/* ****************************************************************************
 *
 * Copyright (c) Microsoft Corporation. 
 *
 * This source code is subject to terms and conditions of the Apache License, Version 2.0. A 
 * copy of the license can be found in the License.html file at the root of this distribution. If 
 * you cannot locate the  Apache License, Version 2.0, please send an email to 
 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 
 * by the terms of the Apache License, Version 2.0.
 *
 * You must not remove this notice, or any other, from this software.
 *
 *
 * ***************************************************************************/


using System;
using System.Linq;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Reflection;

using Microsoft.Scripting.Utils;
using System.Security;

namespace Microsoft.Scripting.Interpreter {
    internal sealed partial class DynamicInstructionN : Instruction {
        private readonly CallInstruction _targetInvocationInstruction;
        private readonly object _targetDelegate;
        private readonly CallSite _site;
        private readonly int _argumentCount;
        private readonly bool _isVoid;

        public DynamicInstructionN(Type delegateType, CallSite site) {
            var methodInfo = delegateType.GetMethod("Invoke");
            var parameters = methodInfo.GetParameters();

            // <Delegate>.Invoke is ok to target by a delegate in partial trust (SecurityException is not thrown):
            _targetInvocationInstruction = CallInstruction.Create(methodInfo, parameters);
            _site = site;
            _argumentCount = parameters.Length - 1;
            _targetDelegate = site.GetType().GetInheritedFields("Target").First().GetValue(site);
        }

        public DynamicInstructionN(Type delegateType, CallSite site, bool isVoid)
            : this(delegateType, site) {
            _isVoid = isVoid;
        }

        public override int ProducedStack { get { return _isVoid ? 0 : 1; } }
        public override int ConsumedStack { get { return _argumentCount; } }

        public override int Run(InterpretedFrame frame) {
            int first = frame.StackIndex - _argumentCount;
            object[] args = new object[1 + _argumentCount];
            args[0] = _site;
            for (int i = 0; i < _argumentCount; i++) {
                args[1 + i] = frame.Data[first + i];
            }

            object ret = _targetInvocationInstruction.InvokeInstance(_targetDelegate, args);
            if (_isVoid) {
                frame.StackIndex = first;
            } else {
                frame.Data[first] = ret;
                frame.StackIndex = first + 1;
            }

            return 1;
        }

        public override string ToString() {
            return "DynamicInstructionN(" + _site + ")";
        }
    }
}