/*
 * 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
 * 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.Reflection;
using log4net;
using OpenMetaverse;
using OpenSim.Framework;
using OpenSim.Region.Environment.Scenes;
using OpenSim.Region.ScriptEngine.Common;
using OpenSim.Region.ScriptEngine.Shared;
using OpenSim.Region.ScriptEngine.Shared.Api;
using System.Collections.Generic;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
using System.Threading;

namespace OpenSim.Region.ScriptEngine.DotNetEngine
{
    public class ScriptManager
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        #region Declares

        private Thread scriptLoadUnloadThread;
        private static Thread staticScriptLoadUnloadThread;
        // private int scriptLoadUnloadThread_IdleSleepms;
        private Queue<LUStruct> LUQueue = new Queue<LUStruct>();
        private static bool PrivateThread;
        private int LoadUnloadMaxQueueSize;
        private Object scriptLock = new Object();
        private bool m_started = false;
        private Dictionary<IScript, DetectParams[]> detparms = new Dictionary<IScript, DetectParams[]>();

        // Load/Unload structure
        private struct LUStruct
        {
            public uint localID;
            public UUID itemID;
            public string script;
            public LUType Action;
            public int startParam;
            public bool postOnRez;
        }

        private enum LUType
        {
            Unknown = 0,
            Load = 1,
            Unload = 2
        }

        // Xantor 20080525: Keep a list of compiled scripts this session for reuse
        public Dictionary<UUID, String> scriptList = new Dictionary<UUID, string>();

        // Object<string, Script<string, script>>
        // IMPORTANT: Types and MemberInfo-derived objects require a LOT of memory.
        // Instead use RuntimeTypeHandle, RuntimeFieldHandle and RunTimeHandle (IntPtr) instead!
        public Dictionary<uint, Dictionary<UUID, IScript>> Scripts =
            new Dictionary<uint, Dictionary<UUID, IScript>>();


        public Scene World
        {
            get { return m_scriptEngine.World; }
        }

        #endregion
        private Compiler.LSL.Compiler LSLCompiler;

        public void Initialize()
        {
            // Create our compiler
            LSLCompiler = new Compiler.LSL.Compiler(m_scriptEngine);
        }

        // KEEP TRACK OF SCRIPTS <int id, whatever script>
        //internal Dictionary<uint, Dictionary<UUID, LSL_BaseClass>> Scripts = new Dictionary<uint, Dictionary<UUID, LSL_BaseClass>>();
        // LOAD SCRIPT
        // UNLOAD SCRIPT
        // PROVIDE SCRIPT WITH ITS INTERFACE TO OpenSim


        public void _StartScript(uint localID, UUID itemID, string Script, int startParam, bool postOnRez)
        {
            m_log.DebugFormat(
                "[{0}]: ScriptManager StartScript: localID: {1}, itemID: {2}",
                m_scriptEngine.ScriptEngineName, localID, itemID);

            //IScriptHost root = host.GetRoot();

            // We will initialize and start the script.
            // It will be up to the script itself to hook up the correct events.
            string CompiledScriptFile = String.Empty;

            SceneObjectPart m_host = World.GetSceneObjectPart(localID);

            if (null == m_host)
            {
                m_log.ErrorFormat(
                    "[{0}]: Could not find scene object part corresponding to localID {1} to start script",
                    m_scriptEngine.ScriptEngineName, localID);

                return;
            }

            // Xantor 20080525: I need assetID here to see if we already compiled this one previously
            UUID assetID = UUID.Zero;
            TaskInventoryItem taskInventoryItem = new TaskInventoryItem();
            if (m_host.TaskInventory.TryGetValue(itemID, out taskInventoryItem))
                assetID = taskInventoryItem.AssetID;

            try
            {
                // Xantor 20080525 see if we already compiled this script this session, stop incessant recompiling on
                // scriptreset, spawning of objects with embedded scripts etc.

                if (scriptList.TryGetValue(assetID, out CompiledScriptFile))
                {
                    m_log.InfoFormat("[SCRIPT]: Found existing compile of assetID {0}: {1}", assetID, CompiledScriptFile);
                }
                else
                {
                    // Compile (We assume LSL)
                    CompiledScriptFile = LSLCompiler.PerformScriptCompile(Script);

