using Microsoft.Win32;

namespace HearingProtector;

internal sealed record AppSettings(double MinPercent, double FullDecayMinutes)
{
    public static AppSettings Default => new(1.0, 30.0);
}

internal static class SettingsStore
{
    private const string KeyPath = @"Software\HearingProtector";
    private const string ValueMin = "MinPercent";
    private const string ValueDecay = "FullDecayMinutes";

    public static AppSettings Load()
    {
        try
        {
            using var key = Registry.CurrentUser.OpenSubKey(KeyPath);
            if (key is null) return AppSettings.Default;

            double min = ReadDouble(key, ValueMin, AppSettings.Default.MinPercent);
            double decay = ReadDouble(key, ValueDecay, AppSettings.Default.FullDecayMinutes);

            if (min < 0 || min > 50) min = AppSettings.Default.MinPercent;
            if (decay < 30 || decay > 360) decay = AppSettings.Default.FullDecayMinutes;

            return new AppSettings(min, decay);
        }
        catch
        {
            return AppSettings.Default;
        }
    }

    public static void Save(AppSettings s)
    {
        try
        {
            using var key = Registry.CurrentUser.CreateSubKey(KeyPath, writable: true);
            if (key is null) return;

            key.SetValue(ValueMin, s.MinPercent, RegistryValueKind.String);
            key.SetValue(ValueDecay, s.FullDecayMinutes, RegistryValueKind.String);
            key.DeleteValue("PollMs", throwOnMissingValue: false);
        }
        catch { }
    }

    private static double ReadDouble(RegistryKey key, string name, double fallback)
    {
        var raw = key.GetValue(name);
        return raw switch
        {
            string s when double.TryParse(s, System.Globalization.CultureInfo.InvariantCulture,
                                          out var d) => d,
            double d => d,
            _ => fallback,
        };
    }
}