/*
 * Copyright © 2012  Google, Inc.
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Google Author(s): Behdad Esfahbod
 */

#include "hb-private.hh"

#include "hb-old-private.hh"

#include "hb-font-private.hh"
#include "hb-buffer-private.hh"

#include <harfbuzz.h>


#ifndef HB_DEBUG_OLD
#define HB_DEBUG_OLD (HB_DEBUG+0)
#endif


static HB_Script
hb_old_script_from_script (hb_script_t script)
{
  switch ((hb_tag_t) script)
  {
    default:
    case HB_SCRIPT_COMMON:		return HB_Script_Common;
    case HB_SCRIPT_GREEK:		return HB_Script_Greek;
    case HB_SCRIPT_CYRILLIC:		return HB_Script_Cyrillic;
    case HB_SCRIPT_ARMENIAN:		return HB_Script_Armenian;
    case HB_SCRIPT_HEBREW:		return HB_Script_Hebrew;
    case HB_SCRIPT_ARABIC:		return HB_Script_Arabic;
    case HB_SCRIPT_SYRIAC:		return HB_Script_Syriac;
    case HB_SCRIPT_THAANA:		return HB_Script_Thaana;
    case HB_SCRIPT_DEVANAGARI:		return HB_Script_Devanagari;
    case HB_SCRIPT_BENGALI:		return HB_Script_Bengali;
    case HB_SCRIPT_GURMUKHI:		return HB_Script_Gurmukhi;
    case HB_SCRIPT_GUJARATI:		return HB_Script_Gujarati;
    case HB_SCRIPT_ORIYA:		return HB_Script_Oriya;
    case HB_SCRIPT_TAMIL:		return HB_Script_Tamil;
    case HB_SCRIPT_TELUGU:		return HB_Script_Telugu;
    case HB_SCRIPT_KANNADA:		return HB_Script_Kannada;
    case HB_SCRIPT_MALAYALAM:		return HB_Script_Malayalam;
    case HB_SCRIPT_SINHALA:		return HB_Script_Sinhala;
    case HB_SCRIPT_THAI:		return HB_Script_Thai;
    case HB_SCRIPT_LAO:			return HB_Script_Lao;
    case HB_SCRIPT_TIBETAN:		return HB_Script_Tibetan;
    case HB_SCRIPT_MYANMAR:		return HB_Script_Myanmar;
    case HB_SCRIPT_GEORGIAN:		return HB_Script_Georgian;
    case HB_SCRIPT_HANGUL:		return HB_Script_Hangul;
    case HB_SCRIPT_OGHAM:		return HB_Script_Ogham;
    case HB_SCRIPT_RUNIC:		return HB_Script_Runic;
    case HB_SCRIPT_KHMER:		return HB_Script_Khmer;
    case HB_SCRIPT_NKO:			return HB_Script_Nko;
    case HB_SCRIPT_INHERITED:		return HB_Script_Inherited;
  }
}


static HB_Bool
hb_old_convertStringToGlyphIndices (HB_Font old_font,
				    const HB_UChar16 *string,
				    hb_uint32 length,
				    HB_Glyph *glyphs,
				    hb_uint32 *numGlyphs,
				    HB_Bool rightToLeft)
{
  hb_font_t *font = (hb_font_t *) old_font->userData;

  for (unsigned int i = 0; i < length; i++)
  {
    hb_codepoint_t u;

    /* TODO Handle UTF-16.  Ugh */
    u = string[i];

    if (rightToLeft)
      u = hb_unicode_mirroring (hb_unicode_funcs_get_default (), u);

    hb_font_get_glyph (font, u, 0, &u); /* TODO Variation selectors */

    glyphs[i] = u;
  }
  *numGlyphs = length; // XXX

  return true;
}

static void
hb_old_getGlyphAdvances (HB_Font old_font,
			 const HB_Glyph *glyphs,
			 hb_uint32 numGlyphs,
			 HB_Fixed *advances,
			 int flags /*HB_ShaperFlag*/)
{
  hb_font_t *font = (hb_font_t *) old_font->userData;

