using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;
using Main.Test.ViewModels;
using Trade.Framework.Controls;

namespace Main.Test;

public partial class MainWindow : WindowBase
{
    public MainWindow()
    {
        InitializeComponent();
        var timer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(500) };
        timer.Tick += (_, _) => ImageStatisticsText.Text = ThumbnailLoader.Statistics;
        Loaded += (_, _) => timer.Start();
        Closed += (_, _) => timer.Stop();
    }

    private async void LoadData_Click(object sender, RoutedEventArgs e)
    {
        SetBusy(true);
        try
        {
            var count = int.Parse((string)((ComboBoxItem)DataSize.SelectedItem).Tag);
            var watch = Stopwatch.StartNew();
            var vm = (MainViewModel)DataContext;
            vm.NetworkImageSize = int.Parse((string)((ComboBoxItem)ImageMode.SelectedItem).Tag);
            await vm.LoadAsync(count);
            OrdersGrid.ScrollIntoView(OrdersGrid.Items[0]);
            await Dispatcher.Yield(DispatcherPriority.ApplicationIdle);
            PerformanceText.Text = $"加载 {count:N0} 行（含生成与首次布局）：{watch.Elapsed.TotalMilliseconds:N0} ms。可继续测试滚动和全选。";
        }
        catch (Exception ex) { PerformanceText.Text = $"加载失败：{ex.Message}"; }
        finally { SetBusy(false); }
    }

    private async void Benchmark_Click(object sender, RoutedEventArgs e)
    {
        SetBusy(true);
        try { PerformanceText.Text = await RunPerformanceTestAsync(); }
        catch (Exception ex) { PerformanceText.Text = $"测试失败：{ex.Message}"; }
        finally { SetBusy(false); }
    }

    private async void ImageBenchmark_Click(object sender, RoutedEventArgs e)
    {
        SetBusy(true);
        try { PerformanceText.Text = await RunImagePerformanceTestAsync(); }
        catch (Exception ex) { PerformanceText.Text = $"图片测试失败：{ex.Message}"; }
        finally { SetBusy(false); }
    }

    public async Task<string> RunImagePerformanceTestAsync()
    {
        if (OrdersGrid.Items.Count == 0 || ((MainViewModel)DataContext).NetworkImageSize == 0)
            return "请先选择 Picsum 图片模式并点击加载数据，再运行图片滚动测试。";
        var viewer = FindVisual<ScrollViewer>(OrdersGrid).First();
        var offset = viewer.VerticalOffset;
        var samples = new[] { new List<double>(), new List<double>() };
        var heartbeat = Stopwatch.StartNew();
        var lastTick = heartbeat.Elapsed.TotalMilliseconds;
        var maxDelay = 0d;
        var pulse = new DispatcherTimer(DispatcherPriority.Normal) { Interval = TimeSpan.FromMilliseconds(50) };
        pulse.Tick += (_, _) =>
        {
            var now = heartbeat.Elapsed.TotalMilliseconds;
            maxDelay = Math.Max(maxDelay, Math.Max(0, now - lastTick - 50));
            lastTick = now;
        };
        pulse.Start();
        try
        {
            viewer.ScrollToHorizontalOffset(0);
            for (var pass = 0; pass < 2; pass++)
            {
                PerformanceText.Text = pass == 0 ? "首次滚动：网络图片正在加载…" : "重复访问相同位置：比较缓存与重新加载…";
                for (var i = 0; i < 40; i++)
                {
                    var watch = Stopwatch.StartNew();
                    viewer.ScrollToVerticalOffset(i % 24);
                    await Dispatcher.Yield(DispatcherPriority.ApplicationIdle);
                    samples[pass].Add(watch.Elapsed.TotalMilliseconds);
                    await Task.Delay(150);
                }
            }
            // 有界等待当前可见图片，避免把尚未完成的请求当作加载成功。
            var wait = Stopwatch.StartNew();
            while (ThumbnailLoader.Pending > 0 && wait.Elapsed < TimeSpan.FromSeconds(8)) await Task.Delay(100);
            var first = samples[0].Order().ToArray(); var revisit = samples[1].Order().ToArray();
            return $"Picsum {((MainViewModel)DataContext).NetworkImageSize}px / {OrdersGrid.Items.Count:N0} 行 | 首次滚动均值 {first.Average():N1} ms / P95 {first[37]:N1} ms | 复访均值 {revisit.Average():N1} ms / P95 {revisit[37]:N1} ms | UI 心跳最大延迟 {maxDelay:N1} ms（非帧率）；图片统计为本次进程累计，取消表示滚出视口。";
        }
        finally { pulse.Stop(); viewer.ScrollToVerticalOffset(offset); }
    }

    // 测量 UI 线程滚动与布局响应，不等同于 GPU 帧率。
    public async Task<string> RunPerformanceTestAsync()
    {
        if (OrdersGrid.Items.Count == 0) return "没有可测试的数据。";
        var viewer = FindVisual<ScrollViewer>(OrdersGrid).First();
        var offset = viewer.VerticalOffset;
        var selected = ((DataGrid)OrdersGrid).SelectedItems.Cast<object>().ToArray();
        var samples = new List<double>();
        try
        {
            OrdersGrid.UnselectAll();
            OrdersGrid.ScrollIntoView(OrdersGrid.Items[0]);
            viewer.ScrollToHorizontalOffset(0);
            await Dispatcher.Yield(DispatcherPriority.ApplicationIdle);
            for (var i = 0; i < 60; i++)
            {
                var watch = Stopwatch.StartNew();
                viewer.ScrollToVerticalOffset(viewer.ScrollableHeight * ((i * 17) % 60) / 59d);
                await Dispatcher.Yield(DispatcherPriority.ApplicationIdle);
                samples.Add(watch.Elapsed.TotalMilliseconds);
            }
            var selectWatch = Stopwatch.StartNew();
            OrdersGrid.SelectAll();
            await Dispatcher.Yield(DispatcherPriority.ApplicationIdle);
            var selectMs = selectWatch.Elapsed.TotalMilliseconds;
            selectWatch.Restart(); OrdersGrid.UnselectAll();
            await Dispatcher.Yield(DispatcherPriority.ApplicationIdle);
            var clearMs = selectWatch.Elapsed.TotalMilliseconds;
            var realized = FindVisual<DataGridRow>(OrdersGrid).Count();
            samples.Sort();
            return $"{OrdersGrid.Items.Count:N0} 行 / 9 列 | 滚动与布局：均值 {samples.Average():N1} ms，P95 {samples[56]:N1} ms，最大 {samples[^1]:N1} ms | 全选 {selectMs:N0} ms / 取消 {clearMs:N0} ms | 已生成行 {realized} | 进程内存 {Process.GetCurrentProcess().WorkingSet64 / 1024 / 1024} MB（不等同帧率）";
        }
        finally
        {
            OrdersGrid.RestoreSelection(selected);
            viewer.ScrollToVerticalOffset(offset);
        }
    }

    private void SetBusy(bool busy)
    {
        LoadButton.IsEnabled = BenchmarkButton.IsEnabled = ImageBenchmarkButton.IsEnabled = DataSize.IsEnabled = ImageMode.IsEnabled = !busy;
        OrdersGrid.IsEnabled = !busy;
    }

    private static IEnumerable<T> FindVisual<T>(DependencyObject parent) where T : DependencyObject
    {
        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            if (child is T match) yield return match;
            foreach (var descendant in FindVisual<T>(child)) yield return descendant;
        }
    }
}