// Copyright ?2014, 2020, Oracle and/or its affiliates.
//
// 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.Collections.Generic;
using System.ComponentModel;
using System.Text;
using MySql.Data.MySqlClient;
using Sog.Properties;

namespace MySql.Data.MySqlClient.Replication
{
    /// <summary>
    /// Manager for Replication and Load Balancing features
    /// </summary>
    internal static class ReplicationManager
    {
        private static List<ReplicationServerGroup> groups = new List<ReplicationServerGroup>();
        private static Object thisLock = new Object();

        // private static Dictionary<string, ReplicationServerSelector> selectors = new Dictionary<string, ReplicationServerSelector>();


        /// <summary>
        /// Returns Replication Server Group List
        /// </summary>
        internal static IList<ReplicationServerGroup> Groups { get; private set; }

        /// <summary>
        /// Adds a Default Server Group to the list
        /// </summary>
        /// <param name="name">Group name</param>
        /// <param name="retryTime">Time between reconnections for failed servers</param>
        /// <returns>Replication Server Group added</returns>
        internal static ReplicationServerGroup AddGroup(string name, int retryTime)
        {
            return AddGroup(name, null, retryTime);
        }

        /// <summary>
        /// Adds a Server Group to the list
        /// </summary>
        /// <param name="name">Group name</param>
        /// <param name="groupType">ServerGroup type reference</param>
        /// <param name="retryTime">Time between reconnections for failed servers</param>
        /// <returns>Server Group added</returns>
        internal static ReplicationServerGroup AddGroup(string name, string groupType, int retryTime)
        {
            if (string.IsNullOrEmpty(groupType))
            {
                groupType = "MySql.Data.MySqlClient.Replication.ReplicationRoundRobinServerGroup";
            }

            Type t = Type.GetType(groupType);
            ReplicationServerGroup g = (ReplicationServerGroup)Activator.CreateInstance(t, name, retryTime) as ReplicationServerGroup;
            groups.Add(g);
            return g;
        }

        /// <summary>
        /// Gets the next server from a replication group
        /// </summary>
        /// <param name="groupName">Group name</param>
        /// <param name="isSource">True if the server to return must be a source</param>
        /// <returns>Replication Server defined by the Load Balancing plugin</returns>
        internal static ReplicationServer GetServer(string groupName, bool isSource)
        {
            ReplicationServerGroup group = GetGroup(groupName);
            return group.GetServer(isSource);
        }

        /// <summary>
        /// Gets a Server Group by name
        /// </summary>
        /// <param name="groupName">Group name</param>
        /// <returns>Server Group if found, otherwise throws an MySqlException</returns>
        internal static ReplicationServerGroup GetGroup(string groupName)
        {
            ReplicationServerGroup group = null;
            foreach (ReplicationServerGroup g in groups)
            {
                if (String.Compare(g.Name, groupName, StringComparison.OrdinalIgnoreCase) != 0)
                {
                    continue;
                }

                group = g;
                break;
            }

            if (group == null)
            {
                throw new MySqlException(String.Format(Resources.ReplicationGroupNotFound, groupName));
            }

            return group;
        }

        /// <summary>
        /// Validates if the replication group name exists
        /// </summary>
        /// <param name="groupName">Group name to validate</param>
        /// <returns><c>true</c> if the replication group name is found; otherwise, <c>false</c></returns>
        internal static bool IsReplicationGroup(string groupName)
        {
            foreach (ReplicationServerGroup g in groups)
            {
                if (String.Compare(g.Name, groupName, StringComparison.OrdinalIgnoreCase) == 0)
                {
                    return true;
                }
            }

            return false;
        }

        /// <summary>
        /// Assigns a new server driver to the connection object
        /// </summary>
        /// <param name="groupName">Group name</param>
        /// <param name="source">True if the server connection to assign must be a source</param>
        /// <param name="connection">MySqlConnection object where the new driver will be assigned</param>
        internal static void GetNewConnection(string groupName, bool source, MySqlConnection connection)
        {
            do
            {
                lock (thisLock)
                {
                    if (!IsReplicationGroup(groupName))
                    {
                        return;
                    }

                    ReplicationServerGroup group = GetGroup(groupName);
                    ReplicationServer server = group.GetServer(source, connection.Settings);

                    if (server == null)
                    {
                        throw new MySqlException(Resources.Replication_NoAvailableServer);
                    }

                    try
                    {
                        bool isNewServer = false;
                        if (connection.driver == null || !connection.driver.IsOpen)
                        {
                            isNewServer = true;
                        }
                        else
                        {
                            MySqlConnectionStringBuilder msb = new MySqlConnectionStringBuilder(server.ConnectionString);
                            if (!msb.Equals(connection.driver.Settings))
                            {
                                isNewServer = true;
                            }
                        }

                        if (isNewServer)
                        {
                            Driver driver = Driver.Create(new MySqlConnectionStringBuilder(server.ConnectionString));
                            connection.driver = driver;
                        }

                        return;
                    }
                    catch (MySqlException ex)
                    {
                        connection.driver = null;
                        server.IsAvailable = false;
                        MySqlTrace.LogError(ex.Number, ex.ToString());
                        if (ex.Number == 1042)
                        {
                            // retry to open a failed connection and update its status
                            group.HandleFailover(server, ex);
                        }
                        else
                        {
                            throw;
                        }
                    }
                }
            } while (true);
        }
    }
}