/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A state used to represent the `TaskBot` when its movement is being managed by an `GKAgent`.

*/

import SpriteKit

import GameplayKit

class TaskBotAgentControlledState: GKState {

    // MARK: Properties

    unowned var entity: TaskBot

    /// The amount of time that has passed since the `TaskBot` became agent-controlled.

    var elapsedTime: TimeInterval = 0.0

    /// The amount of time that has passed since the `TaskBot` last determined an appropriate behavior.

    var timeSinceBehaviorUpdate: TimeInterval = 0.0

    // MARK: Initializers

    required init(entity: TaskBot) {

        self.entity = entity

    }

    // MARK: GKState Life Cycle

    override func didEnter(from previousState: GKState?) {

        super.didEnter(from: previousState)

        // Reset the amount of time since the last behavior update.

        timeSinceBehaviorUpdate = 0.0

        elapsedTime = 0.0

        // Ensure that the agent's behavior is the appropriate behavior for its current mandate.

        entity.agent.behavior = entity.behaviorForCurrentMandate

        /*

            `TaskBot`s recover to a full charge if they're hit with the beam but don't become "good".

            If this `TaskBot` has any charge, restore it to the full amount.

        */

        if let chargeComponent = entity.component(ofType: ChargeComponent.self), chargeComponent.hasCharge {

            let chargeToAdd = chargeComponent.maximumCharge - chargeComponent.charge

            chargeComponent.addCharge(chargeToAdd: chargeToAdd)

        }

    }

    override func update(deltaTime seconds: TimeInterval) {

        super.update(deltaTime: seconds)

        // Update the "time since last behavior update" tracker.

        timeSinceBehaviorUpdate += seconds

        elapsedTime += seconds

        // Check if enough time has passed since the last behavior update, and update the behavior if so.

        if timeSinceBehaviorUpdate >= GameplayConfiguration.TaskBot.behaviorUpdateWaitDuration {

            // When a `TaskBot` is returning to its path patrol start, and gets near enough, it should start to patrol.

            if case let .returnToPositionOnPath(position) = entity.mandate, entity.distanceToPoint(otherPoint: position) <= GameplayConfiguration.TaskBot.thresholdProximityToPatrolPathStartPoint {

                entity.mandate = entity.isGood ? .followGoodPatrolPath : .followBadPatrolPath

            }

            // Ensure the agent's behavior is the appropriate behavior for its current mandate.

            entity.agent.behavior = entity.behaviorForCurrentMandate

            // Reset `timeSinceBehaviorUpdate`, to delay when the entity's behavior is next updated.

            timeSinceBehaviorUpdate = 0.0

        }

    }

    override func isValidNextState(_ stateClass: AnyClass) -> Bool {

        switch stateClass {

            case is FlyingBotPreAttackState.Type, is GroundBotRotateToAttackState.Type, is TaskBotZappedState.Type:

                return true

            default:

                return false

        }

    }

    override func willExit(to nextState: GKState) {

        super.willExit(to: nextState)

        /*

            The `TaskBot` will no longer be controlled by an agent in the steering simulation

            when it leaves the `TaskBotAgentControlledState`.

            Assign an empty behavior to cancel any active agent control.

        */

        entity.agent.behavior = GKBehavior()

    }

}