// Copyright (c) 2004, 2019, Oracle and/or its affiliates. All rights reserved.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
// published by the Free Software Foundation.
//
// This program is also distributed with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation.  The authors of MySQL hereby grant you an
// additional permission to link the program and your derivative works
// with the separately licensed software that they have included with
// MySQL.
//
// Without limiting anything contained in the foregoing, this file,
// which is part of MySQL Connector/NET, is also subject to the
// Universal FOSS Exception, version 1.0, a copy of which can be found at
// http://oss.oracle.com/licenses/universal-foss-exception.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;
using System.Data.Common;
using System.Reflection;
#if !NETCOREAPP
using System.Security.Permissions;
#endif
namespace MySql.Data.MySqlClient
{
    /// <summary>
    /// Represents a set of methods for creating instances of the MySQL client implementation of the data source classes.
    /// </summary>
#if !NETCOREAPP
    [ReflectionPermission(SecurityAction.Assert, MemberAccess = true)]
#endif
    public sealed partial class MySqlClientFactory : DbProviderFactory, IServiceProvider
    {
        /// <summary>
        /// Gets an instance of the <see cref="MySqlClientFactory"/>. 
        /// This can be used to retrieve strongly typed data objects. 
        /// </summary>
        public static MySqlClientFactory Instance = new MySqlClientFactory();
        private Type _dbServicesType;
        private FieldInfo _mySqlDbProviderServicesInstance;

        /// <summary>
        /// Returns a strongly typed <see cref="DbCommand"/> instance. 
        /// </summary>
        /// <returns>A new strongly typed instance of <b>DbCommand</b>.</returns>
        public override DbCommand CreateCommand()
        {
            return new MySqlCommand();
        }

        /// <summary>
        /// Returns a strongly typed <see cref="DbConnection"/> instance. 
        /// </summary>
        /// <returns>A new strongly typed instance of <b>DbConnection</b>.</returns>
        public override DbConnection CreateConnection()
        {
            return new MySqlConnection();
        }

        /// <summary>
        /// Returns a strongly typed <see cref="DbParameter"/> instance. 
        /// </summary>
        /// <returns>A new strongly typed instance of <b>DbParameter</b>.</returns>
        public override DbParameter CreateParameter()
        {
            return new MySqlParameter();
        }

        /// <summary>
        /// Returns a strongly typed <see cref="DbConnectionStringBuilder"/> instance. 
        /// </summary>
        /// <returns>A new strongly typed instance of <b>DbConnectionStringBuilder</b>.</returns>
        public override DbConnectionStringBuilder CreateConnectionStringBuilder()
        {
            return new MySqlConnectionStringBuilder();
        }

        /// <summary>
        /// Returns a strongly typed <see cref="DbCommandBuilder"/> instance. 
        /// </summary>
        /// <returns>A new strongly typed instance of <b>DbCommandBuilder</b>.</returns>
        public override DbCommandBuilder CreateCommandBuilder()
        {
            return new MySqlCommandBuilder();
        }

        /// <summary>
        /// Returns a strongly typed <see cref="DbDataAdapter"/> instance. 
        /// </summary>
        /// <returns>A new strongly typed instance of <b>DbDataAdapter</b>.</returns>
        public override DbDataAdapter CreateDataAdapter()
        {
            return new MySqlDataAdapter();
        }

        #region IServiceProvider Members

        /// <summary>
        /// Provide a simple caching layer
        /// </summary>
        private Type DbServicesType => this._dbServicesType ?? (this._dbServicesType = Type.GetType(
            @"System.Data.Common.DbProviderServices, System.Data.Entity, 
												Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089",
            false));

        private FieldInfo MySqlDbProviderServicesInstance
        {
            get
            {
                if (this._mySqlDbProviderServicesInstance == null)
                {
                    string fullName = Assembly.GetExecutingAssembly().FullName;
                    string assemblyName = fullName.Replace("MySql.Data", "MySql.Data.EntityFramework");
                    string assemblyEf5Name = fullName.Replace("MySql.Data", "MySql.Data.Entity.EF5");
                    fullName = $"MySql.Data.MySqlClient.MySqlProviderServices, {assemblyEf5Name}";

                    Type providerServicesType = Type.GetType(fullName, false);
                    if (providerServicesType == null)
                    {
                        fullName = $"MySql.Data.MySqlClient.MySqlProviderServices, {assemblyName}";
                        providerServicesType = Type.GetType(fullName, false);
                        if (providerServicesType == null)
                        {
                            throw new DllNotFoundException(fullName);
                        }
                    }

                    this._mySqlDbProviderServicesInstance = providerServicesType.GetField("Instance", BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance);
                }

                return this._mySqlDbProviderServicesInstance;
            }
        }

        object IServiceProvider.GetService(Type serviceType)
        {
            // DbProviderServices is the only service we offer up right now
            return serviceType != this.DbServicesType ? null : this.MySqlDbProviderServicesInstance?.GetValue(null);
        }

        #endregion
    }
}