph_covered((const BYTE*)lsf1+offset, glyphs[glyph_index]);
        TRACE("  Coverage index %i\n",index);
        if (index != -1)
        {
            const GSUB_LigatureSet *ls;
            int k, count;

            offset = GET_BE_WORD(lsf1->LigatureSet[index]);
            ls = (const GSUB_LigatureSet*)((const BYTE*)lsf1+offset);
            count = GET_BE_WORD(ls->LigatureCount);
            TRACE("  LigatureSet has %i members\n",count);
            for (k = 0; k < count; k++)
            {
                const GSUB_Ligature *lig;
                int CompCount,l,CompIndex;

                offset = GET_BE_WORD(ls->Ligature[k]);
                lig = (const GSUB_Ligature*)((const BYTE*)ls+offset);
                CompCount = GET_BE_WORD(lig->CompCount) - 1;
                CompIndex = glyph_index+write_dir;
                for (l = 0; l < CompCount && CompIndex >= 0 && CompIndex < *glyph_count; l++)
                {
                    int CompGlyph;
                    CompGlyph = GET_BE_WORD(lig->Component[l]);
                    if (CompGlyph != glyphs[CompIndex])
                        break;
                    CompIndex += write_dir;
                }
                if (l == CompCount)
                {
                    int replaceIdx = glyph_index;
                    if (write_dir < 0)
                        replaceIdx = glyph_index - CompCount;

                    TRACE("    Glyph is 0x%x (+%i) ->",glyphs[glyph_index],CompCount);
                    glyphs[replaceIdx] = GET_BE_WORD(lig->LigGlyph);
                    TRACE("0x%x\n",glyphs[replaceIdx]);
                    if (CompCount > 0)
                    {
                        int j;
                        for (j = replaceIdx + 1; j < *glyph_count; j++)
                            glyphs[j] =glyphs[j+CompCount];
                        *glyph_count = *glyph_count - CompCount;
                    }
                    return replaceIdx + write_dir;
                }
            }
        }
    }
    return GSUB_E_NOGLYPH;
}

static INT GSUB_apply_ChainContextSubst(const GSUB_LookupList* lookup, const GSUB_LookupTable *look, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    int j;
    BOOL done = FALSE;

    TRACE("Chaining Contextual Substitution Subtable\n");
    for (j = 0; j < GET_BE_WORD(look->SubTableCount) && !done; j++)
    {
        const GSUB_ChainContextSubstFormat1 *ccsf1;
        int offset;
        int dirLookahead = write_dir;
        int dirBacktrack = -1 * write_dir;

        offset = GET_BE_WORD(look->SubTable[j]);
        ccsf1 = (const GSUB_ChainContextSubstFormat1*)((const BYTE*)look+offset);
        if (GET_BE_WORD(ccsf1->SubstFormat) == 1)
        {
            FIXME("  TODO: subtype 1 (Simple context glyph substitution)\n");
            continue;
        }
        else if (GET_BE_WORD(ccsf1->SubstFormat) == 2)
        {
            FIXME("  TODO: subtype 2 (Class-based Chaining Context Glyph Substitution)\n");
            continue;
        }
        else if (GET_BE_WORD(ccsf1->SubstFormat) == 3)
        {
            int k;
            int indexGlyphs;
            const GSUB_ChainContextSubstFormat3_1 *ccsf3_1;
            const GSUB_ChainContextSubstFormat3_2 *ccsf3_2;
            const GSUB_ChainContextSubstFormat3_3 *ccsf3_3;
            const GSUB_ChainContextSubstFormat3_4 *ccsf3_4;
            int newIndex = glyph_index;

            ccsf3_1 = (const GSUB_ChainContextSubstFormat3_1 *)ccsf1;

            TRACE("  subtype 3 (Coverage-based Chaining Context Glyph Substitution)\n");

            for (k = 0; k < GET_BE_WORD(ccsf3_1->BacktrackGlyphCount); k++)
            {
                offset = GET_BE_WORD(ccsf3_1->Coverage[k]);
                if (GSUB_is_glyph_covered((const BYTE*)ccsf3_1+offset, glyphs[glyph_index + (dirBacktrack * (k+1))]) == -1)
                    break;
            }
            if (k != GET_BE_WORD(ccsf3_1->BacktrackGlyphCount))
                continue;
            TRACE("Matched Backtrack\n");

            ccsf3_2 = (const GSUB_ChainContextSubstFormat3_2 *)(((LPBYTE)ccsf1)+sizeof(GSUB_ChainContextSubstFormat3_1) + (sizeof(WORD) * (GET_BE_WORD(ccsf3_1->BacktrackGlyphCount)-1)));

