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

[Serializable]
public class ReceptorInstance : Nucleus {
    public ReceptorInstance(Cluster parent, string name) {
        this.parent = parent;
        this.name = name;
        // We explicitly do not add this to the parent, as it is serialized in the ReceptorArray
    }
    public ReceptorInstance(ClusterPrefab prefab, string name) {
        this.cluster = prefab;
        this.name = name;
        // We explicitly do not add this to the prefab, as it is serialized in the ReceptorArray
    }
    public override Nucleus ShallowCloneTo(Cluster parent) {
        ReceptorInstance clone = new(parent, name + " +1") {
            receptor = this.receptor
        };
        return clone;
    }
    public override Nucleus Clone(ClusterPrefab prefab) {
        ReceptorInstance clone = new(prefab, name) {
            receptor = this.receptor
        };
        return clone;
    }

    [SerializeReference]
    public Receptor receptor;

    public override void UpdateStateIsolated() {
    }
}

[Serializable]
public class Receptor : Nucleus {
    public Receptor(Cluster parent, string name) {
        this.parent = parent;
        this.name = name;
        this._instances = new ReceptorInstance[1];
        this._instances[0] = new ReceptorInstance(parent, this.name + "[0]") {
            receptor = this
        };
        this.parent?.nuclei.Add(this);
    }
    public Receptor(ClusterPrefab prefab, string name) {
        this.cluster = prefab;
        this.name = name;
        this._instances = new ReceptorInstance[1];
        this._instances[0] = new ReceptorInstance(prefab, this.name + "[0]") {
            receptor = this
        };
        if (this.cluster != null)
            this.cluster.nuclei.Add(this);
        else
            Debug.LogError("No prefab when adding receptor to prefab");

    }

    public override Nucleus ShallowCloneTo(Cluster parent) {
        Receptor clone = new(parent, name) {
            _instances = new ReceptorInstance[this.instances.Length]
        };
        for (int ix = 0; ix < this.instances.Length; ix++) {
            clone._instances[ix] = new ReceptorInstance(parent, $"{this.name} [{ix}]") {
              receptor = clone
            };
        }

        return clone;
    }

    public override Nucleus Clone(ClusterPrefab prefab) {
        Receptor clone = new(prefab, this.name) {
            _instances = new ReceptorInstance[this.instances.Length]
        };
        for (int ix = 0; ix < this.instances.Length; ix++) {
            clone._instances[ix] = new ReceptorInstance(prefab, this.name) {
                receptor = this
            };
        }

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

    [SerializeReference]
    private ReceptorInstance[] _instances;
    public ReceptorInstance[] instances {
        get {
            return _instances;
        }
    }

    public void AddReceptor(ClusterPrefab prefab) {
        if (this._instances.Length == 0) {
            Debug.LogError("Empty receptor array, cannot add");
            return;
        }
        int newLength = this._instances.Length + 1;
        ReceptorInstance[] newArray = new ReceptorInstance[newLength];

        for (int i = 0; i < this._instances.Length; i++)
            newArray[i] = this._instances[i];
        ReceptorInstance newReceptor = (ReceptorInstance)this._instances[0].Clone(prefab);
        newReceptor.name = $"{this.name} [{this._instances.Length}]";
        newArray[newLength - 1] = newReceptor;

        this._instances = newArray;
    }

    public void RemoveReceptor() {
        int newLength = this._instances.Length - 1;
        if (newLength == 0) {
            Debug.LogWarning("Receptor array cannot be empty");
            return;
        }
        ReceptorInstance[] newPerceptei = new ReceptorInstance[newLength];
        for (int i = 0; i < newLength; i++)
            newPerceptei[i] = this._instances[i];
        // Delete the last perception
        if (this._instances[newLength] is Nucleus nucleus)
            Neuron.Delete(nucleus); //this._nuclei[newLength]);

        this._instances = newPerceptei;
    }

    private Dictionary<int, Nucleus> thingReceivers = new();

