// Copyright (c) 2006, 2008 Edward Rosten

// All rights reserved.

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions

// are met:

//

//  *Redistributions of source code must retain the above copyright

//   notice, this list of conditions and the following disclaimer.

//

//  *Redistributions in binary form must reproduce the above copyright

//   notice, this list of conditions and the following disclaimer in the

//   documentation and/or other materials provided with the distribution.

//

//  *Neither the name of the University of Cambridge nor the names of

//   its contributors may be used to endorse or promote products derived

//   from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER

// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// clang-format off

#include <stdlib.h>

#include "fast.h"

#define Compare(X, Y) ((X)>=(Y))

xy* aom_nonmax_suppression(const xy* corners, const int* scores, int num_corners, int* ret_num_nonmax)

{

  int num_nonmax=0;

  int last_row;

  int* row_start;

  int i, j;

  xy* ret_nonmax;

  const int sz = (int)num_corners;

  /*Point above points (roughly) to the pixel above the one of interest, if there

    is a feature there.*/

  int point_above = 0;

  int point_below = 0;

  if(num_corners < 1)

  {

    *ret_num_nonmax = 0;

    return 0;

  }

  ret_nonmax = (xy*)malloc(num_corners * sizeof(xy));

  /* Find where each row begins

     (the corners are output in raster scan order). A beginning of -1 signifies

     that there are no corners on that row. */

  last_row = corners[num_corners-1].y;

  row_start = (int*)malloc((last_row+1)*sizeof(int));

  for(i=0; i < last_row+1; i++)

    row_start[i] = -1;

  {

    int prev_row = -1;

    for(i=0; i< num_corners; i++)

      if(corners[i].y != prev_row)

      {

        row_start[corners[i].y] = i;

        prev_row = corners[i].y;

      }

  }

  for(i=0; i < sz; i++)

  {

    int score = scores[i];

    xy pos = corners[i];

    /*Check left */

    if(i > 0)

      if(corners[i-1].x == pos.x-1 && corners[i-1].y == pos.y && Compare(scores[i-1], score))

        continue;

    /*Check right*/

    if(i < (sz - 1))

      if(corners[i+1].x == pos.x+1 && corners[i+1].y == pos.y && Compare(scores[i+1], score))

        continue;

    /*Check above (if there is a valid row above)*/

    if(pos.y > 0)

      if (row_start[pos.y - 1] != -1)

      {

        /*Make sure that current point_above is one

          row above.*/

        if(corners[point_above].y < pos.y - 1)

          point_above = row_start[pos.y-1];

        /*Make point_above point to the first of the pixels above the current point,

          if it exists.*/

        for(; corners[point_above].y < pos.y && corners[point_above].x < pos.x - 1; point_above++)

        {}

        for(j=point_above; corners[j].y < pos.y && corners[j].x <= pos.x + 1; j++)

        {

          int x = corners[j].x;

          if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j], score))

            goto cont;

        }

      }

    /*Check below (if there is anything below)*/

    if(pos.y >= 0)

      if (pos.y != last_row && row_start[pos.y + 1] != -1 && point_below < sz) /*Nothing below*/

      {

        if(corners[point_below].y < pos.y + 1)

          point_below = row_start[pos.y+1];

        /* Make point below point to one of the pixels belowthe current point, if it

           exists.*/

        for(; point_below < sz && corners[point_below].y == pos.y+1 && corners[point_below].x < pos.x - 1; point_below++)

        {}

        for(j=point_below; j < sz && corners[j].y == pos.y+1 && corners[j].x <= pos.x + 1; j++)

        {

          int x = corners[j].x;

          if( (x == pos.x - 1 || x ==pos.x || x == pos.x+1) && Compare(scores[j],score))

            goto cont;

        }

      }

    ret_nonmax[num_nonmax++] = corners[i];

cont:

    ;

  }

  free(row_start);

  *ret_num_nonmax = num_nonmax;

  return ret_nonmax;

}

// clang-format on