#include "entity.h"
#include "util.h"

/* only provide non-nul value on `move_x` OR `move_y` */
static int entity_move_single_axis(struct Entity *, int mask, int move_x,
                                   int move_y);

int
entity_move(struct Entity *e, int mask, int move_x, int move_y)
{
	int collided = 0;

	collided |= entity_move_single_axis(e, mask, move_x, 0);
	collided |= entity_move_single_axis(e, mask, 0, move_y) << 1;

	return collided;
}

static int
entity_move_single_axis(struct Entity *e, int mask, int move_x, int move_y)
{
	struct Entity *other;
	int collided = 0;
	const int sign_move_x = sign(move_x);
	const int sign_move_y = sign(move_y);

	if (!move_x && !move_y)
		return 0;

	e->x += move_x;
	e->y += move_y;
	do {
		other = entity_collide(e, mask);
		if (other != NULL)
			collided = 1;
		while (entity_collide_with(e, other, mask)) {
			e->x -= sign_move_x;
			e->y -= sign_move_y;
		}
	} while (other != NULL);

	return collided;
}