/*
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 * modification, are permitted provided that the following conditions are met:
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 *       derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Threading;

using libsecondlife;
using log4net;

namespace OpenSim.Framework.Communications.Cache
{
    internal delegate void AddItemDelegate(InventoryItemBase itemInfo);
    internal delegate void UpdateItemDelegate(InventoryItemBase itemInfo);
    internal delegate void DeleteItemDelegate(LLUUID itemID);

    internal delegate void CreateFolderDelegate(string folderName, LLUUID folderID, ushort folderType, LLUUID parentID);
    internal delegate void MoveFolderDelegate(LLUUID folderID, LLUUID parentID);
    internal delegate void PurgeFolderDelegate(LLUUID folderID);
    internal delegate void UpdateFolderDelegate(string name, LLUUID folderID, ushort type, LLUUID parentID);

    internal delegate void SendInventoryDescendentsDelegate(
        IClientAPI client, LLUUID folderID, bool fetchFolders, bool fetchItems);

    /// <summary>
    /// Stores user profile and inventory data received from backend services for a particular user.
    /// </summary>
    public class CachedUserInfo
    {
        private static readonly ILog m_log
            = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        /// <summary>
        /// The comms manager holds references to services (user, grid, inventory, etc.)
        /// </summary>
        private readonly CommunicationsManager m_commsManager;

        public UserProfileData UserProfile { get { return m_userProfile; } }
        private readonly UserProfileData m_userProfile;

        /// <summary>
        /// Has we received the user's inventory from the inventory service?
        /// </summary>
        private bool m_hasInventory;

        /// <summary>
        /// Inventory requests waiting for receipt of this user's inventory from the inventory service.
        /// </summary>
        private readonly IList<IInventoryRequest> m_pendingRequests = new List<IInventoryRequest>();

        /// <summary>
        /// Has this user info object yet received its inventory information from the invetnroy service?
        /// </summary>
        public bool HasInventory { get { return m_hasInventory; } }

        private InventoryFolderImpl m_rootFolder;
        public InventoryFolderImpl RootFolder { get { return m_rootFolder; } }

        /// <summary>
        /// FIXME: This could be contained within a local variable - it doesn't need to be a field
        /// </summary>
        private IDictionary<LLUUID, IList<InventoryFolderImpl>> pendingCategorizationFolders
            = new Dictionary<LLUUID, IList<InventoryFolderImpl>>();

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="commsManager"></param>
        /// <param name="userProfile"></param>
        public CachedUserInfo(CommunicationsManager commsManager, UserProfileData userProfile)
        {
            m_commsManager = commsManager;
            m_userProfile = userProfile;
        }

        /// <summary>
        /// This allows a request to be added to be processed once we receive a user's inventory
        /// from the inventory service.  If we already have the inventory, the request
        /// is executed immediately instead.
        /// </summary>
        /// <param name="parent"></param>
        public void AddRequest(IInventoryRequest request)
        {
            lock (m_pendingRequests)
            {
                if (m_hasInventory)
                {
                    request.Execute();
                }
                else
                {
                    m_pendingRequests.Add(request);
                }
            }
        }

        /// <summary>
        /// Store a folder pending arrival of its parent
        /// </summary>
        /// <param name="folder"></param>
        private void AddPendingFolder(InventoryFolderImpl folder)
        {
            LLUUID parentFolderId = folder.ParentID;

            if (pendingCategorizationFolders.ContainsKey(parentFolderId))
            {
                pendingCategorizationFolders[parentFolderId].Add(folder);
            }
            else
            {
                IList<InventoryFolderImpl> folders = new List<InventoryFolderImpl>();
                folders.Add(folder);

                pendingCategorizationFolders[parentFolderId] = folders;
            }
        }

        /// <summary>
        /// Add any pending folders which were received before the given folder
        /// </summary>
        /// <param name="parentId">
        /// A <see cref="LLUUID"/>
        /// </param>
        private void ResolvePendingFolders(InventoryFolderImpl newFolder)
        {
            if (pendingCategorizationFolders.ContainsKey(newFolder.ID))
            {
                foreach (InventoryFolderImpl folder in pendingCategorizationFolders[newFolder.ID])
                {
                    //                    m_log.DebugFormat(
                    //                        "[INVENTORY CACHE]: Resolving pending received folder {0} {1} into {2} {3}",
                    //                        folder.name, folder.folderID, parent.name, parent.folderID);

                    lock (newFolder.SubFolders)
                    {
                        if (!newFolder.SubFolders.ContainsKey(folder.ID))
                        {
                            newFolder.SubFolders.Add(folder.ID, folder);
                        }
                    }
                }
            }
        }