            indexGlyphs = GET_BE_WORD(ccsf3_2->InputGlyphCount);
            for (k = 0; k < indexGlyphs; k++)
            {
                offset = GET_BE_WORD(ccsf3_2->Coverage[k]);
                if (GSUB_is_glyph_covered((const BYTE*)ccsf3_1+offset, glyphs[glyph_index + (write_dir * k)]) == -1)
                    break;
            }
            if (k != indexGlyphs)
                continue;
            TRACE("Matched IndexGlyphs\n");

            ccsf3_3 = (const GSUB_ChainContextSubstFormat3_3 *)(((LPBYTE)ccsf3_2)+sizeof(GSUB_ChainContextSubstFormat3_2) + (sizeof(WORD) * (GET_BE_WORD(ccsf3_2->InputGlyphCount)-1)));

            for (k = 0; k < GET_BE_WORD(ccsf3_3->LookaheadGlyphCount); k++)
            {
                offset = GET_BE_WORD(ccsf3_3->Coverage[k]);
                if (GSUB_is_glyph_covered((const BYTE*)ccsf3_1+offset, glyphs[glyph_index + (dirLookahead * (indexGlyphs + k))]) == -1)
                    break;
            }
            if (k != GET_BE_WORD(ccsf3_3->LookaheadGlyphCount))
                continue;
            TRACE("Matched LookAhead\n");

            ccsf3_4 = (const GSUB_ChainContextSubstFormat3_4 *)(((LPBYTE)ccsf3_3)+sizeof(GSUB_ChainContextSubstFormat3_3) + (sizeof(WORD) * (GET_BE_WORD(ccsf3_3->LookaheadGlyphCount)-1)));

            if (GET_BE_WORD(ccsf3_4->SubstCount))
            {
                for (k = 0; k < GET_BE_WORD(ccsf3_4->SubstCount); k++)
                {
                    int lookupIndex = GET_BE_WORD(ccsf3_4->SubstLookupRecord[k].LookupListIndex);
                    int SequenceIndex = GET_BE_WORD(ccsf3_4->SubstLookupRecord[k].SequenceIndex) * write_dir;

                    TRACE("SUBST: %i -> %i %i\n",k, SequenceIndex, lookupIndex);
                    newIndex = GSUB_apply_lookup(lookup, lookupIndex, glyphs, glyph_index + SequenceIndex, write_dir, glyph_count);
                    if (newIndex == -1)
                    {
                        ERR("Chain failed to generate a glyph\n");
                        continue;
                    }
                }
                return newIndex;
            }
            else return GSUB_E_NOGLYPH;
        }
    }
    return -1;
}

static INT GSUB_apply_lookup(const GSUB_LookupList* lookup, INT lookup_index, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    int offset;
    const GSUB_LookupTable *look;

    offset = GET_BE_WORD(lookup->Lookup[lookup_index]);
    look = (const GSUB_LookupTable*)((const BYTE*)lookup + offset);
    TRACE("type %i, flag %x, subtables %i\n",GET_BE_WORD(look->LookupType),GET_BE_WORD(look->LookupFlag),GET_BE_WORD(look->SubTableCount));
    switch(GET_BE_WORD(look->LookupType))
    {
        case 1:
            return GSUB_apply_SingleSubst(look, glyphs, glyph_index, write_dir, glyph_count);
        case 2:
            return GSUB_apply_MultipleSubst(look, glyphs, glyph_index, write_dir, glyph_count);
        case 3:
            return GSUB_apply_AlternateSubst(look, glyphs, glyph_index, write_dir, glyph_count);
        case 4:
            return GSUB_apply_LigatureSubst(look, glyphs, glyph_index, write_dir, glyph_count);
        case 6:
            return GSUB_apply_ChainContextSubst(lookup, look, glyphs, glyph_index, write_dir, glyph_count);
        default:
            FIXME("We do not handle SubType %i\n",GET_BE_WORD(look->LookupType));
    }
    return GSUB_E_NOGLYPH;
}

