/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program 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 General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */


#include "sql_string.h"

#ifdef HAVE_SPATIAL

#include "gcalc_slicescan.h"


#define PH_DATA_OFFSET 8
#define coord_to_float(d) ((double) d)

typedef int (*sc_compare_func)(const void*, const void*);

#define LS_LIST_ITEM Gcalc_dyn_list::Item
#define LS_COMPARE_FUNC_DECL sc_compare_func compare,
#define LS_COMPARE_FUNC_CALL(list_el1, list_el2) (*compare)(list_el1, list_el2)
#define LS_NEXT(A) (A)->next
#define LS_SET_NEXT(A,val) (A)->next= val
#define LS_P_NEXT(A) &(A)->next
#define LS_NAME sort_list
#define LS_SCOPE static
#define LS_STRUCT_NAME sort_list_stack_struct
#include "plistsort.c"


Gcalc_dyn_list::Gcalc_dyn_list(size_t blk_size, size_t sizeof_item):
#ifndef DBUG_OFF
  m_last_item_id(0),
#endif
  m_blk_size(blk_size - ALLOC_ROOT_MIN_BLOCK_SIZE),
  m_sizeof_item(ALIGN_SIZE(sizeof_item)),
  m_points_per_blk((m_blk_size - PH_DATA_OFFSET) / m_sizeof_item),
  m_blk_hook(&m_first_blk),
  m_free(NULL),
  m_keep(NULL)
{}


void Gcalc_dyn_list::format_blk(void* block)
{
  Item *pi_end, *cur_pi, *first_pi;
  DBUG_ASSERT(m_free == NULL);
  first_pi= cur_pi= (Item *)(((char *)block) + PH_DATA_OFFSET);
  pi_end= ptr_add(first_pi, m_points_per_blk - 1);
  do {
    cur_pi= cur_pi->next= ptr_add(cur_pi, 1);
  } while (cur_pi<pi_end);
  cur_pi->next= m_free;
  m_free= first_pi;
}


bool Gcalc_dyn_list::alloc_new_blk()
{
  void *new_block= my_malloc(m_blk_size, MYF(MY_WME));
  if (!new_block)
    return true;
  *m_blk_hook= new_block;
  m_blk_hook= (void**)new_block;
  format_blk(new_block);
  return false;
}


static void free_blk_list(void *list)
{
  void *next_blk;
  while (list)
  {
    next_blk= *((void **)list);
    my_free(list);
    list= next_blk;
  }
}


void Gcalc_dyn_list::cleanup()
{
  *m_blk_hook= NULL;
  free_blk_list(m_first_blk);
  m_first_blk= NULL;
  m_blk_hook= &m_first_blk;
  m_free= NULL;
}


Gcalc_dyn_list::~Gcalc_dyn_list()
{
  cleanup();
}


void Gcalc_dyn_list::reset()
{
  *m_blk_hook= NULL;
  if (m_first_blk)
  {
    free_blk_list(*((void **)m_first_blk));
    m_blk_hook= (void**)m_first_blk;
    m_free= NULL;
    format_blk(m_first_blk);
  }
}


static inline void trim_node(Gcalc_heap::Info *node, Gcalc_heap::Info *prev_node)
{
  if (!node)
    return;
  DBUG_ASSERT((node->left == prev_node) || (node->right == prev_node));
  if (node->left == prev_node)
    node->left= node->right;
  node->right= NULL;
}


static double find_first_different(const Gcalc_heap::Info *p)
{
  if (p->left && (p->left->y != p->y))
    return p->left->y;
  if (p->right && (p->right->y != p->y))
    return p->right->y;
  if (p->left && p->left->left && (p->left->left->y != p->y))
    return p->left->left->y;
  if (p->right && p->right->right && (p->right->right->y != p->y))
    return p->right->right->y;

  return p->y;
}


static int compare_point_info(const void *e0, const void *e1)
{
  const Gcalc_heap::Info *i0= (const Gcalc_heap::Info *)e0;
  const Gcalc_heap::Info *i1= (const Gcalc_heap::Info *)e1;
  if (i0->y != i1->y)
    return i0->y > i1->y;
  double i0_fd= find_first_different(i0);
  double i1_fd= find_first_different(i1);
  if (i0_fd != i1_fd)
    return i0_fd > i1_fd;
  return i0->x > i1->x;
}


