function Garrisonable() {}

Garrisonable.prototype.Schema =
	"<a:help>Controls the garrisonability of an entity.</a:help>" +
	"<a:example>" +
		"<Size>10</Size>" +
	"</a:example>" +
	"<element name='Size' a:help='Number of garrison slots the entity occupies.'>" +
		"<data type='nonNegativeInteger'/>" +
	"</element>";

Garrisonable.prototype.Init = function()
{
};

/**
 * @param {string} type - Unused.
 * @param {number} target - The entity ID of the target to check.
 * @return {Object} - Min and max ranges this entity needs to be in in order to garrison the target.
 */
Garrisonable.prototype.GetRange = function(type, target)
{
	const cmpGarrisonHolder = Engine.QueryInterface(target, IID_GarrisonHolder);
	return cmpGarrisonHolder ? cmpGarrisonHolder.LoadingRange() : { "min": 0, "max": 1 };
};

/**
 * @return {number} - The number of slots this unit takes in a garrisonHolder.
 */
Garrisonable.prototype.UnitSize = function()
{
	return ApplyValueModificationsToEntity("Garrisonable/Size", +this.template.Size, this.entity);
};

/**
 * Calculates the number of slots this unit takes in a garrisonHolder by
 * adding the number of garrisoned slots to the equation.
 *
 * @return {number} - The number of slots this unit and its garrison takes in a garrisonHolder.
 */
Garrisonable.prototype.TotalSize = function()
{
	let size = this.UnitSize();
	const cmpGarrisonHolder = Engine.QueryInterface(this.entity, IID_GarrisonHolder);
	if (cmpGarrisonHolder)
		size += cmpGarrisonHolder.OccupiedSlots();
	return size;
};

/**
 * @return {number} - The entity ID of the entity this entity is garrisoned in.
 */
Garrisonable.prototype.HolderID = function()
{
	return this.holder || INVALID_ENTITY;
};

/**
 * @return {boolean} - Whether we're garrisoned.
 */
Garrisonable.prototype.IsGarrisoned = function()
{
	return !!this.holder;
};

/**
 * @param {number} target - The entity ID to check.
 * @return {boolean} - Whether we can garrison.
 */
Garrisonable.prototype.CanGarrison = function(target)
{
	if (this.holder)
		return false;

	const cmpGarrisonHolder = Engine.QueryInterface(target, IID_GarrisonHolder);
	return cmpGarrisonHolder && cmpGarrisonHolder.IsAllowedToGarrison(this.entity);
};

/**
 * @param {number} target - The entity ID of the entity this entity is being garrisoned in.
 * @return {boolean} - Whether garrisoning succeeded.
 */
Garrisonable.prototype.Garrison = function(target)
{
	if (!this.CanGarrison(target))
		return false;

	const cmpGarrisonHolder = Engine.QueryInterface(target, IID_GarrisonHolder);
	if (!cmpGarrisonHolder || !cmpGarrisonHolder.Garrison(this.entity))
		return false;

	this.holder = target;

	const cmpUnitAI = Engine.QueryInterface(this.entity, IID_UnitAI);
	if (cmpUnitAI)
		cmpUnitAI.SetGarrisoned();

	const cmpPosition = Engine.QueryInterface(this.entity, IID_Position);
	if (cmpPosition)
		cmpPosition.MoveOutOfWorld();

	Engine.PostMessage(this.entity, MT_GarrisonedStateChanged, {
		"oldHolder": INVALID_ENTITY,
		"holderID": target
	});

	return true;
};

/**
 * @param {boolean} forced - Optionally whether the spawning is forced.
 * @return {boolean} - Whether the ungarrisoning succeeded.
 */
Garrisonable.prototype.UnGarrison = function(forced = false)
{
	if (!this.holder)
		return true;

	const pos = PositionHelper.GetSpawnPosition(this.holder, this.entity, forced);
	if (!pos)
		return false;

	const cmpGarrisonHolder = Engine.QueryInterface(this.holder, IID_GarrisonHolder);
	if (!cmpGarrisonHolder || !cmpGarrisonHolder.Eject(this.entity, forced))
		return false;

	const cmpPosition = Engine.QueryInterface(this.entity, IID_Position);
	if (cmpPosition)
	{
		cmpPosition.JumpTo(pos.x, pos.z);
		cmpPosition.SetHeightOffset(0);
	}

	const cmpHolderPosition = Engine.QueryInterface(this.holder, IID_Position);
	if (cmpHolderPosition)
		cmpPosition.SetYRotation(cmpHolderPosition.GetPosition().horizAngleTo(pos));

	const cmpUnitAI = Engine.QueryInterface(this.entity, IID_UnitAI);
	if (cmpUnitAI)
	{
		cmpUnitAI.Ungarrison();
		cmpUnitAI.UnsetGarrisoned();
	}

	Engine.PostMessage(this.entity, MT_GarrisonedStateChanged, {
		"oldHolder": this.holder,
		"holderID": INVALID_ENTITY
	});

	const cmpRallyPoint = Engine.QueryInterface(this.holder, IID_RallyPoint);

	// Need to delete this before ordering to a rally
	// point else we may not garrison another entity.
	delete this.holder;

	if (cmpRallyPoint)
		cmpRallyPoint.OrderToRallyPoint(this.entity, ["garrison"]);

	return true;
};

Garrisonable.prototype.OnEntityRenamed = function(msg)
{
	if (!this.holder)
		return;

	const holder = this.holder;
	this.UnGarrison(true, true);
	const cmpGarrisonable = Engine.QueryInterface(msg.newentity, IID_Garrisonable);
	if (cmpGarrisonable)
		cmpGarrisonable.Garrison(holder, true);
};

Engine.RegisterComponentType(IID_Garrisonable, "Garrisonable", Garrisonable);