/*

 * Copyright © 2004 Carl Worth

 * Copyright © 2006 Red Hat, Inc.

 * Copyright © 2009 Chris Wilson

 * Copyright © 2011 Intel Corporation

 *

 * This library is free software; you can redistribute it and/or

 * modify it either under the terms of the GNU Lesser General Public

 * License version 2.1 as published by the Free Software Foundation

 * (the "LGPL") or, at your option, under the terms of the Mozilla

 * Public License Version 1.1 (the "MPL"). If you do not alter this

 * notice, a recipient may use your version of this file under either

 * the MPL or the LGPL.

 *

 * You should have received a copy of the LGPL along with this library

 * in the file COPYING-LGPL-2.1; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA

 * You should have received a copy of the MPL along with this library

 * in the file COPYING-MPL-1.1

 *

 * The contents of this file are subject to the Mozilla Public License

 * Version 1.1 (the "License"); you may not use this file except in

 * compliance with the License. You may obtain a copy of the License at

 * http://www.mozilla.org/MPL/

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY

 * OF ANY KIND, either express or implied. See the LGPL or the MPL for

 * the specific language governing rights and limitations.

 *

 * The Original Code is the cairo graphics library.

 *

 * The Initial Developer of the Original Code is Carl Worth

 *

 * Contributor(s):

 *  Carl D. Worth <cworth@cworth.org>

 *  Chris Wilson <chris@chris-wilson.co.uk>

 */

/* Provide definitions for standalone compilation */

#include "cairoint.h"

#include "cairo-boxes-private.h"

#include "cairo-error-private.h"

#include "cairo-combsort-inline.h"

#include "cairo-list-private.h"

#include <setjmp.h>

typedef struct _rectangle rectangle_t;

typedef struct _edge edge_t;

struct _edge {

    edge_t *next, *prev;

    edge_t *right;

    cairo_fixed_t x, top;

    int a_or_b;

    int dir;

};

struct _rectangle {

    edge_t left, right;

    int32_t top, bottom;

};

#define UNROLL3(x) x x x

/* the parent is always given by index/2 */

#define PQ_PARENT_INDEX(i) ((i) >> 1)

#define PQ_FIRST_ENTRY 1

/* left and right children are index * 2 and (index * 2) +1 respectively */

#define PQ_LEFT_CHILD_INDEX(i) ((i) << 1)

typedef struct _pqueue {

    int size, max_size;

    rectangle_t **elements;

    rectangle_t *elements_embedded[1024];

} pqueue_t;

typedef struct _sweep_line {

    rectangle_t **rectangles;

    pqueue_t pq;

    edge_t head, tail;

    edge_t *insert_left, *insert_right;

    int32_t current_y;

    int32_t last_y;

    jmp_buf unwind;

} sweep_line_t;

#define DEBUG_TRAPS 0

#if DEBUG_TRAPS

static void

dump_traps (cairo_traps_t *traps, const char *filename)

{

    FILE *file;

    int n;

    if (getenv ("CAIRO_DEBUG_TRAPS") == NULL)

  return;

    file = fopen (filename, "a");

    if (file != NULL) {

  for (n = 0; n < traps->num_traps; n++) {

      fprintf (file, "%d %d L:(%d, %d), (%d, %d) R:(%d, %d), (%d, %d)\n",

         traps->traps[n].top,

         traps->traps[n].bottom,

         traps->traps[n].left.p1.x,

         traps->traps[n].left.p1.y,

         traps->traps[n].left.p2.x,

         traps->traps[n].left.p2.y,

         traps->traps[n].right.p1.x,

         traps->traps[n].right.p1.y,

         traps->traps[n].right.p2.x,

         traps->traps[n].right.p2.y);

  }

  fprintf (file, "\n");

  fclose (file);

    }

}

#else

#define dump_traps(traps, filename)

#endif

static inline int

rectangle_compare_start (const rectangle_t *a,

       const rectangle_t *b)

{

    return a->top - b->top;

}

static inline int

rectangle_compare_stop (const rectangle_t *a,

       const rectangle_t *b)

