metin-launcher/src/Metin2Launcher/Config/LauncherSettings.cs

using System.IO;
using System.Text.Json;
using Metin2Launcher.Logging;

namespace Metin2Launcher.Config;

/// <summary>
/// User-editable settings persisted to .updates/launcher-settings.json.
/// Only honored when DevMode == true for the URL override (defense in depth: a
/// tampered local file alone cannot redirect updates).
/// </summary>
public sealed class LauncherSettings
{
    public string Locale { get; set; } = "cs";
    public bool DevMode { get; set; } = false;
    public string? ManifestUrlOverride { get; set; }

    private static readonly JsonSerializerOptions _opts = new()
    {
        WriteIndented = true,
    };

    public static LauncherSettings Load(string path)
    {
        try
        {
            if (!File.Exists(path))
                return new LauncherSettings();
            var json = File.ReadAllText(path);
            return JsonSerializer.Deserialize<LauncherSettings>(json) ?? new LauncherSettings();
        }
        catch (Exception ex)
        {
            Log.Warn("failed to read launcher settings, using defaults: " + ex.Message);
            return new LauncherSettings();
        }
    }

    public void Save(string path)
    {
        try
        {
            Directory.CreateDirectory(Path.GetDirectoryName(path)!);
            var json = JsonSerializer.Serialize(this, _opts);
            File.WriteAllText(path, json);
        }
        catch (Exception ex)
        {
            Log.Warn("failed to save launcher settings: " + ex.Message);
        }
    }

    /// <summary>
    /// Effective manifest URL respecting dev-mode gating.
    /// </summary>
    public string EffectiveManifestUrl()
    {
        if (DevMode && !string.IsNullOrWhiteSpace(ManifestUrlOverride))
            return ManifestUrlOverride!;
        return LauncherConfig.ManifestUrl;
    }

    /// <summary>
    /// Derives signature URL from the (possibly overridden) manifest URL.
    /// </summary>
    public string EffectiveSignatureUrl()
    {
        var m = EffectiveManifestUrl();
        if (m == LauncherConfig.ManifestUrl)
            return LauncherConfig.SignatureUrl;
        return m + ".sig";
    }

    /// <summary>
    /// Derives the blob base URL from the (possibly overridden) manifest URL.
    /// Same host, sibling /files path.
    /// </summary>
    public string EffectiveBlobBaseUrl()
    {
        var m = EffectiveManifestUrl();
        if (m == LauncherConfig.ManifestUrl)
            return LauncherConfig.BlobBaseUrl;
        try
        {
            var u = new Uri(m);
            return $"{u.Scheme}://{u.Authority}/files";
        }
        catch
        {
            return LauncherConfig.BlobBaseUrl;
        }
    }
}