Session.cs

namespace CodeGame.Client;

using System.Text.Json;
using Directories.Net;

/// <summary>
/// Represents a CodeGame session.
/// </summary>
public class Session
{
    private static readonly string gamesPath = Path.Combine(new BaseDirectories().DataDir, "codegame", "games");

    /// <summary>
    /// The URL of the game server.
    /// </summary>
    public string GameURL { get; internal set; }
    /// <summary>
    /// The username of the player.
    /// </summary>
    public string Username { get; internal set; }
    /// <summary>
    /// The ID of the game.
    /// </summary>
    public string GameId { get; internal set; }
    /// <summary>
    /// The ID of the player.
    /// </summary>
    public string PlayerId { get; internal set; }
    /// <summary>
    /// The player secret.
    /// </summary>
    public string PlayerSecret { get; internal set; }

    /// <summary>
    /// Creates a new session.
    /// </summary>
    public Session(string gameURL, string username, string gameId, string playerId, string playerSecret)
    {
        this.GameURL = gameURL;
        this.Username = username;
        this.GameId = gameId;
        this.PlayerId = playerId;
        this.PlayerSecret = playerSecret;
    }

    /// <summary>
    /// Loads a session from disk.
    /// </summary>
    /// <param name="gameURL">The URL of the game.</param>
    /// <param name="username">The username of the player.</param>
    /// <returns>The loaded session.</returns>
    /// <exception cref="JsonException">Thrown when the session file is invalid.</exception>
    /// <exception cref="IOException">Thrown when the session file cannot be read.</exception>
    public static Session Load(string gameURL, string username)
    {
        using var file = File.Open(Path.Combine(gamesPath, Uri.EscapeDataString(gameURL), username + ".json"), FileMode.Open);
        var data = JsonSerializer.Deserialize<Dictionary<string, string>>(file);
        if (data == null || !data.ContainsKey("game_id") || !data.ContainsKey("player_id") || !data.ContainsKey("player_secret"))
        {
            throw new JsonException("Invalid session file.");
        }
        return new Session(gameURL, username, data["game_id"], data["player_id"], data["player_secret"]);
    }

    /// <summary>
    /// Writes the session to disk.
    /// </summary>
    /// <exception cref="InvalidOperationException">Thrown when one or more fields of the session are empty.</exception>
    /// <exception cref="IOException">Thrown when the session file cannot be written.</exception>
    public void Save()
    {
        if (GameURL == "" || Username == "" || GameId == "" || PlayerId == "" || PlayerSecret == "")
            throw new InvalidOperationException("The session is not complete.");

        var dir = Path.Combine(gamesPath, Uri.EscapeDataString(this.GameURL));

        if (!Directory.Exists(dir)) Directory.CreateDirectory(dir);

        var data = new Dictionary<string, string>(3);
        data.Add("game_id", GameId);
        data.Add("player_id", PlayerId);
        data.Add("player_secret", PlayerSecret);

        using var file = File.Create(Path.Combine(dir, this.Username + ".json"));
        JsonSerializer.Serialize<Dictionary<string, string>>(file, data);
    }

    /// <summary>
    /// Deletes the session file.
    /// </summary>
    /// <exception cref="IOException">Thrown when the session file cannot be deleted.</exception>
    public void Remove()
    {
        if (GameURL == "") return;

        var dir = Path.Combine(gamesPath, Uri.EscapeDataString(GameURL));
        File.Delete(Path.Combine(dir, Username + ".json"));

        if (Directory.GetFiles(dir).Length == 0) Directory.Delete(dir);
    }
}