using UnityEngine;

/// <summary>
/// Caps the frame rate via <see cref="Application.targetFrameRate"/>. VSync is
/// disabled automatically while limiting, because it would otherwise override
/// targetFrameRate. Changes apply live (also in Play mode) via OnValidate.
/// </summary>
[DisallowMultipleComponent]
public class FrameRateLimiter : MonoBehaviour
{
    [Header("Limit")]
    [Tooltip("Cap the frame rate to 'Target FPS' (off = unlimited).")]
    public bool limitFrameRate = true;

    [Tooltip("Target frame rate when the limit is active.")]
    [Range(1, 360)]
    public int targetFps = 60;

    [Header("VSync")]
    [Tooltip("Disable VSync while limiting (VSync would otherwise override the FPS limit). Normally ON.")]
    public bool disableVSyncWhenLimiting = true;

    [Tooltip("VSync count when no limit is active (0 = off, 1 = every refresh, 2 = every second refresh).")]
    [Range(0, 2)]
    public int vSyncCountWhenUnlimited = 0;

    void OnEnable() => Apply();

    void OnValidate()
    {
        if (Application.isPlaying)
            Apply();
    }

    /// <summary>Applies the current FPS + VSync settings.</summary>
    public void Apply()
    {
        if (limitFrameRate)
        {
            if (disableVSyncWhenLimiting)
                QualitySettings.vSyncCount = 0;

            Application.targetFrameRate = Mathf.Max(1, targetFps);
        }
        else
        {
            QualitySettings.vSyncCount = vSyncCountWhenUnlimited;
            Application.targetFrameRate = -1;
        }
    }

    /// <summary>Enable/disable the limit (e.g. for UI buttons).</summary>
    public void SetLimitEnabled(bool enabled)
    {
        limitFrameRate = enabled;
        Apply();
    }

    /// <summary>Set the target FPS and enable the limit (e.g. for UI sliders).</summary>
    public void SetTargetFps(int fps)
    {
        targetFps = Mathf.Max(1, fps);
        limitFrameRate = true;
        Apply();
    }
}