{

    return a->bottom - b->bottom;

}

static inline void

pqueue_init (pqueue_t *pq)

{

    pq->max_size = ARRAY_LENGTH (pq->elements_embedded);

    pq->size = 0;

    pq->elements = pq->elements_embedded;

    pq->elements[PQ_FIRST_ENTRY] = NULL;

}

static inline void

pqueue_fini (pqueue_t *pq)

{

    if (pq->elements != pq->elements_embedded)

  free (pq->elements);

}

static cairo_bool_t

pqueue_grow (pqueue_t *pq)

{

    rectangle_t **new_elements;

    pq->max_size *= 2;

    if (pq->elements == pq->elements_embedded) {

  new_elements = _cairo_malloc_ab (pq->max_size,

           sizeof (rectangle_t *));

  if (unlikely (new_elements == NULL))

      return FALSE;

  memcpy (new_elements, pq->elements_embedded,

    sizeof (pq->elements_embedded));

    } else {

  new_elements = _cairo_realloc_ab (pq->elements,

            pq->max_size,

            sizeof (rectangle_t *));

  if (unlikely (new_elements == NULL))

      return FALSE;

    }

    pq->elements = new_elements;

    return TRUE;

}

static inline void

pqueue_push (sweep_line_t *sweep, rectangle_t *rectangle)

{

    rectangle_t **elements;

    int i, parent;

    if (unlikely (sweep->pq.size + 1 == sweep->pq.max_size)) {

  if (unlikely (! pqueue_grow (&sweep->pq))) {

      longjmp (sweep->unwind,

         _cairo_error (CAIRO_STATUS_NO_MEMORY));

  }

    }

    elements = sweep->pq.elements;

    for (i = ++sweep->pq.size;

   i != PQ_FIRST_ENTRY &&

   rectangle_compare_stop (rectangle,

         elements[parent = PQ_PARENT_INDEX (i)]) < 0;

   i = parent)

    {

  elements[i] = elements[parent];

    }

    elements[i] = rectangle;

}

static inline void

pqueue_pop (pqueue_t *pq)

{

    rectangle_t **elements = pq->elements;

    rectangle_t *tail;

    int child, i;

    tail = elements[pq->size--];

    if (pq->size == 0) {

  elements[PQ_FIRST_ENTRY] = NULL;

  return;

    }

    for (i = PQ_FIRST_ENTRY;

   (child = PQ_LEFT_CHILD_INDEX (i)) <= pq->size;

   i = child)

    {

  if (child != pq->size &&

      rectangle_compare_stop (elements[child+1],

            elements[child]) < 0)

  {

      child++;

  }

  if (rectangle_compare_stop (elements[child], tail) >= 0)

      break;

  elements[i] = elements[child];

    }

    elements[i] = tail;

}

static inline rectangle_t *

rectangle_pop_start (sweep_line_t *sweep_line)

{

    return *sweep_line->rectangles++;

}

static inline rectangle_t *

rectangle_peek_stop (sweep_line_t *sweep_line)

{

    return sweep_line->pq.elements[PQ_FIRST_ENTRY];

}

CAIRO_COMBSORT_DECLARE (_rectangle_sort,

      rectangle_t *,

      rectangle_compare_start)

static void

sweep_line_init (sweep_line_t  *sweep_line,

     rectangle_t  **rectangles,

     int      num_rectangles)

{

    _rectangle_sort (rectangles, num_rectangles);

    rectangles[num_rectangles] = NULL;

    sweep_line->rectangles = rectangles;

    sweep_line->head.x = INT32_MIN;

    sweep_line->head.right = NULL;

    sweep_line->head.dir = 0;

    sweep_line->head.next = &sweep_line->tail;

    sweep_line->tail.x = INT32_MAX;

    sweep_line->tail.right = NULL;

    sweep_line->tail.dir = 0;

    sweep_line->tail.prev = &sweep_line->head;

    sweep_line->insert_left = &sweep_line->tail;

    sweep_line->insert_right = &sweep_line->tail;

    sweep_line->current_y = INT32_MIN;

    sweep_line->last_y = INT32_MIN;

    pqueue_init (&sweep_line->pq);

