// 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.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.AddImport;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.Options;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
 
namespace Microsoft.CodeAnalysis.Editing;
 
public static class ImportAdder
{
    private static async ValueTask<IEnumerable<TextSpan>> GetSpansAsync(Document document, CancellationToken cancellationToken)
    {
        var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
        return [root.FullSpan];
    }
 
    private static async ValueTask<IEnumerable<TextSpan>> GetSpansAsync(Document document, SyntaxAnnotation annotation, CancellationToken cancellationToken)
    {
        var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
        return root.GetAnnotatedNodesAndTokens(annotation).Select(t => t.FullSpan);
    }
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document.
    /// </summary>
    public static async Task<Document> AddImportsAsync(Document document, OptionSet? options = null, CancellationToken cancellationToken = default)
        => await AddImportsFromSyntaxesAsync(document, await GetSpansAsync(document, cancellationToken).ConfigureAwait(false), options, cancellationToken).ConfigureAwait(false);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document within the span specified.
    /// </summary>
    public static Task<Document> AddImportsAsync(Document document, TextSpan span, OptionSet? options = null, CancellationToken cancellationToken = default)
        => AddImportsFromSyntaxesAsync(document, [span], options, cancellationToken);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document within the sub-trees annotated with the <see cref="SyntaxAnnotation"/>.
    /// </summary>
    public static async Task<Document> AddImportsAsync(Document document, SyntaxAnnotation annotation, OptionSet? options = null, CancellationToken cancellationToken = default)
        => await AddImportsFromSyntaxesAsync(document, await GetSpansAsync(document, annotation, cancellationToken).ConfigureAwait(false), options, cancellationToken).ConfigureAwait(false);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document within the spans specified.
    /// </summary>
    public static Task<Document> AddImportsAsync(Document document, IEnumerable<TextSpan> spans, OptionSet? options = null, CancellationToken cancellationToken = default)
        => AddImportsFromSyntaxesAsync(document, spans, options, cancellationToken);
 
    private static async Task<Document> AddImportsFromSyntaxesAsync(Document document, IEnumerable<TextSpan> spans, OptionSet? _, CancellationToken cancellationToken)
    {
        var service = document.GetLanguageService<ImportAdderService>();
        if (service == null)
        {
            return document;
        }
 
        // Since no public options affect the behavior we can ignore options parameter and pass no fallback options:
        var addImportOptions = await document.GetAddImportPlacementOptionsAsync(cancellationToken).ConfigureAwait(false);
        return await service.AddImportsAsync(document, spans, ImportAdderService.Strategy.AddImportsFromSyntaxes, addImportOptions, cancellationToken).ConfigureAwait(false);
    }
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document.
    /// </summary>
    internal static async Task<Document> AddImportsFromSyntaxesAsync(Document document, AddImportPlacementOptions options, CancellationToken cancellationToken)
        => await AddImportsFromSyntaxesAsync(document, await GetSpansAsync(document, cancellationToken).ConfigureAwait(false), options, cancellationToken).ConfigureAwait(false);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document within the sub-trees annotated with the <see cref="SyntaxAnnotation"/>.
    /// </summary>
    internal static async Task<Document> AddImportsFromSyntaxesAsync(Document document, SyntaxAnnotation annotation, AddImportPlacementOptions options, CancellationToken cancellationToken)
        => await AddImportsFromSyntaxesAsync(document, await GetSpansAsync(document, annotation, cancellationToken).ConfigureAwait(false), options, cancellationToken).ConfigureAwait(false);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document within the spans specified.
    /// </summary>
    internal static Task<Document> AddImportsFromSyntaxesAsync(Document document, IEnumerable<TextSpan> spans, AddImportPlacementOptions options, CancellationToken cancellationToken)
        => document.GetRequiredLanguageService<ImportAdderService>().AddImportsAsync(document, spans, ImportAdderService.Strategy.AddImportsFromSyntaxes, options, cancellationToken);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document.
    /// </summary>
    internal static async Task<Document> AddImportsFromSymbolAnnotationAsync(Document document, AddImportPlacementOptions options, CancellationToken cancellationToken)
        => await AddImportsFromSymbolAnnotationAsync(document, await GetSpansAsync(document, cancellationToken).ConfigureAwait(false), options, cancellationToken).ConfigureAwait(false);
 
    /// <summary>
    /// Adds namespace imports / using directives for namespace references found in the document within the sub-trees annotated with the <see cref="SyntaxAnnotation"/>.
    /// </summary>
    internal static async Task<Document> AddImportsFromSymbolAnnotationAsync(Document document, SyntaxAnnotation annotation, AddImportPlacementOptions options, CancellationToken cancellationToken)
        => await AddImportsFromSymbolAnnotationAsync(document, await GetSpansAsync(document, annotation, cancellationToken).ConfigureAwait(false), options, cancellationToken).ConfigureAwait(false);
 
    internal static Task<Document> AddImportsFromSymbolAnnotationAsync(Document document, IEnumerable<TextSpan> spans, AddImportPlacementOptions options, CancellationToken cancellationToken)
        => document.GetRequiredLanguageService<ImportAdderService>().AddImportsAsync(document, spans, ImportAdderService.Strategy.AddImportsFromSymbolAnnotations, options, cancellationToken);
}