using System;
using System.Threading;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
using FsCheck;
using FsCheck.Fluent;
using FsCheck.Xunit;
using Moq;
using Prism.Events;
using XP.Common.Logging.Interfaces;
using XplorePlane.Events;
using XplorePlane.Models;
using XplorePlane.Services.AppState;
using XplorePlane.Services.MainViewport;
using XplorePlane.ViewModels;

namespace XplorePlane.Tests.ViewModels
{
    /// <summary>
    /// FsCheck property-based tests for ViewportPanelViewModel.
    /// Properties 9–10 validate IsAnimatedSwitchEnabled logic and ImageInfo protection.
    /// </summary>
    public class ViewportPanelViewModelPropertyTests
    {
        // ── Helpers ──────────────────────────────────────────────────────────

        /// <summary>
        /// Runs an action on a dedicated STA thread with a SynchronizationContext,
        /// which satisfies Prism's UIThread requirement for EventAggregator.
        /// </summary>
        private static T RunOnStaThread<T>(Func<T> action)
        {
            T result = default;
            Exception exception = null;

            var thread = new Thread(() =>
            {
                SynchronizationContext.SetSynchronizationContext(new DispatcherSynchronizationContext());
                try
                {
                    result = action();
                }
                catch (Exception ex)
                {
                    exception = ex;
                }
            });
            thread.SetApartmentState(ApartmentState.STA);
            thread.Start();
            thread.Join();

            if (exception != null)
                throw new Exception("STA thread threw an exception", exception);

            return result;
        }

        // ── Property 9 ───────────────────────────────────────────────────────

        // Feature: live-image-display, Property 9: AnimatedSwitch 可用状态与连接/CNC 状态一致
        // Validates: Requirements 3.13, 7.5, 7.6
        //
        // For any combination of IsDetectorConnected and IsCncRunning,
        // IsAnimatedSwitchEnabled always equals IsDetectorConnected && !IsCncRunning.
        //
        // The implementation in ViewportPanelViewModel computes:
        //   IsAnimatedSwitchEnabled = _isDetectorConnected && !_isCncRunning
        // We verify this formula holds for all boolean combinations.
        [Property(MaxTest = 100)]
        public Property IsAnimatedSwitchEnabled_AlwaysEqualsDetectorConnectedAndNotCncRunning()
        {
            var gen =
                from isDetectorConnected in ArbMap.Default.GeneratorFor<bool>()
                from isCncRunning in ArbMap.Default.GeneratorFor<bool>()
                select (isDetectorConnected, isCncRunning);

            return Prop.ForAll(
                gen.ToArbitrary(),
                tuple =>
                {
                    var (isDetectorConnected, isCncRunning) = tuple;

                    // Run the entire test on a single STA thread with SynchronizationContext
                    return RunOnStaThread(() =>
                    {
                        var mockViewport = new Mock<IMainViewportService>();
                        mockViewport.Setup(s => s.CurrentDisplayImage).Returns((ImageSource)null);
                        mockViewport.Setup(s => s.CurrentDisplayInfo).Returns("等待探测器图像...");
                        mockViewport.Setup(s => s.IsRealtimeDisplayEnabled).Returns(true);
                        mockViewport.Setup(s => s.IsCncRunning).Returns(isCncRunning);

                        var mockAppState = new Mock<IAppStateService>();
                        mockAppState.SetupAdd(s => s.DetectorStateChanged += It.IsAny<EventHandler<StateChangedEventArgs<DetectorState>>>());

                        var mockLogger = new Mock<ILoggerService>();
                        mockLogger.Setup(l => l.ForModule<ViewportPanelViewModel>()).Returns(mockLogger.Object);

                        var eventAggregator = new EventAggregator();

                        var vm = new ViewportPanelViewModel(
                            mockViewport.Object,
                            eventAggregator,
                            mockAppState.Object,
                            mockLogger.Object);

                        // Simulate detector connection state change via DetectorStateChanged event.
                        var detectorState = new DetectorState(isDetectorConnected, false, 0, "");
                        var oldState = new DetectorState(!isDetectorConnected, false, 0, "");
                        var stateChangedArgs = new StateChangedEventArgs<DetectorState>(oldState, detectorState);
                        mockAppState.Raise(s => s.DetectorStateChanged += null, stateChangedArgs);

                        // Pump the dispatcher to process BeginInvoke callbacks
                        Dispatcher.CurrentDispatcher.Invoke(() => { }, DispatcherPriority.Background);

