using System;
using System.Collections.Generic;
using UnityEngine;
using Unity.Mathematics;
using static Unity.Mathematics.math;

[Serializable]
public class Cluster : INucleus {
    // The ScriptableObject asset from which the runtime object has been created

    [SerializeField]
    protected string _name;
    public virtual string name {
        get => _name;
        set => _name = value;
    }

    public ClusterPrefab storedPrefab;

    public Cluster(Cluster parent, ClusterPrefab realPrefab) {
        this.storedPrefab = realPrefab;
        this.parent = parent;
        this.parent?.nuclei.Add(this);

        ClonePrefab();
    }

    public Cluster(ClusterPrefab realPrefab) {
        this.storedPrefab = realPrefab;
        this.name = realPrefab.name;
        this.cluster = null;
        if (this.cluster != null)
            this.cluster.nuclei.Add(this);

        ClonePrefab();
    }

    public Cluster(ClusterPrefab parent, ClusterPrefab realPrefab) {
        this.storedPrefab = realPrefab;
        //this.prefab = realPrefab.Clone();
        this.name = realPrefab.name;
        this.cluster = parent;
        if (this.cluster != null)
            this.cluster.nuclei.Add(this);

        ClonePrefab();
    }

    private void ClonePrefab() {
        IReceptor[] nucleiArray = this.storedPrefab.nuclei.ToArray();
        // first clone the nuclei without their connections
        foreach (IReceptor nucleus in this.storedPrefab.nuclei)
            nucleus.ShallowCloneTo(this);
        IReceptor[] clonedNuclei = this.nuclei.ToArray();

        // Now clone the connections
        for (int nucleusIx = 0; nucleusIx < nucleiArray.Length; nucleusIx++) {
            IReceptor receptor = nucleiArray[nucleusIx];
            IReceptor clonedSender = clonedNuclei[nucleusIx];
            if (clonedSender == null)
                continue;

            // Copy the receivers, which will also create the synapses
            foreach (INucleus receiver in receptor.receivers) {
                int ix = GetNucleusIndex(nucleiArray, receiver);
                if (ix < 0)
                    continue;

                if (clonedNuclei[ix] is not INucleus clonedReceiver)
                    continue;

                // Find the synapse for the weight
                float weight = 1;
                foreach (Synapse synapse in receiver.synapses) {
                    if (synapse.nucleus == receptor) {
                        weight = synapse.weight;
                        break;
                    }
                }

                clonedSender.AddReceiver(clonedReceiver, weight);
            }
        }
    }

    public virtual IReceptor Clone() {
        Neuron clone = new(this.cluster, this.name) {
            array = this.array,
        };

        foreach (Synapse synapse in this.synapses) {
            Synapse clonedSynapse = clone.AddSynapse(synapse.nucleus);
            clonedSynapse.weight = synapse.weight;
        }
        foreach (INucleus receiver in this.receivers) {
            clone.AddReceiver(receiver);
        }
        return clone;
    }

    public IReceptor ShallowCloneTo(Cluster parent) {
        Cluster clone = new(parent, this.storedPrefab) {
            name = this.name,
        };
        return clone;
    }

    private int GetNucleusIndex(IReceptor[] nucleiArray, IReceptor nucleus) {
        for (int i = 0; i < nucleiArray.Length; i++) {
            if (nucleus == nucleiArray[i])
                return i;
        }
        return -1;
    }

    public ClusterPrefab cluster { get; set; }
    public Cluster parent { get; set; }

    [SerializeReference]
    public List<IReceptor> nuclei = new();

    public List<INucleus> _inputs = null;
    public virtual List<INucleus> inputs {
        get {
            if (this._inputs == null) {
                this._inputs = new();
                foreach (IReceptor receptor in this.nuclei) {
                    if (receptor is INucleus nucleus) {
                        // inputs have no incoming synapses yet.
                        if (nucleus.synapses.Count == 0)
                            this._inputs.Add(nucleus);
                    }
                }
            }
            return this._inputs;
        }
    }

    public virtual INucleus output {//=> this.nuclei[0] as INucleus;
        get {
            if (this.nuclei.Count > 0)
                return this.nuclei[0] as INucleus;
            return null;
        }
    }

    // Not sure if this belongs here...
    [SerializeReference]
    private NucleusArray _array;
    public NucleusArray array {
        get { return _array; }
        set { _array = value; }
    }

    #region Synapses

    [SerializeField]
    private List<Synapse> _synapses = new();
    public List<Synapse> synapses => _synapses;

    public Synapse AddSynapse(IReceptor sendingNucleus, float weight = 1.0f) {
        Synapse synapse = new(sendingNucleus, weight);
        this._synapses.Add(synapse);
        return synapse;
    }

    // Does this even exist already?
    public void RemoveSynapse() {

    }

    #endregion Synapses

    #region Receivers

    [SerializeReference]
    private List<INucleus> _receivers = new();
    public List<INucleus> receivers {
        get { return _receivers; }
        set { _receivers = value; }
    }

    public virtual void AddReceiver(INucleus receivingNucleus, float weight = 1) {
        this._receivers.Add(receivingNucleus);
        receivingNucleus.AddSynapse(this, weight);
    }

    public void RemoveReceiver(INucleus receiverNucleus) {
        this._receivers.RemoveAll(receiver => receiver == receiverNucleus);
        receiverNucleus.synapses.RemoveAll(synapse => synapse.nucleus == this);
    }

    #endregion Receivers

    #region Runtime

    [NonSerialized]
    private int stale = 1000;
    public bool isSleeping => lengthsq(this.outputValue) == 0;

    [NonSerialized]
    protected float3 _outputValue;
    public virtual float3 outputValue {
        get { return _outputValue; }
        set {
            this.stale = 0;
            _outputValue = value;
        }
    }

    #region Update

    public virtual void UpdateState() {
        UpdateState(new float3(0, 0, 0));
    }

    public void UpdateState(float3 inputValue) {
        float3 sum = inputValue; // new(0, 0, 0);

        //Applying the weight factgors
        foreach (Synapse synapse in this.synapses) {
            sum += synapse.weight * synapse.nucleus.outputValue;
        }

        //this.prefab.inputs[0].UpdateState(sum);
        this.inputs[0].UpdateState(sum);

        UpdateResult(this.output.outputValue);
    }

    public virtual void UpdateResult(Vector3 result) {
        // float d = Vector3.Distance(result, this.outputValue);
        // if (d < 0.5f) {
        //     //Debug.Log($"insignificant update: {d}");
        //     return;
        // }

        this.outputValue = result;
        foreach (INucleus receiver in this.receivers)
            receiver.UpdateState();
    }

    public void UpdateNuclei() {
        this.stale++;
        if (this.stale > 2)
            _outputValue = Vector3.zero;

        //foreach (IReceptor nucleus in this.prefab.nuclei)
        foreach (IReceptor nucleus in this.nuclei)
            nucleus.UpdateNuclei();
    }

    #endregion Update

    #endregion Runtime    
}