#pragma once

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

#include "tuples.h"

#ifndef CANVAS_MAX
#define CANVAS_MAX 32
#endif

struct canvas {
  int width;
  int height;
  struct tuple pixels[CANVAS_MAX * CANVAS_MAX];
};

inline static struct canvas canvas(int width, int height)
{
  struct canvas c;
  assert(width < CANVAS_MAX);
  assert(height < CANVAS_MAX);
  c.width = width;
  c.height = height;

  for (int i = 0; i < c.width * c.height; i++) {
    c.pixels[i] = tuple(0.0f, 0.0f, 0.0f, 0.0f);
  }

  return c;
}

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");
  }
}