// 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.Collections.Immutable;
using System.Globalization;
using System.Linq;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Shared.Extensions;

namespace Microsoft.CodeAnalysis.CodeFixes.Suppression;

internal static class SuppressionHelpers
{
    private const string SynthesizedExternalSourceDiagnosticTag = "SynthesizedExternalSourceDiagnostic";
    public static readonly ImmutableArray<string> SynthesizedExternalSourceDiagnosticCustomTags = [SynthesizedExternalSourceDiagnosticTag];

    public static bool CanBeSuppressed(Diagnostic diagnostic)
        => CanBeSuppressedOrUnsuppressed(diagnostic, checkCanBeSuppressed: true);

    public static bool CanBeSuppressedWithAttribute(Diagnostic diagnostic)
    {
        if (IsCompilerDiagnostic(diagnostic))
        {
            return false;
        }

        // IDE0055 cannot be suppressed with an attribute because the formatter implementation only adheres to
        // pragma-based source suppressions.
        return diagnostic.Id != IDEDiagnosticIds.FormattingDiagnosticId;
    }

    public static bool CanBeUnsuppressed(Diagnostic diagnostic)
        => CanBeSuppressedOrUnsuppressed(diagnostic, checkCanBeSuppressed: false);

    private static bool CanBeSuppressedOrUnsuppressed(Diagnostic diagnostic, bool checkCanBeSuppressed)
    {
        if (diagnostic.IsSuppressed == checkCanBeSuppressed ||
            IsNotConfigurableDiagnostic(diagnostic))
        {
            // Don't offer suppression fixes for:
            //   1. Diagnostics with a source suppression.
            //   2. Non-configurable diagnostics (includes compiler errors).
            return false;
        }

        switch (diagnostic.Severity)
        {
            case DiagnosticSeverity.Hidden:
                // Hidden diagnostics should never show up.
                return false;

            case DiagnosticSeverity.Error:
            case DiagnosticSeverity.Warning:
            case DiagnosticSeverity.Info:
                // We allow suppressions for all the remaining configurable, non-hidden diagnostics.
                // Note that compiler errors are not configurable by default, so only analyzer errors are suppressable.
                return true;

            default:
                throw ExceptionUtilities.UnexpectedValue(diagnostic.Severity);
        }
    }

    public static bool IsNotConfigurableDiagnostic(DiagnosticData diagnostic)
        => HasCustomTag(diagnostic.CustomTags, WellKnownDiagnosticTags.NotConfigurable);

    public static bool IsNotConfigurableDiagnostic(Diagnostic diagnostic)
        => HasCustomTag(diagnostic.Descriptor.ImmutableCustomTags(), WellKnownDiagnosticTags.NotConfigurable);

    public static bool IsCompilerDiagnostic(DiagnosticData diagnostic)
        => HasCustomTag(diagnostic.CustomTags, WellKnownDiagnosticTags.Compiler);

    public static bool IsCompilerDiagnostic(Diagnostic diagnostic)
        => HasCustomTag(diagnostic.Descriptor.ImmutableCustomTags(), WellKnownDiagnosticTags.Compiler);

    public static bool IsSynthesizedExternalSourceDiagnostic(DiagnosticData diagnostic)
        => HasCustomTag(diagnostic.CustomTags, SynthesizedExternalSourceDiagnosticTag);

    public static bool IsSynthesizedExternalSourceDiagnostic(Diagnostic diagnostic)
        => HasCustomTag(diagnostic.Descriptor.ImmutableCustomTags(), SynthesizedExternalSourceDiagnosticTag);

    public static bool HasCustomTag(ImmutableArray<string> customTags, string tagToFind)
        => customTags.Any(static (c, tagToFind) => CultureInfo.InvariantCulture.CompareInfo.Compare(c, tagToFind) == 0, tagToFind);
}