#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include "util.h"

s32 reduce(s32 (*f)(s32 x, s32 y), s32 arr[], s32 len)
{
	s32 ret = arr[0];

	for (s32 i = 1; i < len; ++i) {
		ret = f(ret, arr[i]);
	}

	return ret;
}

s32 mul(s32 x, s32 y)
{
	return x * y;
}

s32 max(s32 x, s32 y)
{
	return x > y ? x : y;
}

s32 count_char_in_string(char c, char *s)
{
	s32 count = 0;
	do
		if (c == *s)
			count++;
	while (*s++);
	return count;
}

char *goto_char_in_string(char c, char *s)
{
	do
		if (c == *s)
			return s;
	while (*s++);
	return NULL;
}

#define PP(arr, y,x) (*(*(arr+y)+x))

char filename[] = "in/day12.ref";
// char filename[] = "in/day12.pzl";

#define BUF_LEN 10000
char file_buf[BUF_LEN];

s32 **grid;
s32 **visited;
s32 y_len;
s32 x_len;
s32 start_y;
s32 start_x;
s32 end_y;
s32 end_x;

s32 traverse(s32 steps,s32 y, s32 x)
{
	if (PP(visited,y,x) < steps) {
		return 42000;
	}
	PP(visited,y,x) = steps;
	// if (PP(visited,y,x) == 1) {
	// 	return 12345;
	// }
	// PP(visited,y,x) = 1;

	if ((x==end_x) && (y==end_y)) {
		return steps;
	}

	s32 min = 123456;

	if ( (x+1 < x_len) && (PP(grid,y,x+1) <= (PP(grid,y,x)+1)) ) {
		s32 a = traverse(steps+1, y, x+1);
		if (a < min) {
			min = a;
		}
	}
	if ( (x > 0) && (PP(grid,y,x-1) <= (PP(grid,y,x)+1)) ) {
		s32 a = traverse(steps+1, y, x-1);
		if (a < min) {
			min = a;
		}
	}
	if ( (y+1 < y_len) && (PP(grid,y+1,x) <= (PP(grid,y,x)+1)) ) {
		s32 a = traverse(steps+1, y+1, x);
		if (a < min) {
			min = a;
		}
	}
	if ( (y > 0) && (PP(grid,y-1,x) <= (PP(grid,y,x)+1)) ) {
		s32 a = traverse(steps+1, y-1, x);
		if (a < min) {
			min = a;
		}
	}

	return min;
}


int main()
{
	int fd = open(filename, O_RDONLY);
	s32 data_len = read(fd, file_buf, LEN(file_buf));

	if (data_len == -1) {
		printf("error opening file\n");
		exit(1);
	} else if (data_len == LEN(file_buf)) {
		printf("buffer probably not big enough\n");
		exit(1);
	}
	file_buf[data_len] = '\0';

	y_len = count_char_in_string('\n', file_buf);


	grid = malloc(y_len * sizeof(s32*));
	visited = malloc(y_len * sizeof(s32*));
	char *start  = file_buf;

	for (s32 y = 0; y < y_len; ++y) {
		char *end = goto_char_in_string('\n', start);
		x_len = end - start;

		*(grid+y) = malloc(x_len * sizeof(s32*));
		*(visited+y) = malloc(x_len * sizeof(s32*));

		for (s32 x = 0; x < x_len; ++x) {
			char c = *(start + x);
			if (c == 'S') {
				start_y = y;
				start_x = x;
				c = 'a';
			} else if (c == 'E') {
				end_y = y;
				end_x = x;
				c = 'z';
			}
			*(*(grid+y) + x) = c - 'a';
			*(*(visited+y) + x) = 123456;
			// *(*(visited+y) + x) = 0;
		}
		start = end+1;
	}
	printf("y_len: %d\n", y_len);
	printf("x_len: %d\n", x_len);

	printf("start y: %d\n", start_y);
	printf("start x: %d\n", start_x);
	printf("end y: %d\n", end_y);
	printf("end x: %d\n", end_x);



	s32 res1 = 0;
	s32 res2 = 0;

	res1 = traverse(0, start_y, start_x);


	printf("res1: %d\n", res1);
	printf("res2: %d\n", res2);
	// asm("int3");
}