using System.Collections.Generic;
using System.Linq;

using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

namespace NanoBrain {

    public class ClusterViewer : Editor {

        public class GraphView : VisualElement {
            protected readonly ClusterPrefab prefab;
            protected SerializedObject serializedBrain;
            protected Nucleus currentNucleus;
            protected GameObject gameObject;
            private List<NeuroidLayer> layers = new();
            private readonly Dictionary<Nucleus, Vector2Int> neuroidPositions = new();
            private bool expandArray = false;

            protected ClusterPrefab prefabAsset;
            protected VisualElement outputContainer;
            protected readonly PopupField<string> outputsField;

            public GraphView(ClusterPrefab prefab) {
                this.prefab = prefab;

                name = "content";
                style.flexGrow = 1;

                IMGUIContainer graphContainer = new(OnIMGUI);
                graphContainer.style.position = Position.Absolute;
                graphContainer.style.left = 0; graphContainer.style.top = 0;
                graphContainer.style.right = 0; graphContainer.style.bottom = 0;
                graphContainer.pickingMode = PickingMode.Position;
                graphContainer.focusable = true;
                Add(graphContainer);

                outputContainer = new() {
                    style = {
                    flexDirection = FlexDirection.Row,
                    alignItems = Align.Center,
                }
                };

                List<string> names = this.prefab.outputs.Select(output => output.name).ToList();
                if (names.Count > 0 && names.First() != null) {
                    outputsField = new(names, names.First()) {
                        style = { flexGrow = 1 }
                    };
                    outputsField.RegisterValueChangedCallback(evt => OnOutputChanged(evt.newValue));
                    outputContainer.Add(outputsField);
                }

                Add(outputContainer);

                // Subscribe when added to panel (editor UI ready)
                RegisterCallback<AttachToPanelEvent>(evt => Subscribe());
                RegisterCallback<DetachFromPanelEvent>(evt => Unsubscribe());
            }

            void OnOutputChanged(string outputName) {
                if (this.currentNucleus.parent != null)
                    // Get nucleus in the parent instance
                    this.currentNucleus = this.currentNucleus.parent.GetNucleus(outputName);
                else
                    // Get nucleus in the prefab
                    this.currentNucleus = this.prefab.GetNucleus(outputName);
            }

            bool subscribed = false;
            void Subscribe() {
                if (subscribed) return;
                SceneView.duringSceneGui += OnSceneGUI;
                subscribed = true;
                SceneView.RepaintAll();
            }

            void Unsubscribe() {
                if (!subscribed) return;
                SceneView.duringSceneGui -= OnSceneGUI;
                subscribed = false;
            }

            public void SetGraph(GameObject gameObject, Nucleus nucleus) { //}, VisualElement inspectorContainer) {
                this.gameObject = gameObject;
                //this.cluster = brain;
                if (Application.isPlaying == false)
                    this.serializedBrain = new SerializedObject(this.prefab);
                this.currentNucleus = nucleus;
                Rebuild(); //inspectorContainer);
            }

            void Rebuild() { //VisualElement inspectorContainer) {
                BuildLayers();

                if (this.currentNucleus == null) {
                    // inspectorContainer.Clear();
                    return;
                }

                string path = AssetDatabase.GetAssetPath(this.prefab); // or known path
                this.prefabAsset = AssetDatabase.LoadAssetAtPath<ClusterPrefab>(path);
                if (this.prefabAsset == null) {
                    // create in memory save if it doesn't exist
                    this.prefabAsset = CreateInstance<ClusterPrefab>();
                    //Debug.LogError("Cluster Prefab is not found on disk");
                }
                //DrawInspector(inspectorContainer);
            }

            protected void BuildLayers() {
                // A temporary list to track what's been added to layers
                this.layers = new();
                int layerIx = 0;

