// 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.Generic;
using System.Collections.Immutable;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.LanguageService;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Shared.Utilities;

namespace Microsoft.CodeAnalysis.AddAnonymousTypeMemberName;

internal abstract class AbstractAddAnonymousTypeMemberNameCodeFixProvider<
    TExpressionSyntax,
    TAnonymousObjectInitializer,
    TAnonymousObjectMemberDeclaratorSyntax>
    : SyntaxEditorBasedCodeFixProvider
    where TExpressionSyntax : SyntaxNode
    where TAnonymousObjectInitializer : SyntaxNode
    where TAnonymousObjectMemberDeclaratorSyntax : SyntaxNode
{
    protected abstract bool HasName(TAnonymousObjectMemberDeclaratorSyntax declarator);
    protected abstract TExpressionSyntax GetExpression(TAnonymousObjectMemberDeclaratorSyntax declarator);
    protected abstract TAnonymousObjectMemberDeclaratorSyntax WithName(TAnonymousObjectMemberDeclaratorSyntax declarator, SyntaxToken name);
    protected abstract IEnumerable<string> GetAnonymousObjectMemberNames(TAnonymousObjectInitializer initializer);

    public override async Task RegisterCodeFixesAsync(CodeFixContext context)
    {
        var document = context.Document;
        var cancellationToken = context.CancellationToken;

        var diagnostic = context.Diagnostics[0];
        var declarator = await GetMemberDeclaratorAsync(document, diagnostic, cancellationToken).ConfigureAwait(false);
        if (declarator == null)
        {
            return;
        }

        context.RegisterCodeFix(
            CodeAction.Create(
                CodeFixesResources.Add_member_name,
                GetDocumentUpdater(context),
                nameof(CodeFixesResources.Add_member_name)),
            context.Diagnostics);
    }

    private async Task<TAnonymousObjectMemberDeclaratorSyntax?> GetMemberDeclaratorAsync(
        Document document, Diagnostic diagnostic, CancellationToken cancellationToken)
    {
        var span = diagnostic.Location.SourceSpan;
        var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
        var node = root.FindNode(span, getInnermostNodeForTie: true) as TExpressionSyntax;
        if (node?.Span != span)
        {
            return null;
        }

        if (node.Parent is not TAnonymousObjectMemberDeclaratorSyntax declarator)
        {
            return null;
        }

        // Can't add a name of the declarator already has a name.
        if (HasName(declarator))
        {
            return null;
        }

        if (declarator.Parent is not TAnonymousObjectInitializer)
        {
            return null;
        }

        return declarator;
    }

    protected override async Task FixAllAsync(
        Document document, ImmutableArray<Diagnostic> diagnostics,
        SyntaxEditor editor, CancellationToken cancellationToken)
    {
        // If we're only introducing one name, then add the rename annotation to
        // it so the user can pick a better name if they want.
        var annotation = diagnostics.Length == 1 ? RenameAnnotation.Create() : null;

        var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
        foreach (var diagnostic in diagnostics)
        {
            await FixOneAsync(
                document, semanticModel, diagnostic,
                editor, annotation, cancellationToken).ConfigureAwait(false);
        }
    }

    private async Task FixOneAsync(
        Document document, SemanticModel semanticModel, Diagnostic diagnostic,
        SyntaxEditor editor, SyntaxAnnotation? annotation, CancellationToken cancellationToken)
    {
        var declarator = await GetMemberDeclaratorAsync(document, diagnostic, cancellationToken).ConfigureAwait(false);
        if (declarator == null)
        {
            return;
        }

        var semanticFacts = document.GetRequiredLanguageService<ISemanticFactsService>();
        var name = semanticFacts.GenerateNameForExpression(semanticModel, GetExpression(declarator), capitalize: true, cancellationToken);
        if (string.IsNullOrEmpty(name))
        {
            return;
        }

        var generator = document.GetRequiredLanguageService<SyntaxGeneratorInternal>();
        var syntaxFacts = document.GetRequiredLanguageService<ISyntaxFactsService>();
        editor.ReplaceNode(
            declarator,
            (current, _) =>
            {
                var currentDeclarator = (TAnonymousObjectMemberDeclaratorSyntax)current;
                var initializer = (TAnonymousObjectInitializer)currentDeclarator.GetRequiredParent();
                var existingNames = GetAnonymousObjectMemberNames(initializer);
                var anonymousType = current.Parent;
                var uniqueName = NameGenerator.EnsureUniqueness(name, existingNames, syntaxFacts.IsCaseSensitive);

                var nameToken = generator.Identifier(uniqueName);
                if (annotation != null)
                    nameToken = nameToken.WithAdditionalAnnotations(annotation);

                return WithName(currentDeclarator, nameToken);
            });
    }
}