namespace LuaInterface
{
    using System;
    using System.IO;
    using System.Collections;
    using System.Reflection;
    using System.Collections.Generic;
    using System.Diagnostics;

    /*
     * Cached method
     */
    struct MethodCache
    {
        private MethodBase _cachedMethod;

        public MethodBase cachedMethod
        {
            get
            {
                return _cachedMethod;
            }
            set
            {
                _cachedMethod = value;
                MethodInfo mi = value as MethodInfo;
                if (mi != null)
                {
                    //SJD this is guaranteed to be correct irrespective of actual name used for type..
                    IsReturnVoid = mi.ReturnType == typeof(void);
                }
            }
        }

        public bool IsReturnVoid;

        // List or arguments
        public object[] args;
        // Positions of out parameters
        public int[] outList;
        // Types of parameters
        public MethodArgs[] argTypes;
    }

    /*
     * Parameter information
     */
    struct MethodArgs
    {
        // Position of parameter
        public int index;
        // Type-conversion function
        public ExtractValue extractValue;

        public bool isParamsArray;

        public Type paramsArrayType;
    }

    /*
     * Argument extraction with type-conversion function
     */
    delegate object ExtractValue(IntPtr luaState, int stackPos);

    /*
     * Wrapper class for methods/constructors accessed from Lua.
     *
     * Author: Fabio Mascarenhas
     * Version: 1.0
     */
    class LuaMethodWrapper
    {
        private ObjectTranslator _Translator;
        private MethodBase _Method;
        private MethodCache _LastCalledMethod = new MethodCache();
        private string _MethodName;
        private MemberInfo[] _Members;
        private ExtractValue _ExtractTarget;
        private object _Target;
        private BindingFlags _BindingType;

        /*
         * Constructs the wrapper for a known MethodBase instance
         */
        public LuaMethodWrapper(ObjectTranslator translator, object target, IReflect targetType, MethodBase method)
        {
            _Translator = translator;
            _Target = target;
            if (targetType != null)
                _ExtractTarget = translator.typeChecker.getExtractor(targetType);
            _Method = method;
            _MethodName = method.Name;

            if (method.IsStatic)
            { _BindingType = BindingFlags.Static; }
            else
            { _BindingType = BindingFlags.Instance; }
        }
        /*
         * Constructs the wrapper for a known method name
         */
        public LuaMethodWrapper(ObjectTranslator translator, IReflect targetType, string methodName, BindingFlags bindingType)
        {
            _Translator = translator;
            _MethodName = methodName;

            if (targetType != null)
                _ExtractTarget = translator.typeChecker.getExtractor(targetType);

            _BindingType = bindingType;

            //CP: Removed NonPublic binding search and added IgnoreCase
            _Members = targetType.UnderlyingSystemType.GetMember(methodName, MemberTypes.Method, bindingType | BindingFlags.Public | BindingFlags.IgnoreCase/*|BindingFlags.NonPublic*/);
        }


        /// <summary>
        /// Convert C# exceptions into Lua errors
        /// </summary>
        /// <returns>num of things on stack</returns>
        /// <param name="e">null for no pending exception</param>
        int SetPendingException(Exception e)
        {
            return _Translator.interpreter.SetPendingException(e);
        }

        private static bool IsInteger(double x) {
            return Math.Ceiling(x) == x;
        }


        /*
         * Calls the method. Receives the arguments from the Lua stack
         * and returns values in it.
         */
        public int call(IntPtr luaState)
        {
            MethodBase methodToCall = _Method;
            object targetObject = _Target;
            bool failedCall = true;
            int nReturnValues = 0;

            if (!LuaDLL.lua_checkstack(luaState, 5))
                throw new LuaException("Lua stack overflow");

            bool isStatic = (_BindingType & BindingFlags.Static) == BindingFlags.Static;

            SetPendingException(null);

            if (methodToCall == null) // Method from name
            {
                if (isStatic)
                    targetObject = null;
                else
                    targetObject = _ExtractTarget(luaState, 1);

                //LuaDLL.lua_remove(luaState,1); // Pops the receiver
                if (_LastCalledMethod.cachedMethod != null) // Cached?
                {
                    int numStackToSkip = isStatic ? 0 : 1; // If this is an instance invoe we will have an extra arg on the stack for the targetObject
                    int numArgsPassed = LuaDLL.lua_gettop(luaState) - numStackToSkip;
                    MethodBase method = _LastCalledMethod.cachedMethod;

                    if (numArgsPassed == _LastCalledMethod.argTypes.Length) // No. of args match?
                    {
                        if (!LuaDLL.lua_checkstack(luaState, _LastCalledMethod.outList.Length + 6))
                            throw new LuaException("Lua stack overflow");