                    // Xantor 20080525 Save compiled scriptfile for later use
                    m_log.InfoFormat("[SCRIPT]: Compiled assetID {0}: {1}", assetID, CompiledScriptFile);
                    scriptList.Add(assetID, CompiledScriptFile);
                }

//#if DEBUG
                //long before;
                //before = GC.GetTotalMemory(true); // This force a garbage collect that freezes some windows plateforms
//#endif

                IScript CompiledScript;
                CompiledScript = m_scriptEngine.m_AppDomainManager.LoadScript(CompiledScriptFile);

//#if DEBUG
                //m_scriptEngine.Log.DebugFormat("[" + m_scriptEngine.ScriptEngineName + "]: Script " + itemID + " occupies {0} bytes", GC.GetTotalMemory(true) - before);
//#endif

                CompiledScript.Source = Script;
                CompiledScript.StartParam = startParam;

                // Add it to our script memstruct
                m_scriptEngine.m_ScriptManager.SetScript(localID, itemID, CompiledScript);

                // We need to give (untrusted) assembly a private instance of BuiltIns
                //  this private copy will contain Read-Only FullitemID so that it can bring that on to the server whenever needed.


//                OSSL_BuilIn_Commands LSLB = new OSSL_BuilIn_Commands(m_scriptEngine, m_host, localID, itemID);
                LSL_Api LSL = new LSL_Api();
                OSSL_Api OSSL = new OSSL_Api();

                LSL.Initialize(m_scriptEngine, m_host, localID, itemID);
                OSSL.Initialize(m_scriptEngine, m_host, localID, itemID);

                // Start the script - giving it BuiltIns
                CompiledScript.InitApi("LSL", LSL);
                CompiledScript.InitApi("OSSL", OSSL);

                // Fire the first start-event
                int eventFlags = m_scriptEngine.m_ScriptManager.GetStateEventFlags(localID, itemID);
                m_host.SetScriptEvents(itemID, eventFlags);
                m_scriptEngine.m_EventQueueManager.AddToScriptQueue(localID, itemID, "state_entry", new DetectParams[0], new object[] { });
                if (postOnRez)
                {
                    m_scriptEngine.m_EventQueueManager.AddToScriptQueue(localID, itemID, "on_rez", new DetectParams[0], new object[] { new LSL_Types.LSLInteger(startParam) });
                }
            }
            catch (Exception e) // LEGIT: User Scripting
            {
                //m_scriptEngine.Log.Error("[ScriptEngine]: Error compiling script: " + e.ToString());
                try
                {
                    // DISPLAY ERROR INWORLD
                    string text = "Error compiling script:\r\n" + e.Message.ToString();
                    if (text.Length > 1500)
                        text = text.Substring(0, 1499); // 0-1499 is 1500 characters
                    World.SimChat(Utils.StringToBytes(text), ChatTypeEnum.DebugChannel, 2147483647,
                                  m_host.AbsolutePosition, m_host.Name, m_host.UUID, false);
                }
                catch (Exception e2) // LEGIT: User Scripting
                {
                    m_scriptEngine.Log.Error("[" + m_scriptEngine.ScriptEngineName + "]: Error displaying error in-world: " + e2.ToString());
                    m_scriptEngine.Log.Error("[" + m_scriptEngine.ScriptEngineName + "]: " +
                                                "Errormessage: Error compiling script:\r\n" + e.Message.ToString());
                }
            }
        }

        public void _StopScript(uint localID, UUID itemID)
        {
            IScript LSLBC = GetScript(localID, itemID);
            if (LSLBC == null)
                return;

            // Stop long command on script
            AsyncCommandManager.RemoveScript(m_scriptEngine, localID, itemID);