        /// <summary>
        /// Callback invoked when the inventory is received from an async request to the inventory service
        /// </summary>
        /// <param name="userID"></param>
        /// <param name="inventoryCollection"></param>
        public void InventoryReceive(ICollection<InventoryFolderImpl> folders, ICollection<InventoryItemBase> items)
        {
            // FIXME: Exceptions thrown upwards never appear on the console.  Could fix further up if these
            // are simply being swallowed
            try
            {
                foreach (InventoryFolderImpl folder in folders)
                {
                    FolderReceive(folder);
                }

                foreach (InventoryItemBase item in items)
                {
                    ItemReceive(item);
                }
            }
            catch (Exception e)
            {
                m_log.ErrorFormat("[INVENTORY CACHE]: Error processing inventory received from inventory service, {0}", e);
            }

            // Deal with pending requests
            lock (m_pendingRequests)
            {
                // We're going to change inventory status within the lock to avoid a race condition
                // where requests are processed after the AddRequest() method has been called.
                m_hasInventory = true;

                foreach (IInventoryRequest request in m_pendingRequests)
                {
                    request.Execute();
                }
            }
        }

        /// <summary>
        /// Callback invoked when a folder is received from an async request to the inventory service.
        /// </summary>
        /// <param name="userID"></param>
        /// <param name="folderInfo"></param>
        private void FolderReceive(InventoryFolderImpl newFolder)
        {
            //            m_log.DebugFormat(
            //                "[INVENTORY CACHE]: Received folder {0} {1} for user {2}",
            //                folderInfo.Name, folderInfo.ID, userID);

            if (RootFolder == null)
            {
                if (newFolder.ParentID == LLUUID.Zero)
                {
                    m_rootFolder = newFolder;
                }
                else
                {
                    AddPendingFolder(newFolder);
                }
            }
            else
            {
                InventoryFolderImpl parentFolder = RootFolder.FindFolder(newFolder.ParentID);

                if (parentFolder != null)
                {
                    lock (parentFolder.SubFolders)
                    {
                        if (!parentFolder.SubFolders.ContainsKey(newFolder.ID))
                        {
                            parentFolder.SubFolders.Add(newFolder.ID, newFolder);
                        }
                        else
                        {
                            m_log.WarnFormat(
                                "[INVENTORY CACHE]: Received folder {0} {1} from inventory service which has already been received",
                                newFolder.Name, newFolder.ID);
                        }
                    }
                }
                else
                {
                    AddPendingFolder(newFolder);
                }
            }

            ResolvePendingFolders(newFolder);
        }

        /// <summary>
        /// Callback invoked when an item is received from an async request to the inventory service.
        ///
        /// We're assuming here that items are always received after all the folders
        /// received.
        /// </summary>
        /// <param name="folderInfo"></param>
        private void ItemReceive(InventoryItemBase itemInfo)
        {
            //            m_log.DebugFormat(
            //                "[INVENTORY CACHE]: Received item {0} {1} for user {2}",
            //                itemInfo.Name, itemInfo.ID, userID);
            InventoryFolderImpl folder = RootFolder.FindFolder(itemInfo.Folder);

            if (null == folder)
            {
                m_log.WarnFormat(
                    "Received item {0} {1} but its folder {2} does not exist",
                    itemInfo.Name, itemInfo.ID, itemInfo.Folder);

                return;
            }

            lock (folder.Items)
            {
                folder.Items[itemInfo.ID] = itemInfo;
            }
        }

        /// <summary>
        /// Create a folder in this agent's inventory.
        ///
        /// If the inventory service has not yet delievered the inventory
        /// for this user then the request will be queued.
        /// </summary>
        /// <param name="parentID"></param>
        /// <returns></returns>
        public bool CreateFolder(string folderName, LLUUID folderID, ushort folderType, LLUUID parentID)
        {
            //            m_log.DebugFormat(
            //                "[AGENT INVENTORY]: Creating inventory folder {0} {1} for {2} {3}", folderID, folderName, remoteClient.Name, remoteClient.AgentId);

            if (HasInventory)
            {
                InventoryFolderImpl parentFolder = RootFolder.FindFolder(parentID);

                if (null == parentFolder)
                {
                    m_log.WarnFormat(
                        "[AGENT INVENTORY]: Tried to create folder {0} {1} but the parent {2} does not exist",
                        folderName, folderID, parentID);

                    return false;
                }

                InventoryFolderImpl createdFolder = parentFolder.CreateChildFolder(folderID, folderName, folderType);

                if (createdFolder != null)
                {
                    InventoryFolderBase createdBaseFolder = new InventoryFolderBase();
                    createdBaseFolder.Owner = createdFolder.Owner;
                    createdBaseFolder.ID = createdFolder.ID;
                    createdBaseFolder.Name = createdFolder.Name;
                    createdBaseFolder.ParentID = createdFolder.ParentID;
                    createdBaseFolder.Type = createdFolder.Type;
                    createdBaseFolder.Version = createdFolder.Version;