}

static void

sweep_line_fini (sweep_line_t *sweep_line)

{

    pqueue_fini (&sweep_line->pq);

}

static void

end_box (sweep_line_t *sweep_line, edge_t *left, int32_t bot, cairo_boxes_t *out)

{

    if (likely (left->top < bot)) {

  cairo_status_t status;

  cairo_box_t box;

  box.p1.x = left->x;

  box.p1.y = left->top;

  box.p2.x = left->right->x;

  box.p2.y = bot;

  status = _cairo_boxes_add (out, CAIRO_ANTIALIAS_DEFAULT, &box);

  if (unlikely (status))

      longjmp (sweep_line->unwind, status);

    }

    left->right = NULL;

}

/* Start a new trapezoid at the given top y coordinate, whose edges

 * are `edge' and `edge->next'. If `edge' already has a trapezoid,

 * then either add it to the traps in `traps', if the trapezoid's

 * right edge differs from `edge->next', or do nothing if the new

 * trapezoid would be a continuation of the existing one. */

static inline void

start_or_continue_box (sweep_line_t *sweep_line,

           edge_t *left,

           edge_t *right,

           int     top,

           cairo_boxes_t *out)

{

    if (left->right == right)

  return;

    if (left->right != NULL) {

  if (right != NULL && left->right->x == right->x) {

      /* continuation on right, so just swap edges */

      left->right = right;

      return;

  }

  end_box (sweep_line, left, top, out);

    }

    if (right != NULL && left->x != right->x) {

  left->top = top;

  left->right = right;

    }

}

static inline int is_zero(const int *winding)

{

    return winding[0] == 0 || winding[1] == 0;

}

static inline void

active_edges (sweep_line_t *sweep, cairo_boxes_t *out)

{

    int top = sweep->current_y;

    int winding[2] = { 0 };

    edge_t *pos;

    if (sweep->last_y == sweep->current_y)

  return;

    pos = sweep->head.next;

    if (pos == &sweep->tail)

  return;

    do {

  edge_t *left, *right;

  left = pos;

  do {

      winding[left->a_or_b] += left->dir;

      if (!is_zero (winding))

    break;

      if (left->next == &sweep->tail)

    goto out;

      if (unlikely (left->right != NULL))

    end_box (sweep, left, top, out);

      left = left->next;

  } while (1);

  right = left->next;

  do {

      if (unlikely (right->right != NULL))

    end_box (sweep, right, top, out);

      winding[right->a_or_b] += right->dir;

      if (is_zero (winding)) {

    /* skip co-linear edges */

    if (likely (right->x != right->next->x))

        break;

      }

      right = right->next;

  } while (TRUE);

  start_or_continue_box (sweep, left, right, top, out);

  pos = right->next;

    } while (pos != &sweep->tail);

out:

    sweep->last_y = sweep->current_y;

}

static inline void

sweep_line_delete_edge (sweep_line_t *sweep_line, edge_t *edge, cairo_boxes_t *out)

{

    if (edge->right != NULL) {

  edge_t *next = edge->next;

  if (next->x == edge->x) {

      next->top = edge->top;

      next->right = edge->right;

  } else {

      end_box (sweep_line, edge, sweep_line->current_y, out);

  }

    }

    if (sweep_line->insert_left == edge)

  sweep_line->insert_left = edge->next;

    if (sweep_line->insert_right == edge)

  sweep_line->insert_right = edge->next;

    edge->prev->next = edge->next;

    edge->next->prev = edge->prev;

}

static inline void

sweep_line_delete (sweep_line_t *sweep,

       rectangle_t  *rectangle,

       cairo_boxes_t *out)

{

    sweep_line_delete_edge (sweep, &rectangle->left, out);

    sweep_line_delete_edge (sweep, &rectangle->right, out);

    pqueue_pop (&sweep->pq);

}

static inline void

insert_edge (edge_t *edge, edge_t *pos)

{

    if (pos->x != edge->x) {

  if (pos->x > edge->x) {

      do {

    UNROLL3({

        if (pos->prev->x <= edge->x)

      break;

        pos = pos->prev;

