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

#include <input.h>

#include <result.h>

#define RIMAX_STR 48

struct proc {
	result_t mv;
	off_t field;

//	void* jmp;
};

#define _LIT_MV_FORWARD "forward"
#define _LIT_MV_UP "up"
#define _LIT_MV_DOWN "down"

static const struct proc MAP[255] = {
	['f'] = { .mv = 8, .field = (offsetof(struct psum, forward) / sizeof(result_t)) },
	['u'] = { .mv = 3, .field = (offsetof(struct psum, up) / sizeof(result_t)) },
	['d'] = { .mv = 5, .field = (offsetof(struct psum, down) / sizeof(result_t)) },
};

static const unsigned char DIGITS[255] = {
	['0' ... '9'] = 1,
};

inline static void _fresolv(result_t f[restrict 3], off_t field, result_t v)
{
	f[field & 3] += v;
}

inline static void fresolv(result_t f[restrict 3], const struct proc* restrict p, result_t v)
{
	_fresolv(f, p->field, v);
	//f[p->field] += v;
}

inline static void mresolv(struct psum* restrict add, const struct proc* p, result_t v)
{
	_fresolv((result_t* restrict)add, p->field, v);
	//_fresolv((result_t(*)[3])add, p->field, v);
	//*(((result_t*restrict)add)+p->field) += v;
}



inline static __attribute__((const, always_inline, artificial, gnu_inline)) bool is_digit(char c)
{
	return !!c[DIGITS];
}

inline static result_t ri64p(const char* restrict *restrict pinput)
{
	char dig[RIMAX_STR] = {0};
	size_t i = 0;
	while(is_digit(dig[i]=**pinput)) { i+=1; *pinput+=1; }
#if DEBUG
	assert(i<RIMAX_STR);
#endif
	dig[i] = 0;
#ifdef DEBUG
	fprintf(stderr, "read: %s\n", dig);
#endif
	return atol(dig);
}

__attribute__((pure))
struct psum compute_unnormalised(const char* restrict input)
{
	struct psum res = {0};

	while(*input)
	{
		const struct proc p = (*input)[MAP];
#ifdef DEBUG
		fprintf(stderr, "ch: %c\n", *input);
		assert(p.mv > 0);
#endif
		input+=p.mv;
		result_t n = ri64p(&input);
		fresolv(res._fields, &p, n);
	}

	return res;
}

int part1(result_t* restrict _res)
{	
	position_t final = normalise_position(compute_unnormalised(INPUT));
	*_res = final.hoz * final.depth;

	return 0;
}