/* Pango - Arabic module 
 * arabic module
 *
 * (C) 2000 Karl Koehler<koehler@or.uni-bonn.de>
 *          Owen Taylor <otayler@redhat.com> 
 * 
 */

#include <stdio.h>
#include <glib.h>
#include "pango.h"
#include "pangox.h"
#include "utils.h"
#include <unicode.h>

#include "arconv.h" 
#include "mulefont.h"
#include "langboxfont.h"

/*  #define DEBUG    */
#ifdef DEBUG
#include <stdio.h>
#endif


static PangoEngineRange arabic_range[] = {
    { 0x060B, 0x06D3, "*" }  /* 0x060B, 0x06D3 */
};

static PangoEngineInfo script_engines[] = {
    {
        "ArabicScriptEngineLang",
        PANGO_ENGINE_TYPE_LANG,
        PANGO_RENDER_TYPE_NONE,
        arabic_range, G_N_ELEMENTS(arabic_range)
    },
    {
        "ArabicScriptEngineX",
        PANGO_ENGINE_TYPE_SHAPE,
        PANGO_RENDER_TYPE_X,
        arabic_range, G_N_ELEMENTS(arabic_range)
    }
};

static gint n_script_engines = G_N_ELEMENTS (script_engines);




/*
 * Language script engine
 */

static void 
arabic_engine_break (const char    *text,
                     int            len,
                     PangoAnalysis *analysis,
                     PangoLogAttr  *attrs)
{
    /* Most of the code comes from tamil_engine_break
     * only difference is char stop based on modifiers
     */

    const char *cur = text;
    const char *next;
    gint        i  = 0;
    GUChar4     wc;

    while (*cur)
        {
            if (!_pango_utf8_iterate (cur, &next, &wc))
                return;
            if (cur == next)
                break;
            if ((next - text) > len)
                break;
            cur = next;

            attrs[i].is_white = (wc == ' ' || wc == '\t' || wc == 'n') ? 1 : 0;
            attrs[i].is_break = (i > 0 && attrs[i-1].is_white) || attrs[i].is_white;
            attrs[i].is_char_stop = 1;
            attrs[i].is_word_stop = (i == 0) || attrs[i-1].is_white;
            /* actually, is_word_stop in not correct, but simple and good enough. */
            i++;
        }
}

static PangoEngine *
arabic_engine_lang_new ()
{
    PangoEngineLang *result;
  
    result = g_new (PangoEngineLang, 1);

    result->engine.id = "ArabicScriptEngine";
    result->engine.type = PANGO_ENGINE_TYPE_LANG;
    result->engine.length = sizeof (result);
    result->script_break = arabic_engine_break;

    return (PangoEngine *)result;
}

/*
 * X window system script engine portion
 */

static int
find_unic_font (PangoFont *font,char* charsets[],PangoXSubfont* rfonts)
{
    PangoXSubfont *subfonts;
    int           *subfont_charsets;
    int            n_subfonts;
    int            i;
    int            result = 0;

    n_subfonts = pango_x_list_subfonts (font, charsets, 3, 
                                        &subfonts, &subfont_charsets);
    
    for (i=0; i < n_subfonts; i++)
        {
            if  ( (strcmp (charsets[subfont_charsets[i]], "mulearabic-2") == 0)
                  && arabic_muleinit(font,rfonts) )
                {
                    result = 1; /* we know we have a mulearabic-font ... */
                    break;
                }
            else if ( (strcmp (charsets[subfont_charsets[i]], "iso8859-6.8x") == 0)
                      && arabic_lboxinit(font,rfonts) )
                {
                    result = 2;
                    break;
                } 
            else
                { /* test if the font has Alif-Madda; if so assume it is ok */
                    if ( pango_x_has_glyph /* Alif-Madda */
                         (font,PANGO_X_MAKE_GLYPH(subfonts[i],0xFE81)))
                        {
                            rfonts[0] = subfonts[i];
                            result   = 12;
                            break;
                        }
                    if ( pango_x_has_glyph /* Shadda+Kasra */
                         (font,PANGO_X_MAKE_GLYPH(subfonts[i],0xFC62)))
                        {
                            result = 13; /* extra vowels in font, hopefully */
                            break;
                        }
                    if ( pango_x_has_glyph /* Lam-Min alone */
                         (font,PANGO_X_MAKE_GLYPH(subfonts[i],0xFC42)))
                        {
                            result = 14; /* extra ligatures in font, hopefully */
                            break;
                        }
                }
        }

    g_free (subfonts);
    g_free (subfont_charsets);

    return result;
}

static char *default_charset[] = {
    "iso10646-1",  
    "iso8859-6.8x",
    /*          "iso8859-6.8x" */
    "mulearabic-2"    
};
  


static void
set_glyph (PangoGlyphString *glyphs, 
           PangoFont *font, PangoXSubfont subfont,
           int i, int cluster_start, int glyph, int is_vowel)
{
    PangoRectangle logical_rect;
#ifdef DEBUG
    if ( i < 0){
        fprintf(stderr,"[ar] setglyph: setting glyph %x at index %i, cluster %i\n",
                glyph,i,cluster_start);
        raise(6);
    } else {
        fprintf(stderr,"[ar] setglyph: setting glyph %x at index %i, "
                "cluster %i  ( subfont %x )\n",
                glyph,i,cluster_start,subfont);
    }
#endif

    glyphs->glyphs[i].glyph = PANGO_X_MAKE_GLYPH (subfont, glyph);
  
    glyphs->glyphs[i].geometry.x_offset = 0;
    glyphs->glyphs[i].geometry.y_offset = 0;

    pango_font_get_glyph_extents (font, glyphs->glyphs[i].glyph, NULL, &logical_rect);
    glyphs->log_clusters[i] = cluster_start;
    if (is_vowel)
        {
            glyphs->glyphs[i].geometry.width = 0;
        }
    else
        {
            glyphs->glyphs[i].geometry.width = logical_rect.width;
        }
}


