using System.Collections.Generic;
using UnityEngine;

public class GhostTrailEmitter : MonoBehaviour
{
    [Header("Referencias")]
    [SerializeField] private AntManScaleController scaleController;
    [SerializeField] private Material ghostMaterial;
    [SerializeField] private Transform ghostSourceTransform;
    [SerializeField] private MeshFilter sourceMeshFilter;
    [SerializeField] private MeshRenderer sourceMeshRenderer;
    [SerializeField] private SkinnedMeshRenderer sourceSkinnedMeshRenderer;
    [SerializeField] private bool useSkinnedMeshBake = true;
    [SerializeField] private bool useScaleControllerScaleOnSkinnedGhost = true;

    [Header("Spawn")]
    [SerializeField] [Min(0.01f)] private float spawnInterval = 0.05f;
    [SerializeField] [Min(1)] private int maxActiveGhosts = 32;

    [Header("Fade")]
    [SerializeField] [Min(0.01f)] private float ghostLifetime = 0.35f;
    [SerializeField] [Range(0f, 1f)] private float startAlpha = 0.45f;
    [SerializeField] [Range(0f, 1f)] private float endAlpha = 0f;

    [Header("Debug")]
    [SerializeField] private bool showGhostCountLogs;

    private readonly List<GhostTrailGhost> _activeGhosts = new List<GhostTrailGhost>();

    private Material _fallbackMaterial;
    private bool _isEmitting;
    private float _spawnTimer;

    private void Awake()
    {
        if (scaleController == null)
        {
            scaleController = GetComponent<AntManScaleController>();
        }

        ResolveRenderSources();

        if (ghostMaterial == null)
        {
            _fallbackMaterial = GetFallbackMaterial();
        }
    }

    private void OnEnable()
    {
        if (scaleController != null)
        {
            scaleController.TransitionStarted += HandleTransitionStarted;
            scaleController.TransitionCompleted += HandleTransitionCompleted;
        }
    }

    private void OnDisable()
    {
        if (scaleController != null)
        {
            scaleController.TransitionStarted -= HandleTransitionStarted;
            scaleController.TransitionCompleted -= HandleTransitionCompleted;
        }
    }

    private void LateUpdate()
    {
        if (!_isEmitting)
        {
            return;
        }

        _spawnTimer += Time.deltaTime;
        while (_spawnTimer >= spawnInterval)
        {
            _spawnTimer -= spawnInterval;
            SpawnGhost();
        }
    }

    private void HandleTransitionStarted(Vector3 from, Vector3 to)
    {
        _isEmitting = true;
        _spawnTimer = 0f;
        SpawnGhost();
    }

    private void HandleTransitionCompleted(Vector3 scale)
    {
        _isEmitting = false;
    }

    private void SpawnGhost()
    {
        CleanupNullGhosts();
        EnforceGhostLimit();

        if (!TryGetGhostRenderData(out Mesh meshToUse, out Material materialToUse, out Transform sourceTransform, out bool ownsMesh, out bool fromSkinnedMesh))
        {
            return;
        }

        GameObject ghostObject = new GameObject("GhostTrail");
        ghostObject.transform.SetPositionAndRotation(sourceTransform.position, sourceTransform.rotation);
        ghostObject.transform.localScale = GetGhostScale(sourceTransform, fromSkinnedMesh);

        GhostTrailGhost ghost = ghostObject.AddComponent<GhostTrailGhost>();
        ghost.Initialize(
            meshToUse,
            materialToUse,
            ghostLifetime,
            startAlpha,
            endAlpha,
            this,
            ownsMesh
        );

        _activeGhosts.Add(ghost);

        if (showGhostCountLogs)
        {
            Debug.Log($"[GhostTrailEmitter] Ghosts activos: {_activeGhosts.Count}", this);
        }
    }

    public void NotifyGhostDestroyed(GhostTrailGhost ghost)
    {
        _activeGhosts.Remove(ghost);
    }

    private void CleanupNullGhosts()
    {
        for (int i = _activeGhosts.Count - 1; i >= 0; i--)
        {
            if (_activeGhosts[i] == null)
            {
                _activeGhosts.RemoveAt(i);
            }
        }
    }

    private void EnforceGhostLimit()
    {
        while (_activeGhosts.Count >= maxActiveGhosts)
        {
            GhostTrailGhost oldestGhost = _activeGhosts[0];
            _activeGhosts.RemoveAt(0);

            if (oldestGhost != null)
            {
                Destroy(oldestGhost.gameObject);
            }
        }
    }

    private void ResolveRenderSources()
    {
        if (ghostSourceTransform == null)
        {
            ghostSourceTransform = transform;
        }

        if (sourceSkinnedMeshRenderer == null)
        {
            sourceSkinnedMeshRenderer = ghostSourceTransform.GetComponentInChildren<SkinnedMeshRenderer>(true);
        }

        if (sourceMeshFilter == null)
        {
            sourceMeshFilter = ghostSourceTransform.GetComponentInChildren<MeshFilter>(true);
        }

        if (sourceMeshRenderer == null)
        {
            sourceMeshRenderer = ghostSourceTransform.GetComponentInChildren<MeshRenderer>(true);
        }
    }

    private Material GetFallbackMaterial()
    {
        if (sourceSkinnedMeshRenderer != null)
        {
            return sourceSkinnedMeshRenderer.sharedMaterial;
        }

        if (sourceMeshRenderer != null)
        {
            return sourceMeshRenderer.sharedMaterial;
        }

        return null;
    }

    private bool TryGetGhostRenderData(out Mesh mesh, out Material material, out Transform sourceTransform, out bool ownsMesh, out bool fromSkinnedMesh)
    {
        ResolveRenderSources();

        sourceTransform = ghostSourceTransform != null ? ghostSourceTransform : transform;
        material = ghostMaterial != null ? ghostMaterial : (_fallbackMaterial != null ? _fallbackMaterial : GetFallbackMaterial());

        mesh = null;
        ownsMesh = false;
        fromSkinnedMesh = false;

        if (useSkinnedMeshBake && sourceSkinnedMeshRenderer != null)
        {
            Mesh bakedMesh = new Mesh();
            sourceSkinnedMeshRenderer.BakeMesh(bakedMesh);

            mesh = bakedMesh;
            ownsMesh = true;
            fromSkinnedMesh = true;
            sourceTransform = sourceSkinnedMeshRenderer.transform;
        }
        else if (sourceMeshFilter != null)
        {
            mesh = sourceMeshFilter.sharedMesh;

            if (sourceMeshFilter.transform != null)
            {
                sourceTransform = sourceMeshFilter.transform;
            }
        }

        return mesh != null && material != null;
    }

    private Vector3 GetGhostScale(Transform sourceTransform, bool fromSkinnedMesh)
    {
        if (fromSkinnedMesh && useScaleControllerScaleOnSkinnedGhost && scaleController != null)
        {
            return scaleController.GetCurrentScale();
        }

        return sourceTransform.lossyScale;
    }
}