#ifndef DBUG_OFF
void Gcalc_heap::Info::dbug_print() const
{
  char left_str[64]= "", right_str[64]= "";
  if (left)
    my_snprintf(left_str, sizeof(left_str),
                "(%g,%g,#%u)", left->x, left->y, left->shape);
  if (right)
    my_snprintf(right_str, sizeof(right_str), "(%g,%g,#%u)",
                right->x, right->y, right->shape);
  DBUG_PRINT("info", ("(%g,%g,#%u) left=%s right=%s",
                     x, y, shape, left_str, right_str));
}
#endif


void Gcalc_heap::prepare_operation()
{
  DBUG_ENTER("Gcalc_heap::prepare_operation");
  DBUG_PRINT("info", ("m_n_points=%d", m_n_points));
  DBUG_ASSERT(m_hook);
  *m_hook= NULL;
  m_first= sort_list(compare_point_info, m_first, m_n_points);
  m_hook= NULL; /* just to check it's not called twice */

  DBUG_PRINT("info", ("after sort_list:"));
  /* TODO - move this to the 'normal_scan' loop */
  for (Info *cur= get_first(); cur; cur= cur->get_next())
  {
    trim_node(cur->left, cur);
    trim_node(cur->right, cur);
#ifndef DBUG_OFF
    cur->dbug_print();
#endif
  }
  DBUG_VOID_RETURN;
}


void Gcalc_heap::reset()
{
  if (!m_hook)
  {
    m_hook= &m_first;
    for (; *m_hook; m_hook= &(*m_hook)->next)
    {}
  }

  *m_hook= m_free;
  m_free= m_first;
  m_hook= &m_first;
  m_n_points= 0;
}

int Gcalc_shape_transporter::int_single_point(gcalc_shape_info Info,
                                              double x, double y)
{
  Gcalc_heap::Info *point= m_heap->new_point_info(x, y, Info);
  if (!point)
    return 1;
  point->left= point->right= 0;
  return 0;
}


int Gcalc_shape_transporter::int_add_point(gcalc_shape_info Info,
                                           double x, double y)
{
  Gcalc_heap::Info *point;
  if (!(point= m_heap->new_point_info(x, y, Info)))
    return 1;
  if (m_first)
  {
    m_prev->left= point;
    point->right= m_prev;
  }
  else
    m_first= point;
  m_prev= point;
  return 0;
}


void Gcalc_shape_transporter::int_complete()
{
  DBUG_ASSERT(m_shape_started == 1 || m_shape_started == 3);

  if (!m_first)
    return;

  /* simple point */
  if (m_first == m_prev)
  {
    m_first->right= m_first->left= NULL;
    return;
  }

  /* line */
  if (m_shape_started == 1)
  {
    m_first->right= NULL;
    m_prev->left= m_prev->right;
    m_prev->right= NULL;
    return;
  }

  /* polygon */
  m_first->right= m_prev;
  m_prev->left= m_first;
}


inline int GET_DX_DY(double *dxdy,
                     const Gcalc_heap::Info *p0, const Gcalc_heap::Info *p1)
{
  double dy= p1->y - p0->y;
  *dxdy= p1->x - p0->x;
  return (dy == 0.0) ||
         (*dxdy/= dy)>DBL_MAX ||
         (*dxdy)<-DBL_MAX;
}

Gcalc_scan_iterator::Gcalc_scan_iterator(size_t blk_size) :
  Gcalc_dyn_list(blk_size,
	         (sizeof(point) > sizeof(intersection)) ?
	          sizeof(point) : sizeof(intersection)),
  m_slice0(NULL), m_slice1(NULL)
{}
		  
