using System;
using Steamworks;

namespace MSCO
{
    /// <summary>
    /// Steam-Lobby für P2P: Host erstellt eine Freunde-Lobby, lädt über das Steam-Overlay ein,
    /// Freunde treten über die Einladung bzw. "Spiel beitreten" bei. Die eigentlichen Daten
    /// laufen danach über Steam P2P (siehe SteamConnection).
    /// </summary>
    public class SteamLobby
    {
        const string VersionKey = "msco_version";
        const uint ChatMemberLeftMask = 2 | 4 | 8 | 16; // Left, Disconnected, Kicked, Banned

        public CSteamID LobbyId { get; private set; }
        public bool InLobby { get { return LobbyId.m_SteamID != 0; } }

        /// <summary>Lobby erstellt (Host).</summary>
        public event Action<CSteamID> Created;
        /// <summary>Lobby betreten (Client): Lobby-ID und Host.</summary>
        public event Action<CSteamID, CSteamID> Entered;
        /// <summary>Einladung angenommen / "Spiel beitreten" im Freundesfenster.</summary>
        public event Action<CSteamID> JoinRequested;
        /// <summary>Jemand hat die Lobby verlassen (Steam-ID).</summary>
        public event Action<CSteamID> MemberLeft;
        /// <summary>Fehler (Text für die Statuszeile).</summary>
        public event Action<string> Failed;

        CallResult<LobbyCreated_t> createdResult;
        CallResult<LobbyEnter_t> enterResult;
        Callback<GameLobbyJoinRequested_t> joinRequestedCallback;
        Callback<LobbyChatUpdate_t> chatUpdateCallback;
        Callback<P2PSessionRequest_t> sessionRequestCallback;
        bool initialized;

        public static bool IsAvailable
        {
            get
            {
                try { return SteamAPI.IsSteamRunning() && SteamUser.GetSteamID().m_SteamID != 0; }
                catch { return false; }
            }
        }

        public static string PersonaName
        {
            get
            {
                try { return SteamFriends.GetPersonaName(); }
                catch { return null; }
            }
        }

        public static ulong OwnSteamId
        {
            get
            {
                try { return SteamUser.GetSteamID().m_SteamID; }
                catch { return 0; }
            }
        }

        static HAuthTicket authTicket;
        static bool hasAuthTicket;

        /// <summary>Steam-Anmeldeticket für dedizierte Server (der Server kann es bei Steam prüfen).</summary>
        public static byte[] CreateAuthTicket()
        {
            try
            {
                CancelAuthTicket();
                var buffer = new byte[1024];
                uint length;
                authTicket = SteamUser.GetAuthSessionTicket(buffer, buffer.Length, out length);
                hasAuthTicket = true;
                var ticket = new byte[length];
                Array.Copy(buffer, ticket, length);
                return ticket;
            }
            catch
            {
                return new byte[0];
            }
        }

        public static void CancelAuthTicket()
        {
            if (!hasAuthTicket) return;
            hasAuthTicket = false;
            try { SteamUser.CancelAuthTicket(authTicket); } catch { }
        }

        public bool Init()
        {
            if (initialized) return true;
            if (!IsAvailable) return false;
            try
            {
                createdResult = CallResult<LobbyCreated_t>.Create(OnLobbyCreated);
                enterResult = CallResult<LobbyEnter_t>.Create(OnLobbyEntered);
                joinRequestedCallback = Callback<GameLobbyJoinRequested_t>.Create(OnJoinRequested);
                chatUpdateCallback = Callback<LobbyChatUpdate_t>.Create(OnChatUpdate);
                sessionRequestCallback = Callback<P2PSessionRequest_t>.Create(OnSessionRequest);
                initialized = true;
            }
            catch (Exception e)
            {
                MscoLog.Error("[MSCO] Steam init failed: " + e.Message);
            }
            return initialized;
        }

