// 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;
using System.Linq;
using Microsoft.CodeAnalysis.Editor.UnitTests.Utilities;
using Microsoft.CodeAnalysis.Test.Utilities;
using Microsoft.CodeAnalysis.Testing;
using Microsoft.VisualStudio.Commanding;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Editor;
using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
using Roslyn.Test.Utilities;
using Roslyn.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.Editor.UnitTests.CompleteStatement
{
    [UseExportProvider]
    public abstract class AbstractCompleteStatementTests
    {
        internal const char Semicolon = ';';
 
        internal abstract ICommandHandler GetCommandHandler(EditorTestWorkspace workspace);
 
        protected abstract EditorTestWorkspace CreateTestWorkspace(string code);
 
        /// <summary>
        /// Verify that typing a semicolon at the location in <paramref name="initialMarkup"/> 
        /// marked with 
        ///     - one or more <c>$$</c> for caret positions to test
        ///     - or, <c>[|</c> and <c>|]</c> for testing a selected span
        /// does not perform any special "complete statement" operations, e.g. inserting missing 
        /// delimiters or moving the caret prior to the semicolon character insertion. In other words, 
        /// statement completion does not impact typing behavior for the case.
        /// </summary>
        protected void VerifyNoSpecialSemicolonHandling(string initialMarkup)
        {
            TestFileMarkupParser.GetPositionsAndSpans(initialMarkup, out var output, out var positions, out var spans);
            Contract.ThrowIfTrue(positions.IsEmpty && spans.IsEmpty, "Expected at least one test position");
            Contract.ThrowIfTrue(!positions.IsEmpty && !spans.IsEmpty, "Cannot test positions and spans at the same time");
 
            foreach (var position in positions)
            {
                VerifyTypingSemicolon(
                    output.Insert(position, "$$"),
                    output.Insert(position, ";$$"));
            }
 
            if (!spans.IsEmpty)
            {
                // Only allow unnamed spans for these tests
                Contract.ThrowIfFalse(spans.Keys.ToArray() is [""]);
 
                foreach (var span in spans[""])
                {
                    // Insert the end text first so the second insertion position doesn't require an offset
                    VerifyTypingSemicolon(
                        output.Insert(span.End, "|]").Insert(span.Start, "[|"),
                        output.Insert(span.End, ";$$|]").Insert(span.Start, "[|"));
                }
            }
        }
 
        /// <summary>
        /// Verify that typing a semicolon at the location in <paramref name="initialMarkup"/> marked with <c>$$</c>
        /// produces the result in <paramref name="expectedMarkup"/>. The final caret location in
        /// <paramref name="expectedMarkup"/> is marked with <c>$$</c>.
        /// </summary>
        protected void VerifyTypingSemicolon(string initialMarkup, string expectedMarkup)
        {
            Verify(initialMarkup, expectedMarkup, ExecuteTest);
        }
 
        protected void ExecuteTest(IWpfTextView view, EditorTestWorkspace workspace)
        {
            var commandHandler = GetCommandHandler(workspace);
 
            var commandArgs = new TypeCharCommandArgs(view, view.TextBuffer, Semicolon);
            var nextHandler = CreateInsertTextHandler(view, Semicolon.ToString());
 
            commandHandler.ExecuteCommand(commandArgs, nextHandler, TestCommandExecutionContext.Create());
        }
 
        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, caretPosition + text.Length));
            };
        }
 
        protected void Verify(string initialMarkup, string expectedMarkup,
            Action<IWpfTextView, EditorTestWorkspace> execute,
            Action<EditorTestWorkspace>? setOptions = null)
        {
            using var workspace = CreateTestWorkspace(initialMarkup);
            var testDocument = workspace.Documents.Single();
 
            Assert.True(testDocument.CursorPosition.HasValue || testDocument.SelectedSpans.Any(), "No caret position or selected spans are set!");
            var startCaretPosition = testDocument.CursorPosition ?? testDocument.SelectedSpans.Last().End;
 
            var view = testDocument.GetTextView();
 
            if (testDocument.SelectedSpans.Any())
            {
                var selectedSpan = testDocument.SelectedSpans[0];
 
                var isReversed = selectedSpan.Start == startCaretPosition;
 
                view.Selection.Select(new SnapshotSpan(view.TextSnapshot, selectedSpan.Start, selectedSpan.Length), isReversed);
            }
 
            view.Caret.MoveTo(new SnapshotPoint(view.TextSnapshot, startCaretPosition));
 
            setOptions?.Invoke(workspace);
 
            execute(view, workspace);
            TestFileMarkupParser.GetPosition(expectedMarkup, out var expectedCode, out var expectedPosition);
 
            AssertEx.EqualOrDiff(expectedCode, view.TextSnapshot.GetText());
 
            var endCaretPosition = view.Caret.Position.BufferPosition.Position;
            Assert.True(expectedPosition == endCaretPosition,
                string.Format("Caret positioned incorrectly. Should have been {0}, but was {1}.", expectedPosition, endCaretPosition));
        }
    }
}