// 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.
 
#nullable disable
 
using System;
using System.Threading;
using System.Threading.Tasks;
 
namespace Microsoft.CodeAnalysis.Editing
{
    /// <summary>
    /// An editor for making changes to a document's syntax tree. 
    /// </summary>
    public class DocumentEditor : SyntaxEditor
    {
        private readonly Document _document;
        private readonly SemanticModel _model;
 
        private DocumentEditor(Document document, SemanticModel model, SyntaxNode root)
            : base(root, document.Project.Solution.Services)
        {
            _document = document;
            _model = model;
        }
 
        /// <summary>
        /// Creates a new <see cref="DocumentEditor"/> instance.
        /// </summary>
        public static async Task<DocumentEditor> CreateAsync(Document document, CancellationToken cancellationToken = default)
        {
            if (document == null)
            {
                throw new ArgumentNullException(nameof(document));
            }
 
            var model = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
            var root = model.SyntaxTree.GetRoot(cancellationToken);
            return new DocumentEditor(document, model, root);
        }
 
        /// <summary>
        /// The <see cref="Document"/> specified when the editor was first created.
        /// </summary>
        public Document OriginalDocument => _document;
 
        /// <summary>
        /// The <see cref="CodeAnalysis.SemanticModel"/> of the original document.
        /// </summary>
        public SemanticModel SemanticModel => _model;
 
        /// <summary>
        /// Returns the changed <see cref="Document"/>.
        /// </summary>
        public Document GetChangedDocument()
            => _document.WithSyntaxRoot(this.GetChangedRoot());
    }
}