/* The following thing is actually critical ... */

static void 
arabic_engine_shape (PangoFont        *font, 
                     const char       *text,
                     int               length,
                     PangoAnalysis    *analysis, 
                     PangoGlyphString *glyphs)
{
    PangoXSubfont subfont;
    PangoXSubfont arfonts[3];


    int         n_chars, n_glyph;
    int         i;
    const char *p;
    const char *pold;
    const char *next;
    GUChar4    *wc;
    int         lvl      = 1;

    g_return_if_fail (font != NULL);
    g_return_if_fail (text != NULL);
    g_return_if_fail (length >= 0);
    g_return_if_fail (analysis != NULL);

    /* We assume we have an unicode-font like 10x20 which containes
    **   the needed chars -- or tree mulearabic-coded fonts ...
    */
  
    n_chars = n_glyph = unicode_strlen (text, length);

    if (!(lvl = find_unic_font (font, default_charset,arfonts)))
        {

            PangoGlyph unknown_glyph = pango_x_get_unknown_glyph (font);
            
            pango_glyph_string_set_size (glyphs, n_chars);

            p = text;
            for (i=0; i<n_chars; i++)
                {
                    set_glyph (glyphs, font, 
                               PANGO_X_GLYPH_SUBFONT (unknown_glyph), i, 
                               p - text, PANGO_X_GLYPH_INDEX (unknown_glyph),0);
                    p = unicode_next_utf8 (p);
                }
            return;
        }
    subfont = arfonts[0];

    wc = (GUChar4 *)g_malloc(sizeof(GUChar4)*n_chars);  

    p = text;
    for (i=0; i < n_chars; i++)
        {
            _pango_utf8_iterate (p, &next, &wc[n_chars - i - 1]);
            p = next;
        }
  
  
    if (analysis->level % 2 == 0)
        {
            /* We were called on a LTR directional run (e.g. some numbers); 
               fallback as simple as possible */
            pango_glyph_string_set_size (glyphs, n_chars);

        }
    else 
        {
            arabic_reshape(&n_glyph,wc,lvl);
            pango_glyph_string_set_size (glyphs, n_glyph);
        };


    p    = text;
    pold = p;
    i    = n_chars-1;
#ifdef DEBUG
    fprintf(stderr,"[ar]: after shaping : %i glyphs ",n_glyph);
#endif
    while(i >= 0)
        {
            if (wc[i] == 0)
                {
                    p = unicode_next_utf8 (p);
                    i--;
                }
            else 
                {   
                    int cluster_start ;
                    int is_vowel      = arabic_isvowel(wc[i]);
                    cluster_start     = is_vowel ? pold - text : p - text;

                    if ( lvl ==  1 )
                        {
#ifdef DEBUG
                            fprintf(stderr,"[ar] mule-recoding char %x",
                                    wc[i]);
#endif
                            arabic_mule_recode(&subfont,&(wc[i]),arfonts);
                        }
                    else if ( lvl == 2 )
                        {
                            if (( i > 0 )&&(wc[i-1] == 0))
                                {
                                    arabic_lbox_recode(&subfont,&(wc[i]),
                                                       &(wc[i-1]), arfonts);
                                }
                            else 
                                arabic_lbox_recode(&subfont,&(wc[i]),NULL,
                                                   arfonts);
                        }
                    
                    set_glyph(glyphs, font, subfont, n_glyph - 1,
                              cluster_start, wc[i], is_vowel);
      
                    pold = p;
                    p    = unicode_next_utf8 (p);
                    n_glyph--;
                    i--;
                }
        }

    g_free(wc);
}


static PangoCoverage *
arabic_engine_get_coverage (PangoFont  *font,
                            const char *lang)
{
    GUChar4 i;
    PangoCoverage *result = pango_coverage_new ();

    for (i = 0x60B; i <= 0x66D; i++)
        pango_coverage_set (result, i, PANGO_COVERAGE_EXACT);
    for (i = 0x670; i <= 0x6D3; i++)
        pango_coverage_set (result, i, PANGO_COVERAGE_EXACT);

    return result;
}

static PangoEngine *
arabic_engine_x_new ()
{
    PangoEngineShape *result;
  
    result = g_new (PangoEngineShape, 1);

    result->engine.id = "ArabicScriptEngine";
    result->engine.type = PANGO_ENGINE_TYPE_LANG;
    result->engine.length = sizeof (result);
    result->script_shape = arabic_engine_shape;
    result->get_coverage = arabic_engine_get_coverage;

    return (PangoEngine *)result;
}





/* The following three functions provide the public module API for
 * Pango
 */
#ifdef MODULE_PREFIX
#define MODULE_ENTRY(func) _pango_arabic_##func
#else
#define MODULE_ENTRY(func) func
#endif

void 
MODULE_ENTRY(script_engine_list) (PangoEngineInfo **engines, int *n_engines)
{
    *engines   = script_engines;
    *n_engines = n_script_engines;
}

PangoEngine *
MODULE_ENTRY(script_engine_load) (const char *id)
{
    if (!strcmp (id, "ArabicScriptEngineLang"))
        return arabic_engine_lang_new ();
    else if (!strcmp (id, "ArabicScriptEngineX"))
        return arabic_engine_x_new ();
    else
        return NULL;
}

void 
MODULE_ENTRY(script_engine_unload) (PangoEngine *engine)
{
}