// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at
// http://mozilla.org/MPL/2.0/.

using SimAI.Engine.Entities;
using SimAI.Marshals;

namespace SimAI.Engine
{
    /// <summary>
    /// Holds information about the execution of a routine
    /// </summary>
    public class VMStackFrame
    {
        public VMStackFrame() { }

        /** Thread executing this routine **/
        public VMThread Thread;

        /** Routine that this context relates to **/
        // public VMRoutine Routine;

        /** Current instruction **/
        public ushort InstructionPointer;

        /** The object who executed this behavior **/
        public VMEntity Caller;

        /** The object the code is running on **/
        public VMEntity Callee;

        /** An object selected by the code to perform operations on. **/
        public VMEntity StackObject
        {
            get { return _StackObject; }
            set
            {
                _StackObject = value;
                _StackObjectID = value?.ObjectID ?? 0;
            }
        }
        public short StackObjectID
        {
            get { return _StackObjectID; }
            set
            {
                _StackObjectID = value;
                _StackObject = VM.GetObjectById(value);
            }
        }

        VMEntity _StackObject;
        public short _StackObjectID;

        /** If true, this stack frame is not a subroutine. Return with a continue. **/
        public bool DiscardResult;

        /** Indicates that the current stack frame is part of an action tree.
         ** Set by "idle for input, allow push", when an interaction is selected.
         ** Used to stop recursive interactions, is only false when within "main".
         **/
        public bool ActionTree;

        /** Used to get strings and other resources (for primitives) from the code owner, as it may not be the callee but instead a semiglobal or global. **/
        //public GameIffResource ScopeResource
        //{
        //    get
        //    {
        //        return CodeOwner.Resource;
        //    }
        //}

        //public GameObject CodeOwner;
        /**
         * Routine locals
         */
        public short[] Locals;

        /**
         * Arguments
         */
        public short[] Args;

        //public GameObjectResource CallerPrivate
        //{
        //    get
        //    {
        //        return Caller.Object.Resource;
        //    }
        //}

        //public GameObjectResource CalleePrivate
        //{
        //    get
        //    {
        //        return Callee.Object.Resource;
        //    }
        //}

        //public GameObjectResource StackObjPrivate
        //{
        //    get
        //    {
        //        return StackObject.Object.Resource;
        //    }
        //}

        //public GameGlobal Global
        //{
        //    get
        //    {
        //        return Thread.Context.Globals;
        //    }
        //}

        public VM VM
        {
            get
            {
                return Thread.Context.VM;
            }
        }

        /** Utilities **/
        //public VMInstruction GetCurrentInstruction()
        //{
        //    return Routine.Instructions[InstructionPointer];
        //}

        //public T GetCurrentOperand<T>()
        //{
        //    return (T)GetCurrentInstruction().Operand;
        //}

        #region VM Marshalling Functions
        //public virtual VMStackFrameMarshal Save()
        //{
        //    return new VMStackFrameMarshal
        //    {
        //        RoutineID = Routine?.ID ?? 0,
        //        InstructionPointer = InstructionPointer,
        //        Caller = (Caller == null) ? (short)0 : Caller.ObjectID,
        //        Callee = (Callee == null) ? (short)0 : Callee.ObjectID,
        //        StackObject = StackObjectID,
        //        CodeOwnerGUID = CodeOwner.OBJ.GUID,
        //        Locals = (short[])Locals?.Clone(),
        //        Args = (short[])Args?.Clone(),
        //        DiscardResult = DiscardResult,
        //        ActionTree = ActionTree,
        //    };
        //}

        public virtual void Load(VMStackFrameMarshal input, VMContext context)
        {
            // CodeOwner = GameContent.Get.WorldObjects.Get(input.CodeOwnerGUID);

            // Routine = null;
            //if (input.RoutineID >= 8192) Routine = (VMRoutine)ScopeResource.SemiGlobal.GetRoutine(input.RoutineID);
            //else if (input.RoutineID >= 4096) Routine = (VMRoutine)ScopeResource.GetRoutine(input.RoutineID);
            //else Routine = (VMRoutine)Global.Resource.GetRoutine(input.RoutineID);

            InstructionPointer = input.InstructionPointer;
            Caller = context.VM.GetObjectById(input.Caller);
            Callee = context.VM.GetObjectById(input.Callee);
            StackObjectID = input.StackObject;
            Locals = input.Locals;
            Args = input.Args;
            DiscardResult = input.DiscardResult;
            ActionTree = input.ActionTree;
        }

        public VMStackFrame(VMStackFrameMarshal input, VMContext context, VMThread thread)
        {
            Thread = thread;
            // Load(input, context);
        }
        #endregion
    }
}