/*
 * Copyright © 2011  Martin Hosken
 * Copyright © 2011  SIL International
 * Copyright © 2011,2012  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 graphite2
#define hb_graphite2_shaper_font_data_t gr_font
#include "hb-shaper-impl-private.hh"

#include <graphite2/Font.h>
#include <graphite2/Segment.h>

#include "hb-graphite2.h"

#include "hb-ot-tag.h"


HB_SHAPER_DATA_ENSURE_DECLARE(graphite2, face)
HB_SHAPER_DATA_ENSURE_DECLARE(graphite2, font)


/*
 * shaper face data
 */

typedef struct hb_graphite2_tablelist_t {
  struct hb_graphite2_tablelist_t *next;
  hb_blob_t *blob;
  unsigned int tag;
} hb_graphite2_tablelist_t;

struct hb_graphite2_shaper_face_data_t {
  hb_face_t *face;
  gr_face   *grface;
  hb_graphite2_tablelist_t *tlist;
};

static const void *hb_graphite2_get_table (const void *data, unsigned int tag, size_t *len)
{
  hb_graphite2_shaper_face_data_t *face_data = (hb_graphite2_shaper_face_data_t *) data;
  hb_graphite2_tablelist_t *tlist = face_data->tlist;

  hb_blob_t *blob = NULL;

  for (hb_graphite2_tablelist_t *p = tlist; p; p = p->next)
    if (p->tag == tag) {
      blob = p->blob;
      break;
    }

  if (unlikely (!blob))
  {
    blob = face_data->face->reference_table (tag);

    hb_graphite2_tablelist_t *p = (hb_graphite2_tablelist_t *) calloc (1, sizeof (hb_graphite2_tablelist_t));
    if (unlikely (!p)) {
      hb_blob_destroy (blob);
      return NULL;
    }
    p->blob = blob;
    p->tag = tag;

    /* TODO Not thread-safe, but fairly harmless.
     * We can do the double-chcked pointer cmpexch thing here. */
    p->next = face_data->tlist;
    face_data->tlist = p;
  }

  unsigned int tlen;
  const char *d = hb_blob_get_data (blob, &tlen);
  *len = tlen;
  return d;
}

hb_graphite2_shaper_face_data_t *
_hb_graphite2_shaper_face_data_create (hb_face_t *face)
{
  hb_blob_t *silf_blob = face->reference_table (HB_GRAPHITE2_TAG_SILF);
  /* Umm, we just reference the table to check whether it exists.
   * Maybe add better API for this? */
  if (!hb_blob_get_length (silf_blob))
  {
    hb_blob_destroy (silf_blob);
    return NULL;
  }
  hb_blob_destroy (silf_blob);

  hb_graphite2_shaper_face_data_t *data = (hb_graphite2_shaper_face_data_t *) calloc (1, sizeof (hb_graphite2_shaper_face_data_t));
  if (unlikely (!data))
    hb_blob_destroy (silf_blob);

  data->face = face;
  data->grface = gr_make_face (data, &hb_graphite2_get_table, gr_face_default);

  if (unlikely (!data->grface)) {
    free (data);
    return NULL;
  }

  return data;
}

void
_hb_graphite2_shaper_face_data_destroy (hb_graphite2_shaper_face_data_t *data)
{
  hb_graphite2_tablelist_t *tlist = data->tlist;

  while (tlist)
  {
    hb_graphite2_tablelist_t *old = tlist;
    hb_blob_destroy (tlist->blob);
    tlist = tlist->next;
    free (old);
  }

  gr_face_destroy (data->grface);

  free (data);
}


/*
 * shaper font data
 */

static float hb_graphite2_get_advance (const void *hb_font, unsigned short gid)
{
  return ((hb_font_t *) hb_font)->get_glyph_h_advance (gid);
}

hb_graphite2_shaper_font_data_t *
_hb_graphite2_shaper_font_data_create (hb_font_t *font)
{
  if (unlikely (!hb_graphite2_shaper_face_data_ensure (font->face))) return NULL;

  hb_face_t *face = font->face;
  hb_graphite2_shaper_face_data_t *face_data = HB_SHAPER_DATA_GET (face);

  return gr_make_font_with_advance_fn (font->x_scale, font, &hb_graphite2_get_advance, face_data->grface);
}

void
_hb_graphite2_shaper_font_data_destroy (hb_graphite2_shaper_font_data_t *data)
{
  gr_font_destroy (data);
}


/*
 * shaper shape_plan data
 */

struct hb_graphite2_shaper_shape_plan_data_t {};

hb_graphite2_shaper_shape_plan_data_t *
_hb_graphite2_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
					     const hb_feature_t *user_features HB_UNUSED,
					     unsigned int        num_user_features HB_UNUSED)
{
  return (hb_graphite2_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
}

void
_hb_graphite2_shaper_shape_plan_data_destroy (hb_graphite2_shaper_shape_plan_data_t *data HB_UNUSED)
{
}


