// Copyright (c) 2008-2018 schick Informatik
// Description: Database connector
//

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Data;
using System.Data.SqlClient;

using bsmd.AISService.AIS;

namespace bsmd.AISService.DB
{   

    public class DBConnector
    {        
        private string connectionString;
        private SqlConnection dbCon = null;
        private List<AISWatchkeeper> watchkeeperShips = null;
        private List<AISStaticData> dbShips = null;
        private Dictionary<string, AISStation> updateStations = null;

        public DBConnector() { }

        #region Properties

        public string ConnectionString
        {
            get { return this.connectionString; }
            set { this.connectionString = value; }
        }

        public List<AISStaticData> DBShips
        {
            get
            {
                if (this.dbShips == null)
                {
                    lock (this.dbCon)
                    {
                        this.dbShips = AISStaticData.LoadDBShips(this);
                    }
                }
                return this.dbShips;
            }
            set { this.dbShips = value; }
        }

        public List<AISWatchkeeper> WatchkeeperShips
        {
            get
            {
                if (this.watchkeeperShips == null) this.watchkeeperShips = AISWatchkeeper.GetWatchkeeperShips(this);
                return this.watchkeeperShips;
            }
        }

        #endregion

        #region public methods

        public SqlDataReader ExecuteQuery(string query)
        {
            if (!this.CheckConnection()) return null;

            SqlCommand cmd = new SqlCommand(query, this.dbCon);
            return cmd.ExecuteReader();
        }

        public int ExecuteNonQuery(string query)
        {
            if (!this.CheckConnection()) return 0;
            SqlCommand cmd = new SqlCommand(query, this.dbCon);
            return cmd.ExecuteNonQuery();
        }

        public object ExecuteScalar(string query)
        {
            if (!this.CheckConnection()) return 0;
            SqlCommand cmd = new SqlCommand(query, this.dbCon);
            return cmd.ExecuteScalar();
        }

        public bool Open()
        {
            if (this.dbCon != null && this.dbCon.State == System.Data.ConnectionState.Open) return true;
            try
            {
                this.dbCon = new SqlConnection(this.connectionString);
                this.dbCon.Open();
                if (this.dbCon.State == System.Data.ConnectionState.Open)
                    return true;
            }
            catch (SqlException anException)
            {
                Trace.WriteLine(string.Format("cannot open SQL DB connection: {0}", anException.Message));
            }
            return false;
        }

        public void Close()
        {
            try
            {
                if (this.dbCon != null && this.dbCon.State == System.Data.ConnectionState.Open)
                    this.dbCon.Close();
            }
            catch (Exception) { } // egal 
        }

        public void Update(AIS_Target target)
        {
            if (this.dbCon.State != System.Data.ConnectionState.Open) // reopen
            {
                this.dbCon.Close();
                this.dbCon.Open();
            }

            if (this.updateStations == null)
            {
                this.updateStations = new Dictionary<string, AISStation>();
                Trace.WriteLine("loading stations..");
                List<AISStation> stations = AISStation.LoadStations(this);
                Trace.WriteLine(string.Format("{0} stations loaded", stations.Count));
                foreach (AISStation station in stations)
                    if (!updateStations.ContainsKey(station.Name))
                        updateStations.Add(station.Name, station);
            }

            if (target.LastPosReport != null)
            {
                Hotposition hotposition = Hotposition.LoadForMMSI(target.MMSI, this);
                int? pid = AISPosReport.Save(target, this, updateStations.ContainsKey(target.Station) ? updateStations[target.Station] : null);
                if (pid.HasValue)
                {
                    hotposition.PosReportId = pid.Value;
                    hotposition.Save(this);
                }
            }
            else
            {
                Trace.WriteLine(string.Format("last pos report is null for target {0}", target.MMSI));
            }
            if (target.LastStaticData != null)
            {
                AISStaticData.Save(target, this, updateStations.ContainsKey(target.Station) ? updateStations[target.Station] : null);
            }
            if ((target.Name == null || target.LastDBName == null) && (target.MMSI > 0))
            {
                // preload values from DB
                AISStaticData.PreloadTarget(target, this);
            }

            target.UpdateDB = false; // reset update flag                
            // Watchkeeper check

            if (this.watchkeeperShips == null)
                this.watchkeeperShips = AISWatchkeeper.GetWatchkeeperShips(this);


            if (!target.IsWatchkeeperShip.HasValue && this.watchkeeperShips != null)
            {
                for (int i = 0; i < this.watchkeeperShips.Count; i++)
                {
                    if (this.watchkeeperShips[i].MMSI == target.MMSI) // found it
                        target.IsWatchkeeperShip = true;
                }

                if (!target.IsWatchkeeperShip.HasValue) // didn't find it
                    target.IsWatchkeeperShip = false;
            }


        }

        public void ResetWatchkeeperList()
        {
            this.watchkeeperShips = null;
        }

        public void SaveStation(AISStation station)
        {
            station.Save(this);
        }

        #endregion

        #region private methods

        private bool CheckConnection()
        {
            // if connection has been closed, re-open the connection
            if (this.dbCon.State != System.Data.ConnectionState.Open)
            {
                try
                {
                    this.dbCon.Close();
                    this.Open();
                }
                catch (SqlException ex)
                {
                    System.Diagnostics.Trace.WriteLine(ex.ToString());
                }
            }
            return this.dbCon.State == System.Data.ConnectionState.Open;
        }

        #endregion

    }
}