#include <iostream>
#include <math.h>
#include "draw.h"


int round (double x)
{
  if ((x - (int) x) > 0.5)
      return (int) (x + 1);
  else
      return (int) x;
}
      

void findEdges (int x0, int y0, int x1, int y1, int* left, 
                int* right, int bot)
{
  int dx = abs(x1 - x0);
  int dy = abs(y1 - y0);
       
  if (dy == 0)
      return;

  if (dx == 0)
  {
      if (y1 < y0)
      {
          swapint(x0,x1);
          swapint(y0,y1);
      } 

      for (int i = 0, y = y0; y <= y1; i++, y++)
      {
          if (right[y-bot] == -1)
              right[y-bot] = x0;
          else if (left[y-bot] == -1)
              left[y-bot] = x0;
          else if (x0 < left[y-bot])
              left[y-bot] = x0;
          else if (x0 > right[y-bot])
              right[y-bot] = x0;

          if (right[y-bot] < left[y-bot])
              swapint(left[y-bot], right[y-bot]);
      }

      return;
  }
  
  double m = (y1 - y0) / (double) (x1 - x0);
  double b = y0 - m*x0;

  if (dx > dy)
  {       
      if (x1 < x0)
      {
          swapint(x0,x1);
          swapint(y0,y1);
      }
    
      int y;      
  
      for (int i = 0, x = x0; x <= x1; i++, x++)
      {
          y = round(m*x + b);

          if (right[y-bot] == -1)
              right[y-bot] = x;
          else if (left[y-bot] == -1)
              left[y-bot] = x;
          else if (x < left[y-bot])
              left[y-bot] = x;
          else if (x > right[y-bot])
              right[y-bot] = x;
  
          if (right[y-bot] < left[y-bot])
              swapint(left[y-bot], right[y-bot]);
      }
  }
  else
  {
      if (y1 < y0)
      {
          swapint(x0,x1);
          swapint(y0,y1);
      }
      
      int x;

      for (int i = 0, y = y0; y <= y1; i++, y++)
      {   
          x = round((y - b) / m);

          if (right[y-bot] == -1)
              right[y-bot] = x;
          else if (left[y-bot] == -1)
              left[y-bot] = x;
          else if (x < left[y-bot])
              left[y-bot] = x;
          else if (x > right[y-bot])
              right[y-bot] = x;
  
          if (right[y-bot] < left[y-bot])
              swapint(left[y-bot], right[y-bot]);
      }
  }
}


void drawHLine (Image* dst, int y, int x0, int x1, Pixel& p)
{
  if ((y < 0) ||
      (y >= dst->getHeight()))
      return;
                         
  if ((x0 < 0) ||
      (x1 < 0) ||
      (x0 >= dst->getWidth()) ||
      (x1 >= dst->getWidth()))
      return;

  for (int x = x0; x <= x1; x++)
      dst->setPixel(x, y, p);
}         


void drawQuad (Image* dst, point i, point j, point k, point l, Pixel& p)
{
  int x0 = i.x;
  int y0 = i.y;
  int x1 = j.x;
  int y1 = j.y;
  int x2 = k.x;
  int y2 = k.y;
  int x3 = l.x;
  int y3 = l.y;

  int top    = max4(y0,y1,y2,y3);
  int bot    = min4(y0,y1,y2,y3);
  int height = top - bot + 1;

  int* left  = new int[height];
  int* right = new int[height];

  for (int i = 0; i < height; i++)
  {
    left[i]  = -1;
    right[i] = -1;
  }

  findEdges(x0, y0, x1, y1, left, right, bot);
  findEdges(x1, y1, x2, y2, left, right, bot);
  findEdges(x2, y2, x3, y3, left, right, bot);
  findEdges(x3, y3, x0, y0, left, right, bot); 

  for (int i = 0; i < height; i++)
    drawHLine(dst, bot+i, left[i], right[i], p);

  delete[] left;
  delete[] right;
}


void drawPoly (Image* dst, point* pts, int n, Pixel& p)
{
  int top = 0;
  int bot = 0;
  for (int i = 0; i < n; i++)
  {
    top = max(top, pts[i].y);
    bot = max(top, pts[i].y);
  }

  int height = top - bot + 1;

  int* left  = new int[height];
  int* right = new int[height];

  for (int i = 0; i < height; i++)
  {
    left[i]  = -1;
    right[i] = -1;
  }

  for (int i = 0; i < n; i++)
    findEdges(pts[i].x, pts[i].y, pts[(i+1)%n].x, pts[(i+1)%n].y, 
              left, right, bot);

  for (int i = 0; i < height; i++)
    drawHLine(dst, bot+i, left[i], right[i], p);

  delete[] left;
  delete[] right;
}


void drawCircle(Image* img, int x, int y, int r, Pixel& p)
{
  int left   = x - r;
  int right  = x + r;
  int top    = y - r;    
  int bottom = y + r;

  left   = clamp(left,   0, img->getWidth()  - 1);
  right  = clamp(right,  0, img->getWidth()  - 1);
  top    = clamp(top,    0, img->getHeight() - 1);
  bottom = clamp(bottom, 0, img->getHeight() - 1);
 
  for (int i = left; i <= right; i++)
    for (int j = top; j <= bottom; j++)
      if (((i-x)*(i-x) + (j-y)*(j-y)) <= sqr(r))
        img->setPixel(i,j,p);
}
          
       
void drawAntiAliasedCircle(Image* img, int x, int y, int r, Pixel& p)
{
  double e = 0.7;
          
  int left   = x - r;
  int right  = x + r;
  int top    = y - r;
  int bottom = y + r;

  left   = clamp(left,   0, img->getWidth()  - 1);
  right  = clamp(right,  0, img->getWidth()  - 1);
  top    = clamp(top,    0, img->getHeight() - 1);
  bottom = clamp(bottom, 0, img->getHeight() - 1);
 
  for (int i = left; i <= right; i++)
    for (int j = top; j <= bottom; j++)
      if (((i-x)*(i-x) + (j-y)*(j-y)) <= sqr(r))
      {
        img->setPixel(i,j,p);
      }
      else if (((i-x)*(i-x) + (j-y)*(j-y)) <= sqr(r+e))
      {
        double a = (-r + sqrt(((double) (i-x)*(i-x) + (j-y)*(j-y)))) / e;

        Pixel q;
        img->getPixel(i,j,q);

        Pixel n;
        n.r = (1-a)*p.r + a*q.r;
        n.g = (1-a)*p.g + a*q.g;
        n.b = (1-a)*p.b + a*q.b;

        img->setPixel(i,j,n);
      } 
}