function Foundation() {}

Foundation.prototype.Schema =
	"<a:component type='internal'/><empty/>";

Foundation.prototype.Init = function()
{
	// Foundations are initially 'uncommitted' and do not block unit movement at all
	// (to prevent players exploiting free foundations to confuse enemy units).
	// The first builder to reach the uncommitted foundation will tell friendly units
	// and animals to move out of the way, then will commit the foundation and enable
	// its obstruction once there's nothing in the way.
	this.committed = false;

	this.builders = []; // builder entities
	this.buildMultiplier = 1; // Multiplier for the amount of work builders do.
	
	this.previewEntity = INVALID_ENTITY;
};

Foundation.prototype.InitialiseConstruction = function(owner, template)
{
	this.finalTemplateName = template;

	// We need to know the owner in OnDestroy, but at that point the entity has already been
	// decoupled from its owner, so we need to remember it in here (and assume it won't change)
	this.owner = owner;

	// Remember our cost here, so if it changes after construction begins (from technologies)
	//	we will use the correct values to refund partial construction costs
	var cmpCost = Engine.QueryInterface(this.entity, IID_Cost);
	this.costs = cmpCost.GetResourceCosts();

	this.initialised = true;
};

/**
 * Moving the revelation logic from Build to here makes the building sink if 
 * it is attacked.
 */
Foundation.prototype.OnHealthChanged = function(msg)
{
	// Gradually reveal the final building preview
	var cmpPreviewVisual = Engine.QueryInterface(this.previewEntity, IID_Visual);
	if (cmpPreviewVisual)
		cmpPreviewVisual.SetConstructionProgress(this.GetBuildProgress());
		
	Engine.PostMessage(this.entity, MT_FoundationProgressChanged, { "to": this.GetBuildPercentage() });
};

/**
 * Returns the current build progress in a [0,1] range.
 */
Foundation.prototype.GetBuildProgress = function()
{
	var cmpHealth = Engine.QueryInterface(this.entity, IID_Health)
	var hitpoints = cmpHealth.GetHitpoints();
	var maxHitpoints = cmpHealth.GetMaxHitpoints();
	
	return (hitpoints / maxHitpoints);
};

Foundation.prototype.GetBuildPercentage = function()
{
	return Math.floor(this.GetBuildProgress() * 100);
};

Foundation.prototype.GetNumBuilders = function()
{
	return this.builders.length;
};

Foundation.prototype.IsFinished = function()
{
	return (this.GetBuildProgress() == 1.0);
};

Foundation.prototype.OnDestroy = function()
{
	// Refund a portion of the construction cost, proportional to the amount of build progress remaining

	if (!this.initialised) // this happens if the foundation was destroyed because the player had insufficient resources
		return;

	if (this.previewEntity != INVALID_ENTITY)
	{
		Engine.DestroyEntity(this.previewEntity);
		this.previewEntity = INVALID_ENTITY;
	}

	if (this.IsFinished())
		return;

	var cmpPlayerManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_PlayerManager);
	var cmpPlayer = Engine.QueryInterface(cmpPlayerManager.GetPlayerByID(this.owner), IID_Player);

	for (var r in this.costs)
	{
		var scaled = Math.floor(this.costs[r] * (1.0 - this.GetBuildProgress()));
		if (scaled)
		{
			cmpPlayer.AddResource(r, scaled);
			var cmpStatisticsTracker = QueryPlayerIDInterface(this.owner, IID_StatisticsTracker);
			if (cmpStatisticsTracker)
				cmpStatisticsTracker.IncreaseResourceUsedCounter(r, -scaled);
		}
	}
};

/**
 * Adds a builder to the counter.
 */
Foundation.prototype.AddBuilder = function(builderEnt)
{
	if (this.builders.indexOf(builderEnt) === -1)
	{
		this.builders.push(builderEnt);
		Engine.QueryInterface(this.entity, IID_Visual).SetVariable("numbuilders", this.builders.length);
		this.SetBuildMultiplier();
		Engine.PostMessage(this.entity, MT_FoundationBuildersChanged, { "to": this.builders });
	}
};

Foundation.prototype.RemoveBuilder = function(builderEnt)
{
	if (this.builders.indexOf(builderEnt) !== -1)
 	{
		this.builders.splice(this.builders.indexOf(builderEnt),1);
		Engine.QueryInterface(this.entity, IID_Visual).SetVariable("numbuilders", this.builders.length);
 		this.SetBuildMultiplier();
		Engine.PostMessage(this.entity, MT_FoundationBuildersChanged, { "to": this.builders });
 	}
 };

