using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// Centralizes runtime ticking for note controllers so dense charts do not pay one
/// MonoBehaviour.Update dispatch per active note/hold segment. Per-note movement
/// and judge-zone behavior remains in the original controllers.
/// </summary>
public sealed class NoteRuntimeTickManager : MonoBehaviour
{
    private static NoteRuntimeTickManager instance;

    private readonly List<NoteController> noteControllers = new List<NoteController>(256);
    private readonly List<HoldNoteController> holdControllers = new List<HoldNoteController>(512);

    public static void Register(NoteController controller)
    {
        if (controller == null) return;
        EnsureInstance().RegisterInternal(controller);
    }

    public static void Unregister(NoteController controller)
    {
        if (controller == null || instance == null) return;
        instance.noteControllers.Remove(controller);
    }

    public static void Register(HoldNoteController controller)
    {
        if (controller == null) return;
        EnsureInstance().RegisterInternal(controller);
    }

    public static void Unregister(HoldNoteController controller)
    {
        if (controller == null || instance == null) return;
        instance.holdControllers.Remove(controller);
    }

    private static NoteRuntimeTickManager EnsureInstance()
    {
        if (instance != null) return instance;

        var go = new GameObject("NoteRuntimeTickManager");
        instance = go.AddComponent<NoteRuntimeTickManager>();
        return instance;
    }

    private void Awake()
    {
        if (instance == null)
        {
            instance = this;
        }
        else if (instance != this)
        {
            Destroy(gameObject);
        }
    }

    private void OnDestroy()
    {
        if (instance == this) instance = null;
    }

    private void RegisterInternal(NoteController controller)
    {
        if (!noteControllers.Contains(controller))
            noteControllers.Add(controller);
    }

    private void RegisterInternal(HoldNoteController controller)
    {
        if (!holdControllers.Contains(controller))
            holdControllers.Add(controller);
    }

    private void Update()
    {
        float songTime = GameplayClock.NowSongTime;
        float deltaTime = Time.deltaTime;

        for (int i = noteControllers.Count - 1; i >= 0; i--)
        {
            NoteController controller = noteControllers[i];
            if (controller == null || !controller.isActiveAndEnabled)
            {
                noteControllers.RemoveAt(i);
                continue;
            }

            controller.ManualTick(songTime);
        }

        for (int i = holdControllers.Count - 1; i >= 0; i--)
        {
            HoldNoteController controller = holdControllers[i];
            if (controller == null || !controller.isActiveAndEnabled)
            {
                holdControllers.RemoveAt(i);
                continue;
            }

            controller.ManualTick(songTime, deltaTime);
        }
    }
}