                        object[] args = _LastCalledMethod.args;

                        try
                        {
                            for (int i = 0; i < _LastCalledMethod.argTypes.Length; i++)
                            {
                                MethodArgs type = _LastCalledMethod.argTypes[i];
                                object luaParamValue = type.extractValue(luaState, i + 1 + numStackToSkip);
                                if (_LastCalledMethod.argTypes[i].isParamsArray)
                                {
                                    args[type.index] = _Translator.tableToArray(luaParamValue,type.paramsArrayType);
                                }
                                else
                                {
                                    args[type.index] = luaParamValue;
                                }

                                if (args[type.index] == null &&
                                    !LuaDLL.lua_isnil(luaState, i + 1 + numStackToSkip))
                                {
                                    throw new LuaException("argument number " + (i + 1) + " is invalid");
                                }
                            }
                            if ((_BindingType & BindingFlags.Static) == BindingFlags.Static)
                            {
                                _Translator.push(luaState, method.Invoke(null, args));
                            }
                            else
                            {
                                if (_LastCalledMethod.cachedMethod.IsConstructor)
                                    _Translator.push(luaState, ((ConstructorInfo)method).Invoke(args));
                                else
                                    _Translator.push(luaState, method.Invoke(targetObject,args));
                            }
                            failedCall = false;
                        }
                        catch (TargetInvocationException e)
                        {
                            // Failure of method invocation
                            return SetPendingException(e.GetBaseException());
                        }
                        catch (Exception e)
                        {
                            if (_Members.Length == 1) // Is the method overloaded?
                                // No, throw error
                                return SetPendingException(e);
                        }
                    }
                }

                // Cache miss
                if (failedCall)
                {
                    // System.Diagnostics.Debug.WriteLine("cache miss on " + methodName);

                    // If we are running an instance variable, we can now pop the targetObject from the stack
                    if (!isStatic)
                    {
                        if (targetObject == null)
                        {
                            _Translator.throwError(luaState, String.Format("instance method '{0}' requires a non null target object", _MethodName));
                            LuaDLL.lua_pushnil(luaState);
                            return 1;
                        }

                        LuaDLL.lua_remove(luaState, 1); // Pops the receiver
                    }

                    bool hasMatch = false;
                    string candidateName = null;

                    foreach (MemberInfo member in _Members)
                    {
                        candidateName = member.ReflectedType.Name + "." + member.Name;

                        MethodBase m = (MethodInfo)member;

                        bool isMethod = _Translator.matchParameters(luaState, m, ref _LastCalledMethod);
                        if (isMethod)
                        {
                            hasMatch = true;
                            break;
                        }
                    }
                    if (!hasMatch)
                    {
                        string msg = (candidateName == null)
                            ? "invalid arguments to method call: " + _MethodName
                            : ("invalid arguments to method: " + candidateName);

                        _Translator.throwError(luaState, msg);
                        LuaDLL.lua_pushnil(luaState);
                        return 1;
                    }
                }
            }
            else // Method from MethodBase instance
            {
                if (methodToCall.ContainsGenericParameters)
                {
                    // bool isMethod = //* not used
                    _Translator.matchParameters(luaState, methodToCall, ref _LastCalledMethod);

                    if (methodToCall.IsGenericMethodDefinition)
                    {
                        //need to make a concrete type of the generic method definition
                        List<Type> typeArgs = new List<Type>();

                        foreach (object arg in _LastCalledMethod.args)
                            typeArgs.Add(arg.GetType());

                        MethodInfo concreteMethod = (methodToCall as MethodInfo).MakeGenericMethod(typeArgs.ToArray());