                Nucleus selectedNucleus = this.currentNucleus;
                if (selectedNucleus == null)
                    return;
                NeuroidLayer currentLayer = new() { ix = layerIx };

                if (selectedNucleus is Neuron selectedNeuron && selectedNeuron.receivers != null) {
                    foreach (Nucleus receiver in selectedNeuron.receivers) {
                        Nucleus outputNeuroid = receiver;
                        if (outputNeuroid != null) {
                            AddToLayer(currentLayer, outputNeuroid);
                            // Debug.Log($"layer {layerIx} nucleus {outputNeuroid.name}");
                        }
                    }
                }
                if (currentLayer.neuroids.Count > 0) {
                    this.layers.Add(currentLayer);
                    layerIx++;
                    currentLayer = new() { ix = layerIx };
                }

                AddToLayer(currentLayer, selectedNucleus);
                this.layers.Add(currentLayer);
                // Debug.Log($"layer {layerIx} nucleus {selectedNucleus.name}");

                layerIx++;
                currentLayer = new() { ix = layerIx };

                if (selectedNucleus.synapses != null) {
                    foreach (Synapse synapse in selectedNucleus.synapses) {
                        Nucleus input = synapse.neuron;
                        AddToLayer(currentLayer, input);
                        // Debug.Log($"layer {layerIx} nucleus {input.name}");
                    }
                }
                if (currentLayer.neuroids.Count > 0) {
                    this.layers.Add(currentLayer);
                }
            }

            private void AddToLayer(NeuroidLayer layer, Nucleus nucleus) {
                if (nucleus == null)
                    return;
                layer.neuroids.Add(nucleus);
                //nucleus.layerIx = layer.ix;
                // Store its position
                Vector2Int neuroidPosition = new(layer.ix, layer.neuroids.Count - 1);
                neuroidPositions[nucleus] = neuroidPosition;

            }

            public void OnIMGUI() {
                if (currentNucleus == null)
                    return;

                if (Application.isPlaying == false)
                    serializedBrain.Update();

                Handles.BeginGUI();
                DrawGraph();
                Handles.EndGUI();

            }

            private void DrawGraph() {
                float size = 20;
                Vector3 position = new(150, 210, 0);

                DrawReceivers(this.currentNucleus, position, size);
                DrawSynapses(this.currentNucleus, position, size);

                // Draw selected Nucleus
                if (expandArray) {
                    if (this.currentNucleus is IReceptor receptor1) {
                        float maxValue = 0;
                        foreach (Nucleus nucleus in receptor1.nucleiArray) {
                            if (nucleus is Neuron neuron) {
                                float value = neuron.outputMagnitude;
                                if (value > maxValue)
                                    maxValue = value;
                            }
                        }

                        float spacing = 400f / receptor1.nucleiArray.Count();
                        float margin = 10 + spacing / 2;
                        float xMin = 150 - size;
                        float xMax = 150 + size;
                        float yMin = 10 + margin - size / 2;
                        float yMax = 400 - margin + size;
                        Vector3[] verts = new Vector3[4] {
                            new(xMin, yMin, 0),
                            new(xMax, yMin, 0),
                            new(xMax, yMax, 0),
                            new(xMin, yMax, 0)
                        };
                        Handles.color = Color.black;
                        Handles.DrawAAConvexPolygon(verts);
                        int row = 0;
                        foreach (Nucleus nucleus in receptor1.nucleiArray) {
                            Vector3 pos = new(150, margin + row * spacing, 0.0f);
                            Handles.color = Color.white;
                            // The selected nucleus highlight ring
                            Handles.DrawSolidDisc(pos, Vector3.forward, size + 2);
                            DrawNucleus(nucleus, pos, maxValue, size);
                            row++;
                        }
                        GUIStyle style = new(EditorStyles.label) {
                            alignment = TextAnchor.UpperCenter,
                            normal = { textColor = Color.white },
                            fontStyle = FontStyle.Bold,
                        };
                        Vector3 labelPos = new(150, yMax + size + 5, 0);
                        string receptorName = receptor1.GetName();
                        int colonPos = receptorName.IndexOf(":");
                        if (colonPos > 0) {
                            string baseName = receptorName[..colonPos];
                            Handles.Label(labelPos, baseName, style);
                        }
                        else
                            Handles.Label(labelPos, receptorName, style);
                    }
                    else {
                        Handles.color = Color.white;
                        // The selected nucleus highlight ring
                        Handles.DrawSolidDisc(position, Vector3.forward, size + 2);
                        float maxValue = 1;
                        if (this.currentNucleus is Neuron neuron)
                            maxValue = neuron.outputMagnitude;
                        else if (this.currentNucleus is Cluster cluster)
                            maxValue = cluster.defaultOutput.outputMagnitude;

