/*

 Copyright (C) 2018 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 This class is used as a base class for all game components.

 */

import GameplayKit

import SceneKit

import simd

class BaseComponent: GKComponent {

    public static let EnemyAltitude: Float = -0.46

    private(set) var agent = GKAgent2D()

    public var isAutoMoveNode = true

    func isDead() -> Bool {

        return false

    }

    func positionAgentFromNode() {

        let nodeComponent = entity!.component(ofType: GKSCNNodeComponent.self)!

        let node = nodeComponent.node

        agent.transform = node.simdTransform

    }

    func positionNodeFromAgent() {

        let nodeComponent = entity!.component(ofType: GKSCNNodeComponent.self)!

        let node = nodeComponent.node

        node.simdTransform = agent.transform

    }

    func constrainPosition() {

        var position = agent.position

        if position.x > 2 {

            position.x = 2

        }

        if position.x < -2 {

            position.x = -2

        }

        if position.y > 12.5 {

            position.y = 12.5

        }

        if position.y < 8.5 {

            position.y = 8.5

        }

        agent.position = position

    }

    override func update(deltaTime seconds: TimeInterval) {

        if self.isDead() {

            return

        }

        agent.update(deltaTime: seconds)

        constrainPosition()

        if isAutoMoveNode {

            positionNodeFromAgent()

        }

        super.update(deltaTime: seconds)

    }

    internal func performEnemyDieWithExplosion(_ enemy: SCNNode, direction: simd_float3) {

        guard let explositionScene = SCNScene(named: "Art.scnassets/enemy/enemy_explosion.scn") else {

            print("Missing enemy_explosion.scn")

            return

        }

        SCNTransaction.begin()

        SCNTransaction.animationDuration = 0.4

        SCNTransaction.animationTimingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)

        SCNTransaction.completionBlock = {

            explositionScene.rootNode.enumerateHierarchy({ (node: SCNNode, _: UnsafeMutablePointer<ObjCBool>) in

                guard let particles = node.particleSystems else { return }

                for particle in particles {

                    enemy.addParticleSystem(particle)

                }

            })

            // Hide

            enemy.childNodes.first?.opacity = 0.0

        }

        var direction = direction

        direction.y = 0

        enemy.removeAllAnimations()

        enemy.eulerAngles =

            SCNVector3Make(enemy.eulerAngles.x, enemy.eulerAngles.x + .pi * 4.0, enemy.eulerAngles.z)

        enemy.simdWorldPosition += simd_normalize(direction) * 1.5

        positionAgentFromNode()

        SCNTransaction.commit()

    }

}

extension GKAgent2D {

    var transform: matrix_float4x4 {

        get {

            let quat = simd_quaternion(-Float(rotation - (.pi / 2)), simd_make_float3(0, 1, 0))

            var transform: simd_float4x4 = simd_matrix4x4(quat)

            transform.columns.3 = simd_make_float4(self.position.x, BaseComponent.EnemyAltitude, self.position.y, 1)

            return transform

        }

        set(newTransform) {

            let quatf: simd_quatf = simd_quaternion(newTransform)

            self.rotation = -(simd_angle(quatf) + (.pi / 2))

            self.position = simd_float2(newTransform.columns.3.x, newTransform.columns.3.z)

        }

    }

}