            // TEMP: First serialize it
            //GetSerializedScript(localID, itemID);

            try
            {
                // Get AppDomain
                AppDomain ad = LSLBC.Exec.GetAppDomain();
                // Tell script not to accept new requests
                m_scriptEngine.m_ScriptManager.GetScript(localID, itemID).Exec.StopScript();
                // Remove from internal structure
                m_scriptEngine.m_ScriptManager.RemoveScript(localID, itemID);
                // Tell AppDomain that we have stopped script
                m_scriptEngine.m_AppDomainManager.StopScript(ad);
            }
            catch (Exception e) // LEGIT: User Scripting
            {
                m_scriptEngine.Log.Error("[" + m_scriptEngine.ScriptEngineName + "]: Exception stopping script localID: " + localID + " LLUID: " + itemID.ToString() +
                                            ": " + e.ToString());
            }
        }

        public void ReadConfig()
        {
            // scriptLoadUnloadThread_IdleSleepms = m_scriptEngine.ScriptConfigSource.GetInt("ScriptLoadUnloadLoopms", 30);
            // TODO: Requires sharing of all ScriptManagers to single thread
            PrivateThread = true; // m_scriptEngine.ScriptConfigSource.GetBoolean("PrivateScriptLoadUnloadThread", false);
            LoadUnloadMaxQueueSize = m_scriptEngine.ScriptConfigSource.GetInt("LoadUnloadMaxQueueSize", 100);
        }

        #region Object init/shutdown

        public ScriptEngine m_scriptEngine;

        public ScriptManager(ScriptEngine scriptEngine)
        {
            m_scriptEngine = scriptEngine;
        }
        public void Setup()
        {
            ReadConfig();
            Initialize();
        }
        public void Start()
        {
            m_started = true;


            AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve);

            //
            // CREATE THREAD
            // Private or shared
            //
            if (PrivateThread)
            {
                // Assign one thread per region
                //scriptLoadUnloadThread = StartScriptLoadUnloadThread();
            }
            else
            {
                // Shared thread - make sure one exist, then assign it to the private
                if (staticScriptLoadUnloadThread == null)
                {
                    //staticScriptLoadUnloadThread = StartScriptLoadUnloadThread();
                }
                scriptLoadUnloadThread = staticScriptLoadUnloadThread;
            }
        }

// TODO: unused
//        private static int privateThreadCount = 0;
//         private Thread StartScriptLoadUnloadThread()
//         {
//             Thread t = new Thread(ScriptLoadUnloadThreadLoop);
//             string name = "ScriptLoadUnloadThread:";
//             if (PrivateThread)
//             {
//                 name += "Private:" + privateThreadCount;
//                 privateThreadCount++;
//             }
//             else
//             {
//                 name += "Shared";
//             }
//             t.Name = name;
//             t.IsBackground = true;
//             t.Priority = ThreadPriority.Normal;
//             t.Start();
//             OpenSim.Framework.ThreadTracker.Add(t);
//             return t;
//         }

        ~ScriptManager()
        {
            // Abort load/unload thread
            try
            {
                //PleaseShutdown = true;
                //Thread.Sleep(100);
                if (scriptLoadUnloadThread != null && scriptLoadUnloadThread.IsAlive == true)
                {
                    scriptLoadUnloadThread.Abort();
                    //scriptLoadUnloadThread.Join();
                }
            }
            catch
            {
            }
        }

        #endregion

        #region Load / Unload scripts (Thread loop)

// TODO: unused
//         private void ScriptLoadUnloadThreadLoop()
//         {
//             try
//             {
//                 while (true)
//                 {
//                     if (LUQueue.Count == 0)
//                         Thread.Sleep(scriptLoadUnloadThread_IdleSleepms);
//                     //if (PleaseShutdown)
//                     //    return;
//                     DoScriptLoadUnload();
//                 }
//             }
//             catch (ThreadAbortException tae)
//             {
//                 string a = tae.ToString();
//                 a = String.Empty;
//                 // Expected
//             }
//         }

        public void DoScriptLoadUnload()
        {
            if (!m_started)
                return;

            lock (LUQueue)
            {
                if (LUQueue.Count > 0)
                {
m_scriptEngine.Log.InfoFormat("[{0}]: Loading script", m_scriptEngine.ScriptEngineName);
                    LUStruct item = LUQueue.Dequeue();

                    if (item.Action == LUType.Unload)
                    {
                        _StopScript(item.localID, item.itemID);
                        RemoveScript(item.localID, item.itemID);
                    }
                    else if (item.Action == LUType.Load)
                    {
                        _StartScript(item.localID, item.itemID, item.script, item.startParam, item.postOnRez);
                    }
                }
            }
        }

