using System.Collections.Generic;
using UnityEngine;

public class OrbitalPosition
{
    public float DistanceFromCentre = 0;
    public float RadiusDistance = 0;

    public Transform owner = null;

    public OrbitalPosition(GameObject _owner)
    {
        owner = _owner.transform;
    }

    public Vector3 TranslateToVec3() => new
    (
        x: DistanceFromCentre * Mathf.Cos(RadiusDistance),
        y: DistanceFromCentre * Mathf.Sin(RadiusDistance)
    );
}

public class GlobalOrbitalPositionManager : MonoBehaviour
{
    static GlobalOrbitalPositionManager s_Instance = null;
    private readonly List<OrbitalPosition> m_ObjectInstances = new();
    private readonly List<Transform> m_Rings = new();

    private float m_TimeOfLastRingSpawn = float.NegativeInfinity;

    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)] private static void OnApplicationStart()
    {
        GameObject manager = new("GLOBAL ORBITAL MANAGER");
        DontDestroyOnLoad(manager);

        s_Instance = manager.AddComponent<GlobalOrbitalPositionManager>();
    }

    public void Update()
    {
        if (Time.time - m_TimeOfLastRingSpawn > GlobalOrbitalSettings.GapDistance)
        {
            GameObject newRing = Instantiate(GlobalOrbitalSettings.RingPrefab);
            m_Rings.Add(newRing.transform); 
            newRing.transform.localScale = new Vector3(10f, 10f, 1);

            m_TimeOfLastRingSpawn = Time.time;
        }

        foreach (OrbitalPosition orbitalPosition in m_ObjectInstances)
        {
            orbitalPosition.DistanceFromCentre = Mathf.Clamp(orbitalPosition.DistanceFromCentre - (Time.deltaTime * GlobalOrbitalSettings.DistanceSpeed), 0f, float.PositiveInfinity);
            orbitalPosition.RadiusDistance = (orbitalPosition.RadiusDistance + (Time.deltaTime * GlobalOrbitalSettings.RadiusSpeed)) % (Mathf.PI * 2);

            orbitalPosition.owner.position = orbitalPosition.TranslateToVec3();
        }

        List<Transform> toRemove = new();
        foreach (Transform ring in m_Rings)
        {
            float diff = Time.deltaTime * GlobalOrbitalSettings.DistanceSpeed;
            ring.localScale -= new Vector3(diff, diff, 0f);

            if (ring.localScale.x < 0)
            {
                toRemove.Add(ring);
            }
        }

        foreach (Transform ring in toRemove)
        {
            m_Rings.Remove(ring);
            Destroy(ring.gameObject);
        }
    }

    public static void RegisterOrbitalPositionInstance(OrbitalPosition newInstance) =>
        s_Instance.m_ObjectInstances.Add(newInstance);

    public static void UnregisterOrbitalPositionInstance(OrbitalPosition removedInstance) =>
        s_Instance.m_ObjectInstances.Remove(removedInstance);
}

public abstract class OrbitalPositionBehaviour : MonoBehaviour
{
    protected OrbitalPosition m_OrbitalPosition = null;

    private void Start()
    {
        m_OrbitalPosition = new OrbitalPosition(gameObject);
        GlobalOrbitalPositionManager.RegisterOrbitalPositionInstance(m_OrbitalPosition);

        OnStart();
    }

    private void OnDestroy() =>
        GlobalOrbitalPositionManager.UnregisterOrbitalPositionInstance(m_OrbitalPosition);

    public abstract void OnStart();
}