package net.minecraft.world.phys.shapes;

import net.minecraft.core.BlockPos;
import net.minecraft.core.Direction;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.entity.LivingEntity;
import net.minecraft.world.item.Item;
import net.minecraft.world.item.ItemStack;
import net.minecraft.world.level.CollisionGetter;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.material.FluidState;
import org.jspecify.annotations.Nullable;

public class EntityCollisionContext implements CollisionContext {
	private final boolean descending;
	private final double entityBottom;
	private final boolean placement;
	private final ItemStack heldItem;
	private final boolean alwaysCollideWithFluid;
	@Nullable
	private final Entity entity;

	protected EntityCollisionContext(
		final boolean descending,
		final boolean placement,
		final double entityBottom,
		final ItemStack heldItem,
		final boolean alwaysCollideWithFluid,
		@Nullable final Entity entity
	) {
		this.descending = descending;
		this.placement = placement;
		this.entityBottom = entityBottom;
		this.heldItem = heldItem;
		this.alwaysCollideWithFluid = alwaysCollideWithFluid;
		this.entity = entity;
	}

	@Deprecated
	protected EntityCollisionContext(final Entity entity, final boolean alwaysCollideWithFluid, final boolean placement) {
		this(
			entity.isDescending(),
			placement,
			entity.getY(),
			entity instanceof LivingEntity livingEntity ? livingEntity.getMainHandItem() : ItemStack.EMPTY,
			alwaysCollideWithFluid,
			entity
		);
	}

	@Override
	public boolean isHoldingItem(final Item item) {
		return this.heldItem.is(item);
	}

	@Override
	public boolean alwaysCollideWithFluid() {
		return this.alwaysCollideWithFluid;
	}

	@Override
	public boolean canStandOnFluid(final FluidState fluidStateAbove, final FluidState fluid) {
		return !(this.entity instanceof LivingEntity livingEntity)
			? false
			: livingEntity.canStandOnFluid(fluid) && !fluidStateAbove.getType().isSame(fluid.getType());
	}

	@Override
	public VoxelShape getCollisionShape(final BlockState state, final CollisionGetter collisionGetter, final BlockPos pos) {
		return state.getCollisionShape(collisionGetter, pos, this);
	}

	@Override
	public boolean isDescending() {
		return this.descending;
	}

	@Override
	public boolean isAbove(final VoxelShape shape, final BlockPos pos, final boolean defaultValue) {
		return this.entityBottom > pos.getY() + shape.max(Direction.Axis.Y) - 1.0E-5F;
	}

	@Nullable
	public Entity getEntity() {
		return this.entity;
	}

	@Override
	public boolean isPlacement() {
		return this.placement;
	}

	protected static class Empty extends EntityCollisionContext {
		protected static final CollisionContext WITHOUT_FLUID_COLLISIONS = new EntityCollisionContext.Empty(false);
		protected static final CollisionContext WITH_FLUID_COLLISIONS = new EntityCollisionContext.Empty(true);

		public Empty(final boolean alwaysCollideWithFluid) {
			super(false, false, -Double.MAX_VALUE, ItemStack.EMPTY, alwaysCollideWithFluid, null);
		}

		@Override
		public boolean isAbove(final VoxelShape shape, final BlockPos pos, final boolean defaultValue) {
			return defaultValue;
		}
	}
}