///
/// Copyright (c) 2016-2018 Sensus Slovensko a.s.
///
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 Users.Entities;

namespace Users
{
    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;
        public static ISession CurrentSession;

		/// <summary> Connection string for all sessions </summary>
		private static string connectionString;
		/// 
		public static string ConnectionString
		{
			get { return connectionString; }
			set { connectionString = value; SessionFactory = null; }
		}

		/// <summary> Database type (MySQL or SQLite) for all sessions </summary>
		private static DBType dbType;
		/// 
		public static 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.SQLite:
					cfg = cfg.Database(SQLiteConfiguration.Standard.UsingFile(connectionString));
                    break;
				case DBType.MySql:
                    cfg = cfg.Database(MySQLConfiguration.Standard.ConnectionString(connectionString));
                    break;
			}

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

            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();

            CurrentSession = SessionFactory.OpenSession();
            return CurrentSession;
		}


        /// <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.User> Users;
		public static IList<Entities.Group> Groups;


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

            Users = session.QueryOver<Entities.User>().List();
            Groups = session.QueryOver<Entities.Group>().List();
		}
	}
}