  for (unsigned int i = 0; i < numGlyphs; i++)
    advances[i] = hb_font_get_glyph_h_advance (font, glyphs[i]);
}

static HB_Bool
hb_old_canRender (HB_Font old_font,
		  const HB_UChar16 *string,
		  hb_uint32 length)
{
  return true; // TODO
}

static HB_Error
hb_old_getPointInOutline (HB_Font old_font,
			  HB_Glyph glyph,
			  int flags /*HB_ShaperFlag*/,
			  hb_uint32 point,
			  HB_Fixed *xpos,
			  HB_Fixed *ypos,
			  hb_uint32 *nPoints)
{
  return HB_Err_Ok; // TODO
}

static void
hb_old_getGlyphMetrics (HB_Font old_font,
			HB_Glyph glyph,
			HB_GlyphMetrics *metrics)
{
  // TODO
}

static HB_Fixed
hb_old_getFontMetric (HB_Font old_font,
		      HB_FontMetric metric)
{
  return 0; // TODO
}

static const HB_FontClass hb_old_font_class = {
  hb_old_convertStringToGlyphIndices,
  hb_old_getGlyphAdvances,
  hb_old_canRender,
  hb_old_getPointInOutline,
  hb_old_getGlyphMetrics,
  hb_old_getFontMetric
};


static hb_user_data_key_t hb_old_data_key;

static HB_Error
table_func (void *font, HB_Tag tag, HB_Byte *buffer, HB_UInt *length)
{
  hb_face_t *face = (hb_face_t *) font;
  hb_blob_t *blob = hb_face_reference_table (face, (hb_tag_t) tag);
  unsigned int capacity = *length;
  *length = hb_blob_get_length (blob);
  memcpy (buffer, hb_blob_get_data (blob, NULL), MIN (capacity, *length));
  hb_blob_destroy (blob);
 return HB_Err_Ok;
}

static HB_Face
_hb_old_face_get (hb_face_t *face)
{
  HB_Face data = (HB_Face) hb_face_get_user_data (face, &hb_old_data_key);
  if (likely (data)) return data;

  data = HB_NewFace (face, table_func);

  if (unlikely (!data)) {
    DEBUG_MSG (OLD, face, "HB_NewFace failed");
    return NULL;
  }

  if (unlikely (!hb_face_set_user_data (face, &hb_old_data_key, data,
                                        (hb_destroy_func_t) HB_FreeFace,
                                        false)))
  {
    HB_FreeFace (data);
    data = (HB_Face) hb_face_get_user_data (face, &hb_old_data_key);
    if (data)
      return data;
    else
      return NULL;
  }

  return data;
}


static HB_Font
_hb_old_font_get (hb_font_t *font)
{
  HB_Font data = (HB_Font) calloc (1, sizeof (HB_FontRec));
  if (unlikely (!data)) {
    DEBUG_MSG (OLD, font, "malloc()ing HB_Font failed");
    return NULL;
  }

  data->klass = &hb_old_font_class;
  data->x_ppem = font->x_ppem;
  data->y_ppem = font->y_ppem;
  data->x_scale = font->x_scale; // XXX
  data->y_scale = font->y_scale; // XXX
  data->userData = font;

  if (unlikely (!hb_font_set_user_data (font, &hb_old_data_key, data,
                                        (hb_destroy_func_t) free,
                                        false)))
  {
    free (data);
    data = (HB_Font) hb_font_get_user_data (font, &hb_old_data_key);
    if (data)
      return data;
    else
      return NULL;
  }

  return data;
}

hb_bool_t
_hb_old_shape (hb_font_t          *font,
	       hb_buffer_t        *buffer,
	       const hb_feature_t *features,
	       unsigned int        num_features)
{
  if (unlikely (!buffer->len))
    return true;

  buffer->guess_properties ();

#define FAIL(...) \
  HB_STMT_START { \
    DEBUG_MSG (OLD, NULL, __VA_ARGS__); \
    return false; \
  } HB_STMT_END;

