// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.

using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.Editor.Shared.Options;
using Microsoft.CodeAnalysis.Notification;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.Text.Operations;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.Editor.Implementation.RenameTracking
{
    internal sealed partial class RenameTrackingTaggerProvider
    {
        private class RenameTrackingCodeAction : CodeAction
        {
            private readonly string _title;
            private readonly Document _document;
            private readonly IEnumerable<IRefactorNotifyService> _refactorNotifyServices;
            private readonly ITextUndoHistoryRegistry _undoHistoryRegistry;
            private RenameTrackingCommitter _renameTrackingCommitter;

            public RenameTrackingCodeAction(Document document, string title, IEnumerable<IRefactorNotifyService> refactorNotifyServices, ITextUndoHistoryRegistry undoHistoryRegistry)
            {
                _document = document;
                _title = title;
                _refactorNotifyServices = refactorNotifyServices;
                _undoHistoryRegistry = undoHistoryRegistry;
            }

            public override string Title => _title;

            protected override Task<IEnumerable<CodeActionOperation>> ComputeOperationsAsync(CancellationToken cancellationToken)
            {
                // Invoked directly without previewing.
                if (_renameTrackingCommitter == null)
                {
                    if (!TryInitializeRenameTrackingCommitter(cancellationToken))
                    {
                        return SpecializedTasks.EmptyEnumerable<CodeActionOperation>();
                    }
                }

                var committerOperation = new RenameTrackingCommitterOperation(_renameTrackingCommitter);
                return Task.FromResult(SpecializedCollections.SingletonEnumerable(committerOperation as CodeActionOperation));
            }

            protected override async Task<IEnumerable<CodeActionOperation>> ComputePreviewOperationsAsync(CancellationToken cancellationToken)
            {
                var documentOptions = await _document.GetOptionsAsync(cancellationToken).ConfigureAwait(false);
                if (!documentOptions.GetOption(FeatureOnOffOptions.RenameTrackingPreview) ||
                    !TryInitializeRenameTrackingCommitter(cancellationToken))
                {
                    return await SpecializedTasks.EmptyEnumerable<CodeActionOperation>().ConfigureAwait(false);
                }

                var solutionSet = await _renameTrackingCommitter.RenameSymbolAsync(cancellationToken).ConfigureAwait(false);

                return SpecializedCollections.SingletonEnumerable(
                    (CodeActionOperation)new ApplyChangesOperation(solutionSet.RenamedSolution));
            }

            private bool TryInitializeRenameTrackingCommitter(CancellationToken cancellationToken)
            {
                if (_document.TryGetText(out var text))
                {
                    var textBuffer = text.Container.GetTextBuffer();
                    if (textBuffer.Properties.TryGetProperty(typeof(StateMachine), out StateMachine stateMachine))
                    {
                        if (!stateMachine.CanInvokeRename(out var trackingSession, cancellationToken: cancellationToken))
                        {
                            // The rename tracking could be dismissed while a codefix is still cached
                            // in the lightbulb. If this happens, do not perform the rename requested
                            // and instead let the user know their fix will not be applied. 
                            _document.Project.Solution.Workspace.Services.GetService<INotificationService>()
                                ?.SendNotification(EditorFeaturesResources.The_rename_tracking_session_was_cancelled_and_is_no_longer_available, severity: NotificationSeverity.Error);
                            return false;
                        }

                        var snapshotSpan = stateMachine.TrackingSession.TrackingSpan.GetSpan(stateMachine.Buffer.CurrentSnapshot);
                        var newName = snapshotSpan.GetText();
                        var displayText = string.Format(EditorFeaturesResources.Rename_0_to_1, stateMachine.TrackingSession.OriginalName, newName);
                        _renameTrackingCommitter = new RenameTrackingCommitter(stateMachine, snapshotSpan, _refactorNotifyServices, _undoHistoryRegistry, displayText);
                        return true;
                    }
                }

                return false;
            }

            private sealed class RenameTrackingCommitterOperation : CodeActionOperation
            {
                private readonly RenameTrackingCommitter _committer;

                public RenameTrackingCommitterOperation(RenameTrackingCommitter committer)
                {
                    _committer = committer;
                }

                public override void Apply(Workspace workspace, CancellationToken cancellationToken)
                {
                    _committer.Commit(cancellationToken);
                }
            }
        }
    }
}