/**
 * Sets the build rate multiplier, which is applied to all builders.
 * Yields a total rate of construction equal to numBuilders^0.7
 */
Foundation.prototype.SetBuildMultiplier = function()
{
	var numBuilders = this.builders.length;
	if (numBuilders == 0)
		this.buildMultiplier = 1;
	else
		this.buildMultiplier = Math.pow(numBuilders, 0.7) / numBuilders;
};

/**
 * Perform some number of seconds of construction work.
 * Returns true if the construction is completed.
 */
Foundation.prototype.Build = function(builderEnt, work)
{
	// Do nothing if we've already finished building
	// (The entity will be destroyed soon after completion so
	// this won't happen much)
	if (this.GetBuildProgress() == 1.0)
		return;

	// Handle the initial 'committing' of the foundation
	if (!this.committed)
	{
		var cmpObstruction = Engine.QueryInterface(this.entity, IID_Obstruction);
		if (cmpObstruction && cmpObstruction.GetBlockMovementFlag())
		{
			// If there's any units in the way, ask them to move away
			// and return early from this method.
			// Otherwise enable this obstruction so it blocks any further
			// units, and continue building.

			var collisions = cmpObstruction.GetEntityCollisions(true, true);
			if (collisions.length)
			{
				var cmpFoundationOwnership = Engine.QueryInterface(this.entity, IID_Ownership);
				for each (var ent in collisions)
				{
					var cmpUnitAI = Engine.QueryInterface(ent, IID_UnitAI);
					if (cmpUnitAI)
						cmpUnitAI.LeaveFoundation(this.entity);
					else
					{
						// If obstructing fauna is gaia or our own but doesn't have UnitAI, just destroy it
						var cmpOwnership = Engine.QueryInterface(ent, IID_Ownership);
						var cmpIdentity = Engine.QueryInterface(ent, IID_Identity);
						if (cmpOwnership && cmpIdentity && cmpIdentity.HasClass("Animal")
						    && (cmpOwnership.GetOwner() == 0 || cmpFoundationOwnership && cmpOwnership.GetOwner() == cmpFoundationOwnership.GetOwner()))
							Engine.DestroyEntity(ent);
					}

					// TODO: What if an obstruction has no UnitAI?
				}

				// TODO: maybe we should tell the builder to use a special
				// animation to indicate they're waiting for people to get
				// out the way

				return;
			}

			// The obstruction always blocks new foundations/construction,
			// but we've temporarily allowed units to walk all over it
			// (via CCmpTemplateManager). Now we need to remove that temporary
			// blocker-disabling, so that we'll perform standard unit blocking instead.
			cmpObstruction.SetDisableBlockMovementPathfinding(false, false, -1);
		}

		// Switch foundation to scaffold variant
		var cmpFoundationVisual = Engine.QueryInterface(this.entity, IID_Visual);
		if (cmpFoundationVisual)
			cmpFoundationVisual.SelectAnimation("scaffold", false, 1.0, "");

		// Create preview entity and copy various parameters from the foundation
		if (cmpFoundationVisual && cmpFoundationVisual.HasConstructionPreview())
		{
			this.previewEntity = Engine.AddEntity("construction|"+this.finalTemplateName);
			var cmpFoundationOwnership = Engine.QueryInterface(this.entity, IID_Ownership);
			var cmpPreviewOwnership = Engine.QueryInterface(this.previewEntity, IID_Ownership);
			cmpPreviewOwnership.SetOwner(cmpFoundationOwnership.GetOwner());

			// Initially hide the preview underground
			var cmpPreviewVisual = Engine.QueryInterface(this.previewEntity, IID_Visual);
			if (cmpPreviewVisual)
			{
				cmpPreviewVisual.SetConstructionProgress(0.0);
				cmpPreviewVisual.SetActorSeed(cmpFoundationVisual.GetActorSeed());
				cmpPreviewVisual.SelectAnimation("scaffold", false, 1.0, "");
			}

			var cmpFoundationPosition = Engine.QueryInterface(this.entity, IID_Position);
			var pos = cmpFoundationPosition.GetPosition();
			var rot = cmpFoundationPosition.GetRotation();
			var cmpPreviewPosition = Engine.QueryInterface(this.previewEntity, IID_Position);
			cmpPreviewPosition.SetYRotation(rot.y);
			cmpPreviewPosition.SetXZRotation(rot.x, rot.z);
			cmpPreviewPosition.JumpTo(pos.x, pos.z);
		}

		this.committed = true;
	}

	// Calculate the amount of progress that will be added (where 1.0 = completion)
	var cmpCost = Engine.QueryInterface(this.entity, IID_Cost);
	var amount = work / cmpCost.GetBuildTime();

