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

public class AdvancedMeshMerger : EditorWindow
{
    private string mergedObjectName = "Combined_Mesh_Object";
    private bool saveMeshAsAsset = true;
    private Mesh lastMergedMesh = null;

    [MenuItem("Tools/Advanced Mesh Merger")]
    public static void ShowWindow()
    {
        GetWindow<AdvancedMeshMerger>("Advanced Mesh Merger");
    }

    private void OnGUI()
    {
        GUILayout.Label("Merge Settings", EditorStyles.boldLabel);
        mergedObjectName = EditorGUILayout.TextField("Merged Object Name", mergedObjectName);
        saveMeshAsAsset = EditorGUILayout.Toggle("Save Mesh As Asset", saveMeshAsAsset);

        if (GUILayout.Button("📝 Save Mesh As..."))
            SaveMeshManually();

        if (GUILayout.Button("💾 Save Selected Mesh As..."))
            SaveSelectedMesh();

        if (GUILayout.Button("📤 Export Selected Mesh to .OBJ"))
            ExportSelectedMeshToOBJ();

        if (GUILayout.Button("📤 Export Selected Mesh with Materials to .OBJ"))
            ExportSelectedMeshToOBJWithMaterials();

        GUILayout.Space(10);

        if (GUILayout.Button("🧱 Merge Selected Meshes"))
            MergeMeshes();

        GUILayout.Space(20);
        GUILayout.Label("Selected Object Tools", EditorStyles.boldLabel);

        if (GUILayout.Button("🎯 Center Pivot of Selected Mesh"))
            CenterPivotOfSelected();

        if (GUILayout.Button("🧭 Align Pivot Rotation with Selected"))
            AlignPivotRotationWithSelected();
    }

    private void MergeMeshes()
    {
        GameObject[] selected = Selection.gameObjects;
        if (selected.Length == 0)
        {
            Debug.LogWarning("Select objects with MeshFilters.");
            return;
        }

        Dictionary<Material, List<CombineInstance>> materialToCombine = new();

        foreach (GameObject root in selected)
        {
            foreach (MeshFilter mf in root.GetComponentsInChildren<MeshFilter>())
            {
                MeshRenderer mr = mf.GetComponent<MeshRenderer>();
                if (mf == null || mr == null || mf.sharedMesh == null) continue;

                Mesh mesh = mf.sharedMesh;
                for (int i = 0; i < mesh.subMeshCount; i++)
                {
                    if (i >= mr.sharedMaterials.Length) continue;

                    Material mat = mr.sharedMaterials[i];
                    if (!materialToCombine.ContainsKey(mat))
                        materialToCombine[mat] = new();

                    materialToCombine[mat].Add(new CombineInstance
                    {
                        mesh = mesh,
                        subMeshIndex = i,
                        transform = mf.transform.localToWorldMatrix
                    });
                }
            }
        }

        List<Material> finalMaterials = new();
        List<Mesh> subMeshes = new();

        foreach (var kvp in materialToCombine)
        {
            Mesh subMesh = new();
            subMesh.indexFormat = UnityEngine.Rendering.IndexFormat.UInt32;
            subMesh.CombineMeshes(kvp.Value.ToArray(), true, true);
            subMeshes.Add(subMesh);
            finalMaterials.Add(kvp.Key);
        }

        CombineInstance[] finalCombine = new CombineInstance[subMeshes.Count];
        for (int i = 0; i < subMeshes.Count; i++)
        {
            finalCombine[i] = new CombineInstance
            {
                mesh = subMeshes[i],
                subMeshIndex = 0,
                transform = Matrix4x4.identity
            };
        }

        Mesh finalMesh = new();
        finalMesh.name = mergedObjectName + "_Mesh";
        finalMesh.indexFormat = UnityEngine.Rendering.IndexFormat.UInt32;
        finalMesh.CombineMeshes(finalCombine, false, false);
        lastMergedMesh = finalMesh;

        if (saveMeshAsAsset)
        {
            string folderPath = "Assets/MergedMeshes";
            if (!Directory.Exists(folderPath)) Directory.CreateDirectory(folderPath);
            string assetPath = $"{folderPath}/{mergedObjectName}_Mesh.asset";
            AssetDatabase.CreateAsset(finalMesh, assetPath);
            AssetDatabase.SaveAssets();
            Debug.Log($"💾 Saved mesh asset at: {assetPath}");
        }

        GameObject newObj = new(string.IsNullOrEmpty(mergedObjectName) ? "Combined_Mesh_Object" : mergedObjectName);
        MeshFilter mfFinal = newObj.AddComponent<MeshFilter>();
        MeshRenderer mrFinal = newObj.AddComponent<MeshRenderer>();
        mfFinal.sharedMesh = finalMesh;
        mrFinal.sharedMaterials = finalMaterials.ToArray();

