/* Pango
 * hangul-xft.c:
 *
 * Copyright (C) 2002 Changwoo Ryu
 * Author: Changwoo Ryu <cwryu@debian.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <string.h>

#include "pangoxft.h"
#include "pango-engine.h"
#include "pango-utils.h"

#include "hangul-defs.h"
#include "tables-jamos.i"

#define SCRIPT_ENGINE_NAME "HangulScriptEngineXft"

static PangoEngineRange hangul_ranges[] = {
  /* Language characters */
  { 0x1100, 0x11FF, "*" }, /* Hangul Jamo */
};

static PangoEngineInfo script_engines[] = {
  {
    SCRIPT_ENGINE_NAME,
    PANGO_ENGINE_TYPE_SHAPE,
    PANGO_RENDER_TYPE_XFT,
    hangul_ranges, G_N_ELEMENTS(hangul_ranges)
  }
};

static void
set_glyph (PangoFont *font, PangoGlyphString *glyphs, int i, int offset, PangoGlyph glyph)
{
  PangoRectangle logical_rect;

  glyphs->glyphs[i].glyph = glyph;
  glyphs->glyphs[i].geometry.x_offset = 0;
  glyphs->glyphs[i].geometry.y_offset = 0;
  glyphs->log_clusters[i] = offset;

  pango_font_get_glyph_extents (font, glyphs->glyphs[i].glyph, NULL, &logical_rect);
  glyphs->glyphs[i].geometry.width = logical_rect.width;
}

#define find_char pango_xft_font_get_glyph

static void
render_syllable (PangoFont *font, gunichar *text, int length,
		 PangoGlyphString *glyphs, int *n_glyphs, int cluster_offset)
{
  int index;
  gunichar wc;
  int i, j, composed;

  if (length >= 3 && IS_L_S(text[0]) && IS_V_S(text[1]) && IS_T_S(text[2]))
    composed = 3;
  else if (length >= 2 && IS_L_S(text[0]) && IS_V_S(text[1]))
    composed = 2;
  else
    composed = 0;

  if (composed)
    {
      if (composed == 3)
	wc = S_FROM_LVT(text[0], text[1], text[2]);
      else
	wc = S_FROM_LV(text[0], text[1]);
      index = find_char (font, wc);
      pango_glyph_string_set_size (glyphs, *n_glyphs + 1);
      if (!index)
	set_glyph (font, glyphs, *n_glyphs, cluster_offset,
		   pango_xft_font_get_unknown_glyph (font, wc));
      else
	set_glyph (font, glyphs, *n_glyphs, cluster_offset, index);
      (*n_glyphs)++;
      text += composed;
      length -= composed;
    }

  /* Render the remaining text as uncomposed forms as a fallback.  */
  for (i = 0; i < length; i++)
    {
      int jindex;

      index = find_char (font, text[i]);
      if (index)
	{
	  pango_glyph_string_set_size (glyphs, *n_glyphs + 1);
	  set_glyph (font, glyphs, *n_glyphs, cluster_offset, index);
	  (*n_glyphs)++;
	  continue;
	}

      /* This font has no glyphs on the Hangul Jamo area!  Find a
	 fallback from the Hangul Compatibility Jamo area.  */
      jindex = text[i] - LBASE;
      for (j = 0; j < 3 && (__jamo_to_ksc5601[jindex][j] != 0); j++)
	{
	  wc = __jamo_to_ksc5601[jindex][j] - KSC_JAMOBASE + UNI_JAMOBASE;
	  index = (wc >= 0x3131) ? find_char (font, wc) : 0;
	  pango_glyph_string_set_size (glyphs, *n_glyphs + 1);
	  if (!index)
	    set_glyph (font, glyphs, *n_glyphs, cluster_offset,
		       pango_xft_font_get_unknown_glyph (font, index));
	  else
	    set_glyph (font, glyphs, *n_glyphs, cluster_offset, index);
	  (*n_glyphs)++;
	}
    }
}

static void 
hangul_engine_shape (PangoFont        *font,
		     const char       *text,
		     gint              length,
		     PangoAnalysis    *analysis,
		     PangoGlyphString *glyphs)
{
  int n_chars, n_glyphs;
  int i;
  const char *p, *start;

  gunichar jamos_static[3];
  guint max_jamos = G_N_ELEMENTS (jamos_static);
  gunichar *jamos = jamos_static;
  int n_jamos;

  n_chars = g_utf8_strlen (text, length);
  n_glyphs = 0;
  start = p = text;
  n_jamos = 0;

  for (i = 0; i < n_chars; i++)
    {
      gunichar wc;

      wc = g_utf8_get_char (p);

      /* Check syllable boundaries. */
      if (n_jamos != 0 &&
	  ((IS_T (jamos[n_jamos - 1]) && IS_L (wc)) ||
	   (IS_V (jamos[n_jamos - 1]) && IS_L (wc)) ||
	   (IS_T (jamos[n_jamos - 1]) && IS_V (wc))))
	{
	  /* Draw a syllable. */
	  render_syllable (font, jamos, n_jamos, glyphs,
			   &n_glyphs, start - text);
	  n_jamos = 0;
	  start = p;
	}
      
      if (n_jamos == max_jamos)
	{
	  max_jamos++;
	  if (jamos == jamos_static)
	    {
	      jamos = g_new (gunichar, max_jamos);
	      memcpy(jamos, jamos_static, n_jamos*sizeof(gunichar2));
	    }
	  else
	    jamos = g_renew (gunichar, jamos, max_jamos);
	}

      jamos[n_jamos++] = wc;
      p = g_utf8_next_char (p);
    }

  if (n_jamos != 0)
    render_syllable (font, jamos, n_jamos, glyphs, &n_glyphs,
		     start - text);

  if (jamos != jamos_static)
    g_free(jamos);
}

static PangoCoverage *
hangul_engine_get_coverage (PangoFont  *font,
			   PangoLanguage *lang)
{
  PangoCoverage *result = pango_coverage_new ();
  int i;

  /* Well, no unicode rendering engine could render Hangul Jamo area
     _exactly_, I sure.  */
  for (i = 0x1100; i <= 0x11FF; i++)
    pango_coverage_set (result, i, PANGO_COVERAGE_FALLBACK);
  return result;
}

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

  result->engine.id = SCRIPT_ENGINE_NAME;
  result->engine.type = PANGO_ENGINE_TYPE_SHAPE;
  result->engine.length = sizeof (result);
  result->script_shape = hangul_engine_shape;
  result->get_coverage = hangul_engine_get_coverage;

  return (PangoEngine *)result;
}

/* The following three functions provide the public module API for
 * Pango. If we are compiling it is a module, then we name the
 * entry points script_engine_list, etc. But if we are compiling
 * it for inclusion directly in Pango, then we need them to
 * to have distinct names for this module, so we prepend
 * _pango_hangul_xft__
 */
#ifdef XFT_MODULE_PREFIX
#define MODULE_ENTRY(func) _pango_hangul_xft_##func
#else
#define MODULE_ENTRY(func) func
#endif

/* List the engines contained within this module
 */
void 
MODULE_ENTRY(script_engine_list) (PangoEngineInfo **engines, gint *n_engines)
{
  *engines = script_engines;
  *n_engines = G_N_ELEMENTS (script_engines);
}

/* Load a particular engine given the ID for the engine
 */
PangoEngine *
MODULE_ENTRY(script_engine_load) (const char *id)
{
  if (!strcmp (id, SCRIPT_ENGINE_NAME))
    return hangul_engine_xft_new ();
  else
    return NULL;
}

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