using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using NanoBrain;

namespace CreatureControl {

    /// <summary>
    /// Simulated ant using a NanoBrain
    /// </summary>
    [RequireComponent(typeof(Brain))]
    public class Ant : Insect {
        /// <summary>
        /// inertia controls how quickly the ant can change it direction
        /// </summary>
        private readonly float inertia = 0.2f;
        /// <summary>
        /// The maximum distance at which the ant can smell things
        /// </summary>
        /// The strength of the smell decreases with the inverse square law
        /// to zero at this distance
        private readonly float smellRadius = 0.2f;
        /// <summary>
        /// The angle to the left and right within the ant can smell things
        /// </summary>
        private readonly float smellAngle = 80.0f;

        public GameObject homePheromonePrefab;
        public GameObject foodPheromonePrefab;

        public AntennaTouch touchLeft;
        public AntennaTouch touchRight;

        public Brain nanoBrain;

        // brain input

        /// <summary>
        /// The (heart) beat for the brain
        /// </summary>
        /// It is used by the brain to do things periodically
        /// like placing pheromones
        public Neuron beat;

        public Neuron foodReceptor;
        public Neuron homeReceptor;
        public Cluster foodReceptors;
        public Cluster homeReceptors;

        // brain output
        public Neuron targetDirection;
        public Neuron hasFood;

        public Vector3 linearVelocity; // = Vector3.forward;
        public Vector3 angularVelocity;

        #region Init

        protected override void Awake() {
            base.Awake();

            this.nanoBrain = GetComponentInChildren<Brain>();

            Cluster brain = this.nanoBrain.brain;
            if (brain != null) {
                //--- brain inputs
                this.beat = brain.GetNeuron("Beat");
                if (touchLeft != null)
                    touchLeft.receptor = brain.GetNucleus("Hit Left") as Neuron;
                if (touchRight != null)
                    touchRight.receptor = brain.GetNucleus("Hit Right") as Neuron;
                this.foodReceptor = brain.GetNucleus("Food Receptor") as Neuron;
                this.homeReceptor = brain.GetNucleus("Home Receptor") as Neuron;
                this.foodReceptors = brain.GetNucleus("Food Receptors") as Cluster;
                this.homeReceptors = brain.GetNucleus("Home Receptors") as Cluster;

                //--- brain outputs
                this.targetDirection = brain.GetNucleus("Movement") as Neuron;
                this.hasFood = brain.GetNucleus("Having Food") as Neuron;
            }
        }

        #endregion Init

        #region Start

        protected override void Start() {
            base.Start();

            Cluster brain = this.nanoBrain.brain;
            if (brain != null) {
                // Try to find the Home Pheromones Neuron
                if (brain.GetNucleus("Home Pheromones") is Neuron homePheromones)
                    // and call PlaceHomePheromone when it is firing
                    homePheromones.WhenFiring += PlaceHomePheromone;
                // Try to find the Food Pheromones Neuron
                Neuron foodPheromones = brain.GetNeuron("Food Pheromones");
                if (foodPheromones != null)
                    // and call PlaceFoodPheromone when it is firing
                    foodPheromones.WhenFiring += PlaceFoodPheromone;
            }

            StartCoroutine(Beat());
        }

        #endregion Start

        #region Update

        private int foodPheromoneIx = 0;
        void PlaceFoodPheromone() {
            if (foodPheromonePrefab == null)
                return;

            GameObject pheromoneObj = Instantiate(foodPheromonePrefab);
            pheromoneObj.name = $"To Food {foodPheromoneIx++}";
            pheromoneObj.transform.position = this.model.position;
        }

        private int homePheromoneIx = 0;
        void PlaceHomePheromone() {
            if (homePheromonePrefab == null)
                return;

            GameObject pheromoneObj = Instantiate(homePheromonePrefab);
            pheromoneObj.name = $"To Home {homePheromoneIx++}";
            pheromoneObj.transform.position = this.model.position;
        }

        public override void Update() {
            base.Update();

            UpdateSmell();
            UpdateMovement();
        }

        public virtual void FixedUpdate() {
            CheckGrounded();
        }

        protected void UpdateMovement() {
            if (this.targetDirection == null || this.animator == null)
                return;

