/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
using log4net;
using Nini.Config;

using OpenMetaverse;
using OpenSim.Data;
using OpenSim.Framework;
using OpenSim.Services.Base;
using OpenSim.Services.Interfaces;

namespace OpenSim.OfflineIM
{
    public class OfflineIMService : ServiceBase, IOfflineIMService
    {
        //private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        private IOfflineIMData m_Database = null;
        private int m_MaxOfflineIMs = 25;
        private XmlSerializer m_serializer;
        private static bool m_Initialized = false;

        public OfflineIMService(IConfigSource config) : base(config)
        {
            string dllName = string.Empty;
            string connString = string.Empty;
            string realm = "im_offline";

            //
            // Try reading the [DatabaseService] section, if it exists
            //
            IConfig dbConfig = config.Configs["DatabaseService"];
            if (dbConfig is not null)
            {
                if (dllName.Length == 0)
                    dllName = dbConfig.GetString("StorageProvider", string.Empty);
                if (connString.Length == 0)
                    connString = dbConfig.GetString("ConnectionString", string.Empty);
            }

            //
            // [Messaging] section overrides [DatabaseService], if it exists
            //
            IConfig imConfig = config.Configs["Messaging"];
            if (imConfig is not null)
            {
                dllName = imConfig.GetString("StorageProvider", dllName);
                connString = imConfig.GetString("ConnectionString", connString);
                realm = imConfig.GetString("Realm", realm);
                m_MaxOfflineIMs = imConfig.GetInt("MaxOfflineIMs", m_MaxOfflineIMs);
            }

            //
            // We tried, but this doesn't exist. We can't proceed.
            //
            if (string.IsNullOrEmpty(dllName))
                throw new Exception("No StorageProvider configured");

            m_Database = LoadPlugin<IOfflineIMData>(dllName, new Object[] { connString, realm });
            if (m_Database is null)
                throw new Exception("Could not find a storage interface in the given module " + dllName);

            m_serializer = new XmlSerializer(typeof(GridInstantMessage));
            if (!m_Initialized)
            {
                m_Database.DeleteOld();
                m_Initialized = true;
            }
        }

        public List<GridInstantMessage> GetMessages(UUID principalID)
        {
            List<GridInstantMessage> ims = new List<GridInstantMessage>();

            OfflineIMData[] messages = m_Database.Get("PrincipalID", principalID.ToString());
            if (messages is  null || messages.Length == 0)
                return ims;

            foreach (OfflineIMData m in messages)
            {
                using (MemoryStream mstream = new MemoryStream(Encoding.UTF8.GetBytes(m.Data["Message"])))
                {
                    GridInstantMessage im = (GridInstantMessage)m_serializer.Deserialize(mstream);
                    ims.Add(im);
                }
            }

            // Then, delete them
            m_Database.Delete("PrincipalID", principalID.ToString());

            return ims;
        }

        public bool StoreMessage(GridInstantMessage im, out string reason)
        {
            reason = string.Empty;

            // Check limits
            UUID principalID = new UUID(im.toAgentID);
            long count = m_Database.GetCount("PrincipalID", principalID.ToString());
            if (count >= m_MaxOfflineIMs)
            {
                reason = "Number of offline IMs has maxed out";
                return false;
            }

            string imXml;
            using (MemoryStream mstream = new MemoryStream())
            {
                XmlWriterSettings settings = new XmlWriterSettings();
                settings.Encoding = Util.UTF8NoBomEncoding;

                using (XmlWriter writer = XmlWriter.Create(mstream, settings))
                {
                    m_serializer.Serialize(writer, im);
                    writer.Flush();
                    imXml = Util.UTF8NoBomEncoding.GetString(mstream.ToArray());
                }
            }

            OfflineIMData data = new OfflineIMData();
            data.PrincipalID = principalID;
            data.FromID = new UUID(im.fromAgentID);
            data.Data = new Dictionary<string, string>();
            data.Data["Message"] = imXml;

            return m_Database.Store(data);

        }

        public void DeleteMessages(UUID userID)
        {
            m_Database.Delete("PrincipalID", userID.ToString());
            m_Database.Delete("FromID", userID.ToString());
        }

    }
}