using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;

namespace Plugins.Halcon.Views
{
    /// <summary>
    /// HALCON 主页多画面显示控件（镜像 UCDispVm/UCDispVpp 的角色）：按 RowColNumber 铺设画面框网格，
    /// 支持双击放大/还原。单例，供 <see cref="Engines.HalconEngine"/> 与 HALCON 图像显示插件访问。
    /// </summary>
    public partial class UCDispHalcon : UserControl
    {
        private static readonly Lazy<UCDispHalcon> _instance = new Lazy<UCDispHalcon>(CreateInstance);
        public static UCDispHalcon Instance => _instance.Value;

        /// <summary>
        /// WPF 控件必须在 STA(UI) 线程创建。「Halcon图像显示」节点在流程执行的后台(MTA)线程首次访问 Instance 时
        /// （例如当前主页引擎不是 Halcon、GetMainView 从未在 UI 线程创建过它），若直接 new 会抛
        /// “调用线程必须为 STA”。故不在 UI 线程时经 Dispatcher 切到 UI 线程创建。
        /// </summary>
        private static UCDispHalcon CreateInstance()
        {
            var app = System.Windows.Application.Current;
            if (app != null && !app.Dispatcher.CheckAccess())
                return app.Dispatcher.Invoke(() => new UCDispHalcon());
            return new UCDispHalcon();
        }

        /// <summary>当前画面框集合（下标 = 画面序号-1）。</summary>
        public List<HalconWindow> halconWindow { get; } = new List<HalconWindow>();

        private int[] _rowCol = new[] { 0, 1 };
        private HalconWindow _maximized;

        public UCDispHalcon()
        {
            InitializeComponent();
        }

        /// <summary>{画面总数, 排列方式}：arrange 1=水平最优行列，2=垂直最优行列；总数0=清空。</summary>
        public int[] RowColNumber
        {
            get => _rowCol;
            set
            {
                _rowCol = value ?? new[] { 0, 1 };
                RebuildFrames();
            }
        }

        private void RebuildFrames()
        {
            if (!Dispatcher.CheckAccess()) { Dispatcher.Invoke(new Action(RebuildFrames)); return; }

            // 复位放大态
            MaxGrid.Children.Clear();
            MaxGrid.Visibility = Visibility.Collapsed;
            _maximized = null;

            RootGrid.Children.Clear();
            RootGrid.RowDefinitions.Clear();
            RootGrid.ColumnDefinitions.Clear();
            RootGrid.Visibility = Visibility.Visible;
            halconWindow.Clear();

            int count = _rowCol.Length > 0 ? _rowCol[0] : 0;
            int arrange = _rowCol.Length > 1 ? _rowCol[1] : 1;
            if (count <= 0) return;

            int cols = (int)Math.Ceiling(Math.Sqrt(count));
            if (cols < 1) cols = 1;
            if (arrange == 2)
            {
                int rows = (int)Math.Ceiling(Math.Sqrt(count));
                if (rows < 1) rows = 1;
                cols = (int)Math.Ceiling((double)count / rows);
                if (cols < 1) cols = 1;
            }
            int rowCount = (count + cols - 1) / cols;

            for (int c = 0; c < cols; c++) RootGrid.ColumnDefinitions.Add(new ColumnDefinition());
            for (int r = 0; r < rowCount; r++) RootGrid.RowDefinitions.Add(new RowDefinition());

            for (int i = 0; i < count; i++)
            {
                var w = new HalconWindow(i + 1);
                Grid.SetRow(w, i / cols);
                Grid.SetColumn(w, i % cols);
                // 数量除不尽时，最后一个跨列填满本行剩余位置（不补空白格）
                if (i == count - 1)
                {
                    int remain = cols - (i % cols);
                    if (remain > 1) Grid.SetColumnSpan(w, remain);
                }
                w.MouseDouble += OnFrameDoubleClick;
                RootGrid.Children.Add(w);
                halconWindow.Add(w);
            }
        }

        private void OnFrameDoubleClick(HalconWindow window, int number)
        {
            if (!Dispatcher.CheckAccess()) { Dispatcher.Invoke(() => OnFrameDoubleClick(window, number)); return; }
            if (_maximized == window) return;
            window.MouseDouble -= OnFrameDoubleClick;
            RootGrid.Children.Remove(window);
            RootGrid.Visibility = Visibility.Collapsed;
            MaxGrid.Children.Clear();
            MaxGrid.Children.Add(window);
            MaxGrid.Visibility = Visibility.Visible;
            window.MouseDouble += OnMaxDoubleClick;
            _maximized = window;
        }

        private void OnMaxDoubleClick(HalconWindow window, int number)
        {
            if (!Dispatcher.CheckAccess()) { Dispatcher.Invoke(() => OnMaxDoubleClick(window, number)); return; }
            window.MouseDouble -= OnMaxDoubleClick;
            MaxGrid.Children.Clear();
            MaxGrid.Visibility = Visibility.Collapsed;
            // Grid.Row/Column 附加属性随元素保留，重新加回即落回原位
            RootGrid.Children.Add(window);
            RootGrid.Visibility = Visibility.Visible;
            window.MouseDouble += OnFrameDoubleClick;
            _maximized = null;
        }
    }
}