            Vector3 movementDir = this.targetDirection.outputValue;
            this.linearVelocity =
                (1 - this.inertia) * (Time.deltaTime * movementDir.normalized) +
                this.inertia * this.linearVelocity;
            this.linearVelocity = this.linearVelocity.normalized;

            this.forwardSpeed = this.linearVelocity.z;

            float angleRad = this.linearVelocity.sqrMagnitude > 1e-10f ?
                Mathf.Atan2(this.linearVelocity.x, this.linearVelocity.z) :
                0;
            // map -20..20 degrees to -1..1
            this.rotationSpeed = Mathf.Clamp(angleRad * 3, -1f, 1f);

            this.animator.SetFloat("Forward", this.forwardSpeed);
            this.animator.SetFloat("Rotation", this.rotationSpeed);
        }

        private static readonly WaitForSeconds _waitForSeconds3 = new(3);
        IEnumerator Beat() {
            while (Application.isPlaying) {
                // Beat signal to the brain
                beat?.SetBias(Vector3.one);

                // Set random direction to simulate noisy smells perception
                // which will result in a bit of random walking when no clear
                // smells are received
                float randomAngle = Random.Range(-smellAngle, smellAngle);
                Vector3 randomDirection = Quaternion.AngleAxis(randomAngle, Vector3.up) * Vector3.forward * 0.01f;
                foodReceptor?.SetBias(randomDirection);
                randomAngle = Random.Range(-smellAngle, smellAngle);
                randomDirection = Quaternion.AngleAxis(randomAngle, Vector3.up) * Vector3.forward * 0.01f;
                homeReceptor?.SetBias(randomDirection);

                yield return _waitForSeconds3;
            }
        }

        void UpdateSmell() {
            Collider[] colliders = Physics.OverlapSphere(this.transform.position, smellRadius);
            foreach (Collider collider in colliders) {
                SmellPheromones(collider);
            }
        }

        void SmellPheromones(Collider thing) {
            Vector3 smellDirection = this.transform.InverseTransformPoint(thing.transform.position);
            float distance = smellDirection.magnitude;
            float angle = Vector3.Angle(Vector3.forward, smellDirection);

            if (angle < smellAngle && smellDirection.magnitude > 0.01) {
                // float intensity = pheromone.StrengthAt(distance);
                // Vector3 smell = smellDirection.normalized * intensity;
                Vector3 smell = Vector3.zero;

                int id = thing.GetInstanceID();
                Neuron receptor = null;
                
                Pheromone pheromone = thing.GetComponentInParent<Pheromone>();
                if (pheromone != null) {
                    // multiply by distance to compensate for strong and weak smells
                    smell = pheromone.StrengthAt(smellDirection) * distance / 10;
                    switch (pheromone.type) {
                        case Pheromone.Type.Food:
                            receptor = foodReceptors?.GetNeuron(id, "Output", pheromone.name);
                            //Debug.DrawRay(this.transform.position, this.transform.rotation * smell, Color.magenta);
                            break;
                        case Pheromone.Type.Home:
                            receptor = homeReceptors?.GetNeuron(id, "Output", pheromone.name);
                            //Debug.DrawRay(this.transform.position, this.transform.rotation * smell, Color.cyan);
                            break;
                    }
                }
                Food food = thing.GetComponentInParent<Food>();
                if (food != null) {
                    receptor = foodReceptors?.GetNeuron(id, "Output", food.name);
                    smell = food.StrengthAt(smellDirection) * distance / 10;
                    //Debug.DrawRay(this.transform.position, this.transform.rotation * smell, Color.magenta);
                }
                AntsNest home = thing.GetComponentInParent<AntsNest>();
                if (home != null) {
                    receptor = homeReceptors?.GetNeuron(id, "Output", home.name);
                    smell = home.StrengthAt(smellDirection) * distance / 10;
                    //Debug.DrawRay(this.transform.position, this.transform.rotation * smell, Color.cyan);
                }
                receptor?.ProcessStimulus(smell);
            }
        }

        #endregion Update

    }

}