// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace System.CodeDom
{
    public class CodeMemberMethod : CodeTypeMember
    {
        private readonly CodeParameterDeclarationExpressionCollection _parameters = new CodeParameterDeclarationExpressionCollection();
        private readonly CodeStatementCollection _statements = new CodeStatementCollection();
        private CodeTypeReference _returnType;
        private CodeTypeReferenceCollection _implementationTypes;
        private CodeAttributeDeclarationCollection _returnAttributes;
        private CodeTypeParameterCollection _typeParameters;
 
        private int _populated;
        private const int ParametersCollection = 0x1;
        private const int StatementsCollection = 0x2;
        private const int ImplTypesCollection = 0x4;
 
        public event EventHandler PopulateParameters;
        public event EventHandler PopulateStatements;
        public event EventHandler PopulateImplementationTypes;
 
        public CodeTypeReference ReturnType
        {
            get => _returnType ??= new CodeTypeReference(typeof(void).FullName);
            set => _returnType = value;
        }
 
        public CodeStatementCollection Statements
        {
            get
            {
                if ((_populated & StatementsCollection) == 0)
                {
                    _populated |= StatementsCollection;
                    PopulateStatements?.Invoke(this, EventArgs.Empty);
                }
 
                return _statements;
            }
        }
 
        public CodeParameterDeclarationExpressionCollection Parameters
        {
            get
            {
                if ((_populated & ParametersCollection) == 0)
                {
                    _populated |= ParametersCollection;
                    PopulateParameters?.Invoke(this, EventArgs.Empty);
                }
 
                return _parameters;
            }
        }
 
        public CodeTypeReference PrivateImplementationType { get; set; }
 
        public CodeTypeReferenceCollection ImplementationTypes
        {
            get
            {
                _implementationTypes ??= new CodeTypeReferenceCollection();
 
                if ((_populated & ImplTypesCollection) == 0)
                {
                    _populated |= ImplTypesCollection;
                    PopulateImplementationTypes?.Invoke(this, EventArgs.Empty);
                }
 
                return _implementationTypes;
            }
        }
 
        public CodeAttributeDeclarationCollection ReturnTypeCustomAttributes => _returnAttributes ??= new CodeAttributeDeclarationCollection();
 
        public CodeTypeParameterCollection TypeParameters => _typeParameters ??= new CodeTypeParameterCollection();
    }
}