	// Add an appropriate proportion of hitpoints
	var cmpHealth = Engine.QueryInterface(this.entity, IID_Health);
	var maxHealth = cmpHealth.GetMaxHitpoints();
	var deltaHP = Math.max(work, Math.min(maxHealth, Math.floor(maxHealth * (amount * this.buildMultiplier))));
	if (deltaHP > 0)
	{
		cmpHealth.Increase(deltaHP);
	}

	if (this.GetBuildProgress() >= 1.0)
	{
		// Finished construction

		// Create the real entity
		var building = Engine.AddEntity(this.finalTemplateName);

		// Copy various parameters from the foundation

		var cmpVisual = Engine.QueryInterface(this.entity, IID_Visual);
		var cmpBuildingVisual = Engine.QueryInterface(building, IID_Visual)
		if (cmpVisual && cmpBuildingVisual)
			cmpBuildingVisual.SetActorSeed(cmpVisual.GetActorSeed());

		var cmpPosition = Engine.QueryInterface(this.entity, IID_Position);
		var cmpBuildingPosition = Engine.QueryInterface(building, IID_Position);
		var pos = cmpPosition.GetPosition();
		cmpBuildingPosition.JumpTo(pos.x, pos.z);
		var rot = cmpPosition.GetRotation();
		cmpBuildingPosition.SetYRotation(rot.y);
		cmpBuildingPosition.SetXZRotation(rot.x, rot.z);
		// TODO: should add a ICmpPosition::CopyFrom() instead of all this

		var cmpRallyPoint = Engine.QueryInterface(this.entity, IID_RallyPoint);
		var cmpBuildingRallyPoint = Engine.QueryInterface(building, IID_RallyPoint);
		if(cmpRallyPoint && cmpBuildingRallyPoint)
		{
			var rallyCoords = cmpRallyPoint.GetPositions();
			var rallyData = cmpRallyPoint.GetData();
			for (var i = 0; i < rallyCoords.length; ++i)
			{
				cmpBuildingRallyPoint.AddPosition(rallyCoords[i].x, rallyCoords[i].z);
				cmpBuildingRallyPoint.AddData(rallyData[i]);
			}
		}

		// ----------------------------------------------------------------------
		
		var cmpOwnership = Engine.QueryInterface(this.entity, IID_Ownership);
		var cmpBuildingOwnership = Engine.QueryInterface(building, IID_Ownership);
		cmpBuildingOwnership.SetOwner(cmpOwnership.GetOwner());
		
		// ----------------------------------------------------------------------
		
		// Copy over the obstruction control group IDs from the foundation entities. This is needed to ensure that when a foundation
		// is completed and replaced by a new entity, it remains in the same control group(s) as any other foundation entities that 
		// may surround it. This is the mechanism that is used to e.g. enable wall pieces to be built closely together, ignoring their
		// mutual obstruction shapes (since they would otherwise be prevented from being built so closely together). If the control 
		// groups are not copied over, the new entity will default to a new control group containing only itself, and will hence block
		// construction of any surrounding foundations that it was previously in the same control group with.
		
		// Note that this will result in the completed building entities having control group IDs that equal entity IDs of old (and soon
		// to be deleted) foundation entities. This should not have any consequences, however, since the control group IDs are only meant
		// to be unique identifiers, which is still true when reusing the old ones.
		
		var cmpObstruction = Engine.QueryInterface(this.entity, IID_Obstruction);
		var cmpBuildingObstruction = Engine.QueryInterface(building, IID_Obstruction);
		cmpBuildingObstruction.SetControlGroup(cmpObstruction.GetControlGroup());
		cmpBuildingObstruction.SetControlGroup2(cmpObstruction.GetControlGroup2());
		
		// ----------------------------------------------------------------------
		
		var cmpPlayerStatisticsTracker = QueryOwnerInterface(this.entity, IID_StatisticsTracker);
		cmpPlayerStatisticsTracker.IncreaseConstructedBuildingsCounter(building);
		
		var cmpHealth = Engine.QueryInterface(this.entity, IID_Health);
		var cmpBuildingHealth = Engine.QueryInterface(building, IID_Health);
		cmpBuildingHealth.SetHitpoints(cmpHealth.GetHitpoints());

		PlaySound("constructed", building);

		Engine.PostMessage(this.entity, MT_ConstructionFinished,
			{ "entity": this.entity, "newentity": building });
		Engine.BroadcastMessage(MT_EntityRenamed, { entity: this.entity, newentity: building });

		Engine.DestroyEntity(this.entity);
	}
};

Engine.RegisterComponentType(IID_Foundation, "Foundation", Foundation);