using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate;
using log4net;

namespace TracingDB
{
    public class WPlaceRegistrationMgmt
    {
        static readonly ILog log = LogManager.GetLogger(typeof(WPlaceRegistrationMgmt));

        string workplace;       /// Workplace ID string
        string user;            /// User name
        string ipAddress;       /// IP address of the workplace (not implemented now)
        string processName;     /// Process name
        string workstepName;    /// Workstep name
        DateTime valiUntil;     /// End of validity of this registration

        /// <summary>
        /// Constructor without registering a workplace. Use UpdateRegistration() to register a workplace.
        /// </summary>
        public WPlaceRegistrationMgmt()
        {
        }

        /// <summary>
        /// Constructor that registers a workplace.
        /// </summary>
        /// <param name="session">MySQL DB session</param>
        /// <param name="workplace">Workplace name</param>
        /// <param name="user">User name</param>
        /// <param name="ipAddress">IP address</param>
        /// <param name="processName">Process name</param>
        /// <param name="workstepName">Workstep name</param>
        /// <param name="valiUntil">Registration is valid until this DateTime</param>
        public WPlaceRegistrationMgmt(ISession session, string workplace, string user, string ipAddress, string processName, string workstepName, DateTime valiUntil)
        {
            if (RegisterWorkplace(session, workplace, user, ipAddress, processName, workstepName, valiUntil))
            {
                this.workplace = workplace;
                this.user = user;
                this.ipAddress = ipAddress;
                this.processName = processName;
                this.workstepName = workstepName;
                this.valiUntil = valiUntil;
            }
        }

        /// <summary>
        /// Compares associated information and registers a workplace if anything changed.
        /// </summary>
        /// <param name="session">MySQL DB session</param>
        /// <param name="workplace">Workplace name</param>
        /// <param name="user">User name</param>
        /// <param name="ipAddress">IP address</param>
        /// <param name="processName">Process name</param>
        /// <param name="workstepName">Workstep name</param>
        /// <param name="valiUntil">Registration is valid until this DateTime</param>
        /// <returns>true when successful</returns>
        public bool UpdateRegistration(ISession session, string workplace, string user, string ipAddress, string processName, string workstepName, DateTime valiUntil)
        {
            if (this.workplace != workplace)
            {
                /// Workplace name changed -> Unregister and register with a new name
                if (!UnregisterWorkplace(session, this.workplace)) return false;

                if (RegisterWorkplace(session, workplace, user, ipAddress, processName, workstepName, valiUntil))
                {
                    this.workplace = workplace;
                    this.user = user;
                    this.ipAddress = ipAddress;
                    this.processName = processName;
                    this.workstepName = workstepName;
                    this.valiUntil = valiUntil;
                    return true;    /// Registration successful
                }
                else
                {
                    return false;   /// Registration failed
                }
            }
            else if (this.user != user || this.ipAddress != ipAddress || this.processName != processName || this.workstepName != workstepName)
            {
                /// Anythig else changed -> Update registration
                if (RegisterWorkplace(session, workplace, user, ipAddress, processName, workstepName, valiUntil))
                {
                    this.workplace = workplace;
                    this.user = user;
                    this.ipAddress = ipAddress;
                    this.processName = processName;
                    this.workstepName = workstepName;
                    this.valiUntil = valiUntil;
                    return true;    /// Registration successful
                }
                else
                {
                    return false;   /// Registration failed
                }
            }
            else
            {
                return true;        /// Already registered with identical associated info
            }
        }

        /// <summary>
        /// Unregisters a workplace.
        /// </summary>
        /// <param name="session">MySQL DB session</param>
        /// <returns>true when successful</returns>
        public bool UnregisterWorkplace(ISession session)
        {
            if (UnregisterWorkplace(session, this.workplace))
            {
                this.workplace = string.Empty;
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary>
        /// Register a workplace. Provide associated information.
        /// </summary>
        /// <param name="session">MySQL DB session</param>
        /// <param name="workplace">Workplace name</param>
        /// <param name="user">User name</param>
        /// <param name="ipAddress">IP address</param>
        /// <param name="processName">Process name</param>
        /// <param name="workstepName">Workstep name</param>
        /// <param name="valiUntil">Registration is valid until this DateTime</param>
        /// <returns>true when successful</returns>
        static bool RegisterWorkplace(ISession session, string workplace, string user, string ipAddress, string processName, string workstepName, DateTime valiUntil)
        {
            try
            {
                IList<Entities.WorkplaceRegistration> wpRegs = session
                    .QueryOver<Entities.WorkplaceRegistration>()
                    .Where(x => (x.Workplace == workplace))
                    .List();

                if (wpRegs.Count == 0)
                {
                    Entities.WorkplaceRegistration wpReg = new Entities.WorkplaceRegistration(workplace, user, ipAddress, processName, workstepName);
                    wpRegs.Add(wpReg);
                    session.SaveOrUpdate(wpReg);
                    log.InfoFormat("RegisterWorkplace(., {0}, {1}, ...) successful (new)", workplace, user);
                    return true;
                }
                else if (wpRegs.Count == 1)
                {
                    Entities.WorkplaceRegistration wpReg = wpRegs[0];

                    wpReg.Active = true;
                    wpReg.TimeStamp = DateTime.Now;
                    wpReg.ValidUntil = DateTime.Now + new TimeSpan(8, 0, 0);
                    wpReg.UserName = user;
                    wpReg.IPAddress = ipAddress;
                    wpReg.ProcessName = processName;
                    wpReg.WorkstepName = workstepName;

                    session.SaveOrUpdate(wpReg);
                    session.Flush();
                    log.InfoFormat("RegisterWorkplace(., {0}, {1}, ...) successful", workplace, user);
                    return true;
                }
                else
                {
                    log.ErrorFormat("RegisterWorkplace(., {0}, {1}, ...) failed", workplace, user);
                    return false;
                }
            }
            catch (Exception e)
            {
                log.ErrorFormat("RegisterWorkplace(., {0}, {1}, ...) exception: {2}", workplace, user, e.Message);
                return false;
            }
        }

        /// <summary>
        /// Unregister a workplace.
        /// </summary>
        /// <param name="session">MySQL DB session</param>
        /// <param name="workplace">Workplace name</param>
        /// <returns>true when successful</returns>
        public static bool UnregisterWorkplace(ISession session, string workplace)
        {
            if (workplace == null) return true;     /// no workplace => unregistration successful

            try
            {
                IList<Entities.WorkplaceRegistration> wpRegs = session
                    .QueryOver<Entities.WorkplaceRegistration>()
                    .Where(x => (x.Workplace == workplace))
                    .List();

                if (wpRegs.Count == 1)
                {
                    Entities.WorkplaceRegistration wpReg = wpRegs[0];

                    wpReg.Active = false;
                    wpReg.TimeStamp = DateTime.Now;

                    session.SaveOrUpdate(wpReg);
                    session.Flush();
                    log.InfoFormat("UnregisterWorkplace(., {0}) successful", workplace);
                    return true;
                }
                else
                {
                    log.ErrorFormat("UnregisterWorkplace(., {0}) failed", workplace);
                    return false;
                }
            }
            catch (Exception e)
            {
                log.ErrorFormat("UnregisterWorkplace(., {0}) exception: {1}", workplace, e.Message);
                return false;
            }
        }
    }
}