package net.minecraft.world.entity.ai.targeting;

import net.minecraft.server.level.ServerLevel;
import net.minecraft.world.Difficulty;
import net.minecraft.world.entity.LivingEntity;
import net.minecraft.world.entity.Mob;
import org.jspecify.annotations.Nullable;

public class TargetingConditions {
	public static final TargetingConditions DEFAULT = forCombat();
	private static final double MIN_VISIBILITY_DISTANCE_FOR_INVISIBLE_TARGET = 2.0;
	private final boolean isCombat;
	private double range = -1.0;
	private boolean checkLineOfSight = true;
	private boolean testInvisible = true;
	@Nullable
	private TargetingConditions.Selector selector;

	private TargetingConditions(final boolean isCombat) {
		this.isCombat = isCombat;
	}

	public static TargetingConditions forCombat() {
		return new TargetingConditions(true);
	}

	public static TargetingConditions forNonCombat() {
		return new TargetingConditions(false);
	}

	public TargetingConditions copy() {
		TargetingConditions clone = this.isCombat ? forCombat() : forNonCombat();
		clone.range = this.range;
		clone.checkLineOfSight = this.checkLineOfSight;
		clone.testInvisible = this.testInvisible;
		clone.selector = this.selector;
		return clone;
	}

	public TargetingConditions range(final double range) {
		this.range = range;
		return this;
	}

	public TargetingConditions ignoreLineOfSight() {
		this.checkLineOfSight = false;
		return this;
	}

	public TargetingConditions ignoreInvisibilityTesting() {
		this.testInvisible = false;
		return this;
	}

	public TargetingConditions selector(@Nullable final TargetingConditions.Selector selector) {
		this.selector = selector;
		return this;
	}

	public boolean test(final ServerLevel level, @Nullable final LivingEntity targeter, final LivingEntity target) {
		if (targeter == target) {
			return false;
		} else if (!target.canBeSeenByAnyone()) {
			return false;
		} else if (this.selector != null && !this.selector.test(target, level)) {
			return false;
		} else {
			if (targeter == null) {
				if (this.isCombat && (!target.canBeSeenAsEnemy() || level.getDifficulty() == Difficulty.PEACEFUL)) {
					return false;
				}
			} else {
				if (this.isCombat && (!targeter.canAttack(target) || targeter.isAlliedTo(target))) {
					return false;
				}

				if (this.range > 0.0) {
					double modifier = this.testInvisible ? target.getVisibilityPercent(targeter) : 1.0;
					double visibilityDistance = Math.max(this.range * modifier, 2.0);
					double distanceToSqr = targeter.distanceToSqr(target.getX(), target.getY(), target.getZ());
					if (distanceToSqr > visibilityDistance * visibilityDistance) {
						return false;
					}
				}

				if (this.checkLineOfSight && targeter instanceof Mob mob && !mob.getSensing().hasLineOfSight(target)) {
					return false;
				}
			}

			return true;
		}
	}

	@FunctionalInterface
	public interface Selector {
		boolean test(LivingEntity target, ServerLevel level);
	}
}