                    m_commsManager.InventoryService.AddFolder(createdBaseFolder);

                    return true;
                }
                else
                {
                    m_log.WarnFormat(
                         "[AGENT INVENTORY]: Tried to create folder {0} {1} but the folder already exists",
                         folderName, folderID);

                    return false;
                }
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(CreateFolderDelegate), this, "CreateFolder"),
                        new object[] { folderName, folderID, folderType, parentID }));

                return true;
            }
        }

        /// <summary>
        /// Handle a client request to update the inventory folder
        ///
        /// If the inventory service has not yet delievered the inventory
        /// for this user then the request will be queued.
        ///
        /// FIXME: We call add new inventory folder because in the data layer, we happen to use an SQL REPLACE
        /// so this will work to rename an existing folder.  Needless to say, to rely on this is very confusing,
        /// and needs to be changed.
        /// </summary>
        ///
        /// <param name="folderID"></param>
        /// <param name="type"></param>
        /// <param name="name"></param>
        /// <param name="parentID"></param>
        public bool UpdateFolder(string name, LLUUID folderID, ushort type, LLUUID parentID)
        {
            //            m_log.DebugFormat(
            //                "[AGENT INVENTORY]: Updating inventory folder {0} {1} for {2} {3}", folderID, name, remoteClient.Name, remoteClient.AgentId);

            if (HasInventory)
            {
                InventoryFolderBase baseFolder = new InventoryFolderBase();
                baseFolder.Owner = m_userProfile.ID;
                baseFolder.ID = folderID;
                baseFolder.Name = name;
                baseFolder.ParentID = parentID;
                baseFolder.Type = (short)type;
                baseFolder.Version = RootFolder.Version;

                m_commsManager.InventoryService.UpdateFolder(baseFolder);

                InventoryFolderImpl folder = RootFolder.FindFolder(folderID);
                if (folder != null)
                {
                    folder.Name = name;
                    folder.ParentID = parentID;
                }
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(UpdateFolderDelegate), this, "UpdateFolder"),
                        new object[] { name, folderID, type, parentID }));
            }

            return true;
        }

        /// <summary>
        /// Handle an inventory folder move request from the client.
        ///
        /// If the inventory service has not yet delievered the inventory
        /// for this user then the request will be queued.
        /// </summary>
        ///
        /// <param name="folderID"></param>
        /// <param name="parentID"></param>
        public bool MoveFolder(LLUUID folderID, LLUUID parentID)
        {
            //            m_log.DebugFormat(
            //                "[AGENT INVENTORY]: Moving inventory folder {0} into folder {1} for {2} {3}",
            //                parentID, remoteClient.Name, remoteClient.Name, remoteClient.AgentId);

            if (HasInventory)
            {
                InventoryFolderBase baseFolder = new InventoryFolderBase();
                baseFolder.Owner = m_userProfile.ID;
                baseFolder.ID = folderID;
                baseFolder.ParentID = parentID;

                m_commsManager.InventoryService.MoveFolder(baseFolder);

                InventoryFolderImpl folder = RootFolder.FindFolder(folderID);
                if (folder != null)
                    folder.ParentID = parentID;

                return true;
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(MoveFolderDelegate), this, "MoveFolder"),
                        new object[] { folderID, parentID }));

                return true;
            }
        }

        /// <summary>
        /// This method will delete all the items and folders in the given folder.
        ///
        /// If the inventory service has not yet delievered the inventory
        /// for this user then the request will be queued.
        /// </summary>
        ///
        /// <param name="folderID"></param>
        public bool PurgeFolder(LLUUID folderID)
        {
            //            m_log.InfoFormat("[AGENT INVENTORY]: Purging folder {0} for {1} uuid {2}",
            //                folderID, remoteClient.Name, remoteClient.AgentId);

            if (HasInventory)
            {
                InventoryFolderImpl purgedFolder = RootFolder.FindFolder(folderID);

                if (purgedFolder != null)
                {
                    // XXX Nasty - have to create a new object to hold details we already have
                    InventoryFolderBase purgedBaseFolder = new InventoryFolderBase();
                    purgedBaseFolder.Owner = purgedFolder.Owner;
                    purgedBaseFolder.ID = purgedFolder.ID;
                    purgedBaseFolder.Name = purgedFolder.Name;
                    purgedBaseFolder.ParentID = purgedFolder.ParentID;
                    purgedBaseFolder.Type = purgedFolder.Type;
                    purgedBaseFolder.Version = purgedFolder.Version;

                    m_commsManager.InventoryService.PurgeFolder(purgedBaseFolder);

                    purgedFolder.Purge();

                    return true;
                }
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(PurgeFolderDelegate), this, "PurgeFolder"),
                        new object[] { folderID }));

                return true;
            }

            return false;
        }

        /// <summary>
        /// Add an item to the user's inventory
        /// </summary>
        /// <param name="itemInfo"></param>
        public void AddItem(InventoryItemBase item)
        {
            if (HasInventory)
            {
                if (item.Folder == LLUUID.Zero)
                {
                    InventoryFolderImpl f = FindFolderForType(item.AssetType);
                    if (f != null)
                        item.Folder = f.ID;
                    else
                        item.Folder = RootFolder.ID;
                }
                ItemReceive(item);
                m_commsManager.InventoryService.AddItem(item);
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(AddItemDelegate), this, "AddItem"),
                        new object[] { item }));
            }
        }

