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

public class SmartColliderGeneratorMerged : EditorWindow
{
    private float manualVoxelSize = 0.0f;
    private int mergeClusterSize = 2;
    private bool overwriteExisting = true;
    private bool showPreview = true;
    private bool forceSimpleBox = false;

    private static List<(Vector3 center, Vector3 size, Transform transform)> previewBoxes = new();

    [MenuItem("Tools/Smart Collider Generator (Merged)")]
    public static void ShowWindow()
    {
        var window = GetWindow<SmartColliderGeneratorMerged>("Smart Collider Generator");
        SceneView.duringSceneGui -= DrawPreview;
        SceneView.duringSceneGui += DrawPreview;
        window.Show();
    }

    void OnGUI()
    {
        GUILayout.Label("Collider Optimization Tool", EditorStyles.boldLabel);
        manualVoxelSize = EditorGUILayout.FloatField("Voxel Size (0 = auto)", manualVoxelSize);
        mergeClusterSize = EditorGUILayout.IntSlider("Merge Cluster Size", mergeClusterSize, 1, 5);
        overwriteExisting = EditorGUILayout.Toggle("Overwrite Existing Colliders", overwriteExisting);
        forceSimpleBox = EditorGUILayout.Toggle("Force Simple BoxCollider", forceSimpleBox);
        showPreview = EditorGUILayout.Toggle("Show Collider Preview", showPreview);

        if (GUILayout.Button("Generate Colliders for Selection"))
        {
            GenerateCollidersForSelection();
        }

        if (GUILayout.Button("Refresh Preview"))
        {
            RefreshPreview();
        }
    }

    void GenerateCollidersForSelection()
    {
        foreach (var obj in Selection.objects)
        {
            if (obj is GameObject go)
            {
                string path = AssetDatabase.GetAssetPath(go);
                if (!string.IsNullOrEmpty(path) && PrefabUtility.GetPrefabAssetType(go) != PrefabAssetType.NotAPrefab)
                {
                    ProcessPrefabAsset(go, path);
                }
                else
                {
                    // Scene object
                    var filters = go.GetComponentsInChildren<MeshFilter>();
                    foreach (var filter in filters)
                    {
                        if (filter.sharedMesh == null) continue;

                        if (overwriteExisting)
                        {
                            foreach (var col in filter.GetComponents<Collider>())
                            {
                                if (col != null)
                                    DestroyImmediate(col);
                            }
                        }
                        else if (filter.GetComponent<Collider>() != null)
                        {
                            continue;
                        }

                        ProcessMesh(filter, applyToGameObject: true);
                    }
                }
            }
        }

        previewBoxes.Clear();
        Debug.Log(" Collider generation complete.");
    }

    void ProcessPrefabAsset(GameObject prefabAsset, string assetPath)
    {
        GameObject prefabInstance = PrefabUtility.LoadPrefabContents(assetPath);
        var filters = prefabInstance.GetComponentsInChildren<MeshFilter>();

        foreach (var filter in filters)
        {
            if (filter.sharedMesh == null) continue;

            if (overwriteExisting)
            {
                foreach (var col in filter.GetComponents<Collider>())
                {
                    if (col != null)
                        DestroyImmediate(col);
                }
            }
            else if (filter.GetComponent<Collider>() != null)
            {
                continue;
            }

            ProcessMesh(filter, applyToGameObject: true);
        }

        PrefabUtility.SaveAsPrefabAsset(prefabInstance, assetPath);
        PrefabUtility.UnloadPrefabContents(prefabInstance);

        Debug.Log($" Updated prefab: {assetPath}");
    }

    void RefreshPreview()
    {
        previewBoxes.Clear();
        foreach (GameObject go in Selection.gameObjects)
        {
            var filters = go.GetComponentsInChildren<MeshFilter>();
            foreach (var filter in filters)
            {
                if (filter.sharedMesh == null) continue;
                ProcessMesh(filter, applyToGameObject: false);
            }
        }

        SceneView.RepaintAll();
    }

    void ProcessMesh(MeshFilter filter, bool applyToGameObject)
    {
        var mesh = filter.sharedMesh;
        var bounds = mesh.bounds;
        var size = bounds.size;

        float ratio = Mathf.Max(size.x, size.y, size.z) / Mathf.Max(0.0001f, Mathf.Min(size.x, size.y, size.z));

        if (forceSimpleBox || (mesh.vertexCount < 100 && ratio < 3f))
        {
            if (applyToGameObject)
            {
                var box = filter.gameObject.AddComponent<BoxCollider>();
                box.center = bounds.center;
                box.size = size;
            }
            else
            {
                previewBoxes.Add((bounds.center, size, filter.transform));
            }

            return;
        }

        float voxelSize = manualVoxelSize > 0 ? manualVoxelSize : Mathf.Max(size.x, size.y, size.z) / 10f;
        RunVoxelMerge(filter, mesh, voxelSize, applyToGameObject);
    }

    void RunVoxelMerge(MeshFilter filter, Mesh mesh, float voxelSize, bool applyToGameObject)
    {
        Vector3[] vertices = mesh.vertices;
        Transform t = filter.transform;

        HashSet<Vector3Int> filledVoxels = new();

        foreach (var v in vertices)
        {
            Vector3 world = t.TransformPoint(v);
            Vector3Int voxel = Vector3Int.FloorToInt(world / voxelSize);
            filledVoxels.Add(voxel);
        }

        HashSet<Vector3Int> visited = new();

        foreach (var voxel in filledVoxels)
        {
            if (visited.Contains(voxel)) continue;

            List<Vector3> groupPoints = new();

            for (int x = 0; x < mergeClusterSize; x++)
            {
                for (int y = 0; y < mergeClusterSize; y++)
                {
                    for (int z = 0; z < mergeClusterSize; z++)
                    {
                        Vector3Int offset = voxel + new Vector3Int(x, y, z);
                        if (filledVoxels.Contains(offset) && !visited.Contains(offset))
                        {
                            visited.Add(offset);
                            groupPoints.Add((Vector3)offset * voxelSize);
                        }
                    }
                }
            }

            if (groupPoints.Count == 0) continue;

            Bounds mergedBounds = new Bounds(groupPoints[0], Vector3.zero);
            foreach (var p in groupPoints)
                mergedBounds.Encapsulate(p);

            if (applyToGameObject)
            {
                var box = filter.gameObject.AddComponent<BoxCollider>();
                box.center = t.InverseTransformPoint(mergedBounds.center);
                box.size = Vector3.one * voxelSize * mergeClusterSize;
            }
            else
            {
                previewBoxes.Add((mergedBounds.center, Vector3.one * voxelSize * mergeClusterSize, filter.transform));
            }
        }
    }

    static void DrawPreview(SceneView sceneView)
    {
        if (!EditorWindow.HasOpenInstances<SmartColliderGeneratorMerged>())
            return;

        var window = (SmartColliderGeneratorMerged)EditorWindow.GetWindow(typeof(SmartColliderGeneratorMerged));
        if (!window.showPreview) return;

        Handles.color = new Color(0f, 1f, 0f, 0.3f);

        foreach (var (center, size, transform) in previewBoxes)
        {
            var matrix = Matrix4x4.TRS(transform.position, transform.rotation, transform.lossyScale);
            using (new Handles.DrawingScope(matrix))
            {
                Handles.DrawWireCube(transform.InverseTransformPoint(center), size);
            }
        }
    }
}