///
/// Copyright (c) 2013-2016 Sensus Metering Systems
///
using System;
using System.Collections.Generic;
using FluentNHibernate.Cfg;
using FluentNHibernate.Cfg.Db;
using log4net;
using NHibernate;
using NHibernate.Cfg;
using NHibernate.Tool.hbm2ddl;
using Results.Entities;

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

		/// <summary> Session factory for all regular sessions, not for CreateEmptyResultsDB(). </summary>
		public static ISessionFactory SessionFactory;

		/// <summary> Connection string for all sessions </summary>
		static string connectionString;
		/// 
		public static string ConnectionString
		{
			get { return connectionString; }
            set
            {
                if (value != connectionString)
                {
                    connectionString = value;
                    SessionFactory = null;          /// Clear SessionFactory on connection string change
                }
            }
		}

		/// <summary> Database type (MySQL or SQLite) for all sessions </summary>
		private static Common.DBType dbType;
		/// 
		public static Common.DBType DbType
		{
			get { return dbType; }
			set { dbType = value; SessionFactory = null; }
		}

        /// <summary>
        /// NHibernate session factory (to create the database session 'SessionFactory')
        /// </summary>
        /// <returns>A database session</returns>
		static ISessionFactory CreateSessionFactory()
        {
			return CreateSessionFactory(false);
		}

        /// <summary>
        /// NHibernate session factory (to create the database session 'SessionFactory')
        /// </summary>
		/// <param name="createDB">true = Create a new DB, false = Regular DB</param>
        /// <returns>A database session</returns>
		public static ISessionFactory CreateSessionFactory(bool createDB)
        {
            FluentConfiguration cfg = Fluently.Configure();

			switch (dbType)
			{
				default:
				case Common.DBType.MySql:
                    cfg = cfg.Database(MySQLConfiguration.Standard.ConnectionString(connectionString));
                    break;
                case Common.DBType.SQLite:
                    cfg = cfg.Database(SQLiteConfiguration.Standard.UsingFile(connectionString));
                    break;
            }

            cfg = cfg.Mappings(m => m.FluentMappings.AddFromAssemblyOf<Entities.WaterMeterData>());

            if (createDB)
            {
                return cfg.ExposeConfiguration(BuildSchemaCreate)
                          .BuildConfiguration()
                          .SetProperty("hibernate.connection.connect_timeout", Common.Const.MySqlConnectTimeoutSec)
                          .BuildSessionFactory();
            }
            else
            {
                return cfg.ExposeConfiguration(BuildSchema)
                          .BuildConfiguration()
                          .SetProperty("hibernate.connection.connect_timeout", Common.Const.MySqlConnectTimeoutSec)
                          .BuildSessionFactory();
            }
        }

        static void BuildSchema(Configuration config)
        {
            /// This NHibernate tool takes a configuration with mapping info and exports a database schema
            new SchemaExport(config).SetOutputFile("db_schema");
        }

        static void BuildSchemaCreate(Configuration config)
        {
			/// This NHibernate tool takes a configuration with mapping info and exports a database schema
			new SchemaExport(config).Create(true, true);
        }

		/// Create a NHibernate session for the given database
		public static ISession CreateSession()
		{
			if (string.IsNullOrEmpty(connectionString))
			{
				throw new Exception("Connection string was not specified");
			}

			if (SessionFactory == null) SessionFactory = CreateSessionFactory();

			return SessionFactory.OpenSession();
		}


		public static void SaveObject(object obj)
		{
			SaveObject(CreateSession(), obj);
		}
		/// 
		public static void SaveObject(ISession session, object obj)
		{
            using (var transaction = session.BeginTransaction())
            {
                session.SaveOrUpdate(obj);
                try { transaction.Commit(); }
                catch { }
            }
        }


		public static void DeleteObject(object obj)
		{
			DeleteObject(CreateSession(), obj);
		}
		/// 
		public static void DeleteObject(ISession session, object obj)
        {
            using (var transaction = session.BeginTransaction())
            {
                session.Delete(obj);
                transaction.Commit();
            }
        }


        /// <summary>
        /// Create an empty users database.
		/// Database contains only the user 'admin' and the control board component 'CB'.
        /// </summary>
        /// <param name="dbType">DBType.SQLite or DBType.MySql</param>
        /// <param name="connectionString">Connection string</param>
        /// <returns>true=success, false=error</returns>
		public static bool CreateEmptyDB()
        {
			ISessionFactory sessionFactory = CreateSessionFactory(true);
            if (sessionFactory == null) return false;

            /// Populate the database
            using (var session = sessionFactory.OpenSession())
            {
                using (var transaction = session.BeginTransaction())
                {
                    transaction.Commit();
                }
            }

            return true;
        }


		/// <summary>
		/// Shared data
		/// </summary>
		public static IList<Entities.TestData> TestDataList;
		public static IList<Entities.Components> ComponentsList;
		public static IList<Entities.WaterMeterData> WaterMeterDataList;


