using System.Collections.Generic;
using AcDream.UI.Abstractions.Settings;

namespace AcDream.UI.Abstractions.Panels.Settings;

/// <summary>
/// Particle visibility distance policy. Retail uses the GfxObj-authored
/// distance exactly; Extended is an explicit acdream adaptation for players
/// who prefer longer-lived distant effects with the corresponding CPU cost.
/// </summary>
public enum ParticleRange
{
    Retail = 0,
    Extended = 1,
}

/// <summary>
/// Display-related preferences persisted to <c>settings.json</c>.
/// Modern addition (no retail equivalent for FOV / vsync etc) — replaces
/// the various <c>ACDREAM_*</c> environment variables for resolution +
/// windowed mode with an in-game UI.
///
/// <para>
/// Records are immutable; mutation goes through
/// <see cref="SettingsVM.SetDisplay"/> which assigns a new instance via
/// <c>with</c>-expressions.
/// </para>
/// </summary>
public sealed record DisplaySettings(
    string Resolution,
    bool Fullscreen,
    bool VSync,
    float FieldOfView,
    float Gamma,
    bool ShowFps,
    QualityPreset Quality,
    ParticleRange ParticleRange)
{
    /// <summary>Values used on first launch / when settings.json is absent.
    /// Geometry/render defaults preserve the pre-L.0 runtime state — Resolution
    /// matches the WindowOptions startup size (1280×720), FieldOfView
    /// matches camera FovY (60°), VSync matches WindowOptions (false),
    /// ShowFps matches retail's initially-hidden SmartBox FPS readout.</summary>
    public static DisplaySettings Default { get; } = new(
        Resolution:   "1280x720",
        Fullscreen:   false,
        VSync:        false,
        FieldOfView:  60f,
        Gamma:        1.0f,
        ShowFps:      false,
        Quality:      QualityPreset.High,
        ParticleRange: ParticleRange.Retail);

    /// <summary>16:9 resolution presets offered in the dropdown.</summary>
    public static IReadOnlyList<string> AvailableResolutions { get; } = new[]
    {
        "1280x720",
        "1366x768",
        "1600x900",
        "1920x1080",
        "2560x1440",
        "3840x2160",
    };
}