#include <stdlib.h>
#include <stdio.h>

#include "tuples.h"

struct canvas {
  int width;
  int height;
  struct tuple * pixels;
};

inline static struct canvas canvas(int width, int height)
{
  return (struct canvas){
    width,
    height,
    calloc(width * height, (sizeof (struct tuple)))
  };
}

inline static void canvas_write_pixel(struct canvas canvas, int x, int y, struct tuple color)
{
  struct tuple * pixel = &canvas.pixels[y * canvas.width + x];
  pixel->r = color.r;
  pixel->g = color.g;
  pixel->b = color.b;
  pixel->a = color.a;
}

inline static struct tuple canvas_pixel_at(struct canvas canvas, int x, int y)
{
  return canvas.pixels[y * canvas.width + x];
}

inline static int clamp_0_255(float n)
{
  if (n > 1.0f) {
    return 255;
  } else if (n < 0.0f) {
    return 0;
  } else {
    return (int)(n * 255.0f);
  }
}

inline static void canvas_to_ppm(struct canvas canvas, const char * pathname)
{
  FILE * f = fopen(pathname, "w");
  if (f == NULL) {
    perror("fopen");
  }

  fwrite("P6\n", 3, 1, f);
  fprintf(f, "%d %d\n", canvas.width, canvas.height);
  fwrite("255\n", 4, 1, f);

  for (int i = 0; i < canvas.width * canvas.height; i++) {
    struct tuple * pixel = &canvas.pixels[i];
    char buf[3];
    buf[0] = clamp_0_255(pixel->r);
    buf[1] = clamp_0_255(pixel->g);
    buf[2] = clamp_0_255(pixel->b);
    fwrite(buf, 3, 1, f);
  }

  int ret = fclose(f);
  if (ret != 0) {
    perror("fclose");
  }
}