		/// <summary>
		/// Loads shared data from the database
		/// </summary>
		/// <exception>Throws NHibernate exceptions</exception>
        public static void LoadSharedData(ISession session = null)
		{
            bool openAndCloseSession = (session == null);

            try
            {
                if (openAndCloseSession) session = Results.DB.CreateSession();
			    TestDataList = session.QueryOver<TestData>().List();
                ComponentsList = session.QueryOver<Components>().List();
                WaterMeterDataList = session.QueryOver<WaterMeterData>().List();
            }
            catch (Exception e)
            {
                log.ErrorFormat("Cannot open results DB: {0}", e.Message);
            }
            finally
            {
                if (openAndCloseSession && session != null && session.IsOpen) session.Close();
            }
        }

		/// <summary>
		/// Loads shared data from the database
		/// </summary>
		/// <exception>Throws NHibernate exceptions</exception>
        public static int GetMaxSavedBatchNr(ISession session = null)
		{
            bool openAndCloseSession = (session == null);
            int maxBatchNr = 0;

            try
            {
                if (openAndCloseSession) session = Results.DB.CreateSession();
                IList<Entities.Batch> batches = session.QueryOver<Batch>().List();

                foreach (var b in batches)
                {
                    if (b.BatchNr > maxBatchNr) maxBatchNr = b.BatchNr;
                }
            }
            catch (Exception e)
            {
                log.ErrorFormat("Cannot open results DB: {0}", e.Message);
            }
            finally
            {
                if (openAndCloseSession && session != null && session.IsOpen) session.Close();
            }

			return maxBatchNr;
		}


		/// <summary>
		/// Update TestData, Components and WaterMeterData fo tests and water meters in batch results
		/// with existing data in static lists TestDataList, ComponentsList and WaterMeterDataList.
		/// </summary>
		/// <param name="batch">Batch results</param>
		/// <returns>true when any data modiifed</returns>
		public static bool UpdateBatchData(Entities.Batch batch)
		{
			ISession session = DB.CreateSession();
			
			if (session == null) return false;

			foreach (var tr in batch.TestRslts)
			{
				/// Search in TestDataList and update test data in the new batch
				TestData td = TestData.UpdateList(TestDataList, tr.TestData);
				tr.TestData = td;

				/// Search in ComponentsList and update components in the new batch
				Components cd = Components.UpdateList(ComponentsList, tr.Components);
				tr.Components = cd;
			}

			foreach (var wm in batch.WaterMeters)
			{
				/// Search in WaterMeterDataList and update water meter data in the new batch
				WaterMeterData wmd = WaterMeterData.UpdateList(WaterMeterDataList, wm.WaterMeterData);
				wm.WaterMeterData = wmd;
			}

			return true;		/// TODO: Really check for modifications
		}


		public static bool SaveNewBatch(Entities.Batch batch)
		{
			ISession session = DB.CreateSession();
			if (session == null) return false;

            TestDataList = session.QueryOver<TestData>().List();
            ComponentsList = session.QueryOver<Components>().List();
            WaterMeterDataList = session.QueryOver<WaterMeterData>().List();

			UpdateBatchData(batch);

			ITransaction transaction = session.BeginTransaction();
			if (transaction == null) return false;

			try
			{
				foreach (var td in TestDataList) if (td.Id == 0) session.SaveOrUpdate(td);
				foreach (var cd in ComponentsList) if (cd.Id == 0) session.SaveOrUpdate(cd);
				foreach (var wd in WaterMeterDataList) if (wd.Id == 0) session.SaveOrUpdate(wd);

				log.Debug(batch.ToString(1));
				foreach (var tstRslt in batch.TestRslts)
				{
					log.Debug(tstRslt.ToString(1));
				}

				session.SaveOrUpdate(batch);

				transaction.Commit();
			}
			catch (Exception exc)
			{
				transaction.Rollback();

				log.FatalFormat("Saving results of batch #{0} into the results DB failed: {1}", batch.BatchNr, exc.Message);
				if (exc.InnerException != null && !string.IsNullOrEmpty(exc.InnerException.Message))
				{
					log.FatalFormat("Inner exception message: {0}", exc.InnerException.Message);
				}

				return false;
			}

			session.Flush();

			return true;
		}


		public static Batch LoadBatch(int batchNr)
		{
			IList<Batch> batches;
			ISession session = DB.CreateSession();
			if (session == null) return null;

			try
			{
                TestDataList = session.QueryOver<TestData>().List();
                ComponentsList = session.QueryOver<Components>().List();
                WaterMeterDataList = session.QueryOver<WaterMeterData>().List();

                batches = session.QueryOver<Batch>()
								 .Where(x => (x.BatchNr == batchNr))
								 .List();

                foreach (var batch in batches)
                {
                    batch.TestRslts = session.QueryOver<TestRslt>()
                                             .Where(x => (x.Batch.Id == batch.Id))
                                             .List();

                    batch.WaterMeters = session.QueryOver<WaterMeter>()
                                               .Where(x => (x.Batch.Id == batch.Id))
                                               .List();
                }

                return (batches.Count > 0) ? batches[0] : null;
            }
			catch (Exception exc)
			{
				log.FatalFormat("Cannot load batch #{0}: {1}", batchNr, exc.Message);
				return null;
			}
		}
	}
}