using System.Text.Json;

namespace LehrerApp.Core.Services;

internal class PrivacySettingsConfig
{
    public int RetentionYears { get; set; } = 3;
}

/// <summary>
/// Löschfristen für Dokumentationseinträge (5.4.2). Löscht nichts automatisch — schlägt
/// abgelaufene Einträge nur zur manuellen Prüfung/Löschung vor.
/// </summary>
public class PrivacySettingsService
{
    private readonly string _configPath;
    private PrivacySettingsConfig _config;

    public int RetentionYears => _config.RetentionYears;

    public PrivacySettingsService(string appDataPath)
    {
        _configPath = Path.Combine(appDataPath, "privacy.json");
        _config = Load();
    }

    public void SetRetentionYears(int years)
    {
        _config.RetentionYears = Math.Max(1, years);
        File.WriteAllText(_configPath, JsonSerializer.Serialize(_config));
    }

    public DateTime RetentionCutoff(DateTime? now = null) =>
        (now ?? DateTime.UtcNow).AddYears(-RetentionYears);

    private PrivacySettingsConfig Load()
    {
        try
        {
            if (File.Exists(_configPath))
                return JsonSerializer.Deserialize<PrivacySettingsConfig>(File.ReadAllText(_configPath))
                       ?? new PrivacySettingsConfig();
        }
        catch { /* beschädigte Konfiguration -> Standardwert */ }
        return new PrivacySettingsConfig();
    }
}