        #endregion

        #region Helper functions

        private static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
        {
            //Console.WriteLine("ScriptManager.CurrentDomain_AssemblyResolve: " + args.Name);
            return Assembly.GetExecutingAssembly().FullName == args.Name ? Assembly.GetExecutingAssembly() : null;
        }

        #endregion



        #region Start/Stop/Reset script

        // private readonly Object startStopLock = new Object();

        /// <summary>
        /// Fetches, loads and hooks up a script to an objects events
        /// </summary>
        /// <param name="itemID"></param>
        /// <param name="localID"></param>
        public void StartScript(uint localID, UUID itemID, string Script, int startParam, bool postOnRez)
        {
            lock (LUQueue)
            {
                if ((LUQueue.Count >= LoadUnloadMaxQueueSize) && m_started)
                {
                    m_scriptEngine.Log.Error("[" + m_scriptEngine.ScriptEngineName + "]: ERROR: Load/unload queue item count is at " + LUQueue.Count + ". Config variable \"LoadUnloadMaxQueueSize\" is set to " + LoadUnloadMaxQueueSize + ", so ignoring new script.");
                    return;
                }

                LUStruct ls = new LUStruct();
                ls.localID = localID;
                ls.itemID = itemID;
                ls.script = Script;
                ls.Action = LUType.Load;
                ls.startParam = startParam;
                ls.postOnRez = postOnRez;
                LUQueue.Enqueue(ls);
m_scriptEngine.Log.InfoFormat("[{0}]: Queued script for load", m_scriptEngine.ScriptEngineName);
            }
        }

        /// <summary>
        /// Disables and unloads a script
        /// </summary>
        /// <param name="localID"></param>
        /// <param name="itemID"></param>
        public void StopScript(uint localID, UUID itemID)
        {
            LUStruct ls = new LUStruct();
            ls.localID = localID;
            ls.itemID = itemID;
            ls.Action = LUType.Unload;
            ls.startParam = 0;
            ls.postOnRez = false;
            lock (LUQueue)
            {
                LUQueue.Enqueue(ls);
            }
        }

        // Create a new instance of the compiler (reuse)
        //private Compiler.LSL.Compiler LSLCompiler = new Compiler.LSL.Compiler();


        #endregion

        #region Perform event execution in script

        /// <summary>
        /// Execute a LL-event-function in Script
        /// </summary>
        /// <param name="localID">Object the script is located in</param>
        /// <param name="itemID">Script ID</param>
        /// <param name="FunctionName">Name of function</param>
        /// <param name="args">Arguments to pass to function</param>
        internal void ExecuteEvent(uint localID, UUID itemID, string FunctionName, DetectParams[] qParams, object[] args)
        {
            //cfk 2-7-08 dont need this right now and the default Linux build has DEBUG defined
            ///#if DEBUG
            ///            Console.WriteLine("ScriptEngine: Inside ExecuteEvent for event " + FunctionName);
            ///#endif
            // Execute a function in the script
            //m_scriptEngine.Log.Info("[" + ScriptEngineName + "]: Executing Function localID: " + localID + ", itemID: " + itemID + ", FunctionName: " + FunctionName);
            //ScriptBaseInterface Script = (ScriptBaseInterface)GetScript(localID, itemID);
            IScript Script = GetScript(localID, itemID);
            if (Script == null)
            {
                return;
            }
            //cfk 2-7-08 dont need this right now and the default Linux build has DEBUG defined
            ///#if DEBUG
            ///            Console.WriteLine("ScriptEngine: Executing event: " + FunctionName);
            ///#endif
            // Must be done in correct AppDomain, so leaving it up to the script itself
            detparms[Script] = qParams;
            Script.Exec.ExecuteEvent(FunctionName, args);
            detparms.Remove(Script);
        }