Gcalc_scan_iterator::point
  *Gcalc_scan_iterator::new_slice(Gcalc_scan_iterator::point *example)
{
  Gcalc_dyn_list::Item *item_result= NULL;
  Gcalc_dyn_list::Item **result_hook= &item_result;
  while (example)
  {
    *result_hook= new_slice_point();
    result_hook= &(*result_hook)->next;
    example= example->get_next();
  }
  *result_hook= NULL;
  point *result= static_cast<point*>(item_result);
  return result;
}


void Gcalc_scan_iterator::init(Gcalc_heap *points)
{
  DBUG_ASSERT(points->ready());
  DBUG_ASSERT(!m_slice0 && !m_slice1);

  if (!(m_cur_pi= points->get_first()))
    return;
  m_cur_thread= 0;
  m_sav_slice= NULL;
  m_intersections= NULL;
  m_cur_intersection= NULL;
  m_y1= m_cur_pi->y;
  m_next_is_top_point= true;
  m_bottom_points_count= 0;
}

void Gcalc_scan_iterator::reset()
{
  if (m_slice0)
    free_list(m_slice0);
  if (m_slice1)
    free_list(m_slice1);
  m_slice0= m_slice1= NULL;
  Gcalc_dyn_list::reset();
}

static bool slice_first_equal_x(const Gcalc_scan_iterator::point *p0,
				const Gcalc_scan_iterator::point *p1)
{
  if (p0->horiz_dir == p1->horiz_dir)
    return p0->dx_dy <= p1->dx_dy;
  if (p0->horiz_dir)
    return p0->dx_dy < 0;
  return p1->dx_dy > 0;  /* p1->horiz_dir case */
}


static inline bool slice_first(const Gcalc_scan_iterator::point *p0,
			       const Gcalc_scan_iterator::point *p1)
{
  if (p0->x != p1->x)
    return p0->x < p1->x;
  return slice_first_equal_x(p0, p1);
}


int Gcalc_scan_iterator::insert_top_point()
{
  point *sp0= new_slice_point();
  if (!sp0)
    return 1;

  sp0->pi= m_cur_pi;
  sp0->next_pi= m_cur_pi->left;
  sp0->thread= m_cur_thread++;
  sp0->x= coord_to_float(m_cur_pi->x);
  if (m_cur_pi->left)
  {
    sp0->horiz_dir= GET_DX_DY(&sp0->dx_dy, m_cur_pi, m_cur_pi->left);
    m_event1= scev_thread;

    /*Now just to increase the size of m_slice0 to be same*/
    point *sp1= new_slice_point();
    if (!sp1)
      return 1;
    sp1->next= m_slice0;
    m_slice0= sp1;
  }
  else
  {
    m_event1= scev_single_point;
    sp0->horiz_dir= 0;
    sp0->dx_dy= 0.0;
  }

  /* First we need to find the place to insert.
     Binary search could probably make things faster here,
     but structures used aren't suitable, and the
     scan is usually not really long */
  point *sp= m_slice1;
  point **prev_hook= &m_slice1;
  for (; sp && slice_first(sp, sp0); sp=sp->get_next())
  {
    prev_hook= reinterpret_cast<point**>(&(sp->next));
  }

  if (m_cur_pi->right)
  {
    m_event1= scev_two_threads;
    /*We have two threads so should decide which one will be first*/
    point *sp1= new_slice_point();
    if (!sp1)
      return 1;
    sp1->pi= m_cur_pi;
    sp1->next_pi= m_cur_pi->right;
    sp1->thread= m_cur_thread++;
    sp1->x= sp0->x;
    sp1->horiz_dir= GET_DX_DY(&sp1->dx_dy, m_cur_pi, m_cur_pi->right);
    // Find the slice with stronger left gradient
    if (slice_first_equal_x(sp1, sp0))
    {
      point *tmp= sp0;
      sp0= sp1;
      sp1= tmp;
    }
    sp1->next= sp;
    sp0->next= sp1;
    
    /*Now just to increase the size of m_slice0 to be same*/
    if (!(sp1= new_slice_point()))
      return 1;
    sp1->next= m_slice0;
    m_slice0= sp1;
  }
  else
    sp0->next= sp;

