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

/// <summary>
/// The Nanobrain namespace
/// </summary>
namespace NanoBrain {

/// <summary>
/// A Nucleus is a basic element in a brain cluster
/// </summary>
[Serializable]
public abstract class Nucleus {
    /// <summary>
    /// The name of the Nucleus
    /// </summary>
    public string name;

    /// <summary>
    /// The cluster prefab in which the nucleus is located
    /// </summary>
    [SerializeReference]
    public ClusterPrefab clusterPrefab;
    /// <summary>
    /// The cluster instance in which the nucleus is located
    /// </summary>
    [SerializeReference]
    public Cluster parent;

    /// <summary>
    /// Toggle for printing debugging trace data
    /// </summary>
    public bool trace = false;

    /// <summary>
    /// Function to make a partial clone of this nucleus
    /// </summary>
    /// <param name="parent">The cluster in which the cloned nucleus should be placed</param>
    /// <returns></returns>
    public abstract Nucleus ShallowCloneTo(Cluster parent);
    /// <summary>
    /// Function to clone a nucleus to a Cluster prefab
    /// </summary>
    /// <param name="prefab"></param>
    /// <returns></returns>
    public abstract Nucleus Clone(ClusterPrefab prefab);

    /// <summary>
    /// The types of Nucleus
    /// </summary>
    public enum Type {
        None,
        Neuron,
        MemoryCell,
        Cluster,
        Receptor,
        ClusterReceptor,
    }

    #region Synapses

    /// <summary>
    /// The bias of the nucleus
    /// </summary>
    /// The bias which a value which is always added to the combined value of the nucleus
    /// It does not have a synapse and therefore no weight of source nucleus
    public Vector3 bias = Vector3.zero;

    [SerializeField]
    private List<Synapse> _synapses = new();
    /// <summary>
    /// The synapses of the nucleus
    /// </summary>
    public List<Synapse> synapses => _synapses;

    /// <summary>
    /// Add a new synapse to this nuclues
    /// </summary>
    /// <param name="sendingNucleus">The nucleus from which the signals may originate</param>
    /// <param name="weight">The weight applied to the input. Default value = 1</param>
    /// <returns>The created Synapse</returns>
    /// This will add a new input to this nucleus with the given weight.
    public Synapse AddSynapse(Neuron sendingNucleus, float weight = 1) {
        Synapse synapse = new(sendingNucleus, weight);
        this.synapses.Add(synapse);
        return synapse;
    }

    /// <summary>
    /// Find a synapse
    /// </summary>
    /// <param name="sender">The sender of the input to the Synapse</param>
    /// <returns>The found Synapse or null when the sender has no synapse to this nucleus.</returns>
    public Synapse GetSynapse(Nucleus sender) {
        foreach (Synapse synapse in this.synapses)
            if (synapse.neuron == sender)
                return synapse;
        return null;
    }

    /// <summary>
    /// Remove a synapse from a Nucleus
    /// </summary>
    /// <param name="sendingNucleus">Remote the synapse connecting to this Nucleus</param>
    public void RemoveSynapse(Nucleus sendingNucleus) {
        this.synapses.RemoveAll(synapse => synapse.neuron == sendingNucleus);
    }

    #endregion Synapses

    #region Update

    /// <summary>
    /// Update the state without updating other Nuclei
    /// </summary>
    public abstract void UpdateStateIsolated();

    /// <summary>
    /// Update the state and recursively all Nuclei receiving data from this Nucleus
    /// </summary>
    public virtual void UpdateNuclei() {
    }

    /// <summary>
    /// Set the bias, recalculate the output and update all Nuclei receiving from this Nucleus
    /// </summary>
    /// <param name="inputValue"></param>
    public virtual void SetBias(Vector3 inputValue) {
        this.bias = inputValue;
        this.parent.UpdateFromNucleus(this);
    }

    /// <summary>
    /// Process an external stimulus
    /// </summary>
    /// <param name="inputValue">The value of the stimulus</param>
    /// <param name="thingId">The id of the thing causing the stimulus</param>
    /// <param name="thingName">The name of the thing causing the stimulus</param>
    public virtual void ProcessStimulus(Vector3 inputValue, int thingId = 0, string thingName = "") {
    }

    #endregion Update

}

}