INT OpenType_apply_GSUB_lookup(LPCVOID table, INT lookup_index, WORD *glyphs, INT glyph_index, INT write_dir, INT *glyph_count)
{
    const GSUB_Header *header = (const GSUB_Header *)table;
    const GSUB_LookupList *lookup = (const GSUB_LookupList*)((const BYTE*)header + GET_BE_WORD(header->LookupList));

    return GSUB_apply_lookup(lookup, lookup_index, glyphs, glyph_index, write_dir, glyph_count);
}

static void GSUB_initialize_script_cache(ScriptCache *psc)
{
    int i;

    if (!psc->script_count)
    {
        const GSUB_ScriptList *script;
        const GSUB_Header* header = (const GSUB_Header*)psc->GSUB_Table;
        script = (const GSUB_ScriptList*)((const BYTE*)header + GET_BE_WORD(header->ScriptList));
        psc->script_count = GET_BE_WORD(script->ScriptCount);
        TRACE("initializing %i scripts in this font\n",psc->script_count);
        if (psc->script_count)
        {
            psc->scripts = HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,sizeof(LoadedScript) * psc->script_count);
            for (i = 0; i < psc->script_count; i++)
            {
                int offset = GET_BE_WORD(script->ScriptRecord[i].Script);
                psc->scripts[i].tag = MS_MAKE_TAG(script->ScriptRecord[i].ScriptTag[0], script->ScriptRecord[i].ScriptTag[1], script->ScriptRecord[i].ScriptTag[2], script->ScriptRecord[i].ScriptTag[3]);
                psc->scripts[i].table = ((const BYTE*)script + offset);
            }
        }
    }
}

HRESULT OpenType_GSUB_GetFontScriptTags(ScriptCache *psc, OPENTYPE_TAG searchingFor, int cMaxTags, OPENTYPE_TAG *pScriptTags, int *pcTags, LPCVOID* script_table)
{
    int i;
    HRESULT rc = S_OK;

    GSUB_initialize_script_cache(psc);
    *pcTags = psc->script_count;

    if (!searchingFor && cMaxTags < *pcTags)
        rc = E_OUTOFMEMORY;
    else if (searchingFor)
        rc = USP_E_SCRIPT_NOT_IN_FONT;

    for (i = 0; i < psc->script_count; i++)
    {
        if (i < cMaxTags)
            pScriptTags[i] = psc->scripts[i].tag;

        if (searchingFor)
        {
            if (searchingFor == psc->scripts[i].tag)
            {
                pScriptTags[0] = psc->scripts[i].tag;
                *pcTags = 1;
                if (script_table)
                    *script_table = psc->scripts[i].table;
                rc = S_OK;
                break;
            }
        }
    }
    return rc;
}

static void GSUB_initialize_language_cache(LoadedScript *script)
{
    int i;

    if (!script->language_count)
    {
        const GSUB_Script* table = script->table;
        script->language_count = GET_BE_WORD(table->LangSysCount);
        script->default_language.tag = MS_MAKE_TAG('d','f','l','t');
        script->default_language.table = (const BYTE*)table + GET_BE_WORD(table->DefaultLangSys);

        if (script->language_count)
        {
            TRACE("Deflang %p, LangCount %i\n",script->default_language.table, script->language_count);

            script->languages = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(LoadedLanguage) * script->language_count);

            for (i = 0; i < script->language_count; i++)
            {
                int offset = GET_BE_WORD(table->LangSysRecord[i].LangSys);
                script->languages[i].tag = MS_MAKE_TAG(table->LangSysRecord[i].LangSysTag[0], table->LangSysRecord[i].LangSysTag[1], table->LangSysRecord[i].LangSysTag[2], table->LangSysRecord[i].LangSysTag[3]);
                script->languages[i].table = ((const BYTE*)table + offset);
            }
        }
    }
}

HRESULT OpenType_GSUB_GetFontLanguageTags(ScriptCache *psc, OPENTYPE_TAG script_tag, OPENTYPE_TAG searchingFor, int cMaxTags, OPENTYPE_TAG *pLanguageTags, int *pcTags, LPCVOID* language_table)
{
    int i;
    HRESULT rc = S_OK;
    LoadedScript *script = NULL;

    GSUB_initialize_script_cache(psc);

    for (i = 0; i < psc->script_count; i++)
    {
         if (psc->scripts[i].tag == script_tag)
         {
            script = &psc->scripts[i];
            break;
         }
    }

    if (!script)
        return E_INVALIDARG;

    GSUB_initialize_language_cache(script);

    if (!searchingFor && cMaxTags < script->language_count)
        rc = E_OUTOFMEMORY;
    else if (searchingFor)
        rc = E_INVALIDARG;