                        _Translator.push(luaState, concreteMethod.Invoke(targetObject, _LastCalledMethod.args));
                        failedCall = false;
                    }
                    else if (methodToCall.ContainsGenericParameters)
                    {
                        _Translator.throwError(luaState, "unable to invoke method on generic class as the current method is an open generic method");
                        LuaDLL.lua_pushnil(luaState);
                        return 1;
                    }
                }
                else
                {
                    if (!methodToCall.IsStatic && !methodToCall.IsConstructor && targetObject == null)
                    {
                        targetObject = _ExtractTarget(luaState, 1);
                        LuaDLL.lua_remove(luaState, 1); // Pops the receiver
                    }

                    if (!_Translator.matchParameters(luaState, methodToCall, ref _LastCalledMethod))
                    {
                        _Translator.throwError(luaState, string.Format("invalid arguments to method call {0} of type {1}", methodToCall, methodToCall.ReflectedType));
                        LuaDLL.lua_pushnil(luaState);
                        return 1;
                    }
                }
            }

            if (failedCall)
            {
                if (!LuaDLL.lua_checkstack(luaState, _LastCalledMethod.outList.Length + 6))
                    throw new LuaException("Lua stack overflow");
                try
                {
                    if (isStatic)
                    {
                        _Translator.push(luaState, _LastCalledMethod.cachedMethod.Invoke(null, _LastCalledMethod.args));
                    }
                    else
                    {
                        if (_LastCalledMethod.cachedMethod.IsConstructor)
                            _Translator.push(luaState, ((ConstructorInfo)_LastCalledMethod.cachedMethod).Invoke(_LastCalledMethod.args));
                        else
                        {
                            object returnValue = _LastCalledMethod.cachedMethod.Invoke( targetObject, _LastCalledMethod.args );
                            _Translator.push(luaState, returnValue );
                            
                            LuaTable returnValueLuaBase = returnValue as LuaTable;
                            if( returnValueLuaBase != null && returnValueLuaBase.IsOrphaned )
                            {
                                returnValueLuaBase.Dispose();
                            }
                        }
                    }
                }
                catch (TargetInvocationException e)
                {
                    return SetPendingException(e.GetBaseException());
                }
                catch (Exception e)
                {
                    return SetPendingException(e);
                }
            }

            // Pushes out and ref return values
            for (int index = 0; index < _LastCalledMethod.outList.Length; index++)
            {
                nReturnValues++;

                object outArg = _LastCalledMethod.args[_LastCalledMethod.outList[index]];

                _Translator.push(luaState, outArg );

                LuaTable outArgLuaBase = outArg as LuaTable;
                if( outArgLuaBase != null && outArgLuaBase.IsOrphaned )
                {
                    outArgLuaBase.Dispose();
                }
            }

            //by isSingle 2010-09-10 11:26:31
            //Desc:
            //  if not return void,we need add 1,
            //  or we will lost the function's return value
            //  when call dotnet function like "int foo(arg1,out arg2,out arg3)" in lua code
            if (!_LastCalledMethod.IsReturnVoid && nReturnValues > 0)
            {
                nReturnValues++;
            }

            return nReturnValues < 1 ? 1 : nReturnValues;
        }
    }




    /// <summary>
    /// We keep track of what delegates we have auto attached to an event - to allow us to cleanly exit a LuaInterface session
    /// </summary>
    class EventHandlerContainer : IDisposable
    {
        Dictionary<Delegate, RegisterEventHandler> dict = new Dictionary<Delegate, RegisterEventHandler>();

        public void Add(Delegate handler, RegisterEventHandler eventInfo)
        {
            dict.Add(handler, eventInfo);
        }

        public void Remove(Delegate handler)
        {
            bool found = dict.Remove(handler);
            Debug.Assert(found);
        }

        /// <summary>
        /// Remove any still registered handlers
        /// </summary>
        public void Dispose()
        {
            foreach (KeyValuePair<Delegate, RegisterEventHandler> pair in dict)
            {
                pair.Value.RemovePending(pair.Key);
            }

            dict.Clear();
        }
    }


    /*
     * Wrapper class for events that does registration/deregistration
     * of event handlers.
     *
     * Author: Fabio Mascarenhas
     * Version: 1.0
     */
    class RegisterEventHandler
    {
        object target;
        EventInfo eventInfo;
        EventHandlerContainer pendingEvents;

        public RegisterEventHandler(EventHandlerContainer pendingEvents, object target, EventInfo eventInfo)
        {
            this.target = target;
            this.eventInfo = eventInfo;
            this.pendingEvents = pendingEvents;
        }


        /*
         * Adds a new event handler
         */
        public Delegate Add(LuaFunction function)
        {
            //CP: Fix by Ben Bryant for event handling with one parameter
            //link: http://luaforge.net/forum/message.php?msg_id=9266
            Delegate handlerDelegate = CodeGeneration.Instance.GetDelegate(eventInfo.EventHandlerType, function);
            eventInfo.AddEventHandler(target, handlerDelegate);
            pendingEvents.Add(handlerDelegate, this);

            return handlerDelegate;