        Undo.RegisterCreatedObjectUndo(newObj, "Create Combined Mesh");
        Selection.activeGameObject = newObj;

        Debug.Log($"✅ Combined mesh created with {finalMaterials.Count} materials.");
    }

    private void SaveMeshManually()
    {
        if (lastMergedMesh == null)
        {
            Debug.LogWarning("No mesh to save. Perform a merge first.");
            return;
        }

        string path = EditorUtility.SaveFilePanelInProject("Save Merged Mesh", lastMergedMesh.name, "asset", "Choose location to save the merged mesh.");
        if (!string.IsNullOrEmpty(path))
        {
            Mesh meshCopy = Instantiate(lastMergedMesh);
            AssetDatabase.CreateAsset(meshCopy, path);
            AssetDatabase.SaveAssets();
            Debug.Log($"💾 Mesh manually saved to: {path}");
        }
    }

    private void SaveSelectedMesh()
    {
        GameObject obj = Selection.activeGameObject;
        MeshFilter mf = obj?.GetComponent<MeshFilter>();
        if (mf?.sharedMesh == null)
        {
            Debug.LogWarning("Selected object does not have a valid mesh.");
            return;
        }

        string path = EditorUtility.SaveFilePanelInProject("Save Selected Mesh", mf.sharedMesh.name, "asset", "Choose location to save the selected mesh.");
        if (!string.IsNullOrEmpty(path))
        {
            Mesh meshCopy = Instantiate(mf.sharedMesh);
            AssetDatabase.CreateAsset(meshCopy, path);
            AssetDatabase.SaveAssets();
            Debug.Log($"💾 Saved selected mesh to: {path}");
        }
    }

    private void CenterPivotOfSelected()
    {
        GameObject obj = Selection.activeGameObject;
        MeshFilter mf = obj?.GetComponent<MeshFilter>();
        if (mf?.sharedMesh == null)
        {
            Debug.LogWarning("Select an object with a valid mesh.");
            return;
        }

        Mesh meshCopy = Instantiate(mf.sharedMesh);
        meshCopy.name = mf.sharedMesh.name + "_Centered";

        Vector3[] verts = meshCopy.vertices;
        Vector3 center = meshCopy.bounds.center;

        for (int i = 0; i < verts.Length; i++)
            verts[i] -= center;

        meshCopy.vertices = verts;
        meshCopy.RecalculateBounds();
        mf.sharedMesh = meshCopy;

        obj.transform.position += obj.transform.rotation * center;

        Debug.Log("✅ Pivot centered without changing rotation or position.");
    }

    private void AlignPivotRotationWithSelected()
    {
        GameObject[] selection = Selection.gameObjects;
        if (selection.Length != 2)
        {
            Debug.LogWarning("Select exactly TWO objects:\nFirst: the merged object\nSecond: the reference.");
            return;
        }

        GameObject merged = selection[0];
        GameObject reference = selection[1];

        if (merged.GetComponent<MeshFilter>() == null)
        {
            Debug.LogWarning("First selected object must have a mesh.");
            return;
        }

        GameObject pivotHolder = new GameObject(merged.name + "_Pivot");
        Undo.RegisterCreatedObjectUndo(pivotHolder, "Create Pivot Holder");

        pivotHolder.transform.position = reference.transform.position;
        pivotHolder.transform.rotation = reference.transform.rotation;
        pivotHolder.transform.localScale = Vector3.one;

        merged.transform.SetParent(pivotHolder.transform, true);
        Selection.activeGameObject = pivotHolder;

        Debug.Log("✅ Created pivot wrapper with reference rotation and position.");
    }

    private void ExportSelectedMeshToOBJ()
    {
        GameObject obj = Selection.activeGameObject;
        MeshFilter mf = obj?.GetComponent<MeshFilter>();
        if (mf?.sharedMesh == null)
        {
            Debug.LogWarning("Selected object must have a mesh.");
            return;
        }

        string path = EditorUtility.SaveFilePanel("Export .OBJ", "", obj.name + ".obj", "obj");
        if (string.IsNullOrEmpty(path)) return;

        Mesh mesh = mf.sharedMesh;
        StringBuilder sb = new StringBuilder();

        sb.AppendLine($"# Exported from Unity: {obj.name}");
        foreach (Vector3 v in mesh.vertices)
        {
            Vector3 worldV = obj.transform.TransformPoint(v);
            sb.AppendLine($"v {worldV.x} {worldV.y} {worldV.z}");
        }

        foreach (Vector2 uv in mesh.uv)
            sb.AppendLine($"vt {uv.x} {uv.y}");

        foreach (Vector3 n in mesh.normals)
        {
            Vector3 worldN = obj.transform.TransformDirection(n);
            sb.AppendLine($"vn {worldN.x} {worldN.y} {worldN.z}");
        }

        int[] triangles = mesh.triangles;
        for (int i = 0; i < triangles.Length; i += 3)
        {
            int i0 = triangles[i] + 1;
            int i1 = triangles[i + 1] + 1;
            int i2 = triangles[i + 2] + 1;
            sb.AppendLine($"f {i0}/{i0}/{i0} {i1}/{i1}/{i1} {i2}/{i2}/{i2}");
        }