        public uint GetLocalID(UUID itemID)
        {
            foreach (KeyValuePair<uint, Dictionary<UUID, IScript> > k in Scripts)
            {
                if (k.Value.ContainsKey(itemID))
                    return k.Key;
            }
            return 0;
        }

        public int GetStateEventFlags(uint localID, UUID itemID)
        {
            // Console.WriteLine("GetStateEventFlags for <" + localID + "," + itemID + ">");
            try
            {
                IScript Script = GetScript(localID, itemID);
                if (Script == null)
                {
                    return 0;
                }
                ExecutorBase.scriptEvents evflags = Script.Exec.GetStateEventFlags();
                return (int)evflags;
            }
            catch (Exception)
            {
            }

            return 0;
        }


        #endregion

        #region Internal functions to keep track of script

        public List<UUID> GetScriptKeys(uint localID)
        {
            if (Scripts.ContainsKey(localID) == false)
                return new List<UUID>();

            Dictionary<UUID, IScript> Obj;
            Scripts.TryGetValue(localID, out Obj);

            return new List<UUID>(Obj.Keys);
        }

        public IScript GetScript(uint localID, UUID itemID)
        {
            lock (scriptLock)
            {
                IScript Script = null;

                if (Scripts.ContainsKey(localID) == false)
                    return null;

                Dictionary<UUID, IScript> Obj;
                Scripts.TryGetValue(localID, out Obj);
                if (Obj.ContainsKey(itemID) == false)
                    return null;

                // Get script
                Obj.TryGetValue(itemID, out Script);
                return Script;
            }
        }

        public void SetScript(uint localID, UUID itemID, IScript Script)
        {
            lock (scriptLock)
            {
                // Create object if it doesn't exist
                if (Scripts.ContainsKey(localID) == false)
                {
                    Scripts.Add(localID, new Dictionary<UUID, IScript>());
                }

                // Delete script if it exists
                Dictionary<UUID, IScript> Obj;
                Scripts.TryGetValue(localID, out Obj);
                if (Obj.ContainsKey(itemID) == true)
                    Obj.Remove(itemID);

                // Add to object
                Obj.Add(itemID, Script);
            }
        }

        public void RemoveScript(uint localID, UUID itemID)
        {
            if (localID == 0)
                localID = GetLocalID(itemID);

            // Don't have that object?
            if (Scripts.ContainsKey(localID) == false)
                return;

            // Delete script if it exists
            Dictionary<UUID, IScript> Obj;
            Scripts.TryGetValue(localID, out Obj);
            if (Obj.ContainsKey(itemID) == true)
                Obj.Remove(itemID);
        }

        #endregion


        public void ResetScript(uint localID, UUID itemID)
        {
            IScript s = GetScript(localID, itemID);
            string script = s.Source;
            StopScript(localID, itemID);
            SceneObjectPart part = World.GetSceneObjectPart(localID);
            part.GetInventoryItem(itemID).PermsMask = 0;
            part.GetInventoryItem(itemID).PermsGranter = UUID.Zero;
            StartScript(localID, itemID, script, s.StartParam, false);
        }


        #region Script serialization/deserialization

        public void GetSerializedScript(uint localID, UUID itemID)
        {
            // Serialize the script and return it
            // Should not be a problem
            FileStream fs = File.Create("SERIALIZED_SCRIPT_" + itemID);
            BinaryFormatter b = new BinaryFormatter();
            b.Serialize(fs, GetScript(localID, itemID));
            fs.Close();
        }

        public void PutSerializedScript(uint localID, UUID itemID)
        {
            // Deserialize the script and inject it into an AppDomain

            // How to inject into an AppDomain?
        }

        #endregion

        ///// <summary>
        ///// If set to true then threads and stuff should try to make a graceful exit
        ///// </summary>
        //public bool PleaseShutdown
        //{
        //    get { return _PleaseShutdown; }
        //    set { _PleaseShutdown = value; }
        //}
        //private bool _PleaseShutdown = false;
        
        public DetectParams[] GetDetectParams(IScript script)
        {
            if (detparms.ContainsKey(script))
                return detparms[script];

            return null;
        }
    }
}