// 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.
 
using System;
using System.Collections.Immutable;
using System.Composition;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.CodeAnalysis.CSharp.UseTupleSwap;
 
using static SyntaxFactory;
 
[ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.UseTupleSwap), Shared]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal sealed partial class CSharpUseTupleSwapCodeFixProvider() : SyntaxEditorBasedCodeFixProvider
{
    public override ImmutableArray<string> FixableDiagnosticIds { get; }
        = [IDEDiagnosticIds.UseTupleSwapDiagnosticId];
 
    public override Task RegisterCodeFixesAsync(CodeFixContext context)
    {
        RegisterCodeFix(context, CSharpAnalyzersResources.Use_tuple_to_swap_values, nameof(CSharpAnalyzersResources.Use_tuple_to_swap_values));
        return Task.CompletedTask;
    }
 
    protected override Task FixAllAsync(
        Document document, ImmutableArray<Diagnostic> diagnostics,
        SyntaxEditor editor, CancellationToken cancellationToken)
    {
        foreach (var diagnostic in diagnostics)
            FixOne(editor, diagnostic, cancellationToken);
 
        return Task.CompletedTask;
    }
 
    private static void FixOne(
        SyntaxEditor editor, Diagnostic diagnostic, CancellationToken cancellationToken)
    {
        var localDeclarationStatement = (LocalDeclarationStatementSyntax)diagnostic.AdditionalLocations[0].FindNode(getInnermostNodeForTie: true, cancellationToken);
        // `expr_a = expr_b`;
        var firstAssignmentStatement = (ExpressionStatementSyntax)diagnostic.AdditionalLocations[1].FindNode(getInnermostNodeForTie: true, cancellationToken);
        var secondAssignmentStatement = (ExpressionStatementSyntax)diagnostic.AdditionalLocations[2].FindNode(getInnermostNodeForTie: true, cancellationToken);
 
        editor.RemoveNode(firstAssignmentStatement);
        editor.RemoveNode(secondAssignmentStatement);
 
        var assignment = (AssignmentExpressionSyntax)firstAssignmentStatement.Expression;
        var exprA = assignment.Left.WalkDownParentheses().WithoutTrivia();
        var exprB = assignment.Right.WalkDownParentheses().WithoutTrivia();
 
        var tupleAssignmentStatement = ExpressionStatement(AssignmentExpression(
            SyntaxKind.SimpleAssignmentExpression,
            TupleExpression([Argument(exprB), Argument(exprA)]),
            TupleExpression([Argument(exprA), Argument(exprB)])));
 
        editor.ReplaceNode(localDeclarationStatement, tupleAssignmentStatement.WithTriviaFrom(localDeclarationStatement));
    }
}