                        DrawNucleus(this.currentNucleus, position, maxValue, 20);

                    }
                }
                else {
                    Handles.color = Color.white;
                    // The selected nucleus highlight ring
                    Handles.DrawSolidDisc(position, Vector3.forward, size + 2);
                    float maxValue = 1;
                    if (this.currentNucleus is Neuron neuron)
                        maxValue = neuron.outputMagnitude;
                    else if (this.currentNucleus is Cluster cluster)
                        maxValue = cluster.defaultOutput.outputMagnitude;
                    DrawNucleus(this.currentNucleus, position, maxValue, 20);
                }
            }

            private void DrawReceivers(Nucleus nucleus, Vector3 parentPos, float size) {
                List<Nucleus> receivers;
                if (nucleus is Neuron neuron)
                    receivers = neuron.receivers;
                else if (nucleus is Cluster cluster)
                    receivers = cluster.CollectReceivers();
                else
                    return;

                int nodeCount = receivers.Count(); //neuron != null ? neuron.receivers.Count() : 1;

                // Determine the maximum value in this layer
                // This is used to 'scale' the output value colors of the nuclei
                float maxValue = 0;
                foreach (Nucleus receiver in receivers) {
                    if (receiver is Neuron neuroid) {
                        float value = neuroid.outputMagnitude;
                        if (value > maxValue)
                            maxValue = value;
                    }
                }

                // Determine the spacing of the nuclei in the layer
                float spacing = 400f / nodeCount;
                float margin = 10 + spacing / 2;

                int row = 0;
                List<Nucleus[]> drawnArrays = new();
                foreach (Nucleus receiver in receivers) {
                    if (receiver is Receptor receptor) {
                        if (drawnArrays.Contains(receptor.nucleiArray))
                            continue;
                        drawnArrays.Add(receptor.nucleiArray);
                    }

                    Nucleus receiverNucleus = receiver;
                    if (receiverNucleus == null)
                        continue;

                    Vector3 pos = new(50, margin + row * spacing, 0.0f);
                    Handles.color = Color.white;
                    Handles.DrawLine(parentPos, pos);

                    DrawNucleus(receiverNucleus, pos, maxValue, size);
                    row++;
                }
            }

            private void DrawSynapses(Nucleus nucleus, Vector3 parentPos, float size) {
                int nodeCount = nucleus.synapses.Count;

                // Determine the maximum value in this layer
                // This is used to 'scale' the output value colors of the nuclei
                float maxValue = 0;
                int neuronCount = 0;
                List<Nucleus[]> drawnArrays = new();
                foreach (Synapse synapse in nucleus.synapses) {
                    if (synapse.neuron == null)
                        continue;

                    if (synapse.neuron is Receptor receptor) {
                        if (drawnArrays.Contains(receptor.nucleiArray))
                            continue;
                        drawnArrays.Add(receptor.nucleiArray);
                    }
                    else if (synapse.neuron.parent is ClusterReceptor clusterReceptor) {
                        if (drawnArrays.Contains(clusterReceptor.nucleiArray))
                            continue;
                        drawnArrays.Add(clusterReceptor.nucleiArray);
                    }
                    // Oops...
                    else if (synapse.neuron.parent is Cluster cluster && cluster.clusterArray != null) {
                        if (drawnArrays.Contains(cluster.clusterArray.clusters))
                            continue;
                        drawnArrays.Add(cluster.clusterArray.clusters);
                    }
                    if (synapse.neuron is Neuron synapseNeuron) {
                        float value = synapseNeuron.outputMagnitude * synapse.weight;
                        // Debug.Log($"{synapse.nucleus.name}: {value}  {length(synapse.nucleus.outputValue)} {synapse.weight}");
                        if (value > maxValue)
                            maxValue = value;
                    }
                    neuronCount++;
                }