  *prev_hook= sp0;
  m_event_position1= sp0;

  return 0;
}

enum
{
  intersection_normal= 1,
  intersection_forced= 2
};


static int intersection_found(const Gcalc_scan_iterator::point *sp0,
			      const Gcalc_scan_iterator::point *sp1,
			      unsigned int bottom_points_count)
{
  if (sp1->x < sp0->x)
    return intersection_normal;
  if (sp1->is_bottom() && !sp0->is_bottom() &&
      (bottom_points_count > 1))
      return intersection_forced;
  return 0;
}


#ifndef DBUG_OFF
const char *Gcalc_scan_event_name(enum Gcalc_scan_events event)
{
  switch (event)
  {
    case scev_point:        return "scev_point";
    case scev_thread:       return "scev_thread";
    case scev_two_threads:  return "scev_two_threads";
    case scev_intersection: return "scev_intersection";
    case scev_end:          return "scev_end";
    case scev_two_ends:     return "scev_two_ends";
    case scev_single_point: return "scev_single_point";
  }
  return "scev_unknown";
}


void Gcalc_scan_iterator::point::dbug_print_slice(double y,
                                                  enum Gcalc_scan_events event)
                                                  const
{
  DBUG_PRINT("info", ("y=%g event=%s", y, Gcalc_scan_event_name(event)));
  for (const point *slice= this ; slice ; slice= slice->get_next())
  {
    if (slice->next_pi)
      DBUG_PRINT("into", ("(x=%g,thr#%d) pi=(%g,%g,#%u) next_pi=(%g,%g,#%u)",
                           slice->x, slice->thread,
                           slice->pi->x, slice->pi->y, slice->pi->shape,
                           slice->next_pi->x, slice->next_pi->y,
                           slice->next_pi->shape));
    else
      DBUG_PRINT("info", ("(x=%g,thr#%d) pi=(%g,%g,#%u)",
                           slice->x, slice->thread,
                           slice->pi->x, slice->pi->y, slice->pi->shape));
  }
}
#endif /* DBUG_OFF */


int Gcalc_scan_iterator::normal_scan()
{
  if (m_next_is_top_point)
    if (insert_top_point())
      return 1;

#ifndef DBUG_OFF
  m_slice1->dbug_print_slice(m_y1, m_event1);
#endif

  point *tmp= m_slice0;
  m_slice0= m_slice1;
  m_slice1= tmp;
  m_event0= m_event1;
  m_event_position0= m_event_position1;
  m_y0= m_y1;
  
  if (!(m_cur_pi= m_cur_pi->get_next()))
  {
    free_list(m_slice1);
    m_slice1= NULL;
    return 0;
  }
  
  Gcalc_heap::Info *cur_pi= m_cur_pi;
  m_y1= coord_to_float(cur_pi->y);
  m_h= m_y1 - m_y0; // vertical distance between slices

  point *sp0= m_slice0;
  point *sp1= m_slice1;
  point *prev_sp1= NULL;

  m_bottom_points_count= 0;
  m_next_is_top_point= true;
  bool intersections_found= false;

  for (; sp0; sp0= sp0->get_next())
  {
    if (sp0->next_pi == cur_pi) /* End of the segment */
    {
      sp1->x= coord_to_float(cur_pi->x);
      sp1->pi= cur_pi;
      sp1->thread= sp0->thread;
      sp1->next_pi= cur_pi->left;
      if (cur_pi->left)
	sp1->horiz_dir= GET_DX_DY(&sp1->dx_dy, m_cur_pi, m_cur_pi->left);

      m_next_is_top_point= false;
      
      if (sp1->is_bottom())
      {
	++m_bottom_points_count;
	if (m_bottom_points_count == 1)
	{
	  m_event1= scev_end;
	  m_event_position1= sp1;
	}
	else
	  m_event1= scev_two_ends;
      }
      else
      {
	m_event1= scev_point;
	m_event_position1= sp1;
      }
    }
    else if (!sp0->is_bottom())
    {
      /* Cut current string with the height of the new point*/
      sp1->copy_core(sp0);
      sp1->x= sp1->horiz_dir ? sp0->x :
	(coord_to_float(sp1->pi->x) +
	 (m_y1-coord_to_float(sp1->pi->y)) * sp1->dx_dy);
    }
    else  /* Skip the bottom point in slice0 */
      continue;

