// 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.Diagnostics;
using Microsoft.VisualStudio.InteractiveWindow;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Editor.OptionsExtensionMethods;
using Microsoft.VisualStudio.Text.Operations;
using Microsoft.VisualStudio.Utilities;
using System.Threading;
using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
using Microsoft.VisualStudio.Commanding;
using Microsoft.VisualStudio.Text.Editor.Commanding;
using Microsoft.CodeAnalysis.Options;
 
namespace Microsoft.CodeAnalysis.Interactive
{
    internal abstract class InteractiveCommandHandler :
        ICommandHandler<ExecuteInInteractiveCommandArgs>,
        ICommandHandler<CopyToInteractiveCommandArgs>
    {
        private readonly EditorOptionsService _editorOptionsService;
        private readonly IEditorOperationsFactoryService _editorOperationsFactoryService;
 
        protected InteractiveCommandHandler(
            IContentTypeRegistryService contentTypeRegistryService,
            EditorOptionsService editorOptionsService,
            IEditorOperationsFactoryService editorOperationsFactoryService)
        {
            ContentTypeRegistryService = contentTypeRegistryService;
            _editorOptionsService = editorOptionsService;
            _editorOperationsFactoryService = editorOperationsFactoryService;
        }
 
        protected IContentTypeRegistryService ContentTypeRegistryService { get; }
 
        protected abstract IInteractiveWindow OpenInteractiveWindow(bool focus);
 
        protected abstract ISendToInteractiveSubmissionProvider SendToInteractiveSubmissionProvider { get; }
 
        public string DisplayName => EditorFeaturesResources.Interactive;
 
        private string GetSelectedText(EditorCommandArgs args, CancellationToken cancellationToken)
        {
            var editorOptions = _editorOptionsService.Factory.GetOptions(args.SubjectBuffer);
            return SendToInteractiveSubmissionProvider.GetSelectedText(editorOptions, args, cancellationToken);
        }
 
        CommandState ICommandHandler<ExecuteInInteractiveCommandArgs>.GetCommandState(ExecuteInInteractiveCommandArgs args)
            => CommandState.Available;
 
        bool ICommandHandler<ExecuteInInteractiveCommandArgs>.ExecuteCommand(ExecuteInInteractiveCommandArgs args, CommandExecutionContext context)
        {
            var window = OpenInteractiveWindow(focus: false);
            using (context.OperationContext.AddScope(allowCancellation: true, EditorFeaturesWpfResources.Executing_selection_in_Interactive_Window))
            {
                var submission = GetSelectedText(args, context.OperationContext.UserCancellationToken);
                if (!string.IsNullOrWhiteSpace(submission))
                {
                    window.SubmitAsync([submission]);
                }
            }
 
            return true;
        }
 
        CommandState ICommandHandler<CopyToInteractiveCommandArgs>.GetCommandState(CopyToInteractiveCommandArgs args)
            => CommandState.Available;
 
        bool ICommandHandler<CopyToInteractiveCommandArgs>.ExecuteCommand(CopyToInteractiveCommandArgs args, CommandExecutionContext context)
        {
            var window = OpenInteractiveWindow(focus: true);
            var buffer = window.CurrentLanguageBuffer;
 
            if (buffer != null)
            {
                CopyToWindow(window, args, context);
            }
            else
            {
                Action action = null;
                action = new Action(() =>
                {
                    window.ReadyForInput -= action;
                    CopyToWindow(window, args, context);
                });
 
                window.ReadyForInput += action;
            }
 
            return true;
        }
 
        private void CopyToWindow(IInteractiveWindow window, CopyToInteractiveCommandArgs args, CommandExecutionContext context)
        {
            var buffer = window.CurrentLanguageBuffer;
            Debug.Assert(buffer != null);
 
            using (var edit = buffer.CreateEdit())
            using (var waitScope = context.OperationContext.AddScope(allowCancellation: true,
                EditorFeaturesWpfResources.Copying_selection_to_Interactive_Window))
            {
                var text = GetSelectedText(args, context.OperationContext.UserCancellationToken);
 
                // If the last line isn't empty in the existing submission buffer, we will prepend a
                // newline
                var lastLine = buffer.CurrentSnapshot.GetLineFromLineNumber(buffer.CurrentSnapshot.LineCount - 1);
                if (lastLine.Extent.Length > 0)
                {
                    var editorOptions = _editorOptionsService.Factory.GetOptions(args.SubjectBuffer);
                    text = editorOptions.GetNewLineCharacter() + text;
                }
 
                edit.Insert(buffer.CurrentSnapshot.Length, text);
                edit.Apply();
            }
 
            // Move the caret to the end
            var editorOperations = _editorOperationsFactoryService.GetEditorOperations(window.TextView);
            var endPoint = new VirtualSnapshotPoint(window.TextView.TextBuffer.CurrentSnapshot, window.TextView.TextBuffer.CurrentSnapshot.Length);
            editorOperations.SelectAndMoveCaret(endPoint, endPoint);
        }
    }
}