                // Determine the spacing of the nuclei in the layer
                float spacing = 400f / neuronCount;
                float margin = 10 + spacing / 2;

                int row = 0;
                drawnArrays = new();
                foreach (Synapse synapse in nucleus.synapses) {
                    if (synapse.neuron is null)
                        continue;

                    if (synapse.neuron is Receptor neuron) {
                        if (drawnArrays.Contains(neuron.nucleiArray))
                            continue;
                        drawnArrays.Add(neuron.nucleiArray);
                    }
                    else if (synapse.neuron.parent is ClusterReceptor clusterReceptor) {
                        if (drawnArrays.Contains(clusterReceptor.nucleiArray))
                            continue;
                        drawnArrays.Add(clusterReceptor.nucleiArray);
                    }
                    Vector3 pos = new(250, margin + row * spacing, 0.0f);
                    Handles.color = Color.white;
                    Handles.DrawLine(parentPos, pos);
                    Color color = Color.black;
                    if (Application.isPlaying) {
                        if (maxValue == 0 || !float.IsFinite(maxValue))
                            maxValue = 1;
                        float brightness = 0;
                        if (synapse.neuron is Neuron synapseNeuron)
                            brightness = synapseNeuron.outputMagnitude * synapse.weight / maxValue;
                        color = new Color(brightness, brightness, brightness, 1f);
                    }
                    if (synapse.neuron.parent != null && synapse.neuron.parent != this.currentNucleus.parent) {
                        // the synapse nucleus is part of a subcluster
                        DrawNucleus(synapse.neuron.parent, pos, maxValue, size, color);
                    }
                    // else if (synapse.nucleus.cluster != null && synapse.nucleus.cluster != this.currentNucleus.cluster) {
                    //     DrawNucleus(synapse.nucleus.parent, pos, maxValue, size, color);
                    // }
                    else {
                        DrawNucleus(synapse.neuron, pos, maxValue, size, color);
                    }
                    row++;
                }
            }

            private void DrawNucleus(Nucleus nucleus, Vector3 position, float maxValue, float size) {
                Color color;
                if (Application.isPlaying) {
                    float brightness = 0;
                    if (nucleus is Neuron neuron)
                        brightness = neuron.outputMagnitude / maxValue;
                    color = new Color(brightness, brightness, brightness, 1f);
                }
                else
                    color = Color.black;
                DrawNucleus(nucleus, position, maxValue, size, color);
            }

            private void DrawNucleus(Nucleus nucleus, Vector3 position, float maxValue, float size, Color color) {
                if (nucleus is MemoryCell) {
                    Handles.color = Color.white;
                    Handles.DrawWireDisc(position + Vector3.right * 10, Vector3.forward, size);
                }

                Handles.color = color;
                Handles.DrawSolidDisc(position, Vector3.forward, size);

                Handles.color = Color.white;
                // Position the label in front of the disc
                Vector3 labelPosition = position + (Vector3.forward * 0.1f);

                GUIStyle style = new(EditorStyles.label) {
                    alignment = TextAnchor.MiddleCenter,
                    normal = { textColor = Color.white },
                    fontStyle = FontStyle.Bold,
                };

                if (nucleus is IReceptor receptor1) {
                    if (expandArray) {
                        // Put array indices above elements
                        style.alignment = TextAnchor.LowerCenter;
                        Vector3 labelPos1 = position + Vector3.down * (size + 5); // below disc 
                        int colonPos1 = nucleus.name.IndexOf(":");
                        if (colonPos1 > 0) {
                            string extName = nucleus.name[(colonPos1 + 2)..];
                            Handles.Label(labelPos1, extName, style);
                        }
                    }
                    else {
                        // draw the array size label
                        if (color.grayscale > 0.5f)
                            style.normal.textColor = Color.black;
                        else
                            style.normal.textColor = Color.white;
                        Handles.Label(labelPosition, receptor1.nucleiArray.Length.ToString(), style);
                        style.normal.textColor = Color.white;
                    }
                }
                else if (nucleus is Cluster cluster && cluster.clusterArray != null) {
                    if (expandArray) {
                        // Put array indices above elements
                        style.alignment = TextAnchor.LowerCenter;
                        Vector3 labelPos1 = position + Vector3.down * (size + 5); // below disc 
                        int colonPos1 = nucleus.name.IndexOf(":");
                        if (colonPos1 > 0) {
                            string extName = nucleus.name[(colonPos1 + 2)..];
                            Handles.Label(labelPos1, extName, style);
                        }
                    }
                    else {
                        // draw the array size label
                        if (color.grayscale > 0.5f)
                            style.normal.textColor = Color.black;
                        else
                            style.normal.textColor = Color.white;
                        Handles.Label(labelPosition, cluster.clusterArray.clusters.Length.ToString(), style);
                        style.normal.textColor = Color.white;
                    }
                }

