#include <math.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>

// Question 1:
void copy_rect(
		char *buffer_a, int pitch_a,
		char *buffer_b, int pitch_b,
		int from_min_x, int from_min_y,
		int from_max_x, int from_max_y,
		int   to_min_x, int   to_min_y
	) {

	for (int y = 0; y < (from_max_y - from_min_y); y++) {
		for (int x = 0; x < (from_max_x - from_min_x); x++) {
			int from_idx = (y + from_min_y) * pitch_a + (x + from_min_x);
			int to_idx   = (y + to_min_y  ) * pitch_b + (x + to_min_x  );

			buffer_b[to_idx] = buffer_a[from_idx];
		}
	}
}

// Question 2:
void copy_string(char *from, char *to) {
	int i = 0;
	while (from[i] != 0) {
		to[i] = from[i];
		i++;
	}
	to[i] = 0;
}

// Question 3:
bool contains_color(char unsigned pixel, char unsigned color) {
	char mask = (color << 6) | (color << 4) | (color << 2) | color;
	char masked = ~(pixel ^ mask);
	char masked2 = masked & (masked << 1);
	return (masked2 & 0b10101010) != 0;
}

// Question 4:
struct Image {
	bool *data;
	int width, height;
};

void write_image_ppm(char *filename, struct Image *image) {
	FILE* f = fopen(filename, "w");
	char header[64];
	int header_size = snprintf(header, sizeof(header), "P1\n%d %d\n", image->width, image->height);
	fwrite(header, sizeof(char), header_size, f);
	for (int i = 0; i < image->width * image->height; i++) {
		char *symbol = image->data[i] ? "1" : "0";
		fwrite(symbol, sizeof(char), 1, f);
	}
	fclose(f);
}

void plot(struct Image *image, int x, int y) {
	if ((0 <= x && x < image->width) && (0 <= y && y < image->height)) {
		int idx = y * image->width + x;
		image->data[idx] = true;
	}
}

void outline_circle(struct Image *image, int cx, int cy, int radius) {
	int mid_point = ceil(radius/sqrt(2));

	int oy = -radius;
	for (int ox = 0; ox < mid_point; ox++) {
		if (ox*ox + oy*oy >= radius*radius) {
			oy++;
		}

		plot(image, cx+ox, cy+oy);
		plot(image, cx-ox, cy+oy);
		plot(image, cx+ox, cy-oy);
		plot(image, cx-ox, cy-oy);
		plot(image, cx+oy, cy+ox);
		plot(image, cx-oy, cy+ox);
		plot(image, cx+oy, cy-ox);
		plot(image, cx-oy, cy-ox);
	}
}

int main() {
	int image_width = 100;
	int image_height = 100;
	bool image_data[image_width * image_height];
	memset(image_data, false, sizeof(bool) * image_width * image_height);
	struct Image image = {
		.data = image_data,
		.width = image_width,
		.height = image_height
	};

	for (int i = 8; i < 50; i+=10) {
		outline_circle(&image, 50, 50, i);
	}
	write_image_ppm("image.ppm", &image);

	return 0;
}