    intersections_found= intersections_found ||
      (prev_sp1 && intersection_found(prev_sp1, sp1, m_bottom_points_count));

    prev_sp1= sp1;
    sp1= sp1->get_next();
  }

  if (sp1)
  {
    if (prev_sp1)
      prev_sp1->next= NULL;
    else
      m_slice1= NULL;
    free_list(sp1);
  }

  if (intersections_found)
    return handle_intersections();

  return 0;
}


int Gcalc_scan_iterator::add_intersection(const point *a, const point *b,
				   int isc_kind, Gcalc_dyn_list::Item ***p_hook)
{
  intersection *isc= new_intersection();

  if (!isc)
    return 1;
  m_n_intersections++;
  **p_hook= isc;
  *p_hook= &isc->next;
  isc->thread_a= a->thread;
  isc->thread_b= b->thread;
  if (isc_kind == intersection_forced)
  {
    isc->y= m_y1;
    isc->x= a->x;
    return 0;
  }

  /* intersection_normal */
  const point *a0= a->precursor;
  const point *b0= b->precursor;
  if (!a0->horiz_dir && !b0->horiz_dir)
  {
    double dk= a0->dx_dy - b0->dx_dy;
    double dy= (b0->x - a0->x)/dk;
    isc->y= m_y0 + dy;
    isc->x= a0->x + dy*a0->dx_dy;
    return 0;
  }
  isc->y= m_y1;
  isc->x= a0->horiz_dir ? b->x : a->x;
  return 0;
}


int Gcalc_scan_iterator::find_intersections()
{
  point *sp1= m_slice1;

  m_n_intersections= 0;
  {
    /* Set links between slicepoints */
    point *sp0= m_slice0;
    for (; sp1; sp0= sp0->get_next(),sp1= sp1->get_next())
    {
      while (sp0->is_bottom())
	sp0= sp0->get_next();
      DBUG_ASSERT(sp0->thread == sp1->thread);
      sp1->precursor= sp0;
    }
  }

  Gcalc_dyn_list::Item **hook=
    reinterpret_cast<Gcalc_dyn_list::Item **>(&m_intersections);
  bool intersections_found;

  point *last_possible_isc= NULL;
  do
  {
    sp1= m_slice1;
    point **pprev_s1= &m_slice1;
    intersections_found= false;
    unsigned int bottom_points_count= sp1->is_bottom() ? 1:0;
    sp1= m_slice1->get_next();
    int isc_kind;
    point *cur_possible_isc= NULL;
    for (; sp1 != last_possible_isc;
	 pprev_s1= (point **)(&(*pprev_s1)->next), sp1= sp1->get_next())
    {
      if (sp1->is_bottom())
	++bottom_points_count;
      if (!(isc_kind=intersection_found(*pprev_s1, sp1, bottom_points_count)))
	continue;
      point *prev_s1= *pprev_s1;
      intersections_found= true;
      if (add_intersection(prev_s1, sp1, isc_kind, &hook))
	return 1;
      *pprev_s1= sp1;
      prev_s1->next= sp1->next;
      sp1->next= prev_s1;
      sp1= prev_s1;
      cur_possible_isc= sp1;
    }
    last_possible_isc= cur_possible_isc;
  } while (intersections_found);

  *hook= NULL;
  return 0;
}


static int compare_intersections(const void *e0, const void *e1)
{
  Gcalc_scan_iterator::intersection *i0= (Gcalc_scan_iterator::intersection *)e0;
  Gcalc_scan_iterator::intersection *i1= (Gcalc_scan_iterator::intersection *)e1;
  return i0->y > i1->y;
}


inline void Gcalc_scan_iterator::sort_intersections()
{
  m_intersections= (intersection *)sort_list(compare_intersections,
                                             m_intersections,m_n_intersections);
}


int Gcalc_scan_iterator::handle_intersections()
{
  DBUG_ASSERT(m_slice1->next);

  if (find_intersections())
    return 1;
  sort_intersections();

