// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Threading;
using Microsoft.AspNetCore.Razor.Language;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Razor;
using Microsoft.CodeAnalysis.Razor.ProjectSystem;
using Microsoft.VisualStudio.Test;
using Microsoft.VisualStudio.Text;
using Moq;
using Xunit;

namespace Microsoft.VisualStudio.Editor.Razor
{
    public class DefaultVisualStudioRazorParserTest : ForegroundDispatcherTestBase
    {
        public DefaultVisualStudioRazorParserTest()
        {
            Workspace = TestWorkspace.Create();
            ProjectSnapshot = new EphemeralProjectSnapshot(Workspace.Services, "c:\\SomeProject.csproj");

            var engine = RazorProjectEngine.Create(RazorConfiguration.Default, RazorProjectFileSystem.Empty);
            ProjectEngineFactory = Mock.Of<ProjectSnapshotProjectEngineFactory>(
                f => f.Create(
                    It.IsAny<ProjectSnapshot>(),
                    It.IsAny<RazorProjectFileSystem>(),
                    It.IsAny<Action<RazorProjectEngineBuilder>>()) == engine);
        }

        private ProjectSnapshot ProjectSnapshot { get; }

        private ProjectSnapshotProjectEngineFactory ProjectEngineFactory { get; }

        private Workspace Workspace { get; }

        private VisualStudioDocumentTracker CreateDocumentTracker(bool isSupportedProject = true)
        {
            var documentTracker = Mock.Of<VisualStudioDocumentTracker>(tracker =>
            tracker.TextBuffer == new TestTextBuffer(new StringTextSnapshot(string.Empty)) &&
                tracker.ProjectPath == "c:\\SomeProject.csproj" &&
                tracker.ProjectSnapshot == ProjectSnapshot &&
                tracker.FilePath == "c:\\SomeFilePath.cshtml" &&
                tracker.IsSupportedProject == isSupportedProject);

            return documentTracker;
        }

        [ForegroundFact]
        public void ReparseOnForeground_NoopsIfDisposed()
        {
            // Arrange
            var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>());
            parser.Dispose();

            // Act & Assert
            parser.ReparseOnForeground(null);
        }

        [ForegroundFact]
        public void OnIdle_NoopsIfDisposed()
        {
            // Arrange
            var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>());
            parser.Dispose();

            // Act & Assert
            parser.OnIdle(null);
        }

        [ForegroundFact]
        public void OnDocumentStructureChanged_NoopsIfDisposed()
        {
            // Arrange
            var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>());
            parser.Dispose();

            // Act & Assert
            parser.OnDocumentStructureChanged(new object());
        }

        [ForegroundFact]
        public void OnDocumentStructureChanged_IgnoresEditsThatAreOld()
        {
            // Arrange
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                var called = false;
                parser.DocumentStructureChanged += (sender, e) => called = true;
                parser._latestChangeReference = new BackgroundParser.ChangeReference(null, new StringTextSnapshot(string.Empty));
                var args = new BackgroundParserResultsReadyEventArgs(
                    new BackgroundParser.ChangeReference(new SourceChange(0, 0, string.Empty), new StringTextSnapshot(string.Empty)),
                    TestRazorCodeDocument.CreateEmpty());

                // Act
                parser.OnDocumentStructureChanged(args);

                // Assert
                Assert.False(called);
            }
        }

        [ForegroundFact]
        public void OnDocumentStructureChanged_FiresForLatestTextBufferEdit()
        {
            // Arrange
            var documentTracker = CreateDocumentTracker();
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                documentTracker,
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                var called = false;
                parser.DocumentStructureChanged += (sender, e) => called = true;
                var latestChange = new SourceChange(0, 0, string.Empty);
                var latestSnapshot = documentTracker.TextBuffer.CurrentSnapshot;
                parser._latestChangeReference = new BackgroundParser.ChangeReference(latestChange, latestSnapshot);
                var codeDocument = TestRazorCodeDocument.CreateEmpty();
                codeDocument.SetSyntaxTree(RazorSyntaxTree.Parse(TestRazorSourceDocument.Create()));
                var args = new BackgroundParserResultsReadyEventArgs(
                    parser._latestChangeReference,
                    codeDocument);

                // Act
                parser.OnDocumentStructureChanged(args);