    *pcTags = script->language_count;

    for (i = 0; i < script->language_count; i++)
    {
        if (i < cMaxTags)
            pLanguageTags[i] = script->languages[i].tag;

        if (searchingFor)
        {
            if (searchingFor == script->languages[i].tag)
            {
                pLanguageTags[0] = script->languages[i].tag;
                *pcTags = 1;
                if (language_table)
                    *language_table = script->languages[i].table;
                rc = S_OK;
                break;
            }
        }
    }

    if (script->default_language.table)
    {
        if (i < cMaxTags)
            pLanguageTags[i] = script->default_language.tag;

        if (searchingFor  && FAILED(rc))
        {
            pLanguageTags[0] = script->default_language.tag;
            if (language_table)
                *language_table = script->default_language.table;
        }
        i++;
        *pcTags = (*pcTags) + 1;
    }

    return rc;
}


static void GSUB_initialize_feature_cache(LPCVOID table, LoadedLanguage *language)
{
    int i;

    if (!language->feature_count)
    {
        const GSUB_LangSys *lang= language->table;
        const GSUB_Header *header = (const GSUB_Header *)table;
        const GSUB_FeatureList *feature_list;

        language->feature_count = GET_BE_WORD(lang->FeatureCount);
        TRACE("%i features\n",language->feature_count);

        if (language->feature_count)
        {
            language->features = HeapAlloc(GetProcessHeap(),0,sizeof(LoadedFeature)*language->feature_count);

            feature_list = (const GSUB_FeatureList*)((const BYTE*)header + GET_BE_WORD(header->FeatureList));

            for (i = 0; i < language->feature_count; i++)
            {
                const GSUB_Feature *feature;
                int j;
                int index = GET_BE_WORD(lang->FeatureIndex[i]);

                language->features[i].tag = MS_MAKE_TAG(feature_list->FeatureRecord[index].FeatureTag[0], feature_list->FeatureRecord[index].FeatureTag[1], feature_list->FeatureRecord[index].FeatureTag[2], feature_list->FeatureRecord[index].FeatureTag[3]);
                language->features[i].feature = ((const BYTE*)feature_list + GET_BE_WORD(feature_list->FeatureRecord[index].Feature));
                feature = (const GSUB_Feature*)language->features[i].feature;
                language->features[i].lookup_count = GET_BE_WORD(feature->LookupCount);
                language->features[i].lookups = HeapAlloc(GetProcessHeap(),0,sizeof(WORD) * language->features[i].lookup_count);
                for (j = 0; j < language->features[i].lookup_count; j++)
                    language->features[i].lookups[j] = GET_BE_WORD(feature->LookupListIndex[j]);
            }
        }
    }
}

HRESULT OpenType_GSUB_GetFontFeatureTags(ScriptCache *psc, OPENTYPE_TAG script_tag, OPENTYPE_TAG language_tag, BOOL filtered, OPENTYPE_TAG searchingFor, int cMaxTags, OPENTYPE_TAG *pFeatureTags, int *pcTags, LoadedFeature** feature)
{
    int i;
    HRESULT rc = S_OK;
    LoadedScript *script = NULL;
    LoadedLanguage *language = NULL;

    GSUB_initialize_script_cache(psc);

    for (i = 0; i < psc->script_count; i++)
    {
        if (psc->scripts[i].tag == script_tag)
        {
            script = &psc->scripts[i];
            break;
        }
    }

    if (!script)
    {
        *pcTags = 0;
        if (!filtered)
            return S_OK;
        else
            return E_INVALIDARG;
    }

    GSUB_initialize_language_cache(script);

    if (script->default_language.table && script->default_language.tag == language_tag)
        language = &script->default_language;
    else
    {
        for (i = 0; i < script->language_count; i++)
        {
            if (script->languages[i].tag == language_tag)
            {
                language = &script->languages[i];
                break;
            }
        }
    }

    if (!language)
    {
        *pcTags = 0;
        return S_OK;
    }

    GSUB_initialize_feature_cache(psc->GSUB_Table, language);

    *pcTags = language->feature_count;

    if (!searchingFor && cMaxTags < *pcTags)
        rc = E_OUTOFMEMORY;
    else if (searchingFor)
        rc = E_INVALIDARG;

    for (i = 0; i < language->feature_count; i++)
    {
        if (i < cMaxTags)
            pFeatureTags[i] = language->features[i].tag;

        if (searchingFor)
        {
            if (searchingFor == language->features[i].tag)
            {
                pFeatureTags[0] = language->features[i].tag;
                *pcTags = 1;
                if (feature)
                    *feature = &language->features[i];
                rc = S_OK;
                break;
            }
        }
    }
    return rc;
}