///
/// Copyright (c) 2020-2021 Sensus Slovensko a.s.
///
using System;
using System.Collections.Generic;
using FluentNHibernate.Cfg;
using FluentNHibernate.Cfg.Db;
using NHibernate;
using NHibernate.Cfg;
using NHibernate.Tool.hbm2ddl;
using Common;
using SharedDatabase.Entities;

namespace SharedDatabase
{
    public static class EventsDB
    {
		/// <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 DBType.MySql:
                    cfg = cfg.Database(MySQLConfiguration.Standard.ConnectionString(connectionString));
                    break;
                case DBType.SQLite:
                    cfg = cfg.Database(SQLiteConfiguration.Standard.UsingFile(connectionString));
                    break;
            }

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

            if (createDB)
            {
                return cfg.ExposeConfiguration(BuildSchemaCreate).BuildSessionFactory();
            }
            else
            {
                return cfg.ExposeConfiguration(BuildSchema).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 (initially empty)
		/// </summary>
        public static string BenchName = "undefined";
        public static IList<Entities.Event> RecentEvents = null;
        static IList<Entities.Subscriber> allSubscribers = null;

        /// <summary>
        /// Set test bench name used in SharedDatabase.Entities.Event constructors
        /// </summary>
        public static void SetBenchName(string benchName)
        {
            EventsDB.BenchName = benchName;
        }

		/// <summary>
		/// Loads shared data from the database
		/// </summary>
        public static void LoadSubscribers(ISession session)
        {
            allSubscribers = session.QueryOver<Subscriber>().List();
        }

        /// <summary>
        /// Loads shared data from the database
        /// </summary>
        public static void LoadRecentEvents(ISession session, string benchName, int days)
        {
            RecentEvents = session.QueryOver<Event>()
                                  .Where(e => (e.Bench == benchName))
                                  .And(e => (e.TimeStamp >= DateTime.Now - new TimeSpan(days, 0, 0, 0)))
                                  .List();
        }

        public static void SaveEvent(ISession session, Event evnt, SubscriberGroup groups)
        {
            if (allSubscribers == null) return;
            IList<Subscriber> thisEventSubscribers = new List<Subscriber>();
            foreach (var s in allSubscribers)
            {
                if ((s.Groups & (long)groups) != 0)
                {
                    /// Subscriber 's' belongs to at least one of SubscriberGroup(s) in 'groups' bit field
                    thisEventSubscribers.Add(s);
                }
            }
            evnt.Bench = BenchName;
            evnt.Subscribers = thisEventSubscribers;
            session.SaveOrUpdate(evnt);
            session.Flush();
        }
    }
}