                if (expandArray == false || nucleus is not IReceptor) {
                    // put name below nucleus
                    Vector3 labelPos = position - Vector3.down * (size + 5); // below neuron
                    style.alignment = TextAnchor.UpperCenter;

                    nucleus.name ??= "";
                    int colonPos = nucleus.name.IndexOf(":");
                    if (colonPos > 0 && colonPos < nucleus.name.Length - 2) {
                        // if it is an array, we should not show the :0 of the first element
                        string baseName = nucleus.name[..colonPos];
                        Handles.Label(labelPos, baseName, style);
                    }
                    else
                        Handles.Label(labelPos, nucleus.name, style);
                }

                // Draw Cluster ring
                if (nucleus is Cluster) {
                    Handles.color = Color.white;
                    Handles.DrawWireDisc(position, Vector3.forward, size + 5);
                }

                // Tooltip
                Rect neuronRect = new(position.x - size, position.y - size, size * 2, size * 2);
                int id = GUIUtility.GetControlID(FocusType.Passive);
                Event e = Event.current;
                EventType et = e.GetTypeForControl(id);
                if (e != null && neuronRect.Contains(e.mousePosition)) {
                    // Process Hover
                    HandleMouseHover(nucleus, neuronRect);
                    // Process click
                    if (e.type == EventType.MouseDown && e.button == 0) {
                        // Consume the event so the scene doesn't also handle it
                        e.Use();
                        HandleClicked(nucleus);
                    }
                }
            }

            private void HandleMouseHover(Nucleus nucleus, Rect rect) {
                GUIContent tooltip;
                if (nucleus is Neuron neuron) {
                    tooltip = new(
                        $"{nucleus.name}" +
                        $"\nValue: {neuron.outputMagnitude}");
                }
                else
                    tooltip = new($"{nucleus.name}");

                Vector2 mousePosition = Event.current.mousePosition;

                // Display tooltip with some offset
                Vector2 tooltipSize = GUI.skin.box.CalcSize(tooltip);
                Rect tooltipRect = new Rect(mousePosition.x + 10, mousePosition.y + 10, tooltipSize.x, tooltipSize.y);

                GUI.Box(tooltipRect, tooltip);
            }

            private void HandleClicked(Nucleus nucleus) {
                if (nucleus == this.currentNucleus) {
                    if (nucleus is Receptor || nucleus is ClusterReceptor)
                        expandArray = !expandArray;
                    else
                        expandArray = false;
                }
                else {
                    this.currentNucleus = nucleus;
                    expandArray = false;
                    BuildLayers();
                }
            }

            void OnSceneGUI(SceneView sceneView) {
                if (this.gameObject != null) {
                    if (this.currentNucleus is IReceptor receptor) {
                        foreach (Nucleus nucleus in receptor.nucleiArray) {
                            if (nucleus is Neuron neuron) {
                                Vector3 worldVector = this.gameObject.transform.TransformVector(neuron.outputValue);
                                Handles.color = Color.yellow;
                                Handles.DrawLine(this.gameObject.transform.position, this.gameObject.transform.position + worldVector);
                            }
                        }
                    }
                    else {
                        if (this.currentNucleus is Neuron currentNeuron) {
                            Vector3 worldVector = this.gameObject.transform.TransformVector(currentNeuron.outputValue);
                            Handles.color = Color.yellow;
                            Handles.DrawLine(this.gameObject.transform.position, this.gameObject.transform.position + worldVector);
                        }
                    }
                }
            }

        }
    }

    public class NeuroidLayer {
        public int ix = 0;
        public List<Nucleus> neuroids = new();
    }
}