        /// <summary>Jedes Frame aufrufen, damit Steam-Callbacks ankommen.</summary>
        public void Tick()
        {
            if (!initialized) return;
            try { SteamAPI.RunCallbacks(); } catch { }
        }

        public void Create(int maxPlayers)
        {
            if (!Init()) { Fail("Steam is not running"); return; }
            Leave();
            createdResult.Set(SteamMatchmaking.CreateLobby(ELobbyType.k_ELobbyTypeFriendsOnly, maxPlayers));
        }

        public void Join(CSteamID lobby)
        {
            if (!Init()) { Fail("Steam is not running"); return; }
            Leave();
            enterResult.Set(SteamMatchmaking.JoinLobby(lobby));
        }

        public void OpenInviteDialog()
        {
            if (InLobby) SteamFriends.ActivateGameOverlayInviteDialog(LobbyId);
        }

        public void Leave()
        {
            if (!InLobby) return;
            try { SteamMatchmaking.LeaveLobby(LobbyId); } catch { }
            LobbyId = new CSteamID(0);
        }

        public bool IsMember(CSteamID user)
        {
            if (!InLobby) return false;
            int count = SteamMatchmaking.GetNumLobbyMembers(LobbyId);
            for (int i = 0; i < count; i++)
                if (SteamMatchmaking.GetLobbyMemberByIndex(LobbyId, i) == user) return true;
            return false;
        }

        // ---------------------------------------------------------------- Callbacks

        void OnLobbyCreated(LobbyCreated_t result, bool ioFailure)
        {
            if (ioFailure || result.m_eResult != EResult.k_EResultOK)
            {
                Fail("Could not create Steam lobby (" + result.m_eResult + ")");
                return;
            }
            LobbyId = new CSteamID(result.m_ulSteamIDLobby);
            SteamMatchmaking.SetLobbyData(LobbyId, VersionKey, MSCO.ProtocolVersion); // ältere Mods vergleichen genau
            if (Created != null) Created(LobbyId);
        }

        void OnLobbyEntered(LobbyEnter_t result, bool ioFailure)
        {
            if (ioFailure || result.m_EChatRoomEnterResponse != 1) // 1 = Success
            {
                Fail("Could not join the lobby (full or closed)");
                return;
            }
            LobbyId = new CSteamID(result.m_ulSteamIDLobby);

            string hostVersion = SteamMatchmaking.GetLobbyData(LobbyId, VersionKey);
            if (!string.IsNullOrEmpty(hostVersion) && !MSCO.Compatible(hostVersion))
            {
                Leave();
                Fail("Version mismatch (host " + hostVersion + ", you " + MSCO.ModVersion + ")");
                return;
            }
            CSteamID owner = SteamMatchmaking.GetLobbyOwner(LobbyId);
            if (Entered != null) Entered(LobbyId, owner);
        }

        void OnJoinRequested(GameLobbyJoinRequested_t request)
        {
            if (JoinRequested != null) JoinRequested(request.m_steamIDLobby);
        }

        void OnChatUpdate(LobbyChatUpdate_t update)
        {
            if (update.m_ulSteamIDLobby != LobbyId.m_SteamID) return;
            if ((update.m_rgfChatMemberStateChange & ChatMemberLeftMask) == 0) return;
            if (MemberLeft != null) MemberLeft(new CSteamID(update.m_ulSteamIDUserChanged));
        }

        void OnSessionRequest(P2PSessionRequest_t request)
        {
            // Nur Verbindungen von Spielern aus unserer Lobby annehmen
            if (IsMember(request.m_steamIDRemote))
                SteamNetworking.AcceptP2PSessionWithUser(request.m_steamIDRemote);
        }

        void Fail(string message)
        {
            if (Failed != null) Failed(message);
        }

        /// <summary>Wurde das Spiel über eine Steam-Einladung gestartet? ("+connect_lobby &lt;id&gt;")</summary>
        public static CSteamID LobbyFromCommandLine()
        {
            string[] args = Environment.GetCommandLineArgs();
            for (int i = 0; i < args.Length - 1; i++)
            {
                ulong id;
                if (args[i] == "+connect_lobby" && ulong.TryParse(args[i + 1], out id)) return new CSteamID(id);
            }
            return new CSteamID(0);
        }
    }
}