    })

      } while (TRUE);

  } else {

      do {

    UNROLL3({

        pos = pos->next;

        if (pos->x >= edge->x)

      break;

    })

      } while (TRUE);

  }

    }

    pos->prev->next = edge;

    edge->prev = pos->prev;

    edge->next = pos;

    pos->prev = edge;

}

static inline void

sweep_line_insert (sweep_line_t *sweep, rectangle_t *rectangle)

{

    edge_t *pos;

    /* right edge */

    pos = sweep->insert_right;

    insert_edge (&rectangle->right, pos);

    sweep->insert_right = &rectangle->right;

    /* left edge */

    pos = sweep->insert_left;

    if (pos->x > sweep->insert_right->x)

  pos = sweep->insert_right->prev;

    insert_edge (&rectangle->left, pos);

    sweep->insert_left = &rectangle->left;

    pqueue_push (sweep, rectangle);

}

static cairo_status_t

intersect (rectangle_t **rectangles, int num_rectangles, cairo_boxes_t *out)

{

    sweep_line_t sweep_line;

    rectangle_t *rectangle;

    cairo_status_t status;

    sweep_line_init (&sweep_line, rectangles, num_rectangles);

    if ((status = setjmp (sweep_line.unwind)))

  goto unwind;

    rectangle = rectangle_pop_start (&sweep_line);

    do {

  if (rectangle->top != sweep_line.current_y) {

      rectangle_t *stop;

      stop = rectangle_peek_stop (&sweep_line);

      while (stop != NULL && stop->bottom < rectangle->top) {

    if (stop->bottom != sweep_line.current_y) {

        active_edges (&sweep_line, out);

        sweep_line.current_y = stop->bottom;

    }

    sweep_line_delete (&sweep_line, stop, out);

    stop = rectangle_peek_stop (&sweep_line);

      }

      active_edges (&sweep_line, out);

      sweep_line.current_y = rectangle->top;

  }

  sweep_line_insert (&sweep_line, rectangle);

    } while ((rectangle = rectangle_pop_start (&sweep_line)) != NULL);

    while ((rectangle = rectangle_peek_stop (&sweep_line)) != NULL) {

  if (rectangle->bottom != sweep_line.current_y) {

      active_edges (&sweep_line, out);

      sweep_line.current_y = rectangle->bottom;

  }

  sweep_line_delete (&sweep_line, rectangle, out);

    }

unwind:

    sweep_line_fini (&sweep_line);

    return status;

}

static cairo_status_t

_cairo_boxes_intersect_with_box (const cairo_boxes_t *boxes,

         const cairo_box_t *box,

         cairo_boxes_t *out)

{

    cairo_status_t status;

    int i, j;

    if (out == boxes) { /* inplace update */

  struct _cairo_boxes_chunk *chunk;

  out->num_boxes = 0;

  for (chunk = &out->chunks; chunk != NULL; chunk = chunk->next) {

      for (i = j = 0; i < chunk->count; i++) {

    cairo_box_t *b = &chunk->base[i];

    b->p1.x = MAX (b->p1.x, box->p1.x);

    b->p1.y = MAX (b->p1.y, box->p1.y);

    b->p2.x = MIN (b->p2.x, box->p2.x);

    b->p2.y = MIN (b->p2.y, box->p2.y);

    if (b->p1.x < b->p2.x && b->p1.y < b->p2.y) {

        if (i != j)

      chunk->base[j] = *b;

        j++;

    }

      }

      /* XXX unlink empty chains? */

      chunk->count = j;

      out->num_boxes += j;

  }

    } else {

  const struct _cairo_boxes_chunk *chunk;

  _cairo_boxes_clear (out);

  _cairo_boxes_limit (out, box, 1);

  for (chunk = &boxes->chunks; chunk != NULL; chunk = chunk->next) {

      for (i = 0; i < chunk->count; i++) {

    status = _cairo_boxes_add (out,

             CAIRO_ANTIALIAS_DEFAULT,

             &chunk->base[i]);

    if (unlikely (status))

        return status;