/*
 * shaper
 */

struct hb_graphite2_cluster_t {
  unsigned int base_char;
  unsigned int num_chars;
  unsigned int base_glyph;
  unsigned int num_glyphs;
};

hb_bool_t
_hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
		     hb_font_t          *font,
		     hb_buffer_t        *buffer,
		     const hb_feature_t *features,
		     unsigned int        num_features)
{
  hb_face_t *face = font->face;
  gr_face *grface = HB_SHAPER_DATA_GET (face)->grface;
  gr_font *grfont = HB_SHAPER_DATA_GET (font);

  const char *lang = hb_language_to_string (hb_buffer_get_language (buffer));
  const char *lang_end = strchr (lang, '-');
  int lang_len = lang_end ? lang_end - lang : -1;
  gr_feature_val *feats = gr_face_featureval_for_lang (grface, lang ? hb_tag_from_string (lang, lang_len) : 0);

  while (num_features--)
  {
    const gr_feature_ref *fref = gr_face_find_fref (grface, features->tag);
    if (fref)
      gr_fref_set_feature_value (fref, features->value, feats);
    features++;
  }

  gr_segment *seg = NULL;
  const gr_slot *is;
  unsigned int ci = 0, ic = 0;
  float curradvx = 0., curradvy = 0.;

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

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

  ALLOCATE_ARRAY (uint32_t, chars, buffer->len);

  for (unsigned int i = 0; i < buffer->len; ++i)
    chars[i] = buffer->info[i].codepoint;

  hb_tag_t script_tag[2];
  hb_ot_tags_from_script (hb_buffer_get_script (buffer), &script_tag[0], &script_tag[1]);

  seg = gr_make_seg (grfont, grface,
		     script_tag[1] == HB_TAG_NONE ? script_tag[0] : script_tag[1],
		     feats,
		     gr_utf32, chars, buffer->len,
		     2 | (hb_buffer_get_direction (buffer) == HB_DIRECTION_RTL ? 1 : 0));

  if (unlikely (!seg)) {
    if (feats) gr_featureval_destroy (feats);
    return false;
  }

  unsigned int glyph_count = gr_seg_n_slots (seg);
  if (unlikely (!glyph_count)) {
    if (feats) gr_featureval_destroy (feats);
    gr_seg_destroy (seg);
    return false;
  }

  scratch = (char *) buffer->get_scratch_buffer (&scratch_size);
  while ((sizeof (hb_graphite2_cluster_t) * buffer->len +
	  sizeof (hb_codepoint_t) * glyph_count) > scratch_size)
  {
    buffer->ensure (buffer->allocated * 2);
    if (unlikely (buffer->in_error)) {
      if (feats) gr_featureval_destroy (feats);
      gr_seg_destroy (seg);
      return false;
    }
    scratch = (char *) buffer->get_scratch_buffer (&scratch_size);
  }

  ALLOCATE_ARRAY (hb_graphite2_cluster_t, clusters, buffer->len);
  ALLOCATE_ARRAY (hb_codepoint_t, gids, glyph_count);

  memset (clusters, 0, sizeof (clusters[0]) * buffer->len);

  hb_codepoint_t *pg = gids;
  for (is = gr_seg_first_slot (seg), ic = 0; is; is = gr_slot_next_in_segment (is), ic++)
  {
    unsigned int before = gr_slot_before (is);
    unsigned int after = gr_slot_after (is);
    *pg = gr_slot_gid (is);
    pg++;
    while (clusters[ci].base_char > before && ci)
    {
      clusters[ci-1].num_chars += clusters[ci].num_chars;
      clusters[ci-1].num_glyphs += clusters[ci].num_glyphs;
      ci--;
    }

    if (gr_slot_can_insert_before (is) && clusters[ci].num_chars && before >= clusters[ci].base_char + clusters[ci].num_chars)
    {
      hb_graphite2_cluster_t *c = clusters + ci + 1;
      c->base_char = clusters[ci].base_char + clusters[ci].num_chars;
      c->num_chars = before - c->base_char;
      c->base_glyph = ic;
      c->num_glyphs = 0;
      ci++;
    }
    clusters[ci].num_glyphs++;

    if (clusters[ci].base_char + clusters[ci].num_chars < after + 1)
	clusters[ci].num_chars = after + 1 - clusters[ci].base_char;
  }
  ci++;

  buffer->clear_output ();
  for (unsigned int i = 0; i < ci; ++i)
    buffer->replace_glyphs (clusters[i].num_chars, clusters[i].num_glyphs, gids + clusters[i].base_glyph);
  buffer->swap_buffers ();

  if (HB_DIRECTION_IS_BACKWARD(buffer->props.direction))
    curradvx = gr_seg_advance_X(seg);

  hb_glyph_position_t *pPos;
  for (pPos = hb_buffer_get_glyph_positions (buffer, NULL), is = gr_seg_first_slot (seg);
       is; pPos++, is = gr_slot_next_in_segment (is))
  {
    pPos->x_offset = gr_slot_origin_X (is) - curradvx;
    pPos->y_offset = gr_slot_origin_Y (is) - curradvy;
    pPos->x_advance = gr_slot_advance_X (is, grface, grfont);
    pPos->y_advance = gr_slot_advance_Y (is, grface, grfont);
    if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
      curradvx -= pPos->x_advance;
    pPos->x_offset = gr_slot_origin_X (is) - curradvx;
    if (!HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
      curradvx += pPos->x_advance;
    pPos->y_offset = gr_slot_origin_Y (is) - curradvy;
    curradvy += pPos->y_advance;
  }
  if (!HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
    pPos[-1].x_advance += gr_seg_advance_X(seg) - curradvx;

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

  if (feats) gr_featureval_destroy (feats);
  gr_seg_destroy (seg);

  return true;
}