AppConfig.cs

using System.Text.Json;

namespace BatteryDown;

internal sealed class AppConfig
{
    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        WriteIndented = true,
    };

    public int DelaySeconds { get; set; }

    public int ShutdownDelaySeconds { get; set; } = 60;

    public bool ShutdownImmediatelyWhenLocked { get; set; }

    public static string DirectoryPath =>
        Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "BatteryDown");

    public static string FilePath => Path.Combine(DirectoryPath, "config.json");

    public static AppConfig Load() => LoadFrom(FilePath);

    public static AppConfig LoadFrom(string filePath)
    {
        try
        {
            if (File.Exists(filePath))
            {
                var json = File.ReadAllText(filePath);
                var config = JsonSerializer.Deserialize<AppConfig>(json) ?? new AppConfig();

                using var document = JsonDocument.Parse(json);
                if (!document.RootElement.TryGetProperty(nameof(DelaySeconds), out _) &&
                    document.RootElement.TryGetProperty("DelayMinutes", out var oldDelay) &&
                    oldDelay.TryGetInt32(out var oldDelayMinutes))
                {
                    config.DelaySeconds = checked(oldDelayMinutes * 60);
                }

                return Normalize(config);
            }
        }
        catch (JsonException)
        {
            // A damaged config should not prevent the user from opening the settings window.
        }

        return new AppConfig();
    }

    public void Save()
    {
        Normalize(this);
        Directory.CreateDirectory(DirectoryPath);
        File.WriteAllText(FilePath, JsonSerializer.Serialize(this, JsonOptions));
    }

    private static AppConfig Normalize(AppConfig config)
    {
        config.DelaySeconds = Math.Clamp(config.DelaySeconds, 0, 3600);
        config.ShutdownDelaySeconds = Math.Clamp(config.ShutdownDelaySeconds, 10, 3600);
        return config;
    }
}