      }

  }

    }

    return CAIRO_STATUS_SUCCESS;

}

cairo_status_t

_cairo_boxes_intersect (const cairo_boxes_t *a,

      const cairo_boxes_t *b,

      cairo_boxes_t *out)

{

    rectangle_t stack_rectangles[CAIRO_STACK_ARRAY_LENGTH (rectangle_t)];

    rectangle_t *rectangles;

    rectangle_t *stack_rectangles_ptrs[ARRAY_LENGTH (stack_rectangles) + 1];

    rectangle_t **rectangles_ptrs;

    const struct _cairo_boxes_chunk *chunk;

    cairo_status_t status;

    int i, j, count;

    if (unlikely (a->num_boxes == 0 || b->num_boxes == 0)) {

  _cairo_boxes_clear (out);

  return CAIRO_STATUS_SUCCESS;

    }

    if (a->num_boxes == 1) {

  cairo_box_t box = a->chunks.base[0];

  return _cairo_boxes_intersect_with_box (b, &box, out);

    }

    if (b->num_boxes == 1) {

  cairo_box_t box = b->chunks.base[0];

  return _cairo_boxes_intersect_with_box (a, &box, out);

    }

    rectangles = stack_rectangles;

    rectangles_ptrs = stack_rectangles_ptrs;

    count = a->num_boxes + b->num_boxes;

    if (count > ARRAY_LENGTH (stack_rectangles)) {

  rectangles = _cairo_malloc_ab_plus_c (count,

                sizeof (rectangle_t) +

                sizeof (rectangle_t *),

                sizeof (rectangle_t *));

  if (unlikely (rectangles == NULL))

      return _cairo_error (CAIRO_STATUS_NO_MEMORY);

  rectangles_ptrs = (rectangle_t **) (rectangles + count);

    }

    j = 0;

    for (chunk = &a->chunks; chunk != NULL; chunk = chunk->next) {

  const cairo_box_t *box = chunk->base;

  for (i = 0; i < chunk->count; i++) {

      if (box[i].p1.x < box[i].p2.x) {

    rectangles[j].left.x = box[i].p1.x;

    rectangles[j].left.dir = 1;

    rectangles[j].right.x = box[i].p2.x;

    rectangles[j].right.dir = -1;

      } else {

    rectangles[j].right.x = box[i].p1.x;

    rectangles[j].right.dir = 1;

    rectangles[j].left.x = box[i].p2.x;

    rectangles[j].left.dir = -1;

      }

      rectangles[j].left.a_or_b = 0;

      rectangles[j].left.right = NULL;

      rectangles[j].right.a_or_b = 0;

      rectangles[j].right.right = NULL;

      rectangles[j].top = box[i].p1.y;

      rectangles[j].bottom = box[i].p2.y;

      rectangles_ptrs[j] = &rectangles[j];

      j++;

  }

    }

    for (chunk = &b->chunks; chunk != NULL; chunk = chunk->next) {

  const cairo_box_t *box = chunk->base;

  for (i = 0; i < chunk->count; i++) {

      if (box[i].p1.x < box[i].p2.x) {

    rectangles[j].left.x = box[i].p1.x;

    rectangles[j].left.dir = 1;

    rectangles[j].right.x = box[i].p2.x;

    rectangles[j].right.dir = -1;

      } else {

    rectangles[j].right.x = box[i].p1.x;

    rectangles[j].right.dir = 1;

    rectangles[j].left.x = box[i].p2.x;

    rectangles[j].left.dir = -1;

      }

      rectangles[j].left.a_or_b = 1;

      rectangles[j].left.right = NULL;

      rectangles[j].right.a_or_b = 1;

      rectangles[j].right.right = NULL;

      rectangles[j].top = box[i].p1.y;

      rectangles[j].bottom = box[i].p2.y;

      rectangles_ptrs[j] = &rectangles[j];

      j++;

  }

    }

    assert (j == count);

    _cairo_boxes_clear (out);

    status = intersect (rectangles_ptrs, j, out);

    if (rectangles != stack_rectangles)

  free (rectangles);

    return status;

}