/*
 * 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
 */

#define HB_SHAPER icu_le
#define hb_icu_le_shaper_font_data_t PortableFontInstance
#include "hb-shaper-impl-private.hh"

#include "hb-icu-le/PortableFontInstance.h"

#include <layout/LEScripts.h>
#include <layout/loengine.h>
#include <unicode/uscript.h>
#include <unicode/unistr.h>


/* Duplicated here so we don't depend on hb-icu. */

static hb_script_t
_hb_icu_script_to_script (UScriptCode script)
{
  if (unlikely (script == USCRIPT_INVALID_CODE))
    return HB_SCRIPT_INVALID;

  return hb_script_from_string (uscript_getShortName (script), -1);
}

static UScriptCode
_hb_icu_script_from_script (hb_script_t script)
{
  if (unlikely (script == HB_SCRIPT_INVALID))
    return USCRIPT_INVALID_CODE;

  for (unsigned int i = 0; i < USCRIPT_CODE_LIMIT; i++)
    if (unlikely (_hb_icu_script_to_script ((UScriptCode) i) == script))
      return (UScriptCode) i;

  return USCRIPT_UNKNOWN;
}


/*
 * shaper face data
 */

struct hb_icu_le_shaper_face_data_t {};

hb_icu_le_shaper_face_data_t *
_hb_icu_le_shaper_face_data_create (hb_face_t *face HB_UNUSED)
{
  return (hb_icu_le_shaper_face_data_t *) HB_SHAPER_DATA_SUCCEEDED;
}

void
_hb_icu_le_shaper_face_data_destroy (hb_icu_le_shaper_face_data_t *data HB_UNUSED)
{
}


/*
 * shaper font data
 */

hb_icu_le_shaper_font_data_t *
_hb_icu_le_shaper_font_data_create (hb_font_t *font)
{
  LEErrorCode status = LE_NO_ERROR;
  unsigned int x_ppem = font->x_ppem ? font->x_ppem : 72;
  unsigned int y_ppem = font->y_ppem ? font->y_ppem : 72;
  hb_icu_le_shaper_font_data_t *data = new PortableFontInstance (font->face,
								 font->x_scale / x_ppem,
								 font->y_scale / y_ppem,
								 x_ppem,
								 y_ppem,
								 status);
  if (status != LE_NO_ERROR) {
    delete (data);
    return NULL;
  }

  return data;
}

void
_hb_icu_le_shaper_font_data_destroy (hb_icu_le_shaper_font_data_t *data)
{
  delete (data);
}


/*
 * shaper shape_plan data
 */

struct hb_icu_le_shaper_shape_plan_data_t {};

hb_icu_le_shaper_shape_plan_data_t *
_hb_icu_le_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
					  const hb_feature_t *user_features,
					  unsigned int        num_user_features)
{
  return (hb_icu_le_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
}

void
_hb_icu_le_shaper_shape_plan_data_destroy (hb_icu_le_shaper_shape_plan_data_t *data)
{
}


/*
 * shaper
 */

hb_bool_t
_hb_icu_le_shape (hb_shape_plan_t    *shape_plan,
		  hb_font_t          *font,
		  hb_buffer_t        *buffer,
		  const hb_feature_t *features,
		  unsigned int        num_features)
{
  LEFontInstance *font_instance = HB_SHAPER_DATA_GET (font);
  le_int32 script_code = _hb_icu_script_from_script (shape_plan->props.script);
  le_int32 language_code = -1 /* TODO */;
  le_int32 typography_flags = 3; /* Needed for ligatures and kerning */
  LEErrorCode status = LE_NO_ERROR;
  le_engine *le = le_create ((const le_font *) font_instance,
			     script_code,
			     language_code,
			     typography_flags,
			     &status);
  if (status != LE_NO_ERROR)
  { le_close (le); return false; }

retry:

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

  LEUnicode *pchars = (LEUnicode *) scratch;
  unsigned int chars_len = 0;
  for (unsigned int i = 0; i < buffer->len; i++) {
    hb_codepoint_t c = buffer->info[i].codepoint;
    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));
    }
  }

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

  ALLOCATE_ARRAY (LEUnicode, chars, chars_len);
  ALLOCATE_ARRAY (unsigned int, clusters, chars_len);

  chars_len = 0;
  for (unsigned int i = 0; i < buffer->len; i++) {
    hb_codepoint_t c = buffer->info[i].codepoint;
    if (likely (c < 0x10000))
      clusters[chars_len++] = buffer->info[i].cluster;
    else if (unlikely (c >= 0x110000))
      clusters[chars_len++] = buffer->info[i].cluster;
    else {
      clusters[chars_len++] = buffer->info[i].cluster;
      clusters[chars_len++] = buffer->info[i].cluster;
    }
  }

  unsigned int glyph_count = le_layoutChars (le,
					     chars,
					     0,
					     chars_len,
					     chars_len,
					     HB_DIRECTION_IS_BACKWARD (buffer->props.direction),
					     0., 0.,
					     &status);
  if (status != LE_NO_ERROR)
  { le_close (le); return false; }

  unsigned int num_glyphs = scratch_size / (sizeof (LEGlyphID) +
					    sizeof (le_int32) +
					    sizeof (float) * 2);

  if (unlikely (glyph_count >= num_glyphs || glyph_count > buffer->allocated)) {
    buffer->ensure (buffer->allocated * 2);
    if (buffer->in_error)
    { le_close (le); return false; }
    goto retry;
  }

  ALLOCATE_ARRAY (LEGlyphID, glyphs, glyph_count);
  ALLOCATE_ARRAY (le_int32, indices, glyph_count);
  ALLOCATE_ARRAY (float, positions, glyph_count * 2 + 2);

  le_getGlyphs (le, glyphs, &status);
  le_getCharIndices (le, indices, &status);
  le_getGlyphPositions (le, positions, &status);

#undef ALLOCATE_ARRAY

  /* Ok, we've got everything we need, now compose output buffer,
   * very, *very*, carefully! */

  unsigned int j = 0;
  hb_glyph_info_t *info = buffer->info;
  for (unsigned int i = 0; i < glyph_count; i++)
  {
    if (glyphs[i] >= 0xFFFE)
	continue;

    info[j].codepoint = glyphs[i];
    info[j].cluster = clusters[indices[i]];

    /* icu-le doesn't seem to have separate advance values. */
    info[j].mask = positions[2 * i + 2] - positions[2 * i];
    info[j].var1.u32 = 0;
    info[j].var2.u32 = -positions[2 * i + 1];

    j++;
  }
  buffer->len = j;

  buffer->clear_positions ();

  for (unsigned int i = 0; i < buffer->len; 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;
  }

  le_close (le);
  return true;
}