/* Copyright (C) 2014-2019 Tal Aloni <tal.aloni.il@gmail.com>. All rights reserved.
 * 
 * You can redistribute this program and/or modify it under the terms of
 * the GNU Lesser Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
 */
using System;
using System.Collections.Generic;
using System.IO;
using SMBLibrary.SMB2;
using Utilities;

namespace SMBLibrary.Server
{
    internal class SMB2ConnectionState : ConnectionState
    {
        // Key is SessionID
        private Dictionary<ulong, SMB2Session> m_sessions = new Dictionary<ulong, SMB2Session>();
        private ulong m_nextSessionID = 1;
        // Key is AsyncID
        private Dictionary<ulong, SMB2AsyncContext> m_pendingRequests = new Dictionary<ulong, SMB2AsyncContext>();
        private ulong m_nextAsyncID = 1;

        public SMB2ConnectionState(ConnectionState state) : base(state)
        {
        }

        public ulong? AllocateSessionID()
        {
            for (ulong offset = 0; offset < UInt64.MaxValue; offset++)
            {
                ulong sessionID = (ulong)(m_nextSessionID + offset);
                if (sessionID == 0 || sessionID == 0xFFFFFFFF)
                {
                    continue;
                }
                if (!m_sessions.ContainsKey(sessionID))
                {
                    m_nextSessionID = (ulong)(sessionID + 1);
                    return sessionID;
                }
            }
            return null;
        }

        public SMB2Session CreateSession(ulong sessionID, string userName, string machineName, byte[] sessionKey, object accessToken, bool signingRequired)
        {
            SMB2Session session = new SMB2Session(this, sessionID, userName, machineName, sessionKey, accessToken, signingRequired);
            lock (m_sessions)
            {
                m_sessions.Add(sessionID, session);
            }
            return session;
        }

        public SMB2Session GetSession(ulong sessionID)
        {
            SMB2Session session;
            m_sessions.TryGetValue(sessionID, out session);
            return session;
        }

        public void RemoveSession(ulong sessionID)
        {
            SMB2Session session;
            m_sessions.TryGetValue(sessionID, out session);
            if (session != null)
            {
                session.Close();
                lock (m_sessions)
                {
                    m_sessions.Remove(sessionID);
                }
            }
        }

        public override void CloseSessions()
        {
            lock (m_sessions)
            {
                foreach (SMB2Session session in m_sessions.Values)
                {
                    session.Close();
                }

                m_sessions.Clear();
            }
        }

        public override List<SessionInformation> GetSessionsInformation()
        {
            List<SessionInformation> result = new List<SessionInformation>();
            lock (m_sessions)
            {
                foreach (SMB2Session session in m_sessions.Values)
                {
                    result.Add(new SessionInformation(this.ClientEndPoint, this.Dialect, session.UserName, session.MachineName, session.GetOpenFilesInformation(), session.CreationDT));
                }
            }
            return result;
        }

        private ulong? AllocateAsyncID()
        {
            for (ulong offset = 0; offset < UInt64.MaxValue; offset++)
            {
                ulong asyncID = (ulong)(m_nextAsyncID + offset);
                if (asyncID == 0 || asyncID == 0xFFFFFFFF)
                {
                    continue;
                }
                if (!m_pendingRequests.ContainsKey(asyncID))
                {
                    m_nextAsyncID = (ulong)(asyncID + 1);
                    return asyncID;
                }
            }
            return null;
        }

        public SMB2AsyncContext CreateAsyncContext(FileID fileID, SMB2ConnectionState connection, ulong sessionID, uint treeID)
        {
            ulong? asyncID = AllocateAsyncID();
            if (asyncID == null)
            {
                return null;
            }
            SMB2AsyncContext context = new SMB2AsyncContext();
            context.AsyncID = asyncID.Value;
            context.FileID = fileID;
            context.Connection = connection;
            context.SessionID = sessionID;
            context.TreeID = treeID;
            lock (m_pendingRequests)
            {
                m_pendingRequests.Add(asyncID.Value, context);
            }
            return context;
        }

        public SMB2AsyncContext GetAsyncContext(ulong asyncID)
        {
            SMB2AsyncContext context;
            lock (m_pendingRequests)
            {
                m_pendingRequests.TryGetValue(asyncID, out context);
            }
            return context;
        }

        public void RemoveAsyncContext(SMB2AsyncContext context)
        {
            lock (m_pendingRequests)
            {
                m_pendingRequests.Remove(context.AsyncID);
            }
        }
    }
}