using UnityEngine;
using FMODUnity;
using FMOD.Studio;
using System.Collections;

public class FirstPersonOcclusion : MonoBehaviour
{
    [Header("FMOD Event")]
    [SerializeField] private EventReference SelectAudio;

    private EventInstance AudioOccluded;
    private EventDescription AudioDes;
    private StudioListener Listener;
    private PLAYBACK_STATE pb;

    [Header("Occlusion Options")]
    [SerializeField][Range(0f, 10f)] private float SoundOcclusionWidening = 1f;
    [SerializeField][Range(0f, 10f)] private float PlayerOcclusionWidening = 1f;
    [SerializeField] private LayerMask OcclusionLayer;

    private bool AudioIsVirtual;
    private float MaxDistance;
    private float ListenerDistance;
    private float lineCastHitCount = 0f;
    private Color colour;

    private bool initialisedExternally = false;

    // ============================================================
    // NEW — Optional external initialiser
    // ============================================================
    public void InitialiseWithInstance(EventInstance instance)
    {
        AudioOccluded = instance;
        initialisedExternally = true;

        RuntimeManager.AttachInstanceToGameObject(
            AudioOccluded,
            gameObject,
            GetComponent<Rigidbody>()
        );

        AudioOccluded.getDescription(out AudioDes);
        AudioDes.getMinMaxDistance(out float min, out MaxDistance);
    }

    // ============================================================
    // ORIGINAL START — kept exactly the same unless external init used
    // ============================================================
    private IEnumerator Start()
    {
        // If already initialised, skip internal creation
        if (!initialisedExternally)
        {
            AudioOccluded = RuntimeManager.CreateInstance(SelectAudio);
            RuntimeManager.AttachInstanceToGameObject(AudioOccluded, gameObject);
            AudioOccluded.start();
            AudioOccluded.release();

            AudioDes = RuntimeManager.GetEventDescription(SelectAudio);
            AudioDes.getMinMaxDistance(out float minDistance, out MaxDistance);
        }

        // Find listener (kept exactly as before)
        yield return new WaitUntil(() => FindObjectOfType<StudioListener>() != null);
        Listener = FindObjectOfType<StudioListener>();
    }

    // ============================================================
    // UNCHANGED core functionality
    // ============================================================
    private void FixedUpdate()
    {
        if (Listener == null) return;

        AudioOccluded.isVirtual(out AudioIsVirtual);
        AudioOccluded.getPlaybackState(out pb);
        ListenerDistance = Vector3.Distance(transform.position, Listener.transform.position);

        if (!AudioIsVirtual && pb == PLAYBACK_STATE.PLAYING && ListenerDistance <= MaxDistance)
        {
            OccludeBetween(transform.position, Listener.transform.position);
        }

        lineCastHitCount = 0f;
    }

    private void OccludeBetween(Vector3 sound, Vector3 listener)
    {
        Vector3 SoundLeft = CalculatePoint(sound, listener, SoundOcclusionWidening, true);
        Vector3 SoundRight = CalculatePoint(sound, listener, SoundOcclusionWidening, false);

        Vector3 ListenerLeft = CalculatePoint(listener, sound, PlayerOcclusionWidening, true);
        Vector3 ListenerRight = CalculatePoint(listener, sound, PlayerOcclusionWidening, false);

        Vector3 SoundAbove = new Vector3(sound.x, sound.y + SoundOcclusionWidening, sound.z);
        Vector3 SoundBelow = new Vector3(sound.x, sound.y - SoundOcclusionWidening, sound.z);
        Vector3 ListenerAbove = new Vector3(listener.x, listener.y + PlayerOcclusionWidening * .5f, listener.z);
        Vector3 ListenerBelow = new Vector3(listener.x, listener.y - PlayerOcclusionWidening * .5f, listener.z);

        CastLine(SoundLeft, ListenerLeft);
        CastLine(SoundLeft, listener);
        CastLine(SoundLeft, ListenerRight);

        CastLine(sound, ListenerLeft);
        CastLine(sound, listener);
        CastLine(sound, ListenerRight);

        CastLine(SoundRight, ListenerLeft);
        CastLine(SoundRight, listener);
        CastLine(SoundRight, ListenerRight);

        CastLine(SoundAbove, ListenerAbove);
        CastLine(SoundBelow, ListenerBelow);

        colour = (PlayerOcclusionWidening == 0f || SoundOcclusionWidening == 0f) ? Color.blue : Color.green;

        SetParameter();
    }

    private Vector3 CalculatePoint(Vector3 a, Vector3 b, float m, bool posOrneg)
    {
        float n = Vector3.Distance(new Vector3(a.x, 0f, a.z), new Vector3(b.x, 0f, b.z));
        if (n == 0f) return a;

        float mn = (m / n);
        float x, z;

        if (posOrneg)
        {
            x = a.x + (mn * (a.z - b.z));
            z = a.z - (mn * (a.x - b.x));
        }
        else
        {
            x = a.x - (mn * (a.z - b.z));
            z = a.z + (mn * (a.x - b.x));
        }

        return new Vector3(x, a.y, z);
    }

    private void CastLine(Vector3 Start, Vector3 End)
    {
        RaycastHit hit;
        bool isHit = Physics.Linecast(Start, End, out hit, OcclusionLayer);

        if (isHit)
        {
            lineCastHitCount++;
            //Debug.DrawLine(Start, End, Color.red);
        }
        else
        {
            //Debug.DrawLine(Start, End, colour);
        }
    }

    private void SetParameter()
    {
        float occlusionValue = lineCastHitCount / 11;
        AudioOccluded.setParameterByName("Occlusion", occlusionValue);
    }
}