using System.Text.Json;

namespace EchoHub.Client.Config;

public static class ConfigManager
{
    private static readonly string ConfigDir = Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".echohub");

    private static readonly string ConfigPath = Path.Combine(ConfigDir, "config.json");

    /// <summary>Directory holding the client config and local key material.</summary>
    public static string ConfigDirectory => ConfigDir;

    // Load-mutate-save cycles run from both the UI thread and background tasks
    // (token refresh, room keys, last-read checkpoints) — serialize file access.
    private static readonly Lock FileLock = new();

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        WriteIndented = true,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
    };

    public static ClientConfig Load()
    {
        lock (FileLock)
        {
            try
            {
                if (!File.Exists(ConfigPath))
                    return new ClientConfig();

                var json = File.ReadAllText(ConfigPath);
                return JsonSerializer.Deserialize<ClientConfig>(json, JsonOptions) ?? new ClientConfig();
            }
            catch
            {
                return new ClientConfig();
            }
        }
    }

    public static void Save(ClientConfig config)
    {
        lock (FileLock)
        {
            try
            {
                Directory.CreateDirectory(ConfigDir);
                var json = JsonSerializer.Serialize(config, JsonOptions);
                File.WriteAllText(ConfigPath, json);
            }
            catch
            {
                // Silently fail — config save is best-effort
            }
        }
    }

    public static void SaveServer(SavedServer server)
    {
        lock (FileLock)
        {
            var config = Load();
            var existing = config.SavedServers.FindIndex(s =>
                string.Equals(s.Url, server.Url, StringComparison.OrdinalIgnoreCase));

            if (existing >= 0)
                config.SavedServers[existing] = server;
            else
                config.SavedServers.Add(server);

            Save(config);
        }
    }

    public static void RemoveServer(string url)
    {
        lock (FileLock)
        {
            var config = Load();
            config.SavedServers.RemoveAll(s =>
                string.Equals(s.Url, url, StringComparison.OrdinalIgnoreCase));

            Save(config);
        }
    }
}