  m_sav_slice= m_slice1;
  m_sav_y= m_y1;
  m_slice1= new_slice(m_sav_slice);
  
  m_cur_intersection= m_intersections;
  m_pre_intersection_hook= NULL;
  return intersection_scan();
}


int Gcalc_scan_iterator::pop_suitable_intersection()
{
  intersection *prev_i= m_cur_intersection;
  intersection *cur_i= prev_i->get_next();
  for (; cur_i; prev_i= cur_i, cur_i= cur_i->get_next())
  {
    point *prev_p= m_slice0;
    point *sp= prev_p->get_next();
    for (; sp; prev_p= sp, sp= sp->get_next())
    {
      if ((prev_p->thread == cur_i->thread_a) &&
	  (sp->thread == cur_i->thread_b))
      {
	/* Move cur_t on the top of the list */
	if (prev_i == m_cur_intersection)
	{
	  m_cur_intersection->next= cur_i->next;
	  cur_i->next= m_cur_intersection;
	  m_cur_intersection= cur_i;
	}
	else
	{
          Gcalc_dyn_list::Item *tmp= m_cur_intersection->next;
	  m_cur_intersection->next= cur_i->next;
	  prev_i->next= m_cur_intersection;
	  m_cur_intersection= cur_i;
	  cur_i->next= tmp;
	}
	return 0;
      }
    }
  }
  return 1;
}


int Gcalc_scan_iterator::intersection_scan()
{
  if (m_pre_intersection_hook) /*Skip the first point*/
  {
    point *next= (*m_pre_intersection_hook)->get_next();
    (*m_pre_intersection_hook)->next= next->next;
    next->next= *m_pre_intersection_hook;
    *m_pre_intersection_hook= next;
    m_event0= scev_intersection;
    m_event_position0= next;
    point *tmp= m_slice1;
    m_slice1= m_slice0;
    m_slice0= tmp;
    m_y0= m_y1;
    m_cur_intersection= m_cur_intersection->get_next();
    if (!m_cur_intersection)
    {
      m_h= m_sav_y - m_y1;
      m_y1= m_sav_y;
      free_list(m_slice1);
      m_slice1= m_sav_slice;
      free_list(m_intersections);
      return 0;
    }
  }

  m_y1= m_cur_intersection->y;
  m_h= m_y1 - m_y0;

  point *sp0;
  point **psp1;

redo_loop:
  sp0= m_slice0;
  psp1= &m_slice1;
  for (; sp0; sp0= sp0->get_next())
  {
    point *sp1= *psp1;
    if (sp0->thread == m_cur_intersection->thread_a)
    {
      point *next_s0= sp0;
      /* Skip Bottom points */
      do
	next_s0= next_s0->get_next();
      while(next_s0->is_bottom()); /* We always find nonbottom point here*/
      /* If the next point's thread isn't the thread of intersection,
	 we try to find suitable intersection */
      if (next_s0->thread != m_cur_intersection->thread_b)
      {
	/* It's really rare case - sometimes happen when
	   there's two intersections with the same Y
	   Move suitable one to the beginning of the list
	*/
	if (pop_suitable_intersection())
          return 1;
	goto redo_loop;
      }
      m_pre_intersection_hook= psp1;
      sp1->copy_core(sp0);
      sp1->x= m_cur_intersection->x;
      sp0= next_s0;
      sp1= sp1->get_next();
      sp1->copy_core(sp0);
      sp1->x= m_cur_intersection->x;
      psp1= (point **)&sp1->next;
      continue;
    }
    if (!sp0->is_bottom())
    {
      sp1->copy_core(sp0);
      sp1->x= sp1->horiz_dir ? sp0->x :
	(coord_to_float(sp1->pi->x) +
	 (m_y1-coord_to_float(sp1->pi->y)) * sp1->dx_dy);
    }
    else
      /* Skip bottom point */
      continue;
    psp1= (point **)&sp1->next;
  }

  if (*psp1)
  {
    free_list(*psp1);
    *psp1= NULL;
  }

  return 0;
}

#endif /* HAVE_SPATIAL */
