using System;
using System.IO;
using System.Text.Json;

namespace codelanguage;

/// <summary>Serializable Pager session used for one-click craft:// joins.</summary>
public sealed record CraftSavedSession(
    string HubUrl,
    string Username,
    string SessionToken,
    DateTimeOffset SavedAtUtc);

/// <summary>
/// Local, per-user session cache written by the Pager after a successful Hub
/// sign-in. The opaque Hub token lets a newly launched Dream Seeker join a
/// craft:// link without asking the player to type their key again.
/// </summary>
public static class CraftSessionStore
{
    public static string DefaultPath => Path.Combine(
        System.Environment.GetFolderPath(System.Environment.SpecialFolder.LocalApplicationData),
        "CraftPlusPlus",
        "pager-session.json");

    public static CraftSavedSession? Load(string? path = null)
    {
        string file = ResolvePath(path);
        try
        {
            if (!File.Exists(file)) return null;
            var session = JsonSerializer.Deserialize<CraftSavedSession>(File.ReadAllText(file));
            if (session == null || string.IsNullOrWhiteSpace(session.Username) ||
                string.IsNullOrWhiteSpace(session.SessionToken))
                return null;
            return session;
        }
        catch
        {
            return null;
        }
    }

    public static void Save(string hubUrl, string username, string sessionToken, string? path = null)
    {
        if (string.IsNullOrWhiteSpace(username) || string.IsNullOrWhiteSpace(sessionToken)) return;
        string file = ResolvePath(path);
        try
        {
            string? directory = Path.GetDirectoryName(file);
            if (!string.IsNullOrEmpty(directory)) Directory.CreateDirectory(directory);
            var session = new CraftSavedSession(hubUrl ?? "", username, sessionToken, DateTimeOffset.UtcNow);
            string temporary = file + ".tmp";
            File.WriteAllText(temporary, JsonSerializer.Serialize(session));
            File.Move(temporary, file, overwrite: true);
            if (!OperatingSystem.IsWindows())
                File.SetUnixFileMode(file, UnixFileMode.UserRead | UnixFileMode.UserWrite);
        }
        catch
        {
            // The session cache is best-effort; manual login remains available.
        }
    }

    public static void Clear(string? path = null)
    {
        string file = ResolvePath(path);
        try
        {
            if (File.Exists(file)) File.Delete(file);
        }
        catch { }
    }

    private static string ResolvePath(string? path) =>
        string.IsNullOrWhiteSpace(path) ? DefaultPath : path;
}