// 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 Microsoft.CodeAnalysis.CodeStyle;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;

namespace Microsoft.CodeAnalysis.CSharp.RemoveConfusingSuppression;

[DiagnosticAnalyzer(LanguageNames.CSharp)]
internal sealed class CSharpRemoveConfusingSuppressionDiagnosticAnalyzer : AbstractBuiltInCodeStyleDiagnosticAnalyzer
{
    public CSharpRemoveConfusingSuppressionDiagnosticAnalyzer()
        : base(IDEDiagnosticIds.RemoveConfusingSuppressionForIsExpressionDiagnosticId,
               EnforceOnBuildValues.RemoveConfusingSuppressionForIsExpression,
               option: null,
               new LocalizableResourceString(nameof(CSharpAnalyzersResources.Remove_unnecessary_suppression_operator), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)),
               new LocalizableResourceString(nameof(CSharpAnalyzersResources.Suppression_operator_has_no_effect_and_can_be_misinterpreted), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)))
    {
    }

    public override DiagnosticAnalyzerCategory GetAnalyzerCategory() => DiagnosticAnalyzerCategory.SemanticSpanAnalysis;

    protected override void InitializeWorker(AnalysisContext context)
        => context.RegisterSyntaxNodeAction(AnalyzeSyntax, SyntaxKind.IsExpression, SyntaxKind.IsPatternExpression);

    private void AnalyzeSyntax(SyntaxNodeAnalysisContext context)
    {
        var node = context.Node;
        var left = node switch
        {
            BinaryExpressionSyntax binary => binary.Left,
            IsPatternExpressionSyntax isPattern => isPattern.Expression,
            _ => throw ExceptionUtilities.UnexpectedValue(node),
        };

        if (left.Kind() != SyntaxKind.SuppressNullableWarningExpression)
            return;

        context.ReportDiagnostic(DiagnosticHelper.Create(
            Descriptor,
            ((PostfixUnaryExpressionSyntax)left).OperatorToken.GetLocation(),
            NotificationOption2.Warning,
            context.Options,
            [node.GetLocation()],
            properties: null));
    }
}