#include "entity.h"
#include "game.h"
#include "map.h"
#include "cfg.h"
#include "entitytag.h"
#include <stddef.h>
#include <string.h>
#include <stdio.h>

static void
_points(Entity *this, int ox, int oy, int *x0, int *x1, int *y0, int *y1)
{
	*x0 = this->pos[0] - this->width / 2 + ox;
	*y0 = this->pos[1] - this->width / 2 + oy;
	*x1 = *x0 + this->width - 1;
	*y1 = *y0 + this->height - 1;
}

unsigned int
entity_type(const char *type)
{
	for (unsigned int i = 0; i < num_entitytags; i++)
		if (strcmp(type, entitytags[i].name) == 0)
			return i + 1;
	fprintf(stderr, "unknown type '%s'\n", type);
	return 0;
}

bool
entity_collide(Entity *this, [[maybe_unused]] Game *g, int ox, int oy)
{
	int x0, y0, x1, y1;
	_points(this, ox, oy, &x0, &x1, &y0, &y1);
	return (map_get_px(x0, y0) == 1 || map_get_px(x0, y1) == 1 ||
	        map_get_px(x1, y0) == 1 || map_get_px(x1, y1) == 1);
}

bool
entity_meet(Entity *this, Entity *other)
{
	int tx0, ty0, tx1, ty1;
	int ox0, oy0, ox1, oy1;
	_points(this, 0, 0, &tx0, &tx1, &ty0, &ty1);
	_points(other, 0, 0, &ox0, &ox1, &oy0, &oy1);
	return (tx0 < ox1 && tx1 > ox0 && ty0 < oy1 && ty1 > oy0);
}

Entity *
entity_place_meeting(Entity *this, Game *g, unsigned int type)
{
	for (int i = 0; i < MAX_ENTITIES; i++)
		if (this != &g->entities[i] && g->entities[i].type == type &&
		    entity_meet(this, &g->entities[i]))
			return &g->entities[i];
	return NULL;
}

void
entity_move(Entity *this, Game *g)
{
	this->bonk_ceiling = false;
	if (this->ignore_solids) {
		for (int a = 0; a < 2; a++) {
			const double sum = this->vel[a] + this->rem[a];
			int spd = (int)sum;
			this->rem[a] = sum - spd;
			this->pos[a] += spd;
		}
		return;
	}
	if (entity_collide(this, g, 0, 0)) {
		this->vel[0] = 0.0;
		this->vel[1] = 0.0;
		this->rem[0] = 0.0;
		this->rem[1] = 0.0;
		return;
	}
	for (int a = 0; a < 2; a++) {
		const double sum = this->vel[a] + this->rem[a];
		int spd = (int)sum;
		this->rem[a] = sum - spd;
		const int sign = (spd > 0) - (spd < 0);
		if (sign == 0)
			continue;
		while (spd != 0) {
			this->pos[a] += sign;
			if (entity_collide(this, g, 0, 0)) {
				this->pos[a] -= sign;
				this->rem[a] = 0.0;
				this->vel[a] = 0.0;
				if (a == 1 && sign == -1)
					this->bonk_ceiling = true;
				break;
			}
			spd -= sign;
		}
	}
}

Entity *
entity_init(Entity *this, unsigned int type, int x, int y)
{
	entitytags[type - 1].init(this, x, y);
	return this;
}