namespace AcDream.App.Rendering;

/// <summary>
/// Resolves the user's presentation preference into a bounded render policy.
/// A normal client is never uncapped: disabling VSync selects a software
/// ceiling at the active monitor's refresh rate. Only the explicit startup
/// diagnostic may disable both mechanisms.
/// </summary>
internal readonly record struct FramePacingPolicy(
    bool UseVSync,
    double? SoftwareLimitHz)
{
    internal const double FallbackRefreshHz = 60d;

    public static FramePacingPolicy Resolve(
        bool requestedVSync,
        bool uncappedRendering,
        int? monitorRefreshHz)
    {
        if (uncappedRendering)
            return new FramePacingPolicy(UseVSync: false, SoftwareLimitHz: null);

        if (requestedVSync)
            return new FramePacingPolicy(UseVSync: true, SoftwareLimitHz: null);

        double refreshHz = monitorRefreshHz is > 0
            ? monitorRefreshHz.Value
            : FallbackRefreshHz;
        return new FramePacingPolicy(UseVSync: false, SoftwareLimitHz: refreshHz);
    }
}