using GLTFast;
using System;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;
using UnityEngine;

public class ModelGenerationUtils : MonoBehaviour
{
    public static ModelGenerationUtils Instance { get; private set; }

    private void Awake()
    {
        Instance = this;
    }

    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    /**
     * Generate model by starting a new Python subprocess
     * NOT USED IN LATEST VERSION
    **/
    public async Task<string> GenerateModelAsync(string inputPrompt)
    {
        return await Task.Run(() =>
        {
            // Path to your virtual environment's python.exe
            string pythonExe = @"D:\users\henrisel\DeltaVR3DModelGeneration\3d-generation-pipeline\.venv\Scripts\python.exe";

            // Path to your Python script
            string scriptPath = @"D:\users\henrisel\DeltaVR3DModelGeneration\3d-generation-pipeline\start_pipeline.py";

            // Arguments to pass to the script
            string arguments = $"{scriptPath} --prompt \"{inputPrompt}\"";

            ProcessStartInfo psi = new ProcessStartInfo
            {
                FileName = pythonExe,
                Arguments = arguments,
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            };

            using (Process process = new Process())
            {
                process.StartInfo = psi;
                process.OutputDataReceived += (sender, e) => UnityEngine.Debug.Log(e.Data);
                process.ErrorDataReceived += (sender, e) => UnityEngine.Debug.LogError(e.Data);

                process.Start();

                string output = process.StandardOutput.ReadToEnd();
                string error = process.StandardError.ReadToEnd();

                process.WaitForExit();


                // Extract model path from output
                foreach (string line in output.Split('\n'))
                {
                    if (line.StartsWith("Generated 3D model file: "))
                    {
                        return line.Replace("Generated 3D model file: ", "").Trim();
                    }
                }

                throw new Exception("Failed to generate 3D model!");
            }
        });
    }

    /**
     * Spawn model stored on disk
     * NOT USED IN LATEST VERSION
     * 
    **/
    public async Task<GameObject> SpawnModel(string modelPath)
    {
        var gltf = new GltfImport();
        bool loadSuccess = await gltf.Load(modelPath);
        if (loadSuccess)
        {
            string objectName = Path.GetFileName(modelPath);
            return await SpawnModel(gltf, objectName);
        }

        throw new Exception("Failed to load GameObject from model" + modelPath);
    }

    public async Task<GameObject> SpawnModel(byte[] modelBinary, float boundingSphereDiameter = 0)
    {
        var gltf = new GltfImport();
        bool loadSuccess = await gltf.Load(modelBinary);
        if (loadSuccess)
        {
            return await SpawnModel(gltf, "GeneratedModel", boundingSphereDiameter);
        }

        throw new Exception("Failed to load GameObject from binary!");
    }

    public async Task<GameObject> SpawnModel(GltfImport gltfImport, string objectName, float boundingSphereDiameter = 0)
    {
        GameObject spawningParent = new GameObject("Parent-" + objectName);

        bool spawnSuccess = await gltfImport.InstantiateMainSceneAsync(spawningParent.transform);
        if (spawnSuccess)
        {
            Transform spawnedObjectWorldTransform = spawningParent.transform.GetChild(0).transform;
            GameObject spawnedObjectBody = spawnedObjectWorldTransform.GetChild(0).transform.gameObject;
            MeshCollider collider = spawnedObjectBody.AddComponent<MeshCollider>();
            collider.convex = true;
            MeshRenderer renderer = spawnedObjectBody.GetComponent<MeshRenderer>();
            renderer.material.SetFloat("metallicFactor", 0);

            AdjustScale(spawnedObjectBody, collider, boundingSphereDiameter);

            spawnedObjectBody.name = objectName;
            return spawnedObjectBody;
        }

        throw new Exception("Failed to spawn GameObject " + objectName);
    }

    private async void AdjustScale(GameObject obj, MeshCollider collider, float boundingSphereDiameter)
    {

        // Wait one frame to ensure collider cooking & bounds are valid
        await Task.Yield();

        // --- Compute current bounding sphere diameter (from world AABB) ---
        Bounds b = collider.bounds; // world-space AABB
        float currentDiameter = 2f * b.extents.magnitude;

        if (boundingSphereDiameter <= 0f)
        {
            UnityEngine.Debug.Log("Not adjusting scale");
            return;
        }

        if (currentDiameter <= Mathf.Epsilon)
            throw new Exception("Spawned mesh has zero-sized bounds; cannot scale to target diameter.");

        // --- Compute and apply uniform scale ---
        float scaleFactor = boundingSphereDiameter / currentDiameter;
        obj.transform.localScale *= scaleFactor;

        // Give Unity a moment to recompute bounds after scaling, then do a corrective pass
        await Task.Yield();

        // Corrective pass (optional): re-measure and nudge scale to reduce residual error
        Bounds b2 = collider.bounds;
        float newDiameter = 2f * b2.extents.magnitude;

        // Only correct if off by more than a tiny epsilon (1%)
        const float tolerance = 0.01f; // 1%
        float err = Mathf.Abs(newDiameter - boundingSphereDiameter) / boundingSphereDiameter;
        if (err > tolerance && newDiameter > Mathf.Epsilon)
        {
            float correction = boundingSphereDiameter / newDiameter;
            obj.transform.localScale *= correction;
            // No need to wait again unless you need to read back the final diameter immediately
        }
    }


    public static Texture2D CreateTexture(byte[] imageBytes)
    {
        var tex = new Texture2D(2, 2, TextureFormat.RGBA32, false);
        // ImageConversion.LoadImage returns bool (true = success)
        if (!ImageConversion.LoadImage(tex, imageBytes, markNonReadable: false))
        {
            Destroy(tex);
            throw new InvalidOperationException("Failed to decode image bytes into Texture2D.");
        }

        tex.filterMode = FilterMode.Bilinear;
        tex.wrapMode = TextureWrapMode.Clamp;

        return tex;
    }

    public static Sprite CreateSprite(Texture2D tex)
    {
        var sprite = Sprite.Create(
            tex,
            new Rect(0, 0, tex.width, tex.height),
            new Vector2(0.5f, 0.5f),
            pixelsPerUnit: 100f
        );

        return sprite;
    }
}