        /// <summary>
        /// Update an item in the user's inventory
        /// </summary>
        /// <param name="userID"></param>
        /// <param name="itemInfo"></param>
        public void UpdateItem(InventoryItemBase item)
        {
            if (HasInventory)
            {
                m_commsManager.InventoryService.UpdateItem(item);
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(UpdateItemDelegate), this, "UpdateItem"),
                        new object[] { item }));
            }
        }

        /// <summary>
        /// Delete an item from the user's inventory
        ///
        /// If the inventory service has not yet delievered the inventory
        /// for this user then the request will be queued.
        /// </summary>
        /// <param name="itemID"></param>
        /// <returns>
        /// true on a successful delete or a if the request is queued.
        /// Returns false on an immediate failure
        /// </returns>
        public bool DeleteItem(LLUUID itemID)
        {
            if (HasInventory)
            {
                // XXX For historical reasons (grid comms), we need to retrieve the whole item in order to delete, even though
                // really only the item id is required.
                InventoryItemBase item = RootFolder.FindItem(itemID);

                if (null == item)
                {
                    m_log.WarnFormat("[AGENT INVENTORY]: Tried to delete item {0} which does not exist", itemID);

                    return false;
                }

                if (RootFolder.DeleteItem(item.ID))
                {
                    return m_commsManager.InventoryService.DeleteItem(item);
                }
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(DeleteItemDelegate), this, "DeleteItem"),
                        new object[] { itemID }));

                return true;
            }

            return false;
        }

        /// <summary>
        /// Send details of the inventory items and/or folders in a given folder to the client.
        /// </summary>
        /// <param name="client"></param>
        /// <param name="folderID"></param>
        /// <param name="fetchFolders"></param>
        /// <param name="fetchItems"></param>
        /// <returns>true if the request was queued or successfully processed, false otherwise</returns>
        public bool SendInventoryDecendents(IClientAPI client, LLUUID folderID, bool fetchFolders, bool fetchItems)
        {
            if (HasInventory)
            {
                InventoryFolderImpl folder;

                if ((folder = RootFolder.FindFolder(folderID)) != null)
                {
                    //                            m_log.DebugFormat(
                    //                                "[AGENT INVENTORY]: Found folder {0} for client {1}",
                    //                                folderID, remoteClient.AgentId);

                    client.SendInventoryFolderDetails(
                        client.AgentId, folderID, folder.RequestListOfItems(),
                        folder.RequestListOfFolders(), fetchFolders, fetchItems);

                    return true;
                }
                else
                {
                    m_log.WarnFormat(
                        "[AGENT INVENTORY]: Could not find folder {0} requested by user {1} {2}",
                        folderID, client.Name, client.AgentId);

                    return false;
                }
            }
            else
            {
                AddRequest(
                    new InventoryRequest(
                        Delegate.CreateDelegate(typeof(SendInventoryDescendentsDelegate), this, "SendInventoryDecendents", false, false),
                        new object[] { client, folderID, fetchFolders, fetchItems }));

                return true;
            }
        }

        private InventoryFolderImpl FindFolderForType(int type)
        {
            if (RootFolder == null)
                return null;

            lock (RootFolder.SubFolders)
            {
                foreach (InventoryFolderImpl f in RootFolder.SubFolders.Values)
                {
                    if (f.Type == type)
                        return f;
                }
            }
            return null;
        }
    }

    /// <summary>
    /// Should be implemented by callers which require a callback when the user's inventory is received
    /// </summary>
    public interface IInventoryRequest
    {
        /// <summary>
        /// This is the method executed once we have received the user's inventory by which the request can be fulfilled.
        /// </summary>
        void Execute();
    }

    /// <summary>
    /// Generic inventory request
    /// </summary>
    class InventoryRequest : IInventoryRequest
    {
        private Delegate m_delegate;
        private Object[] m_args;

        internal InventoryRequest(Delegate delegat, Object[] args)
        {
            m_delegate = delegat;
            m_args = args;
        }

        public void Execute()
        {
            if(m_delegate != null)
                m_delegate.DynamicInvoke(m_args);
        }
    }
}