// 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.Composition;
using System.Diagnostics.CodeAnalysis;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeRefactorings;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.LanguageService;
using Microsoft.CodeAnalysis.PickMembers;
using Microsoft.CodeAnalysis.Shared.Extensions;

namespace Microsoft.CodeAnalysis.GenerateOverrides;

[ExportCodeRefactoringProvider(LanguageNames.CSharp, LanguageNames.VisualBasic,
    Name = PredefinedCodeRefactoringProviderNames.GenerateOverrides), Shared]
[ExtensionOrder(After = PredefinedCodeRefactoringProviderNames.AddConstructorParametersFromMembers)]
[SuppressMessage("RoslynDiagnosticsReliability", "RS0034:Exported parts should have [ImportingConstructor]", Justification = "Used incorrectly by tests")]
internal sealed partial class GenerateOverridesCodeRefactoringProvider(IPickMembersService? pickMembersService) : CodeRefactoringProvider
{
    private readonly IPickMembersService? _pickMembersService_forTestingPurposes = pickMembersService;

    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public GenerateOverridesCodeRefactoringProvider() : this(null)
    {
    }

    public override async Task ComputeRefactoringsAsync(CodeRefactoringContext context)
    {
        var (document, textSpan, cancellationToken) = context;
        var helpers = document.GetRequiredLanguageService<IRefactoringHelpersService>();
        var sourceText = await document.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
        var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);

        // We offer the refactoring when the user is either on the header of a class/struct,
        // or if they're between any members of a class/struct and are on a blank line.
        if (!helpers.IsOnTypeHeader(root, textSpan.Start, out var typeDeclaration) &&
            !helpers.IsBetweenTypeMembers(sourceText, root, textSpan.Start, out typeDeclaration))
        {
            return;
        }

        var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);

        // Only supported on classes/structs.
        var containingType = (INamedTypeSymbol)semanticModel.GetRequiredDeclaredSymbol(typeDeclaration, cancellationToken);

        var overridableMembers = containingType.GetOverridableMembers(cancellationToken);
        if (overridableMembers.Length == 0)
            return;

        context.RegisterRefactoring(
            new GenerateOverridesWithDialogCodeAction(
                this, document, textSpan, containingType, overridableMembers),
            typeDeclaration.Span);
    }
}