// 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.Runtime.InteropServices;
using Microsoft.CodeAnalysis;
using Microsoft.VisualStudio.LanguageServices.Implementation.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.InternalElements;
 
[ComVisible(true)]
[ComDefaultInterface(typeof(EnvDTE80.CodeVariable2))]
public sealed class CodeVariable : AbstractCodeMember, EnvDTE.CodeVariable, EnvDTE80.CodeVariable2
{
    internal static EnvDTE.CodeVariable Create(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey,
        int? nodeKind)
    {
        var element = new CodeVariable(state, fileCodeModel, nodeKey, nodeKind);
        var result = (EnvDTE.CodeVariable)ComAggregate.CreateAggregatedObject(element);
 
        fileCodeModel.OnCodeElementCreated(nodeKey, (EnvDTE.CodeElement)result);
 
        return result;
    }
 
    internal static EnvDTE.CodeVariable CreateUnknown(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        int nodeKind,
        string name)
    {
        var element = new CodeVariable(state, fileCodeModel, nodeKind, name);
        return (EnvDTE.CodeVariable)ComAggregate.CreateAggregatedObject(element);
    }
 
    private CodeVariable(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey,
        int? nodeKind)
        : base(state, fileCodeModel, nodeKey, nodeKind)
    {
    }
 
    private CodeVariable(
        CodeModelState state,
        FileCodeModel fileCodeModel,
        int nodeKind,
        string name)
        : base(state, fileCodeModel, nodeKind, name)
    {
    }
 
    private ITypeSymbol GetSymbolType()
    {
        var symbol = LookupSymbol();
        if (symbol != null)
        {
            switch (symbol.Kind)
            {
                case SymbolKind.Field:
                    return ((IFieldSymbol)symbol).Type;
                case SymbolKind.Property:
                    // Note: VB WithEvents fields are represented as properties
                    return ((IPropertySymbol)symbol).Type;
            }
        }
 
        return null;
    }
 
    public override EnvDTE.vsCMElement Kind
    {
        get { return EnvDTE.vsCMElement.vsCMElementVariable; }
    }
 
    public EnvDTE80.vsCMConstKind ConstKind
    {
        get
        {
            return CodeModelService.GetConstKind(LookupNode());
        }
 
        set
        {
            UpdateNode(FileCodeModel.UpdateConstKind, value);
        }
    }
 
    public override EnvDTE.CodeElements Children
    {
        get { return Attributes; }
    }
 
    public object InitExpression
    {
        get
        {
            return CodeModelService.GetInitExpression(LookupNode());
        }
 
        set
        {
            if (value is null or string)
            {
                UpdateNode(FileCodeModel.UpdateInitExpression, (string)value);
                return;
            }
 
            // TODO(DustinCa): Legacy VB throws E_INVALIDARG if value is not a string.
            throw Exceptions.ThrowEFail();
        }
    }
 
    public bool IsConstant
    {
        get
        {
            return CodeModelService.GetIsConstant(LookupNode());
        }
 
        set
        {
            UpdateNode(FileCodeModel.UpdateIsConstant, value);
        }
    }
 
    public EnvDTE.CodeTypeRef Type
    {
        get
        {
            var type = GetSymbolType();
            if (type == null)
            {
                throw Exceptions.ThrowEFail();
            }
 
            return CodeTypeRef.Create(this.State, this, GetProjectId(), type);
        }
 
        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);
        }
    }
}