using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Threading;
using System.Windows.Forms;
using ThreadingTimer = System.Threading.Timer;
using UITimer = System.Windows.Forms.Timer;

namespace InvoicingTool
{
    /// <summary>
    /// 表示一个加载圆圈动画
    /// </summary>
    [ToolboxBitmap(typeof(LoadingCircle), "LoadingCircleIcon.png")]
    public partial class LoadingCircle : UserControl
    {
        #region 构造

        public LoadingCircle()
        {
            InitializeComponent();

            //双缓冲，禁擦背景
            SetStyle(
                ControlStyles.AllPaintingInWmPaint |
                ControlStyles.UserPaint |
                ControlStyles.OptimizedDoubleBuffer,
                true);

            //初始化绘图timer
            _graphicsTmr = new UITimer { Interval = 1 };
            //Invalidate()强制重绘,绘图操作在OnPaint中实现
            _graphicsTmr.Tick += (sender1, e1) => Invalidate(false);

            _dotSize = Width / 10f;

            //初始化"点"
            DotCount = 5;
            _dots = new Dot[DotCount];
            Color = Color.White;
        }

        #endregion 构造

        #region 属性

        /// <summary>
        ///     圆心
        /// </summary>
        [Browsable(false)]
        public PointF CircleCenter
        {
            get { return new PointF(Width / 2f, Height / 2f); }
        }

        /// <summary>
        ///     半径
        /// </summary>
        [Browsable(false)]
        public float CircleRadius
        {
            get { return Width / 2f - _dotSize; }
        }

        /// <summary>
        ///     颜色
        /// </summary>
        [Browsable(true), Category("Appearance"), Description("设置\"点\"的前景色")]
        public Color Color { get; set; }

        /// <summary>
        ///     数量
        /// </summary>
        [Browsable(true),Category("Appearance"),Description("设置\"点\"的数量\n有效值1-10"),DefaultValue(5)]
        public UInt32 DotCount { get; set; }
        #endregion 属性

        #region 字段

        //点数组
        private  Dot[] _dots;

        //Timers
        private readonly UITimer _graphicsTmr;
        private ThreadingTimer _actionTmr;

        //点大小
        private float _dotSize;

        //是否活动
        private bool _isActived;

        //是否绘制:用于状态重置时挂起与恢复绘图
        private bool _isDrawing = true;

        //Timer计数:用于延迟启动每个点
        private int _timerCount;

        #endregion 字段

        #region 常量

        //动作间隔(Timer)
        private const int ActionInterval = 30;

        //计数基数：用于计算每个点启动延迟：index * timerCountRadix
        private const int TimerCountRadix = 45;

        #endregion 常量

        #region 方法

        //检查是否重置
        private bool CheckToReset()
        {
            return _dots.Count(d => d.Opacity > 0) == 0;
        }

        //初始化点元素
        private void CreateDots()
        {
            if (DotCount < 1 || DotCount > 10)
                DotCount = 5;
            _dots = new Dot[DotCount];
            for (int i = 0; i < _dots.Length; ++i)
                _dots[i] = new Dot(CircleCenter, CircleRadius);
        }

        /// <summary>
        ///     开关
        /// </summary>
        public bool Switch()
        {
            if (!_isActived)
                Start();
            else
                Stop();

            return _isActived;
        }

        /// <summary>
        /// 开始
        /// </summary>
        public void Start()
        {
            CreateDots();

            _timerCount = 0;
            foreach (Dot dot in _dots)
                dot.Reset();

            _graphicsTmr.Start();

            //初始化动作timer
            _actionTmr = new ThreadingTimer(
                state =>
                {
                    //动画动作
                    for (int i = 0; i < _dots.Length; i++)
                        if (_timerCount++ > i * TimerCountRadix)
                            _dots[i].DotAction();

                    //是否重置
                    if (CheckToReset())
                    {
                        //重置前暂停绘图
                        _isDrawing = false;

                        _timerCount = 0;

                        foreach (Dot dot in _dots)
                            dot.Reset();

                        //恢复绘图
                        _isDrawing = true;
                    }

                    _actionTmr.Change(ActionInterval, Timeout.Infinite);
                },
                null, ActionInterval, Timeout.Infinite);

            _isActived = true;
        }

        /// <summary>
        /// 停止
        /// </summary>
        public void Stop()
        {
            _graphicsTmr.Stop();
            _actionTmr.Dispose();
            _isActived = false;
        }

        #endregion 方法

        #region 重写

        protected override void OnPaint(PaintEventArgs e)
        {
            if (_isActived && _isDrawing)
            {
                //抗锯齿
                e.Graphics.SmoothingMode = SmoothingMode.HighQuality;

                using (var bmp = new Bitmap(200, 200))
                {
                    //缓冲绘制
                    using (Graphics bufferGraphics = Graphics.FromImage(bmp))
                    {
                        //抗锯齿
                        bufferGraphics.SmoothingMode = SmoothingMode.HighQuality;
                        foreach (Dot dot in _dots)
                        {
                            var rect = new RectangleF(
                                new PointF(dot.Location.X - _dotSize / 2, dot.Location.Y - _dotSize / 2),
                                new SizeF(_dotSize, _dotSize));

                            bufferGraphics.FillEllipse(new SolidBrush(Color.FromArgb(dot.Opacity, Color)),
                                rect);
                        }
                    }

                    //贴图
                    e.Graphics.DrawImage(bmp, new PointF(0, 0));
                } //bmp disposed
            }

            base.OnPaint(e);
        }

        protected override void OnResize(EventArgs e)
        {
            Height = Width;
            _dotSize = Width / 12f;

            base.OnResize(e);
        }

        #endregion 重写
    }
}