/* Pango
 * pango-ot-ruleset.c: Shaping using OpenType features
 *
 * Copyright (C) 2000 Red Hat Software
 *
 * 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 <freetype/internal/ftmemory.h>

#include <pango/pango-ot.h>
#include "pango-ot-private.h"

#define PANGO_SCALE_26_6 (PANGO_SCALE / (1<<6))
#define PANGO_UNITS_26_6(d) (PANGO_SCALE_26_6 * (d))

typedef struct _PangoOTRule PangoOTRule;

struct _PangoOTRule 
{
  gulong     property_bit;
  FT_UShort  feature_index;
  guint      table_type : 1;
};

static void pango_ot_ruleset_class_init (GObjectClass   *object_class);
static void pango_ot_ruleset_init       (PangoOTRuleset *ruleset);
static void pango_ot_ruleset_finalize   (GObject        *object);

static GObjectClass *parent_class;

GType
pango_ot_ruleset_get_type (void)
{
  static GType object_type = 0;

  if (!object_type)
    {
      static const GTypeInfo object_info =
      {
        sizeof (PangoOTRulesetClass),
        (GBaseInitFunc) NULL,
        (GBaseFinalizeFunc) NULL,
        (GClassInitFunc)pango_ot_ruleset_class_init,
        NULL,           /* class_finalize */
        NULL,           /* class_data */
        sizeof (PangoOTRuleset),
        0,              /* n_preallocs */
        (GInstanceInitFunc)pango_ot_ruleset_init,
      };
      
      object_type = g_type_register_static (G_TYPE_OBJECT,
                                            "PangoOTRuleset",
                                            &object_info, 0);
    }
  
  return object_type;
}

static void 
pango_ot_ruleset_class_init (GObjectClass *object_class)
{
  parent_class = g_type_class_peek_parent (object_class);
  
  object_class->finalize = pango_ot_ruleset_finalize;
}

static void 
pango_ot_ruleset_init (PangoOTRuleset *ruleset)
{
  ruleset->rules = g_array_new (FALSE, FALSE, sizeof (PangoOTRule));
}

static void 
pango_ot_ruleset_finalize (GObject *object)
{
  PangoOTRuleset *ruleset = PANGO_OT_RULESET (object);

  g_array_free (ruleset->rules, TRUE);
  g_object_unref (ruleset->info);
}

/**
 * pango_ot_ruleset_new:
 * @info: a #PangoOTInfo.
 * @returns: a new #PangoOTRuleset.
 *
 * Creates a new #PangoOTRuleset for the given OpenType info.
 **/
PangoOTRuleset *
pango_ot_ruleset_new (PangoOTInfo *info)
{
  PangoOTRuleset *ruleset;

  ruleset = g_object_new (PANGO_TYPE_OT_RULESET, NULL);

  ruleset->info = g_object_ref (info);

  return ruleset;
}

/**
 * pango_ot_ruleset_add_feature:
 * @ruleset: a #PangoOTRuleset.
 * @table_type: the table type to add a feature to.
 * @feature_index: the index of the feature to add.
 * @property_bit: the property bit to use for this feature. 
 *
 * Adds a feature to the ruleset. See pango_ot_ruleset_shape()
 * for an explanation of @property_bit.
 **/
void
pango_ot_ruleset_add_feature (PangoOTRuleset   *ruleset,
			      PangoOTTableType  table_type,
			      guint             feature_index,
			      gulong            property_bit)
{
  PangoOTRule tmp_rule;

  g_return_if_fail (PANGO_OT_IS_RULESET (ruleset));

  tmp_rule.table_type = table_type;
  tmp_rule.feature_index = feature_index;
  tmp_rule.property_bit = property_bit;

  g_array_append_val (ruleset->rules, tmp_rule);
}

/**
 * pango_ot_ruleset_shape:
 * @ruleset: a #PangoOTRuleset.
 * @glyphs: a pointer to a #PangoGlyphString.
 * @properties: an array containing one #gulong bitfield for each glyph,
 *   which gives the glyph's properties: If a certain bit is set for a glyph, 
 *   the feature which has the same bit set in its property value is applied.
 *
 * Shapes a string of glyphs with the given properties according to @ruleset.
 **/
void
pango_ot_ruleset_shape (PangoOTRuleset   *ruleset,
			PangoGlyphString *glyphs,
			gulong           *properties)
{
  int i;
  int last_cluster;
  int result;
  
  TTO_GSUB gsub = NULL;
  TTO_GPOS gpos = NULL;
  
