// 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.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.AddImport;

/// <summary>
/// Code action we use when just adding a using, possibly with a project or metadata reference.  We don't use the
/// standard code action types because we want to do things like show a glyph if this will do more than just add an
/// import.
/// </summary>
internal abstract class AddImportCodeAction : CodeAction
{
    protected readonly AddImportFixData FixData;
    private readonly CodeActionPriority _priority;

    public override string Title { get; }
    public sealed override ImmutableArray<string> Tags { get; }

    public sealed override string EquivalenceKey => Title;

    /// <summary>
    /// The <see cref="Document"/> we started the add-import analysis in.
    /// </summary>
    protected readonly Document OriginalDocument;

    /// <summary>
    /// The changes to make to <see cref="OriginalDocument"/> to add the import.
    /// </summary>
    private readonly ImmutableArray<TextChange> _textChanges;

    protected AddImportCodeAction(
        Document originalDocument,
        AddImportFixData fixData,
        ImmutableArray<string> additionalTags)
    {
        OriginalDocument = originalDocument;
        FixData = fixData;

        Title = fixData.Title;
        Tags = fixData.Tags.ToImmutableArrayOrEmpty().AddRange(additionalTags);
        _priority = fixData.Priority;
        _textChanges = fixData.TextChanges.ToImmutableArrayOrEmpty();

        // Backdoor that allows this provider to use the high-priority bucket.
        this.CustomTags = this.CustomTags.Add(CodeAction.CanBeHighPriorityTag);
    }

    protected sealed override CodeActionPriority ComputePriority()
        => _priority;

    protected async Task<Document> GetUpdatedDocumentAsync(CancellationToken cancellationToken)
    {
        var oldText = await OriginalDocument.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
        var newText = oldText.WithChanges(_textChanges);
        var newDocument = OriginalDocument.WithText(newText);

        return newDocument;
    }
}