// 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.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CSharp.CodeGeneration;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.PooledObjects;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.CSharp.ExtractMethod;
 
internal sealed partial class CSharpMethodExtractor
{
    private abstract partial class CSharpCodeGenerator
    {
        public sealed class MultipleStatementsCodeGenerator(
            CSharpSelectionResult selectionResult,
            AnalyzerResult analyzerResult,
            CSharpCodeGenerationOptions options,
            bool localFunction) : CSharpCodeGenerator(selectionResult, analyzerResult, options, localFunction)
        {
            protected override SyntaxToken CreateMethodName()
                => GenerateMethodNameForStatementGenerators();
 
            protected override ImmutableArray<StatementSyntax> GetInitialStatementsForMethodDefinitions()
            {
                var firstSeen = false;
                var firstStatementUnderContainer = this.SelectionResult.GetFirstStatementUnderContainer();
                var lastStatementUnderContainer = this.SelectionResult.GetLastStatementUnderContainer();
 
                using var _ = ArrayBuilder<StatementSyntax>.GetInstance(out var list);
                foreach (var statement in GetStatementsFromContainer(firstStatementUnderContainer.Parent))
                {
                    // reset first seen
                    if (!firstSeen)
                    {
                        firstSeen = statement == firstStatementUnderContainer;
                    }
 
                    // continue until we see the first statement
                    if (!firstSeen)
                    {
                        continue;
                    }
 
                    list.Add(statement);
 
                    // exit if we see last statement
                    if (statement == lastStatementUnderContainer)
                    {
                        break;
                    }
                }
 
                return list.ToImmutableAndClear();
            }
 
            private static IEnumerable<StatementSyntax> GetStatementsFromContainer(SyntaxNode node)
            {
                Contract.ThrowIfNull(node);
                Contract.ThrowIfFalse(node.IsStatementContainerNode());
 
                return node switch
                {
                    BlockSyntax blockNode => blockNode.Statements,
                    SwitchSectionSyntax switchSectionNode => switchSectionNode.Statements,
                    GlobalStatementSyntax globalStatement => ((CompilationUnitSyntax)globalStatement.Parent).Members.OfType<GlobalStatementSyntax>().Select(globalStatement => globalStatement.Statement),
                    _ => throw ExceptionUtilities.UnexpectedValue(node),
                };
            }
 
            protected override SyntaxNode GetFirstStatementOrInitializerSelectedAtCallSite()
                => this.SelectionResult.GetFirstStatementUnderContainer();
 
            protected override SyntaxNode GetLastStatementOrInitializerSelectedAtCallSite()
                => this.SelectionResult.GetLastStatementUnderContainer();
 
            protected override Task<SyntaxNode> GetStatementOrInitializerContainingInvocationToExtractedMethodAsync(CancellationToken cancellationToken)
            {
                var statement = GetStatementContainingInvocationToExtractedMethodWorker();
                return Task.FromResult<SyntaxNode>(statement.WithAdditionalAnnotations(CallSiteAnnotation));
            }
        }
    }
}