using System.Collections.Generic;
using UnityEngine;

[CreateAssetMenu(menuName = "Passer/Cluster")]
public class ClusterPrefab : ScriptableObject {
    // The ScriptableObject asset from which the runtime object has been created
    public string hello = "hello";

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


    public virtual Nucleus output => this.nuclei[0] as Nucleus;

    public List<Nucleus> _inputs = null;
    public virtual List<Nucleus> inputs {
        get {
            if (this._inputs == null) {
                this._inputs = new();
                foreach (Nucleus receptor in this.nuclei) {
                    if (receptor is Nucleus nucleus) {
                        // inputs have no incoming synapses yet.
                        if (nucleus.synapses.Count == 0)
                            this._inputs.Add(nucleus);
                    }
                }
            }
            return this._inputs;
        }
    }
    private List<Nucleus> _outputs = null;
    public List<Nucleus> outputs {
        get {
            if (this._outputs == null)
                RefreshOutputs();
            return this._outputs;
        }
    }
    public void RefreshOutputs() {
        this._outputs = new();
        foreach (Nucleus nucleus in this.nuclei) {
            if (nucleus.receivers.Count == 0)
                this._outputs.Add(nucleus);
        }
    }

    public Nucleus GetNucleus(string nucleusName) {
        foreach (Nucleus nucleus in this.nuclei) {
            if (nucleus.name == nucleusName)
                return nucleus;
        }
        return null;
    }

    // Call this function to ensure that there is at least one nucleus
    // This is an invariant and should be ensured before the nucleus is used
    // because output requires it.
    public void EnsureInitialization() {
        nuclei ??= new List<Nucleus>();
        if (nuclei.Count == 0)
            new Neuron(this, "Output"); // Every cluster should have at least 1 neuron
    }

    public void GarbageCollection() {
        HashSet<Nucleus> visitedNuclei = new();
        foreach (Nucleus output in this.outputs)
            MarkNuclei(visitedNuclei, output);
        //MarkNuclei(visitedNuclei, this.output);
        //Debug.Log($"Garbage collection found {visitedNuclei.Count} Nuclei");
        this.nuclei.RemoveAll(nucleus => nucleus is Nucleus n && visitedNuclei.Contains(n) == false);
    }

    public void MarkNuclei(HashSet<Nucleus> visitedNuclei, Nucleus nucleus) {
        if (nucleus is null)
            return;

        visitedNuclei.Add(nucleus);
        if (nucleus.synapses != null) {
            HashSet<Synapse> visitedSynapses = new();
            foreach (Synapse synapse in nucleus.synapses) {
                if (synapse != null && synapse.nucleus != null) {
                    visitedSynapses.Add(synapse);
                    if (synapse.nucleus is Nucleus synapse_nucleus)
                        MarkNuclei(visitedNuclei, synapse_nucleus);
                }
            }
            nucleus.synapses.RemoveAll(synapse => visitedSynapses.Contains(synapse) == false);
        }
        if (nucleus.receivers != null) {
            HashSet<Nucleus> visitedReceivers = new();
            foreach (Nucleus receiver in nucleus.receivers) {
                if (receiver != null && receiver != null) {
                    visitedReceivers.Add(receiver);
                    visitedNuclei.Add(receiver);
                }
            }
            nucleus.receivers.RemoveAll(receiver => visitedReceivers.Contains(receiver) == false);
        }
    }

    public virtual void UpdateNuclei() {
        foreach (Nucleus nucleus in this.nuclei)
            nucleus.UpdateNuclei();
    }
}