    public override void ProcessStimulus(int thingId, Vector3 inputValue, string thingName = null) {
        ProcessStimulus(inputValue, thingId, thingName);
    }
    public void ProcessStimulus(Vector3 inputValue, int thingId = 0, string thingName = null) {
        CleanupReceivers();
        if (!thingReceivers.TryGetValue(thingId, out Nucleus selectedReceiver)) {
            //Debug.Log($" no receiver found for {thingId}");
            // No existing nucleus for this thing
            selectedReceiver = SelectReceptor(thingId, inputValue);
        }
        if (selectedReceiver == null)
            return;

        if (thingName != null) {
            string baseName = selectedReceiver.name;
            int colonPos = selectedReceiver.name.IndexOf(":");
            if (colonPos > 0)
                baseName = selectedReceiver.name[..colonPos];
            selectedReceiver.name = baseName + ": " + thingName;
        }

        //if (selectedReceiver is Neuron selectedNucleus) {
        selectedReceiver.stale = 0;
        selectedReceiver.outputValue = inputValue;
        this.parent.UpdateFromNucleus(this);
        //selectedNucleus.ProcessStimulus(inputValue);
        //}
    }

    private void CleanupReceivers() {
        // Remove a thing-receiver connection when the nucleus is inactive
        List<int> receiversToRemove = new();
        thingReceivers ??= new();

        foreach (KeyValuePair<int, Nucleus> item in thingReceivers) {
            if (item.Value.isSleeping)
                receiversToRemove.Add(item.Key);
        }
        foreach (int thingId in receiversToRemove) {
            Nucleus selectedReceiver = thingReceivers[thingId];

            // Debug.Log($" removed receiver for {thingId}");
            thingReceivers.Remove(thingId);

            int colonPos = selectedReceiver.name.IndexOf(":");
            if (colonPos > 0)
                selectedReceiver.name = selectedReceiver.name[..colonPos];
        } 

    }

    private Nucleus SelectReceptor(int thingId, float3 inputValue) {
        // No existing nucleus for this thing
        float inputMagnitude = length(inputValue);
        Nucleus selectedReceiver = null;
        float selectedMagnitude = 0;
        foreach (Nucleus receiver in this._instances) {
            if (thingReceivers.ContainsValue(receiver) == false) {
                // We found an unusued receiver
                // Debug.Log($"{thingId} -> [{receiver.name}]");
                thingReceivers.Add(thingId, receiver);
                return receiver;
            }
            else if (receiver.isSleeping) {
                // A sleeping receiver is not active and can therefore always be used
                thingReceivers.Add(thingId, receiver);
                Debug.Log($"{thingId} -> [{selectedReceiver.name}]");
                return receiver;
            }
            else if (selectedReceiver == null) {
                // If we haven't found a receiver yet, just start by taking the first
                selectedReceiver = receiver;
                selectedMagnitude = length(selectedReceiver.outputValue);
            }
            // Look for the receiver with the lowest magnitude
            else {
                float magnitude = length(receiver.outputValue);

                if (magnitude < inputMagnitude && length(receiver.outputValue) < selectedMagnitude) {
                    selectedReceiver = receiver;
                    selectedMagnitude = length(selectedReceiver.outputValue);
                }
            }
        }
        if (selectedReceiver != null) {
            // Replace the receiver
            // Find the thingId current associated with the receiver
            int keyToRemove = thingReceivers.FirstOrDefault(r => r.Value.Equals(selectedReceiver)).Key;
            if (keyToRemove != 0 || thingReceivers.ContainsKey(keyToRemove))
                thingReceivers.Remove(keyToRemove);
            // And add the new association
            thingReceivers.Add(thingId, selectedReceiver);
        }
        return selectedReceiver;
    }

    public override void UpdateStateIsolated() {
        float3 sum = this.bias;

        // Receptors do not have inputs, so we ignore the synapses
        foreach (Nucleus nucleus in this._instances)
            sum += nucleus.outputValue;

        this.outputValue = sum / _instances.Length;
        this.stale = 0;

        UpdateNuclei();
    }

    public override void UpdateNuclei() {
        foreach (Nucleus nucleus in this.instances) {
            nucleus.stale++;
            if (nucleus.stale > staleValueForSleep && lengthsq(nucleus.outputValue) > 0) {
                nucleus.outputValue = Vector3.zero;
                //this.UpdateStateIsolated();
                this.parent.UpdateFromNucleus(this);
            }
        }
    }
}