// 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;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Text;
using Microsoft.Cci;
using Microsoft.CodeAnalysis.CodeGen;
using Microsoft.CodeAnalysis.Debugging;
 
namespace Microsoft.CodeAnalysis.Emit.EditAndContinue
{
    internal sealed class DeletedMethodBody : IMethodBody
    {
        private readonly DeletedMethodDefinition _methodDef;
        private readonly ImmutableArray<byte> _ilBytes;
 
        public DeletedMethodBody(DeletedMethodDefinition methodDef, EmitContext context)
        {
            _methodDef = methodDef;
            _ilBytes = GetIL(context);
        }
 
        public ImmutableArray<ExceptionHandlerRegion> ExceptionRegions => ImmutableArray<ExceptionHandlerRegion>.Empty;
 
        public bool AreLocalsZeroed => false;
 
        public bool HasStackalloc => false;
 
        public ImmutableArray<ILocalDefinition> LocalVariables => ImmutableArray<ILocalDefinition>.Empty;
 
        public IMethodDefinition MethodDefinition => _methodDef;
 
        public StateMachineMoveNextBodyDebugInfo MoveNextBodyInfo => null;
 
        public ushort MaxStack => 8;
 
        public ImmutableArray<byte> IL => _ilBytes;
 
        public ImmutableArray<SequencePoint> SequencePoints => ImmutableArray<SequencePoint>.Empty;
 
        public bool HasDynamicLocalVariables => false;
 
        public ImmutableArray<LocalScope> LocalScopes => ImmutableArray<LocalScope>.Empty;
 
        public Cci.IImportScope ImportScope => null;
 
        public DebugId MethodId => default;
 
        public ImmutableArray<StateMachineHoistedLocalScope> StateMachineHoistedLocalScopes => ImmutableArray<StateMachineHoistedLocalScope>.Empty;
 
        public string StateMachineTypeName => null;
 
        public ImmutableArray<EncHoistedLocalInfo> StateMachineHoistedLocalSlots => default;
 
        public ImmutableArray<ITypeReference> StateMachineAwaiterSlots => default;
 
        public ImmutableArray<ClosureDebugInfo> ClosureDebugInfo => ImmutableArray<ClosureDebugInfo>.Empty;
 
        public ImmutableArray<LambdaDebugInfo> LambdaDebugInfo => ImmutableArray<LambdaDebugInfo>.Empty;
 
        public ImmutableArray<SourceSpan> CodeCoverageSpans => ImmutableArray<SourceSpan>.Empty;
 
        public StateMachineStatesDebugInfo StateMachineStatesDebugInfo => default;
 
        private static ImmutableArray<byte> GetIL(EmitContext context)
        {
            var missingMethodExceptionStringStringConstructor = context.Module.CommonCompilation.CommonGetWellKnownTypeMember(WellKnownMember.System_MissingMethodException__ctor);
            Debug.Assert(missingMethodExceptionStringStringConstructor is not null);
 
            var builder = new ILBuilder((ITokenDeferral)context.Module, null, OptimizationLevel.Debug, false);
            builder.EmitOpCode(System.Reflection.Metadata.ILOpCode.Newobj, 4);
            builder.EmitToken(missingMethodExceptionStringStringConstructor.GetCciAdapter(), context.SyntaxNode!, context.Diagnostics);
            builder.EmitThrow(isRethrow: false);
            builder.Realize();
 
            return builder.RealizedIL;
        }
 
        public bool IsPrimaryConstructor => false;
    }
}