using System;
using System.Collections.Generic;
using UnityEngine;

public class OrbitalPosition
{
    public Int64 pRing = 0;
    public float DistanceFromCentre = 0;
    public float RadiusDistance = 0;

    public Transform owner = null;

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

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

public class Ring : MonoBehaviour
{
    public Int64 ID;
}

public class GlobalOrbitalPositionManager : MonoBehaviour
{
    static GlobalOrbitalPositionManager s_Instance = null;
    private readonly List<OrbitalPosition> m_ObjectInstances = new();
    private readonly List<Ring> m_Rings = new();
    private readonly Dictionary<Int64, float> m_Distances = new();

    private float m_TimeOfLastRingSpawn = float.NegativeInfinity;

    private Int64 m_LastGeneratedRing = 0;
    public static Int64 LastRingID => s_Instance.m_LastGeneratedRing;

    public static float GetDistanceOf(Int64 rowID) => s_Instance.m_Distances[rowID];

    Vector3[] m_PrecalculatedPositions;

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

        s_Instance = manager.AddComponent<GlobalOrbitalPositionManager>();
        s_Instance.m_PrecalculatedPositions = new Vector3[365];

        for (int i = 0; i < 365; i++)
        {
            s_Instance.m_PrecalculatedPositions[i] = new Vector3
            (
                x: Mathf.Cos(Mathf.Deg2Rad * i),
                y: Mathf.Sin(Mathf.Deg2Rad * i),
                z: 0
            );
        }
    }

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

            Ring ring = newRing.AddComponent<Ring>();
            ring.ID = m_LastGeneratedRing + 1;
            m_Rings.Add(ring);

            LineRenderer renderer = newRing.GetComponentInChildren<LineRenderer>();
            renderer.positionCount = 365;
            renderer.startWidth = 0.1f;
            renderer.endWidth = 0.1f;

            renderer.material = new(Shader.Find("Sprites/Default"));

            renderer.startColor = Color.white;
            renderer.endColor = Color.white;

            m_LastGeneratedRing = ring.ID;

            m_TimeOfLastRingSpawn = Time.time;
        }

        List<Ring> toRemove = new();
        int index = 0;
        m_Distances.Clear();

        foreach (Ring ring in m_Rings)
        {
            float diff = Time.deltaTime * GlobalOrbitalSettings.DistanceSpeed;
            ring.transform.localScale -= new Vector3(diff, diff, 0f);

            LineRenderer renderer = ring.GetComponentInChildren<LineRenderer>();
            for (int vert = 0; vert < 365; vert++)
            {
                renderer.SetPosition(vert, m_PrecalculatedPositions[vert] * ring.transform.localScale.x);
            }

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

            m_Distances[ring.ID] = ring.transform.localScale.x;
            index++;
        }

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

        foreach (OrbitalPosition orbitalPosition in m_ObjectInstances)
        {
            if (!m_Distances.ContainsKey(orbitalPosition.pRing))
                orbitalPosition.pRing = m_LastGeneratedRing;

            float distance = m_Distances[orbitalPosition.pRing];
            orbitalPosition.DistanceFromCentre = distance;
            orbitalPosition.RadiusDistance = (orbitalPosition.RadiusDistance + (Time.deltaTime * GlobalOrbitalSettings.RadiusSpeed)) % (Mathf.PI * 2);

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

    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();
}