#include "libwasm.h"
#include "canvas.h"

int round (const double a) {
  return int (a + 0.5);
}

Canvas::Canvas(const int w, const int h) : width(w), height(h),
  outpixel(0u), current(0xFF000000), matrix (1.0, 0.0, 0.0, -1.0, 0.5 * (real) w, 0.5 * (real) (h)) {
  data = new Color [w * h];
}

Canvas::~Canvas() {
  delete [] data;
}
void Canvas::fill (const Color & c) {
  for (int y=0; y<height; y++) {
    for (int x=0; x<width; x++) {
      at (x, y) = c;
    }
  }
}
Color & Canvas::at (const int x, const int y) {
  if (!bound(x, y)) return outpixel;
  const int result = x + y * width;
  return data [result];
}
bool Canvas::bound (const int x, const int y) const {
  if (x < 0)       return false;
  if (y < 0)       return false;
  if (x >= width)  return false;
  if (y >= height) return false;
  return true;
}
void Canvas::line (const int xp, const int yp, const int xe, const int ye, const bool doted) {
  bool dot = true;
  int x1 = xp, y1 = yp;
  const int x2 = xe, y2 = ye;
  bool done = false;
  int mx = 0, my = 0;
  // Determine direction and distance
  const int xd = (x1 < x2) ? 1 : -1;
  const int yd = (y1 < y2) ? 1 : -1;
  const int xl = (x1 < x2) ? (x2 - x1) : (x1 - x2);
  const int yl = (y1 < y2) ? (y2 - y1) : (y1 - y2);
  while (!done) {
    if (x1 == x2 && y1 == y2) done = true;
    if (dot) at(x1,y1) = current;    // Plot pixel
    if (doted) dot = !dot;
    mx += xl;
    if (x1 != x2 && mx > yl) x1 += xd, mx -= yl;
    my += yl;
    if (y1 != y2 && my > xl) y1 += yd, my -= xl;
  }
}
void Canvas::rect (const int x0, const int y0, const int x1, const int y1) {
  for (int y=y0; y<y1; y++) {
    for (int x=x0; x<x1; x++) {
      at(x, y) = current;
    }
  }
}

void Canvas::line (const FPoint & begin, const FPoint & end, const bool doted) {
  const FPoint b (matrix * begin);
  const FPoint e (matrix * end  );
  const int x0 = (const int) round (b.x);
  const int y0 = (const int) round (b.y);
  const int x1 = (const int) round (e.x);
  const int y1 = (const int) round (e.y);
  // printf("%d:%d - %d:%d\n", x0, y0, x1, y1);
  line (x0, y0, x1, y1, doted);
}
void Canvas::circ (const FPoint & center, const real radius) {
  if (radius == 0) return;
  double x = radius, y = 0.0;
  const double dx = 1.0 / radius;
  const double ms = radius * 6.3;
  real count = 0.0;
  // kruh se da nakreslit i bez sin a cos, rychle ale trochu nepresne
  for (;;) {
    x += y * dx; y -= x * dx;
    const FPoint e (center.x + x, center.y + y);
    const FPoint t (matrix * e);
    at ((int) round (t.x), (int) round (t.y)) = current;
    count += 1.0;
    if (count > ms) break;
  }
}
void Canvas::setMatrix (const Matrix& m) {
  matrix = m;
}