#include <math.h>
#include <evas_common_soft16.h>
#include "evas_soft16_scanline_fill.c"

typedef struct _RGBA_Edge RGBA_Edge;
typedef struct _RGBA_Vertex RGBA_Vertex;

struct _RGBA_Edge
{
   float x, dx;
   int i;
};

struct _RGBA_Vertex
{
   float x, y;
   int i;
};

#define POLY_EDGE_DEL(_i)                                               \
{                                                                       \
   int _j;                                                              \
                                                                        \
   for (_j = 0; (_j < num_active_edges) && (edges[_j].i != _i); _j++);  \
   if (_j < num_active_edges)                                           \
     {                                                                  \
	num_active_edges--;                                             \
	memmove(&(edges[_j]), &(edges[_j + 1]),                         \
	        (num_active_edges - _j) * sizeof(RGBA_Edge));           \
     }                                                                  \
}

#define POLY_EDGE_ADD(_i, _y)                                           \
{                                                                       \
   int _j;                                                              \
   float _dx;                                                           \
   RGBA_Vertex *_p, *_q;                                                \
   if (_i < (n - 1)) _j = _i + 1;                                       \
   else _j = 0;                                                         \
   if (point[_i].y < point[_j].y)                                       \
     {                                                                  \
	_p = &(point[_i]);                                              \
	_q = &(point[_j]);                                              \
     }                                                                  \
   else                                                                 \
     {                                                                  \
	_p = &(point[_j]);                                              \
	_q = &(point[_i]);                                              \
     }                                                                  \
   edges[num_active_edges].dx = _dx = (_q->x - _p->x) / (_q->y - _p->y); \
   edges[num_active_edges].x = (_dx * ((float)_y + 0.5 - _p->y)) + _p->x; \
   edges[num_active_edges].i = _i;                                      \
   num_active_edges++;                                                  \
}

static int
polygon_point_sorter(const void *a, const void *b)
{
   RGBA_Vertex *p, *q;

   p = (RGBA_Vertex *)a;
   q = (RGBA_Vertex *)b;
   if (p->y <= q->y) return -1;
   return 1;
}

static int
polygon_edge_sorter(const void *a, const void *b)
{
   RGBA_Edge *p, *q;

   p = (RGBA_Edge *)a;
   q = (RGBA_Edge *)b;
   if (p->x <= q->x) return -1;
   return 1;
}

void
evas_common_soft16_polygon_draw(Soft16_Image *dst, RGBA_Draw_Context *dc, RGBA_Polygon_Point *points, int x, int y)
{
   RGBA_Polygon_Point *pt;
   RGBA_Vertex       *point;
   RGBA_Edge         *edges;
   int                num_active_edges;
   int                n;
   int                i, j, k;
   int                y0, y1, yi;
   int                ext_x, ext_y, ext_w, ext_h;
   int               *sorted_index;
   DATA8 alpha;
   DATA16 rgb565;
   DATA32 rgb565_unpack;

   alpha = A_VAL(&dc->col.col) >> 3;
   if (alpha == 0)
     return;
   alpha++;

   rgb565 = RGB_565_FROM_COMPONENTS(R_VAL(&dc->col.col),
				    G_VAL(&dc->col.col),
				    B_VAL(&dc->col.col));
   rgb565_unpack = RGB_565_UNPACK(rgb565);

   ext_x = 0;
   ext_y = 0;
   ext_w = dst->cache_entry.w;
   ext_h = dst->cache_entry.h;
   if (dc->clip.use)
     RECTS_CLIP_TO_RECT(ext_x, ext_y, ext_w, ext_h,
			dc->clip.x, dc->clip.y, dc->clip.w, dc->clip.h);

   if ((ext_w <= 0) || (ext_h <= 0))
     return;

   n = 0;
   EINA_INLIST_FOREACH(points, pt) n++;

   if (n < 3)
     return;

   edges = malloc(sizeof(RGBA_Edge) * n);
   if (!edges)
     return;

   point = malloc(sizeof(RGBA_Vertex) * n);
   if (!point)
     {
	free(edges);
	return;
     }

   sorted_index = malloc(sizeof(int) * n);
   if (!sorted_index)
     {
	free(edges);
	free(point);
	return;
     }

   k = 0;
   EINA_INLIST_FOREACH(points, pt)
     {
	point[k].x = pt->x + x;
	point[k].y = pt->y + y;
	point[k].i = k;
	k++;
     }
   qsort(point, n, sizeof(RGBA_Vertex), polygon_point_sorter);

   for (k = 0; k < n; k++)
     sorted_index[k] = point[k].i;

   k = 0;
   EINA_INLIST_FOREACH(points, pt)
     {
	point[k].x = pt->x + x;
	point[k].y = pt->y + y;
	point[k].i = k;
	k++;
     }

   y0 = MAX(ext_y, ceil(point[sorted_index[0]].y - 0.5));
   y1 = MIN(ext_y + ext_h - 1, floor(point[sorted_index[n - 1]].y - 0.5));

   k = 0;
   num_active_edges = 0;

   for (yi = y0; yi <= y1; yi++)
     {
	for (; (k < n) && (point[sorted_index[k]].y <= ((float)yi + 0.5)); k++)
	  {
	     i = sorted_index[k];

	     if (i > 0) j = i - 1;
	     else j = n - 1;
	     if (point[j].y <= ((float)yi - 0.5))
	       {
		  POLY_EDGE_DEL(j)
	       }
	     else if (point[j].y > ((float)yi + 0.5))
	       {
		  POLY_EDGE_ADD(j, yi)
	       }
	     if (i < (n - 1)) j = i + 1;
	     else j = 0;
	     if (point[j].y <= ((float)yi - 0.5))
	       {
		  POLY_EDGE_DEL(i)
	       }
	     else if (point[j].y > ((float)yi + 0.5))
	       {
		  POLY_EDGE_ADD(i, yi)
	       }
	  }

	qsort(edges, num_active_edges, sizeof(RGBA_Edge), polygon_edge_sorter);

	for (j = 0; j < num_active_edges; j += 2)
	  {
	     int x0, x1;

	     x0 = ceil(edges[j].x - 0.5);
	     if (j < (num_active_edges - 1))
	       x1 = floor(edges[j + 1].x - 0.5);
	     else
	       x1 = x0;
	     if ((x1 >= ext_x) && (x0 < (ext_x + ext_w)) && (x0 <= x1))
	       {
		  DATA16 *dst_itr;
		  int w;

		  if (x0 < ext_x) x0 = ext_x;
		  if (x1 >= (ext_x + ext_w)) x1 = ext_x + ext_w - 1;

		  w = (x1 - x0) + 1;
		  dst_itr = dst->pixels + (yi * dst->stride) + x0;

		  if (alpha == 32)
		    _soft16_scanline_fill_solid_solid(dst_itr, w, rgb565);
		  else
		    _soft16_scanline_fill_transp_solid(dst_itr, w, rgb565_unpack, alpha);
	       }
	     edges[j].x += edges[j].dx;
	     edges[j + 1].x += edges[j + 1].dx;
	  }
     }

   free(edges);
   free(point);
   free(sorted_index);
}