        File.WriteAllText(path, sb.ToString());
        Debug.Log($"📤 Exported mesh to: {path}");
    }

    private void ExportSelectedMeshToOBJWithMaterials()
    {
        GameObject obj = Selection.activeGameObject;
        if (obj == null)
        {
            Debug.LogWarning("No GameObject selected.");
            return;
        }

        MeshFilter mf = obj.GetComponent<MeshFilter>();
        MeshRenderer mr = obj.GetComponent<MeshRenderer>();
        if (mf == null || mf.sharedMesh == null || mr == null)
        {
            Debug.LogWarning("Selected object must have MeshFilter and MeshRenderer.");
            return;
        }

        string folderPath = EditorUtility.SaveFolderPanel("Export .OBJ with Materials", "", obj.name);
        if (string.IsNullOrEmpty(folderPath)) return;

        Mesh mesh = mf.sharedMesh;
        string objName = obj.name;
        string objPath = Path.Combine(folderPath, objName + ".obj");
        string mtlPath = Path.Combine(folderPath, objName + ".mtl");

        Vector3[] vertices = mesh.vertices;
        Vector3[] normals = mesh.normals;
        Vector2[] uvs = mesh.uv;

        using (StreamWriter sw = new StreamWriter(objPath))
        {
            sw.WriteLine($"# Exported from Unity: {objName}");
            sw.WriteLine($"mtllib {objName}.mtl");

            // Vertices
            foreach (Vector3 v in vertices)
            {
                Vector3 worldV = obj.transform.TransformPoint(v);
                sw.WriteLine($"v {worldV.x} {worldV.y} {worldV.z}");
            }

            // UVs (if available)
            if (uvs != null && uvs.Length == vertices.Length)
            {
                foreach (Vector2 uv in uvs)
                    sw.WriteLine($"vt {uv.x} {uv.y}");
            }
            else
            {
                for (int i = 0; i < vertices.Length; i++)
                    sw.WriteLine("vt 0 0");
            }

            // Normals
            if (normals != null && normals.Length == vertices.Length)
            {
                foreach (Vector3 n in normals)
                {
                    Vector3 worldN = obj.transform.TransformDirection(n).normalized;
                    sw.WriteLine($"vn {worldN.x} {worldN.y} {worldN.z}");
                }
            }
            else
            {
                for (int i = 0; i < vertices.Length; i++)
                    sw.WriteLine("vn 0 1 0");
            }

            // Faces per submesh
            int vertexOffset = 1;
            for (int sub = 0; sub < mesh.subMeshCount; sub++)
            {
                Material mat = mr.sharedMaterials.Length > sub ? mr.sharedMaterials[sub] : null;
                string matName = mat ? mat.name : $"Material_{sub}";
                sw.WriteLine($"usemtl {matName}");

                int[] tris = mesh.GetTriangles(sub);
                for (int i = 0; i < tris.Length; i += 3)
                {
                    int a = tris[i] + vertexOffset;
                    int b = tris[i + 1] + vertexOffset;
                    int c = tris[i + 2] + vertexOffset;
                    sw.WriteLine($"f {a}/{a}/{a} {b}/{b}/{b} {c}/{c}/{c}");
                }
            }
        }

        using (StreamWriter sw = new StreamWriter(mtlPath))
        {
            for (int i = 0; i < mr.sharedMaterials.Length; i++)
            {
                Material mat = mr.sharedMaterials[i];
                string matName = mat ? mat.name : $"Material_{i}";
                sw.WriteLine($"newmtl {matName}");

                Texture2D tex = mat.mainTexture as Texture2D;
                if (tex != null)
                {
                    string texAssetPath = AssetDatabase.GetAssetPath(tex);
                    string texFileName = Path.GetFileName(texAssetPath);
                    string destTexPath = Path.Combine(folderPath, texFileName);

                    try
                    {
                        File.Copy(texAssetPath, destTexPath, true);
                        sw.WriteLine($"map_Kd {texFileName}");
                    }
                    catch
                    {
                        Debug.LogWarning($"⚠ Could not copy texture: {texFileName}");
                    }
                }

                sw.WriteLine("Kd 1.000 1.000 1.000");
                sw.WriteLine("Ka 0.000 0.000 0.000");
                sw.WriteLine("Ks 0.000 0.000 0.000");
                sw.WriteLine("d 1.0");
                sw.WriteLine("illum 1");
                sw.WriteLine();
            }
        }

        Debug.Log($"📤 Exported {objName}.obj with materials and textures to: {folderPath}");
    }
}