using UnityEngine;

namespace BehaviorDesigner.Runtime.Tasks.Movement
{
    [TaskDescription("Flee from the target specified using the Unity NavMesh.")]
    [TaskCategory("Movement")] 
    [HelpURL("http://www.opsive.com/assets/BehaviorDesigner/Movement/documentation.php?id=4")]
    [TaskIcon("Assets/Behavior Designer Movement/Editor/Icons/{SkinColor}FleeIcon.png")]
    public class ActionFlee : Action
    {
        [Tooltip("The speed of the agent")]
        public SharedFloat speed;
        [Tooltip("Angular speed of the agent")]
        public SharedFloat angularSpeed;
        [Tooltip("The agent has fleed when the square magnitude is greater than this value")]
        public SharedFloat fleedMinDistance = 5;
        [Tooltip("The agent has fleed when the square magnitude is greater than this value")]
        public SharedFloat fleedMaxDistance = 15;
        [Tooltip("The distance to look ahead when fleeing")]
        public SharedFloat lookAheadDistance = 5;
        [Tooltip("The transform that the agent is fleeing from")]
        public SharedTransform targetTransform;
        [Tooltip("If target is null then use the target position")]
        public SharedVector3 targetPosition;

        // True if the target is a transform
        private bool dynamicTarget;
        // A cache of the NavMeshAgent
        private UnityEngine.AI.NavMeshAgent navMeshAgent;

        private float fleedDistance;

        public override void OnAwake()
        {
            // cache for quick lookup
            navMeshAgent = gameObject.GetComponent<UnityEngine.AI.NavMeshAgent>();
        }

        public override void OnStart()
        {
            if (navMeshAgent == null)
            {
                navMeshAgent = gameObject.GetComponent<UnityEngine.AI.NavMeshAgent>();
            }

            // the target is dynamic if the target transform is not null and has a valid
            dynamicTarget = (targetTransform != null && targetTransform.Value != null);
            fleedDistance = UnityEngine.Random.Range(fleedMinDistance.Value, fleedMaxDistance.Value);

            // set the speed, angular speed, and destination then enable the agent
            navMeshAgent.speed = speed.Value;
            navMeshAgent.angularSpeed = angularSpeed.Value;
            navMeshAgent.enabled = true;
            navMeshAgent.destination = Target();
        }

        // Flee from the target. Return success once the agent has fleed the target by moving far enough away from it
        // Return running if the agent is still fleeing
        public override TaskStatus OnUpdate()
        {
            if (!navMeshAgent.pathPending && Vector3.SqrMagnitude(transform.position - Target()) > fleedDistance) {
                return TaskStatus.Success;
            }

            navMeshAgent.destination = FleePosition();
            return TaskStatus.Running;
        }

        public override void OnEnd()
        {
            // Disable the nav mesh
            navMeshAgent.enabled = false;
        }

        // return targetPosition if targetTransform is null
        private Vector3 Target()
        {
            if (dynamicTarget) {
                return targetTransform.Value.position;
            }
            return targetPosition.Value;
        }

        // Flee in the opposite direction
        private Vector3 FleePosition()
        {
            return transform.position + (transform.position - Target()).normalized * lookAheadDistance.Value;
        }

        // Reset the public variables
        public override void OnReset()
        {
            speed = 10;
            angularSpeed = 10;
            lookAheadDistance = 5;
        }
    }
}