// 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.Diagnostics.CodeAnalysis;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Editor.Host;
using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
using Microsoft.CodeAnalysis.Editor.Undo;
using Microsoft.CodeAnalysis.Notification;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.VisualStudio.Commanding;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Editor;
using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
using Microsoft.VisualStudio.Utilities;
 
namespace Microsoft.CodeAnalysis.ChangeSignature;
 
internal abstract class AbstractChangeSignatureCommandHandler(IThreadingContext threadingContext)
    : ICommandHandler<ReorderParametersCommandArgs>,
      ICommandHandler<RemoveParametersCommandArgs>
{
    private readonly IThreadingContext _threadingContext = threadingContext;
 
    public string DisplayName => EditorFeaturesResources.Change_Signature;
 
    public CommandState GetCommandState(ReorderParametersCommandArgs args)
        => GetCommandState(args.SubjectBuffer);
 
    public CommandState GetCommandState(RemoveParametersCommandArgs args)
        => GetCommandState(args.SubjectBuffer);
 
    private static CommandState GetCommandState(ITextBuffer subjectBuffer)
        => IsAvailable(subjectBuffer, out _) ? CommandState.Available : CommandState.Unspecified;
 
    public bool ExecuteCommand(RemoveParametersCommandArgs args, CommandExecutionContext context)
        => ExecuteCommand(args.TextView, args.SubjectBuffer, context);
 
    public bool ExecuteCommand(ReorderParametersCommandArgs args, CommandExecutionContext context)
        => ExecuteCommand(args.TextView, args.SubjectBuffer, context);
 
    private static bool IsAvailable(ITextBuffer subjectBuffer, [NotNullWhen(true)] out Workspace? workspace)
        => subjectBuffer.TryGetWorkspace(out workspace) &&
           workspace.CanApplyChange(ApplyChangesKind.ChangeDocument) &&
           subjectBuffer.SupportsRefactorings();
 
    private bool ExecuteCommand(ITextView textView, ITextBuffer subjectBuffer, CommandExecutionContext context)
    {
        using (context.OperationContext.AddScope(allowCancellation: true, FeaturesResources.Change_signature))
        {
            return _threadingContext.JoinableTaskFactory.Run(() => ExecuteCommandAsync(textView, subjectBuffer, context));
        }
    }
 
    private static async Task<bool> ExecuteCommandAsync(ITextView textView, ITextBuffer subjectBuffer, CommandExecutionContext context)
    {
        if (!IsAvailable(subjectBuffer, out var workspace))
            return false;
 
        var caretPoint = textView.GetCaretPoint(subjectBuffer);
        if (!caretPoint.HasValue)
            return false;
 
        var document = await subjectBuffer.CurrentSnapshot.GetFullyLoadedOpenDocumentInCurrentContextWithChangesAsync(context.OperationContext).ConfigureAwait(true);
        if (document == null)
            return false;
 
        var changeSignatureService = document.GetRequiredLanguageService<AbstractChangeSignatureService>();
 
        var cancellationToken = context.OperationContext.UserCancellationToken;
 
        // TODO: Make asynchronous and avoid expensive semantic operations on UI thread:
        // https://github.com/dotnet/roslyn/issues/62135
 
        // Async operation to determine the change signature
        var changeSignatureContext = await changeSignatureService.GetChangeSignatureContextAsync(
            document,
            caretPoint.Value.Position,
            restrictToDeclarations: false,
            cancellationToken).ConfigureAwait(true);
 
        // UI thread bound operation to show the change signature dialog.
        var changeSignatureOptions = AbstractChangeSignatureService.GetChangeSignatureOptions(changeSignatureContext);
 
        // Async operation to compute the new solution created from the specified options.
        var result = await changeSignatureService.ChangeSignatureWithContextAsync(
            changeSignatureContext, changeSignatureOptions, cancellationToken).ConfigureAwait(true);
 
        // UI thread bound operation to show preview changes dialog / show error message, then apply the solution changes (if applicable).
        HandleResult(result, document.Project.Solution, workspace, context);
 
        return true;
    }
 
    private static void HandleResult(ChangeSignatureResult result, Solution oldSolution, Workspace workspace, CommandExecutionContext context)
    {
        var notificationService = workspace.Services.GetRequiredService<INotificationService>();
        if (!result.Succeeded)
        {
            if (result.ChangeSignatureFailureKind != null)
            {
                ShowError(result.ChangeSignatureFailureKind.Value, context.OperationContext, notificationService);
            }
 
            return;
        }
 
        if (result.ConfirmationMessage != null && !notificationService.ConfirmMessageBox(result.ConfirmationMessage, severity: NotificationSeverity.Warning))
        {
            return;
        }
 
        var finalSolution = result.UpdatedSolution;
 
        var previewService = workspace.Services.GetService<IPreviewDialogService>();
        if (previewService != null && result.PreviewChanges)
        {
            // We are about to show a modal UI dialog so we should take over the command execution
            // wait context. That means the command system won't attempt to show its own wait dialog 
            // and also will take it into consideration when measuring command handling duration.
            context.OperationContext.TakeOwnership();
            finalSolution = previewService.PreviewChanges(
                string.Format(EditorFeaturesResources.Preview_Changes_0, EditorFeaturesResources.Change_Signature),
                "vs.csharp.refactoring.preview",
                EditorFeaturesResources.Change_Signature_colon,
                result.Name,
                result.Glyph.GetValueOrDefault(),
                result.UpdatedSolution,
                oldSolution);
        }
 
        if (finalSolution == null)
        {
            // User clicked cancel.
            return;
        }
 
        using var workspaceUndoTransaction = workspace.OpenGlobalUndoTransaction(FeaturesResources.Change_signature);
        if (workspace.TryApplyChanges(finalSolution))
        {
            workspaceUndoTransaction.Commit();
        }
 
        // TODO: handle failure
    }
 
    private static void ShowError(ChangeSignatureFailureKind reason, IUIThreadOperationContext operationContext, INotificationService notificationService)
    {
        switch (reason)
        {
            case ChangeSignatureFailureKind.DefinedInMetadata:
                ShowMessage(FeaturesResources.The_member_is_defined_in_metadata, NotificationSeverity.Error, operationContext, notificationService);
                break;
            case ChangeSignatureFailureKind.IncorrectKind:
                ShowMessage(FeaturesResources.You_can_only_change_the_signature_of_a_constructor_indexer_method_or_delegate, NotificationSeverity.Error, operationContext, notificationService);
                break;
        }
 
        static void ShowMessage(string errorMessage, NotificationSeverity severity, IUIThreadOperationContext operationContext, INotificationService notificationService)
        {
            operationContext.TakeOwnership();
            notificationService.SendNotification(errorMessage, severity: severity);
        }
    }
}