/* ****************************************************************************

 *

 * 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.Dynamic;

using System.Reflection;



using Microsoft.Scripting.Actions.Calls;

using Microsoft.Scripting.Runtime;

using Microsoft.Scripting.Utils;



using AstUtils = Microsoft.Scripting.Ast.Utils;



namespace Microsoft.Scripting.Actions {



    public partial class DefaultBinder : ActionBinder {

        public DynamicMetaObject DeleteMember(string name, DynamicMetaObject target) {

            return DeleteMember(name, target, new DefaultOverloadResolverFactory(this));

        }



        public DynamicMetaObject DeleteMember(string name, DynamicMetaObject target, OverloadResolverFactory resolutionFactory) {

            return DeleteMember(name, target, resolutionFactory, null);

        }



        public DynamicMetaObject DeleteMember(string name, DynamicMetaObject target, OverloadResolverFactory resolutionFactory, DynamicMetaObject errorSuggestion) {

            ContractUtils.RequiresNotNull(name, "name");

            ContractUtils.RequiresNotNull(target, "target");



            return MakeDeleteMemberTarget(

                new SetOrDeleteMemberInfo(

                    name,

                    resolutionFactory

                ),

                target.Restrict(target.GetLimitType()),

                errorSuggestion

            );

        }



        private DynamicMetaObject MakeDeleteMemberTarget(SetOrDeleteMemberInfo delInfo, DynamicMetaObject target, DynamicMetaObject errorSuggestion) {

            Type type = target.GetLimitType();

            BindingRestrictions restrictions = target.Restrictions;

            DynamicMetaObject self = target;



            if (typeof(TypeTracker).IsAssignableFrom(type)) {

                restrictions = restrictions.Merge(

                    BindingRestrictions.GetInstanceRestriction(target.Expression, target.Value)

                );



                type = ((TypeTracker)target.Value).Type;

                self = null;

            }



            delInfo.Body.Restrictions = restrictions;



            if (self == null || !MakeOperatorDeleteMemberBody(delInfo, self, type, "DeleteMember")) {

                MemberGroup group = GetMember(MemberRequestKind.Delete, type, delInfo.Name);

                if (group.Count != 0) {

                    if (group[0].MemberType == TrackerTypes.Property) {

                        MethodInfo del = ((PropertyTracker)group[0]).GetDeleteMethod(PrivateBinding);

                        if (del != null) {

                            MakePropertyDeleteStatement(delInfo, self, del);

                            return delInfo.Body.GetMetaObject(target);

                        }

                    }



                    delInfo.Body.FinishError(errorSuggestion ?? MakeError(MakeUndeletableMemberError(GetDeclaringMemberType(group), delInfo.Name), typeof(void)));

                } else {

                    delInfo.Body.FinishError(errorSuggestion ?? MakeError(MakeMissingMemberErrorForDelete(type, self, delInfo.Name), typeof(void)));

                }

            }



            return delInfo.Body.GetMetaObject(target);

        }



        private static Type GetDeclaringMemberType(MemberGroup group) {

            Type t = typeof(object);

            foreach (MemberTracker mt in group) {

                if (t.IsAssignableFrom(mt.DeclaringType)) {

                    t = mt.DeclaringType;

                }

            }

            return t;

        }



        private void MakePropertyDeleteStatement(SetOrDeleteMemberInfo delInfo, DynamicMetaObject instance, MethodInfo delete) {

            delInfo.Body.FinishCondition(

                instance == null ? 

                    MakeCallExpression(delInfo.ResolutionFactory, delete) :

                    MakeCallExpression(delInfo.ResolutionFactory, delete, instance)

            );

        }



        /// <summary> if a member-injector is defined-on or registered-for this type call it </summary>

        private bool MakeOperatorDeleteMemberBody(SetOrDeleteMemberInfo delInfo, DynamicMetaObject instance, Type type, string name) {

            MethodInfo delMem = GetMethod(type, name);



            if (delMem != null) {

                DynamicMetaObject call = MakeCallExpression(delInfo.ResolutionFactory, delMem, instance, new DynamicMetaObject(AstUtils.Constant(delInfo.Name), BindingRestrictions.Empty, delInfo.Name));



                if (delMem.ReturnType == typeof(bool)) {

                    delInfo.Body.AddCondition(

                        call.Expression,

                        AstUtils.Constant(null)

                    );

                } else {

                    delInfo.Body.FinishCondition(call);

                }



                return delMem.ReturnType != typeof(bool);

            }

            return false;

        }



        /// <summary>

        /// Helper class for flowing information about the GetMember request.

        /// </summary>

        private sealed class SetOrDeleteMemberInfo {

            public readonly string Name;

            public readonly OverloadResolverFactory ResolutionFactory;

            public readonly ConditionalBuilder Body = new ConditionalBuilder();



            public SetOrDeleteMemberInfo(string name, OverloadResolverFactory resolutionFactory) {

                Name = name;

                ResolutionFactory = resolutionFactory;

            }

        }

    }

}