                        // Simulate CNC running state via StateChanged on the viewport service
                        mockViewport.Setup(s => s.IsCncRunning).Returns(isCncRunning);
                        mockViewport.Raise(s => s.StateChanged += null, EventArgs.Empty);

                        // Pump the dispatcher again
                        Dispatcher.CurrentDispatcher.Invoke(() => { }, DispatcherPriority.Background);

                        // The core invariant: IsAnimatedSwitchEnabled == IsDetectorConnected && !IsCncRunning
                        return vm.IsAnimatedSwitchEnabled == (vm.IsDetectorConnected && !isCncRunning);
                    });
                });
        }

        // ── Property 10 ──────────────────────────────────────────────────────

        // Feature: live-image-display, Property 10: 测量模式下 ImageInfo 不被覆盖
        // Validates: Requirements 5.3
        //
        // For any active measurement mode (CurrentMeasurementMode != None) and any number
        // of StateChanged triggers, ImageInfo always retains the measurement hint text
        // and is not overwritten by service state.
        //
        // Implementation note: ViewportPanelViewModel.OnMainViewportStateChanged calls
        //   UpdateFromState(updateInfo: CurrentMeasurementMode == MeasurementToolMode.None)
        // When CurrentMeasurementMode != None, updateInfo is false, so ImageInfo is NOT updated.
        // We verify this by directly setting CurrentMeasurementMode and triggering StateChanged.
        [Property(MaxTest = 100)]
        public Property ActiveMeasurementMode_ImageInfo_NotOverwrittenByStateChanged()
        {
            // Generate non-None measurement modes
            var modeGen = Gen.Elements(
                MeasurementToolMode.PointDistance,
                MeasurementToolMode.PointLineDistance,
                MeasurementToolMode.Angle,
                MeasurementToolMode.ThroughHoleFillRate);

            var gen =
                from mode in modeGen
                from triggerCount in Gen.Choose(1, 20)
                select (mode, triggerCount);

            return Prop.ForAll(
                gen.ToArbitrary(),
                tuple =>
                {
                    var (mode, triggerCount) = tuple;

                    // Run the entire test on a single STA thread with SynchronizationContext
                    return RunOnStaThread(() =>
                    {
                        var mockViewport = new Mock<IMainViewportService>();
                        mockViewport.Setup(s => s.CurrentDisplayImage).Returns((ImageSource)null);
                        mockViewport.Setup(s => s.CurrentDisplayInfo).Returns("等待探测器图像...");
                        mockViewport.Setup(s => s.IsRealtimeDisplayEnabled).Returns(true);
                        mockViewport.Setup(s => s.IsCncRunning).Returns(false);

                        var mockAppState = new Mock<IAppStateService>();
                        mockAppState.SetupAdd(s => s.DetectorStateChanged += It.IsAny<EventHandler<StateChangedEventArgs<DetectorState>>>());

                        var mockLogger = new Mock<ILoggerService>();
                        mockLogger.Setup(l => l.ForModule<ViewportPanelViewModel>()).Returns(mockLogger.Object);

                        var eventAggregator = new EventAggregator();

                        var vm = new ViewportPanelViewModel(
                            mockViewport.Object,
                            eventAggregator,
                            mockAppState.Object,
                            mockLogger.Object);

                        // Directly set the measurement mode on the ViewModel.
                        // This bypasses the UIThread event dispatch issue and directly
                        // sets the backing field that controls ImageInfo protection.
                        vm.CurrentMeasurementMode = mode;

                        // Set ImageInfo to the measurement hint text (as OnMeasurementToolActivated would)
                        vm.ImageInfo = vm.MeasurementModeText;
                        string measurementInfo = vm.ImageInfo;

                        // Verify measurement mode is active
                        if (vm.CurrentMeasurementMode == MeasurementToolMode.None)
                            return false;

                        // Trigger StateChanged multiple times.
                        // The handler calls BeginInvoke — we pump the dispatcher to process callbacks.
                        for (int i = 0; i < triggerCount; i++)
                        {
                            mockViewport.Raise(s => s.StateChanged += null, EventArgs.Empty);
                            // Pump the dispatcher to process BeginInvoke callbacks
                            Dispatcher.CurrentDispatcher.Invoke(() => { }, DispatcherPriority.Background);
                        }

                        // ImageInfo must still be the measurement hint text, not the service info.
                        // This holds because UpdateFromState is called with updateInfo: false
                        // when CurrentMeasurementMode != None.
                        return vm.ImageInfo == measurementInfo;
                    });
                });
        }
    }
}