#include "img.h"
#include "aliases.h"
#include "mem_arena.h"
#include "pam.h"
#include "utils.h"
#include <stdbool.h>
#include <stddef.h>
#include <string.h>

internal i64 calculate_pixel_index(Buffer *buffer, u64 x, u64 y, u64 base_size);

bool _init_buffer(Arena *arena, Buffer *buffer, u64 base_size) {
  if (!arena || !buffer || buffer->width == 0 || buffer->height == 0) {
    return false;
  }

  u64 size = buffer->width * buffer->height * base_size;
  buffer->buf = wapp_mem_arena_alloc(arena, size);

  return buffer->buf != NULL;
}

u8 *_get_pixel(Buffer *buffer, u64 x, u64 y, u64 base_size) {
  i64 idx = calculate_pixel_index(buffer, x, y, base_size);
  if (idx == -1) {
    idx = 0;
  }

  return ((u8 *)(buffer->buf)) + idx;
}

void _set_pixel(Buffer *buffer, u64 x, u64 y, void *value, u64 base_size) {
  i64 idx = calculate_pixel_index(buffer, x, y, base_size);
  if (idx == -1) {
    return;
  }

  memcpy(((u8 *)(buffer->buf)) + idx, value, base_size);
  return;
}

void _clear_buffer(Buffer *buffer, void *value, u64 base_size) {
  for (u64 y = 0; y < buffer->height; ++y) {
    for (u64 x = 0; x < buffer->width; ++x) {
      _set_pixel(buffer, x, y, value, base_size);
    }
  }
}

void draw_line(Image *img, u64 x0, u64 y0, u64 x1, u64 y1, Colour colour) {
  u64 dx = absolute((i64)x1 - (i64)x0);
  u64 dy = absolute((i64)y1 - (i64)y0);
  f32 t = 0.0f;
  i64 x = 0;
  i64 y = 0;

  if (dx > dy) {
    if (x0 > x1) {
      swap(u64, x0, x1);
      swap(u64, y0, y1);
    }

    for (u64 x = x0; x < x1; ++x) {
      t = (f32)(x - x0) / (f32)(x1 - x0);
      y = (i64)y0 + ((i64)y1 - (i64)y0) * t;
      set_pixel(img, x, y, &colour);
    }
  } else {
    if (y0 > y1) {
      swap(u64, x0, x1);
      swap(u64, y0, y1);
    }

    for (u64 y = y0; y < y1; ++y) {
      t = (f32)(y - y0) / (f32)(y1 - y0);
      x = (i64)x0 + ((i64)x1 - (i64)x0) * t;
      set_pixel(img, x, y, &colour);
    }
  }
}

void save_image(const Image *img, const char *filename) {
  write_p7_image(img->width, img->height, (u8 *)(img->buf), filename);
}

internal i64 calculate_pixel_index(Buffer *buffer, u64 x, u64 y,
                                   u64 base_size) {
  if (x < 0 || y < 0 || x >= buffer->width || y >= buffer->height) {
    return -1;
  }

  return (y * buffer->width + x) * base_size;
}