using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;

namespace Future.Contract
{
    /// <summary>
    /// 加载遮罩：用于后台执行耗时加载任务时提供操作遮罩
    /// </summary>
    public class LoadingAdorner : Adorner
    {
        [AllowNull]
        private Grid _Layout;
        [AllowNull]
        private TextBlock _Feedback;
        [AllowNull]
        private AdornerLayer _AdornerLayer;
        [AllowNull]
        private VisualCollection _Visuals;

        private Cursor _Cursor;

        private System.Windows.Threading.DispatcherTimer _UiTimer = new System.Windows.Threading.DispatcherTimer();
        /// <summary>
        /// 对目标元素提供加载遮罩
        /// </summary>
        /// <param name="adornedElement">要进行遮盖的视觉元素</param>
        private LoadingAdorner(UIElement adornedElement) : base(adornedElement)
        {
            PrepareLoading();
        }
        private LoadingAdorner(UIElement adornedElement, string feedback, double progress = -1.1) : base(adornedElement)
        {
            PrepareLoading(feedback, progress);
        }

        /// <summary>
        /// 反馈信息
        /// </summary>
        public string Feedback
        {
            get { return (string)GetValue(FeedbackProperty); }
            set { SetValue(FeedbackProperty, value); Refresh(); }
        }

        // Using a DependencyProperty as the backing store for Feedback.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FeedbackProperty =
            DependencyProperty.Register("Feedback", typeof(string), typeof(LoadingAdorner), new PropertyMetadata("请稍等..."));

        /// <summary>
        /// 进度信息
        /// </summary>
        public double Progress
        {
            get { return (double)GetValue(ProgressProperty); }
            set { SetValue(ProgressProperty, value); Refresh(); }
        }

        // Using a DependencyProperty as the backing store for Progress.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty ProgressProperty =
            DependencyProperty.Register("Progress", typeof(double), typeof(LoadingAdorner), new PropertyMetadata(-1.1));

        /// <summary>
        /// 准备启动：生成装饰器需要的内容
        /// </summary>
        /// <param name="feedback"></param>
        private void PrepareLoading(string feedback = "", double progress = -1.1)
        {
            _Visuals = new VisualCollection(this);
            _Layout = new Grid
            {
                Cursor = Cursors.Wait,
                ForceCursor = true
            };
            _Layout.Children.Add(new Border()
            {
                Background = Brushes.Gray,
                Opacity = 0.85,
            });
            _Feedback = new TextBlock()
            {
                Text = feedback,
                //FontSize=14,
                Foreground = Brushes.White,
                HorizontalAlignment = HorizontalAlignment.Center,
                VerticalAlignment = VerticalAlignment.Center,
                Margin = new Thickness(10)
            };
            _Layout.Children.Add(_Feedback);

            _Visuals.Add(_Layout);

            FeedbackProgress(feedback, progress);

            _UiTimer.Interval = TimeSpan.FromMilliseconds(200);
            _UiTimer.Tick += (s, e) => Animate();
            _UiTimer.Start();

            _AdornerLayer = AdornerLayer.GetAdornerLayer(AdornedElement);
            _AdornerLayer?.Add(this);

            if (AdornedElement is FrameworkElement)
            {
                FrameworkElement target = (FrameworkElement)AdornedElement;
                _Cursor = target.Cursor;
                target.Cursor = Cursors.Wait;
            }
        }
        /// <summary>
        /// 开始装载：可以保证每个控件上方只会出现一个加载遮罩层
        /// </summary>
        /// <param name="adornedElement">加载目标</param>
        /// <param name="feedback">反馈信息</param>
        /// <param name="progress">进度信息</param>
        /// <returns>加载遮罩装饰器</returns>
        public static LoadingAdorner BeginLoading(UIElement adornedElement, string feedback = "", double progress = -1)
        {
            var adorners = AdornerLayer.GetAdornerLayer(adornedElement)?.GetAdorners(adornedElement)?.OfType<LoadingAdorner>();
            if (adorners != null && adorners.Count() == 1) return adorners.ToArray()[0];

            return new LoadingAdorner(adornedElement, feedback, progress);
        }
        /// <summary>
        /// 结束加载：清除一个控件上方所有的加载遮罩层
        /// </summary>
        /// <param name="adornedElement">用标元素</param>
        public static void FinishLoading(UIElement adornedElement)
        {
            var adornerLayer = AdornerLayer.GetAdornerLayer(adornedElement);
            var adorners = adornerLayer?.GetAdorners(adornedElement);
            if (adorners == null) return;
            for (int i = adorners.Length - 1; i >= 0; i--)
                if (adorners[i] is LoadingAdorner)
                    ((LoadingAdorner)adorners[i]).Finish();
        }
        /// <summary>
        /// 进度反馈：用于向装饰器反馈当前进度
        /// </summary>
        /// <param name="feedback">信息：进度遮罩上显示的信息</param>
        /// <param name="progress">进度：0~1的小数，代表?%,其他数值无效</param>
        public void FeedbackProgress(string feedback = "", double progress = -1)
        {
            if (!string.IsNullOrEmpty(feedback)) Feedback = feedback;
            if (progress >= 0 && progress <= 1) Progress = progress;
        }

        private string _ProgressInfo = "请稍等...";
        /// <summary>
        /// 用于更新“进度信息”
        /// </summary>
        private void Refresh()
        {
            string prog = "-*-";
            if (0 <= Progress && Progress <= 1)
                prog = string.Format("{0:0%}", Progress).PadLeft(3);
            _ProgressInfo = $"[{prog}] : {Feedback.TrimEnd('.')} ... ";
        }
        /// <summary>
        /// 循环动画
        /// </summary>
        private void Animate()
        {
            string info = _Feedback.Text;
            if (!string.IsNullOrEmpty(info) && info.Length > 0)
            {
                char end = info[info.Length - 1];
                info = _ProgressInfo;

                switch (end)
                {
                    case '|': { info = info + '/'; } break;
                    case '/': { info = info + '-'; } break;
                    case '-': { info = info + '\\'; } break;
                    case '\\': { info = info + '|'; } break;
                    default: { info = info + '|'; } break;
                }
                _Feedback.Text = info;
            }
            else _Feedback.Text = _ProgressInfo + "|";
        }
        /// <summary>
        /// 结束装载
        /// </summary>
        public void Finish()
        {
            _UiTimer.Stop();

            if (AdornedElement is FrameworkElement)
            {
                ((FrameworkElement)AdornedElement).Cursor = _Cursor;
            }

            _AdornerLayer?.Remove(this);
        }

        protected override int VisualChildrenCount => _Visuals.Count;

        protected override Visual GetVisualChild(int index) => _Visuals[index];

        protected override Size ArrangeOverride(Size finalSize)
        {
            _Layout.Arrange(new Rect(new Point(0, 0), finalSize));
            return finalSize;
        }
    }
}