// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
#nullable disable
 
using System.Collections.Immutable;
using System.Linq;
using System.Runtime.InteropServices;
using Microsoft.CodeAnalysis;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Collections;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.InternalElements;
 
[ComVisible(true)]
[ComDefaultInterface(typeof(EnvDTE80.CodeFunction2))]
public partial class CodeFunction : AbstractCodeMember, ICodeElementContainer<CodeParameter>, ICodeElementContainer<CodeAttribute>, EnvDTE.CodeFunction, EnvDTE80.CodeFunction2, IMethodXML, IMethodXML2
{
    internal static EnvDTE.CodeFunction Create(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey,
        int? nodeKind)
    {
        var element = new CodeFunction(state, fileCodeModel, nodeKey, nodeKind);
        var result = (EnvDTE.CodeFunction)ComAggregate.CreateAggregatedObject(element);
 
        fileCodeModel.OnCodeElementCreated(nodeKey, (EnvDTE.CodeElement)result);
 
        return result;
    }
 
    internal static EnvDTE.CodeFunction CreateUnknown(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        int nodeKind,
        string name)
    {
        var element = new CodeFunction(state, fileCodeModel, nodeKind, name);
        return (EnvDTE.CodeFunction)ComAggregate.CreateAggregatedObject(element);
    }
 
    internal CodeFunction(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey,
        int? nodeKind)
        : base(state, fileCodeModel, nodeKey, nodeKind)
    {
    }
 
    internal CodeFunction(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        int nodeKind,
        string name)
        : base(state, fileCodeModel, nodeKind, name)
    {
    }
 
    EnvDTE.CodeElements ICodeElementContainer<CodeParameter>.GetCollection()
        => this.Parameters;
 
    EnvDTE.CodeElements ICodeElementContainer<CodeAttribute>.GetCollection()
        => this.Attributes;
 
    private IMethodSymbol MethodSymbol
    {
        get { return (IMethodSymbol)LookupSymbol(); }
    }
 
    internal override ImmutableArray<SyntaxNode> GetParameters()
        => [.. CodeModelService.GetParameterNodes(LookupNode())];
 
    protected override object GetExtenderNames()
        => CodeModelService.GetFunctionExtenderNames();
 
    protected override object GetExtender(string name)
        => CodeModelService.GetFunctionExtender(name, LookupNode(), LookupSymbol());
 
    public override EnvDTE.vsCMElement Kind
    {
        get { return EnvDTE.vsCMElement.vsCMElementFunction; }
    }
 
    public bool CanOverride
    {
        get
        {
            return CodeModelService.GetCanOverride(LookupNode());
        }
 
        set
        {
            UpdateNode(FileCodeModel.UpdateCanOverride, value);
        }
    }
 
    public EnvDTE.vsCMFunction FunctionKind
    {
        get
        {
            if (LookupSymbol() is not IMethodSymbol symbol)
            {
                throw Exceptions.ThrowEUnexpected();
            }
 
            return CodeModelService.GetFunctionKind(symbol);
        }
    }
 
    public bool IsOverloaded
    {
        get
        {
            var symbol = (IMethodSymbol)LookupSymbol();
 
            // Only methods and constructors can be overloaded
            if (symbol.MethodKind is not MethodKind.Ordinary and
                not MethodKind.Constructor)
            {
                return false;
            }
 
            var methodsOfName = symbol.ContainingType.GetMembers(symbol.Name)
                                                     .Where(m => m.Kind == SymbolKind.Method);
 
            return methodsOfName.Count() > 1;
        }
    }
 
    public EnvDTE.CodeElements Overloads
    {
        get
        {
            return OverloadsCollection.Create(this.FileCodeModel.State, this);
        }
    }
 
    public override EnvDTE.CodeElements Children
    {
        get { return UnionCollection.Create(this.State, this, (ICodeElements)this.Attributes, (ICodeElements)this.Parameters); }
    }
 
    public EnvDTE.CodeTypeRef Type
    {
        get
        {
            return CodeTypeRef.Create(this.State, this, GetProjectId(), MethodSymbol.ReturnType);
        }
 
        set
        {
            // The type is sometimes part of the node key, so we should be sure to reacquire
            // it after updating it. Note that we pass trackKinds: false because it's possible
            // that UpdateType might change the kind of a node (e.g. change a VB Sub to a Function).
 
            UpdateNodeAndReacquireNodeKey(FileCodeModel.UpdateType, value, trackKinds: false);
        }
    }
}