using UnityEngine;

public class DayNightCycle_BuiltIn : MonoBehaviour
{
    [Header("Time")]
    [Range(0f, 1f)] public float time01 = 0.25f;
    public float dayLengthSeconds = 600f;

    [Header("Sun (Directional Light)")]
    public Light sun;
    public float sunYaw = 170f;
    public AnimationCurve sunIntensity = AnimationCurve.EaseInOut(0, 0, 1, 1.2f);
    public Gradient sunColor;

    [Header("Ambient (Environment Light)")]
    public AnimationCurve ambientIntensity = AnimationCurve.EaseInOut(0, 0.2f, 1, 1.0f);
    public Gradient ambientColor;

    [Header("Fog")]
    public bool useFog = true;
    public AnimationCurve fogDensity = AnimationCurve.EaseInOut(0, 0.02f, 1, 0.006f);
    public Gradient fogColor;

    void Reset()
    {
        sunColor = new Gradient();
        sunColor.SetKeys(
            new[] {
                new GradientColorKey(new Color(0.25f, 0.35f, 0.55f), 0f),
                new GradientColorKey(new Color(1.00f, 0.85f, 0.65f), 0.25f),
                new GradientColorKey(Color.white, 0.5f),
                new GradientColorKey(new Color(1.00f, 0.55f, 0.35f), 0.75f),
            },
            new[] {
                new GradientAlphaKey(1f, 0f),
                new GradientAlphaKey(1f, 1f)
            }
        );

        ambientColor = new Gradient();
        ambientColor.SetKeys(
            new[] {
                new GradientColorKey(new Color(0.08f, 0.10f, 0.18f), 0f),
                new GradientColorKey(new Color(0.55f, 0.55f, 0.60f), 0.5f),
                new GradientColorKey(new Color(0.25f, 0.20f, 0.25f), 0.75f)
            },
            new[] {
                new GradientAlphaKey(1f, 0f),
                new GradientAlphaKey(1f, 1f)
            }
        );

        fogColor = new Gradient();
        fogColor.SetKeys(
            new[] {
                new GradientColorKey(new Color(0.05f, 0.07f, 0.12f), 0f),
                new GradientColorKey(new Color(0.65f, 0.75f, 0.85f), 0.5f),
                new GradientColorKey(new Color(0.40f, 0.25f, 0.20f), 0.75f)
            },
            new[] {
                new GradientAlphaKey(1f, 0f),
                new GradientAlphaKey(1f, 1f)
            }
        );
    }

    void Update()
    {
        time01 += Time.deltaTime / Mathf.Max(1f, dayLengthSeconds);
        if (time01 >= 1f) time01 -= 1f;

        Apply(time01);
    }

    void Apply(float t)
    {
        // 1) 태양 회전
        if (sun)
        {
            float sunAngle = t * 360f - 90f;
            sun.transform.rotation = Quaternion.Euler(sunAngle, sunYaw, 0f);

            // 2) 태양 밝기/색
            sun.intensity = sunIntensity.Evaluate(t);
            if (sunColor != null) sun.color = sunColor.Evaluate(t);
        }

        // 3) Ambient(환경광) - 확실한 방식
        RenderSettings.ambientMode = UnityEngine.Rendering.AmbientMode.Flat;
        Color c = ambientColor.Evaluate(t);
        float k = ambientIntensity.Evaluate(t);
        RenderSettings.ambientLight = c * k;

        // 4) Fog
        if (useFog)
        {
            RenderSettings.fog = true;
            RenderSettings.fogColor = fogColor.Evaluate(t);
            RenderSettings.fogDensity = fogDensity.Evaluate(t);
        }
        else
        {
            RenderSettings.fog = false;
        }

        // 5) 환경 갱신
        DynamicGI.UpdateEnvironment();
    }
}