using System.IO;

namespace UtopiaCanteenSystem.Data;

/// <summary>
/// Central location for persistent paths (database and config). Uses LocalApplicationData
/// so data survives app updates when the application is deployed from a file server.
/// </summary>
public static class DatabasePath
{
    private static string? _appDataFolder;
    private static string? _dbPath;

    /// <summary>
    /// Folder under LocalApplicationData for DB and config. Created on first use.
    /// </summary>
    public static string GetAppDataFolder()
    {
        if (_appDataFolder != null)
            return _appDataFolder;

        _appDataFolder = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
            "UtopiaCanteenSystem");
        Directory.CreateDirectory(_appDataFolder);
        return _appDataFolder;
    }

    /// <summary>
    /// Full path to the SQLite database file. If a DB exists in the legacy app-directory
    /// location, it is copied to the new location once.
    /// </summary>
    public static string GetDbPath()
    {
        if (_dbPath != null)
            return _dbPath;

        var folder = GetAppDataFolder();
        _dbPath = Path.Combine(folder, "utopia_canteen.db");
        MigrateLegacyDbIfNeeded(_dbPath);
        return _dbPath;
    }

    /// <summary>
    /// Full path to appsettings.json (remember-me credentials and other config).
    /// Stored in the same persistent folder so it survives updates. If a config exists
    /// in the legacy app-directory location, it is copied to the new location once.
    /// </summary>
    public static string GetConfigPath()
    {
        var folder = GetAppDataFolder();
        var newPath = Path.Combine(folder, "appsettings.json");
        MigrateLegacyConfigIfNeeded(newPath);
        return newPath;
    }

    private static void MigrateLegacyDbIfNeeded(string newPath)
    {
        if (File.Exists(newPath))
            return;

        var legacyPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "utopia_canteen.db");
        if (!File.Exists(legacyPath))
            return;

        try
        {
            File.Copy(legacyPath, newPath);
        }
        catch
        {
            // If copy fails, app will start with a new DB at new path.
        }
    }

    private static void MigrateLegacyConfigIfNeeded(string newPath)
    {
        if (File.Exists(newPath))
            return;

        var legacyPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "appsettings.json");
        if (!File.Exists(legacyPath))
            return;

        try
        {
            File.Copy(legacyPath, newPath);
        }
        catch
        {
            // If copy fails, app will start with a new config at new path.
        }
    }
}