/*
 * 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 OpenSim 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
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 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using OpenSim.Framework;
using OpenSim.Framework.Communications.Cache;
using OpenSim.Region.Environment.Interfaces;
using OpenSim.Region.Environment.Modules.World.Serialiser;
using OpenSim.Region.Environment.Modules.World.Terrain;
using OpenSim.Region.Environment.Scenes;
using System.Collections.Generic;
using System.Reflection;
using System.Threading;
using libsecondlife;
using log4net;
using Nini.Config;

namespace OpenSim.Region.Environment.Modules.World.Archiver
{
    /// <summary>
    /// Prepare to write out an archive.
    /// </summary>
    public class ArchiveWriteRequestPreparation
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        protected Scene m_scene;
        protected string m_savePath;

        /// <summary>
        /// Used as a temporary store of an asset which represents an object.  This can be a null if no appropriate
        /// asset was found by the asset service.
        /// </summary>
        protected AssetBase m_requestedObjectAsset;

        /// <summary>
        /// Signal whether we are currently waiting for the asset service to deliver an asset.
        /// </summary>
        protected bool m_waitingForObjectAsset;

        /// <summary>
        /// Constructor
        /// </summary>
        public ArchiveWriteRequestPreparation(Scene scene, string savePath)
        {
            m_scene = scene;
            m_savePath = savePath;
        }

        /// <summary>
        /// The callback made when we request the asset for an object from the asset service.
        /// </summary>
        public void AssetRequestCallback(LLUUID assetID, AssetBase asset)
        {
            lock (this)
            {
                m_requestedObjectAsset = asset;
                m_waitingForObjectAsset = false;
                Monitor.Pulse(this);
            }
        }
        
        /// <summary>
        /// Get an asset synchronously, potentially using an asynchronous callback.  If the 
        /// asynchronous callback is used, we will wait for it to complete.
        /// </summary>
        /// <param name="uuid"></param>
        /// <returns></returns>
        protected AssetBase GetAsset(LLUUID uuid)
        {
            m_waitingForObjectAsset = true;
            m_scene.AssetCache.GetAsset(uuid, AssetRequestCallback, true);

            // The asset cache callback can either
            //
            // 1. Complete on the same thread (if the asset is already in the cache) or
            // 2. Come in via a different thread (if we need to go fetch it).
            //
            // The code below handles both these alternatives.
            lock (this)
            {
                if (m_waitingForObjectAsset)
                {
                    Monitor.Wait(this);
                    m_waitingForObjectAsset = false;
                }
            }          
            
            return m_requestedObjectAsset;
        }

        /// <summary>
        /// Get all the asset uuids associated with a given object.  This includes both those directly associated with
        /// it (e.g. face textures) and recursively, those of items within it's inventory (e.g. objects contained
        /// within this object).
        /// </summary>
        /// <param name="sceneObject"></param>
        /// <param name="assetUuids"></param>
        protected void GetSceneObjectAssetUuids(SceneObjectGroup sceneObject, IDictionary<LLUUID, int> assetUuids)
        {
            m_log.DebugFormat(
                "[ARCHIVER]: Getting assets for object {0}, {1}", sceneObject.RootPart.Name, sceneObject.UUID);

            foreach (SceneObjectPart part in sceneObject.GetParts())
            {
                m_log.DebugFormat(
                    "[ARCHIVER]: Getting part {0}, {1} for object {2}", part.Name, part.UUID, sceneObject.UUID);

                LLObject.TextureEntry textureEntry = part.Shape.Textures;

                // Get the prim's default texture.  This will be used for faces which don't have their own texture
                assetUuids[textureEntry.DefaultTexture.TextureID] = 1;

                // XXX: Not a great way to iterate through face textures, but there's no
                // other method available to tell how many faces there actually are
                int i = 0;
                foreach (LLObject.TextureEntryFace texture in textureEntry.FaceTextures)
                {
                    if (texture != null)
                    {
                        m_log.DebugFormat("[ARCHIVER]: Got face {0}", i++);
                        assetUuids[texture.TextureID] = 1;
                    }
                }
                foreach (TaskInventoryItem tii in part.TaskInventory.Values)
                {
                    if (!assetUuids.ContainsKey(tii.AssetID))
                    {
                        assetUuids[tii.AssetID] = 1;

                        if ((int)InventoryType.Object == tii.Type)
                        {
                            AssetBase objectAsset = GetAsset(tii.AssetID);

                            if (null != objectAsset)
                            {
                                string xml = Helpers.FieldToUTF8String(objectAsset.Data);
                                SceneObjectGroup sog = new SceneObjectGroup(m_scene, m_scene.RegionInfo.RegionHandle, xml);
                                GetSceneObjectAssetUuids(sog, assetUuids);
                            }
                        }
                        else
                        {
                            m_log.DebugFormat("[ARCHIVER]: Recording asset {0} in object {1}", tii.AssetID, part.UUID);
                        }
                    }
                }
            }
        }

        public void ArchiveRegion()
        {
            Dictionary<LLUUID, int> assetUuids = new Dictionary<LLUUID, int>();

            List<EntityBase> entities = m_scene.GetEntities();
            List<SceneObjectGroup> sceneObjects = new List<SceneObjectGroup>();

            // Filter entities so that we only have scene objects.
            // FIXME: Would be nicer to have this as a proper list in InnerScene, since lots of methods
            // end up having to do this
            foreach (EntityBase entity in entities)
            {
                if (entity is SceneObjectGroup)
                    sceneObjects.Add((SceneObjectGroup)entity);
            }
            
            foreach (SceneObjectGroup sceneObject in sceneObjects)
            {
                GetSceneObjectAssetUuids(sceneObject, assetUuids);
            }

            m_log.DebugFormat(
                "[ARCHIVER]: {0} scene objects to serialize requiring save of {1} assets", 
                sceneObjects.Count, assetUuids.Count);

            // Asynchronously request all the assets required to perform this archive operation
            ArchiveWriteRequestExecution awre 
                = new ArchiveWriteRequestExecution(
                    sceneObjects, 
                    m_scene.RequestModuleInterface<ITerrainModule>(),
                    m_scene.RequestModuleInterface<IRegionSerialiser>(),
                    m_scene.RegionInfo.RegionName,
                    m_savePath);
            new AssetsRequest(assetUuids.Keys, m_scene.AssetCache, awre.ReceivedAllAssets).Execute();
        }
    }
}