                // Assert
                Assert.True(called);
            }
        }

        [ForegroundFact]
        public void OnDocumentStructureChanged_FiresForOnlyLatestTextBufferReparseEdit()
        {
            // Arrange
            var documentTracker = CreateDocumentTracker();
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                documentTracker,
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                var called = false;
                parser.DocumentStructureChanged += (sender, e) => called = true;
                var latestSnapshot = documentTracker.TextBuffer.CurrentSnapshot;
                parser._latestChangeReference = new BackgroundParser.ChangeReference(null, latestSnapshot);
                var codeDocument = TestRazorCodeDocument.CreateEmpty();
                codeDocument.SetSyntaxTree(RazorSyntaxTree.Parse(TestRazorSourceDocument.Create()));
                var badArgs = new BackgroundParserResultsReadyEventArgs(
                    // This is a different reparse edit, shouldn't be fired for this call
                    new BackgroundParser.ChangeReference(null, latestSnapshot),
                    codeDocument);
                var goodArgs = new BackgroundParserResultsReadyEventArgs(
                    parser._latestChangeReference,
                    codeDocument);

                // Act - 1
                parser.OnDocumentStructureChanged(badArgs);

                // Assert - 1
                Assert.False(called);

                // Act - 2
                parser.OnDocumentStructureChanged(goodArgs);

                // Assert - 2
                Assert.True(called);
            }
        }

        [ForegroundFact]
        public void StartIdleTimer_DoesNotRestartTimerWhenAlreadyRunning()
        {
            // Arrange
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>())
            {
                BlockBackgroundIdleWork = new ManualResetEventSlim(),
                IdleDelay = TimeSpan.FromSeconds(5)
            })
            {
                parser.StartIdleTimer();
                using (var currentTimer = parser._idleTimer)
                {

                    // Act
                    parser.StartIdleTimer();
                    var afterTimer = parser._idleTimer;

                    // Assert
                    Assert.NotNull(currentTimer);
                    Assert.Same(currentTimer, afterTimer);
                }
            }
        }

        [ForegroundFact]
        public void StopIdleTimer_StopsTimer()
        {
            // Arrange
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>())
            {
                BlockBackgroundIdleWork = new ManualResetEventSlim(),
                IdleDelay = TimeSpan.FromSeconds(5)
            })
            {
                parser.StartIdleTimer();
                var currentTimer = parser._idleTimer;

                // Act
                parser.StopIdleTimer();

                // Assert
                Assert.NotNull(currentTimer);
                Assert.Null(parser._idleTimer);
            }
        }

        [ForegroundFact]
        public void StopParser_DetachesFromTextBufferChangeLoop()
        {
            // Arrange
            var documentTracker = CreateDocumentTracker();
            var textBuffer = (TestTextBuffer)documentTracker.TextBuffer;
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                parser.StartParser();

                // Act
                parser.StopParser();

                // Assert
                Assert.Empty(textBuffer.AttachedChangedEvents);
                Assert.Null(parser._parser);
            }
        }

        [ForegroundFact]
        public void StartParser_AttachesToTextBufferChangeLoop()
        {
            // Arrange
            var documentTracker = CreateDocumentTracker();
            var textBuffer = (TestTextBuffer)documentTracker.TextBuffer;
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                documentTracker,
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                // Act
                parser.StartParser();

                // Assert
                Assert.Equal(1, textBuffer.AttachedChangedEvents.Count);
                Assert.NotNull(parser._parser);
            }
        }

        [ForegroundFact]
        public void TryReinitializeParser_ReturnsTrue_IfProjectIsSupported()
        {
            // Arrange
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(isSupportedProject: true),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                // Act
                var result = parser.TryReinitializeParser();

                // Assert
                Assert.True(result);
            }
        }

        [ForegroundFact]
        public void TryReinitializeParser_ReturnsFalse_IfProjectIsNotSupported()
        {
            // Arrange
            using (var parser = new DefaultVisualStudioRazorParser(
                Dispatcher,
                CreateDocumentTracker(isSupportedProject: false),
                ProjectEngineFactory,
                new DefaultErrorReporter(),
                Mock.Of<VisualStudioCompletionBroker>()))
            {
                // Act
                var result = parser.TryReinitializeParser();

                // Assert
                Assert.False(result);
            }
        }
    }
}