using System.Collections.Generic;
using UnityEngine;

public class NoiseManager : MonoBehaviour
{
    [System.Serializable]
    public class NoiseEvent
    {
        public Vector3 position;
        public float intensity;
        public float timestamp;
    }

    public float noiseLifetime = 1.25f;

    public static NoiseManager Instance { get; private set; }
    public static IReadOnlyList<NoiseEvent> ActiveNoises => activeNoises;

    private static readonly List<NoiseEvent> activeNoises = new List<NoiseEvent>();

    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(gameObject);
            return;
        }

        Instance = this;
    }

    private void Update()
    {
        PruneExpiredNoise();
    }

    public static void EmitNoise(Vector3 position, float intensity)
    {
        EnsureInstance();
        PruneExpiredNoise();

        // Шум живёт короткое время, чтобы враги реагировали на свежие события, а не на старые следы.
        activeNoises.Add(new NoiseEvent
        {
            position = position,
            intensity = intensity,
            timestamp = Time.time
        });
    }

    public static NoiseEvent GetClosestNoise(Vector3 listenerPosition, float hearingRange)
    {
        PruneExpiredNoise();

        NoiseEvent closest = null;
        float closestDistance = float.MaxValue;

        for (int i = 0; i < activeNoises.Count; i++)
        {
            NoiseEvent noise = activeNoises[i];
            float effectiveRange = Mathf.Max(0.1f, hearingRange * noise.intensity);
            float distance = Vector3.Distance(listenerPosition, noise.position);

            if (distance > effectiveRange || distance >= closestDistance)
            {
                continue;
            }

            closest = noise;
            closestDistance = distance;
        }

        return closest;
    }

    public static void ClearNoise()
    {
        activeNoises.Clear();
    }

    private static void EnsureInstance()
    {
        if (Instance != null || !Application.isPlaying)
        {
            return;
        }

        GameObject managerObject = new GameObject("NoiseManager");
        Instance = managerObject.AddComponent<NoiseManager>();
    }

    private static void PruneExpiredNoise()
    {
        float lifetime = Instance != null ? Instance.noiseLifetime : 1.25f;
        float minTimestamp = Time.time - lifetime;

        for (int i = activeNoises.Count - 1; i >= 0; i--)
        {
            if (activeNoises[i].timestamp < minTimestamp)
            {
                activeNoises.RemoveAt(i);
            }
        }
    }
}