// 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.Linq;
using Microsoft.CodeAnalysis.Editor.UnitTests.Utilities;
using Microsoft.CodeAnalysis.Test.Utilities;
using Microsoft.VisualStudio.Commanding;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Editor;
using Roslyn.Test.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.Editor.UnitTests
{
    [UseExportProvider]
    public abstract class AbstractTypingCommandHandlerTest<TCommandArgs> where TCommandArgs : CommandArgs
    {
        internal abstract ICommandHandler<TCommandArgs> GetCommandHandler(EditorTestWorkspace workspace);
 
        protected abstract EditorTestWorkspace CreateTestWorkspace(string initialMarkup);
 
        protected abstract (TCommandArgs, string insertionText) CreateCommandArgs(ITextView textView, ITextBuffer textBuffer);
 
        protected void Verify(string initialMarkup, string expectedMarkup, Action<EditorTestWorkspace> initializeWorkspace = null)
        {
            using var workspace = CreateTestWorkspace(initialMarkup);
            initializeWorkspace?.Invoke(workspace);
 
            var testDocument = workspace.Documents.Single();
            var view = testDocument.GetTextView();
            view.Caret.MoveTo(new SnapshotPoint(view.TextSnapshot, testDocument.CursorPosition.Value));
 
            var commandHandler = GetCommandHandler(workspace);
 
            var (args, insertionText) = CreateCommandArgs(view, view.TextBuffer);
            var nextHandler = CreateInsertTextHandler(view, insertionText);
 
            if (!commandHandler.ExecuteCommand(args, TestCommandExecutionContext.Create()))
            {
                nextHandler();
            }
 
            MarkupTestFile.GetPosition(expectedMarkup, out var expectedCode, out int expectedPosition);
 
            Assert.Equal(expectedCode, view.TextSnapshot.GetText());
 
            var caretPosition = view.Caret.Position.BufferPosition.Position;
            Assert.True(expectedPosition == caretPosition,
                string.Format("Caret positioned incorrectly. Should have been {0}, but was {1}.", expectedPosition, caretPosition));
        }
 
        protected void VerifyTabs(string initialMarkup, string expectedMarkup)
            => Verify(ReplaceTabTags(initialMarkup), ReplaceTabTags(expectedMarkup));
 
        private static string ReplaceTabTags(string markup) => markup.Replace("<tab>", "\t");
 
        private static Action CreateInsertTextHandler(ITextView textView, string text)
        {
            return () =>
            {
                var caretPosition = textView.Caret.Position.BufferPosition;
                var newSpanshot = textView.TextBuffer.Insert(caretPosition, text);
                textView.Caret.MoveTo(new SnapshotPoint(newSpanshot, (int)caretPosition + text.Length));
            };
        }
    }
}