#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<stdbool.h>
#include<unistd.h>

struct antenna {
	char type;
	int xy[2];
	struct antenna *next;
};

void add_antenna(struct antenna *head, char type, int *xy)
{
	// traverse list until last member
	while(head->next) head = head->next;
	
	// allocate and store ptr
	if (head->type) {
		head->next = malloc(sizeof(struct antenna));
		head = head->next;
	}

	head->type = type;
	head->xy[0] = xy[0];
	head->xy[1] = xy[1];
	head->next = 0;
}

int main ()
{
	struct antenna *list = malloc(sizeof(struct antenna));
	list->type = '\0';
	// figure out data dimensions
	FILE *input = fopen("./input", "r");
	int width =  0;
	int height = 1;
	while (fgetc(input) != '\n') width++;
	for (char c = fgetc(input); c != EOF; c = fgetc(input)) {
		if (c == '\n')
			height++;
	}
	rewind(input);
	printf("Dimensions: %d x %d\n", width, height);

	// make 2d array
	char **grid = malloc(width * sizeof(char*));
	grid[0] = malloc(width * height);
	for (int i = 1; i < width; i++) {
		grid[i] = grid[0] + i * height;
	}

	// put the data in the array
	for (int i = 0; i < height; i++) {
		for (int j = 0; j < width; j++) {
			grid[j][i] = fgetc(input);
			if (grid[j][i] != '.') {
				// store antenna in list
				int xy[] = {j, i};
				add_antenna(list, grid[j][i], xy);
				printf("Antenna %c coords: %d/%d\n", grid[j][i], j, i);
			}
		}
		// skip newline
		fgetc(input);
	}
	fclose(input);

	struct antenna *current = list;
	struct antenna *other = list;
	// for each antenna in list
	while (current) {
		// find delta to other of same frequency
		while (other) {
			if (current->type == other->type && current != other) {
				int delta[2];
				delta[0] = other->xy[0] - current->xy[0];
				delta[1] = other->xy[1] - current->xy[1];
				// apply # to other + delta
				int pos[2] = {other->xy[0], other->xy[1]};
				while (
						(pos[0] + delta[0]) >= 0 &&
						(pos[0] + delta[0]) < width &&
						(pos[1] + delta[1]) >= 0 &&
						(pos[1] + delta[1]) < height) {
						pos[0] = pos[0] + delta[0];
						pos[1] = pos[1] + delta[1];
						grid[pos[0]][pos[1]] = '#';
				}
				pos[0] = other->xy[0];
				pos[1] = other->xy[1];
				while (
						(pos[0] - delta[0]) >= 0 &&
						(pos[0] - delta[0]) < width &&
						(pos[1] - delta[1]) >= 0 &&
						(pos[1] - delta[1]) < height) {
						pos[0] = pos[0] - delta[0];
						pos[1] = pos[1] - delta[1];
						grid[pos[0]][pos[1]] = '#';
				}

			}
			other = other->next;
		}
		other = list;
		current = current->next;
	}

	// iterate through array again and sum it
	int sum_x = 0;
	for (int i = 0; i < height; i++) {
		for (int j = 0; j < width; j++) {
			if (grid[j][i] == '#')
				sum_x++;
			printf("%c", grid[j][i]);
		}
		printf("\n");
	}

	printf("total antinodes: %d\n", sum_x);
}