  TTO_GSUB_String *in_string = NULL;
  TTO_GSUB_String *out_string = NULL;
  TTO_GSUB_String *result_string = NULL;

  gboolean need_gsub = FALSE;
  gboolean need_gpos = FALSE;

  g_return_if_fail (PANGO_OT_IS_RULESET (ruleset));

  for (i = 0; i < ruleset->rules->len; i++)
    {
      PangoOTRule *rule = &g_array_index (ruleset->rules, PangoOTRule, i);

      if (rule->table_type == PANGO_OT_TABLE_GSUB)
	need_gsub = TRUE;
      else 
	need_gpos = TRUE;
    }

  if (need_gsub)
    {
      gsub = pango_ot_info_get_gsub (ruleset->info);

      if (gsub)
	TT_GSUB_Clear_Features (gsub);
    }

  if (need_gpos)
    {
      gpos = pango_ot_info_get_gpos (ruleset->info);

      if (gpos)
	TT_GPOS_Clear_Features (gpos);
    }

  for (i = 0; i < ruleset->rules->len; i++)
    {
      PangoOTRule *rule = &g_array_index (ruleset->rules, PangoOTRule, i);

      if (rule->table_type == PANGO_OT_TABLE_GSUB)
	{
	  if (gsub)
	    TT_GSUB_Add_Feature (gsub, rule->feature_index, rule->property_bit);
	}
      else
	{
	  if (gpos)
	    TT_GPOS_Add_Feature (gpos, rule->feature_index, rule->property_bit);
	}
    }

  if (!gsub && !gpos)
    return;

  result = TT_GSUB_String_New (ruleset->info->face->memory, &in_string);
  g_assert (result == FT_Err_Ok);

  result = TT_GSUB_String_Set_Length (in_string, glyphs->num_glyphs);
  g_assert (result == FT_Err_Ok);

  for (i = 0; i < glyphs->num_glyphs; i++)
    {
      in_string->string[i] = glyphs->glyphs[i].glyph;
      in_string->properties[i] = properties[i];
      in_string->logClusters[i] = glyphs->log_clusters[i];
    }
  in_string->max_ligID = i;
  
  if (gsub)
    {
      result = TT_GSUB_String_New (ruleset->info->face->memory,
                                   &out_string);
      g_assert (result == FT_Err_Ok);
      result_string = out_string;

      TT_GSUB_Apply_String (gsub, in_string, out_string);
    }
  else
    result_string = in_string;

  if (gpos)
    {
      TTO_GPOS_Data *outgpos = NULL;

      if (!TT_GPOS_Apply_String (ruleset->info->face, gpos, 0, result_string, &outgpos,
				 FALSE /* enable device-dependant values */,
				 FALSE /* Even though this might be r2l text, RTL is handled elsewhere */))
	{
	  for (i = 0; i < result_string->length; i++)
	    {
	      FT_Pos x_pos = outgpos[i].x_pos;
	      FT_Pos y_pos = outgpos[i].y_pos;
	      int back = i;
	      int j;

	      while (outgpos[back].back != 0)
		{
		  back  -= outgpos[back].back;
		  x_pos += outgpos[back].x_pos;
		  y_pos += outgpos[back].y_pos;
		}

	      for (j = back; j < i; j++)
	        glyphs->glyphs[i].geometry.x_offset -= glyphs->glyphs[j].geometry.width;

	      glyphs->glyphs[i].geometry.x_offset += PANGO_UNITS_26_6(x_pos);
	      glyphs->glyphs[i].geometry.y_offset += PANGO_UNITS_26_6(y_pos);

	      if (outgpos[i].new_advance)
		glyphs->glyphs[i].geometry.width  = PANGO_UNITS_26_6(outgpos[i].x_advance);
	      else
		glyphs->glyphs[i].geometry.width += PANGO_UNITS_26_6(outgpos[i].x_advance);
	    }

	  FT_Free(gpos->memory, (void *)outgpos);
	}
    }

  pango_glyph_string_set_size (glyphs, result_string->length);

  last_cluster = -1;
  for (i = 0; i < result_string->length; i++)
    {
      glyphs->glyphs[i].glyph = result_string->string[i];

      glyphs->log_clusters[i] = result_string->logClusters[i];
      if (glyphs->log_clusters[i] != last_cluster)
	glyphs->glyphs[i].attr.is_cluster_start = 1;
      else
	glyphs->glyphs[i].attr.is_cluster_start = 0;

      last_cluster = glyphs->log_clusters[i];
    }

  if (in_string)
    TT_GSUB_String_Done (in_string);
  if (out_string)
    TT_GSUB_String_Done (out_string);
}