            //MethodInfo mi = eventInfo.EventHandlerType.GetMethod("Invoke");
            //ParameterInfo[] pi = mi.GetParameters();
            //LuaEventHandler handler=CodeGeneration.Instance.GetEvent(pi[1].ParameterType,function);

            //Delegate handlerDelegate=Delegate.CreateDelegate(eventInfo.EventHandlerType,handler,"HandleEvent");
            //eventInfo.AddEventHandler(target,handlerDelegate);
            //pendingEvents.Add(handlerDelegate, this);

            //return handlerDelegate;
        }

        /*
         * Removes an existing event handler
         */
        public void Remove(Delegate handlerDelegate)
        {
            RemovePending(handlerDelegate);
            pendingEvents.Remove(handlerDelegate);
        }

        /*
         * Removes an existing event handler (without updating the pending handlers list)
         */
        internal void RemovePending(Delegate handlerDelegate)
        {
            eventInfo.RemoveEventHandler(target, handlerDelegate);
        }
    }

    /*
     * Base wrapper class for Lua function event handlers.
     * Subclasses that do actual event handling are created
     * at runtime.
     *
     * Author: Fabio Mascarenhas
     * Version: 1.0
     */
    public class LuaEventHandler
    {
        public LuaFunction handler = null;

        // CP: Fix provided by Ben Bryant for delegates with one param
        // link: http://luaforge.net/forum/message.php?msg_id=9318
        public void handleEvent(object[] args)
        {
            handler.Call(args);
        }
        //public void handleEvent(object sender,object data)
        //{
        //    handler.call(new object[] { sender,data },new Type[0]);
        //}
    }

    /*
     * Wrapper class for Lua functions as delegates
     * Subclasses with correct signatures are created
     * at runtime.
     *
     * Author: Fabio Mascarenhas
     * Version: 1.0
     */
    public class LuaDelegate
    {
        public Type[] returnTypes;
        public LuaFunction function;
        public LuaDelegate()
        {
            function = null;
            returnTypes = null;
        }
        public object callFunction(object[] args, object[] inArgs, int[] outArgs)
        {
            // args is the return array of arguments, inArgs is the actual array
            // of arguments passed to the function (with in parameters only), outArgs
            // has the positions of out parameters
            object returnValue;
            int iRefArgs;
            object[] returnValues = function.call(inArgs, returnTypes);
            if (returnTypes[0] == typeof(void))
            {
                returnValue = null;
                iRefArgs = 0;
            }
            else
            {
                returnValue = returnValues[0];
                iRefArgs = 1;
            }
            // Sets the value of out and ref parameters (from
            // the values returned by the Lua function).
            for (int i = 0; i < outArgs.Length; i++)
            {
                args[outArgs[i]] = returnValues[iRefArgs];
                iRefArgs++;
            }
            return returnValue;
        }
    }

    /*
     * Static helper methods for Lua tables acting as CLR objects.
     *
     * Author: Fabio Mascarenhas
     * Version: 1.0
     */
    public class LuaClassHelper
    {
        /*
         *  Gets the function called name from the provided table,
         * returning null if it does not exist
         */
        public static LuaFunction getTableFunction(LuaTable luaTable, string name)
        {
            object funcObj = luaTable.rawget(name);
            if (funcObj is LuaFunction)
                return (LuaFunction)funcObj;
            else
                return null;
        }
        /*
         * Calls the provided function with the provided parameters
         */
        public static object callFunction(LuaFunction function, object[] args, Type[] returnTypes, object[] inArgs, int[] outArgs)
        {
            // args is the return array of arguments, inArgs is the actual array
            // of arguments passed to the function (with in parameters only), outArgs
            // has the positions of out parameters
            object returnValue;
            int iRefArgs;
            object[] returnValues = function.call(inArgs, returnTypes);
            if (returnTypes[0] == typeof(void))
            {
                returnValue = null;
                iRefArgs = 0;
            }
            else
            {
                returnValue = returnValues[0];
                iRefArgs = 1;
            }
            for (int i = 0; i < outArgs.Length; i++)
            {
                args[outArgs[i]] = returnValues[iRefArgs];
                iRefArgs++;
            }
            return returnValue;
        }
    }
}