  HB_Face old_face = _hb_old_face_get (font->face);
  if (unlikely (!old_face))
    FAIL ("Couldn't get old face");

  HB_Font old_font = _hb_old_font_get (font);
  if (unlikely (!old_font))
    FAIL ("Couldn't get old font");

retry:

  unsigned int scratch_size;
  char *scratch = (char *) buffer->get_scratch_buffer (&scratch_size);

#define utf16_index() var1.u32
  HB_UChar16 *pchars = (HB_UChar16 *) scratch;
  unsigned int chars_len = 0;
  for (unsigned int i = 0; i < buffer->len; i++) {
    hb_codepoint_t c = buffer->info[i].codepoint;
    buffer->info[i].utf16_index() = chars_len;
    if (likely (c < 0x10000))
      pchars[chars_len++] = c;
    else if (unlikely (c >= 0x110000))
      pchars[chars_len++] = 0xFFFD;
    else {
      pchars[chars_len++] = 0xD800 + ((c - 0x10000) >> 10);
      pchars[chars_len++] = 0xDC00 + ((c - 0x10000) & ((1 << 10) - 1));
    }
  }
#undef utf16_index


#define ALLOCATE_ARRAY(Type, name, len) \
  name = (Type *) scratch; \
  scratch += len * sizeof (name[0]); \
  scratch_size -= len * sizeof (name[0]);


  HB_ShaperItem item = {0};

  ALLOCATE_ARRAY (const HB_UChar16, item.string, chars_len);
  item.stringLength = chars_len;
  item.item.pos = 0;
  item.item.length = item.stringLength;
  item.item.script = hb_old_script_from_script (buffer->props.script);
  item.item.bidiLevel = HB_DIRECTION_IS_FORWARD (buffer->props.direction) ? 0 : 1;

  item.font = old_font;
  item.face = old_face;
  item.shaperFlags = 0;

  item.glyphIndicesPresent = false;

  /* TODO Alignment. */
  unsigned int num_glyphs = scratch_size / (sizeof (HB_Glyph) +
					    sizeof (HB_GlyphAttributes) +
					    sizeof (HB_Fixed) +
					    sizeof (HB_FixedPoint) +
					    sizeof (unsigned short));

  item.num_glyphs = num_glyphs;
  ALLOCATE_ARRAY (HB_Glyph, item.glyphs, num_glyphs);
  ALLOCATE_ARRAY (HB_GlyphAttributes, item.attributes, num_glyphs);
  ALLOCATE_ARRAY (HB_Fixed, item.advances, num_glyphs);
  ALLOCATE_ARRAY (HB_FixedPoint, item.offsets, num_glyphs);
  ALLOCATE_ARRAY (unsigned short, item.log_clusters, num_glyphs);

  if (!HB_ShapeItem (&item))
    return false;

  if (unlikely (item.num_glyphs > num_glyphs))
  {
    buffer->ensure (buffer->allocated * 2);
    if (buffer->in_error)
      FAIL ("Buffer resize failed");
    goto retry;
  }
  num_glyphs = item.num_glyphs;

#undef ALLOCATE_ARRAY

  hb_glyph_info_t *info = buffer->info;
  for (unsigned int i = 0; i < num_glyphs; i++)
  {
    info[i].codepoint = item.glyphs[i];
    info[i].cluster = item.log_clusters[i];

    info[i].mask = item.advances[i];
    info[i].var1.u32 = item.offsets[i].x;
    info[i].var2.u32 = item.offsets[i].y;
  }
  buffer->len = num_glyphs;

  buffer->clear_positions ();

  unsigned int count = buffer->len;
  for (unsigned int i = 0; i < count; ++i) {
    hb_glyph_info_t *info = &buffer->info[i];
    hb_glyph_position_t *pos = &buffer->pos[i];

    /* TODO vertical */
    pos->x_advance = info->mask;
    pos->x_offset = info->var1.u32;
    pos->y_offset = info->var2.u32;
  }

  if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
    buffer->reverse ();

  return true;
}