using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Asa.Theme
{
    /// <summary>
    /// 列表框
    /// </summary>
    [DefaultProperty("Text")]
    [DefaultEvent("SelectedIndexChanged")]
    public partial class FlatList : FlatBase
    {
        private int _itemH;           //属性，项的高度
        private int _index;

        private List<string> _list = new List<string>();
        private Rectangle[] _listRect;
        private RectangleF[] _listStrRect;
        private Rectangle _borderRect;
        private Rectangle _scrollRect;

        private bool _scrollDown;
        private int _scrollY;
        private int _over = -1;
        private int _allItemH;   //所有的项的高度之和
        private int _showItemH;  //显示的项的高度
        private float _step;     //每像素表示多少距离
        private int offsetY = 0;
        private bool scroll = false;

        private const int SCROLL_W = 8;
        private const int BORDER_W = 2;
        private const int SCROLL_H = 50;

        /// <summary>
        /// 列表框
        /// </summary>
        public FlatList()
        {
            InitializeComponent();

            ItemHeight = 30;
            //BorderStyle = BorderStyle.All;
            _index = -1;

            MouseWheel += FlatList_MouseWheel;
        }


        #region 属性
        /// <summary>
        /// 控件中文本的字体
        /// </summary>
        [Browsable(true), Category("外观"), Description("控件中文本的字体")]
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        public override Font Font
        {
            get => base.Font;
            set
            {
                base.Font = value;
                CalcSize();
                Refresh();
            }
        }

        /// <summary>
        /// 单条文本项的高度
        /// </summary>
        [Browsable(true), Category("外观"), Description("单条文本项的高度"), DefaultValue(30)]
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        public int ItemHeight
        {
            set
            {
                _itemH = value;
                CalcSize();
                Refresh();
            }
            get
            {
                return _itemH;
            }
        }

        /// <summary>
        /// 选中项的文本
        /// </summary>
        [Browsable(true), Category("外观"), Description("选中项的文本")]
        public new string Text
        {
            get
            {
                if (_list.Count == 0)
                    return "";
                else if (_index == -1)
                    return "";
                else
                    return _list[_index];
            }
        }

        /// <summary>
        /// 选中项的索引
        /// </summary>
        [Browsable(false)]
        public int SelectedIndex
        {
            set
            {
                if (_list.Count == 0 || value < 0 || value >= _list.Count)
                    _index = -1;
                else
                    _index = value;
                Refresh();
                SelectedIndexChanged?.Invoke(this);
            }
            get
            {
                return _index;
            }
        }

        /// <summary>
        /// 列表的总数
        /// </summary>
        [Browsable(false)]
        public int Count { get { return _list.Count; } }

        #endregion
        

        #region 方法
        /// <summary>
        /// 列表框添加文本项
        /// </summary>
        /// <param name="s"></param>
        public void ItemAdd(params string[] s)
        {
            _list.AddRange(s);
            CalcSize();
            Refresh();
        }

        /// <summary>
        /// 移除指定索引的元素
        /// </summary>
        /// <param name="n">要移除的元素从零开始的索引</param>
        public void ItemRemove(int n)
        {
            if (n < 0 || n >= _list.Count) return;
            _list.RemoveAt(n); _list.RemoveAt(n);

            if (n == _index)
            {
                _index = -1;
            }
            else if (n < _index)
            {
                _index--;
            }

            CalcSize();
            Refresh();
        }

        /// <summary>
        /// 移除当前选中的元素
        /// </summary>
        public void ItemRemove()
        {
            if (_index == -1) return;
            _list.RemoveAt(_index);
            _index = -1;
            CalcSize();
            Refresh();
        }

        /// <summary>
        /// 清空列表框
        /// </summary>
        public void ItemClear()
        {
            _list.Clear();
            CalcSize();
            Refresh();
        }

        /// <summary>
        /// 列表所有文本
        /// </summary>
        /// <returns></returns>
        public string[] Items()
        {
            return _list.ToArray();
        }

        /// <summary>
        /// 列表指定文本
        /// </summary>
        /// <returns></returns>
        public string Items(int idx)
        {
            return _list[idx];
        }

        /// <summary>
        /// 设置指定列表的文本
        /// </summary>
        /// <param name="idx"></param>
        /// <param name="s"></param>
        public void Items(int idx, string s)
        {
            _list[idx] = s;
            CalcSize();
            Refresh();
        }

        /// <summary>
        /// 选中列表的第一项
        /// </summary>
        public void SelectedFirst()
        {
            if (_list.Count == 0)
            {
                _index = -1;
            }
            else
            {
                _index = 0;
            }
            Refresh();
            SelectedIndexChanged?.Invoke(this);
        }

        /// <summary>
        /// 选中列表的最后一项
        /// </summary>
        public void SelectedLast()
        {
            if (_list.Count == 0)
            {
                _index = -1;
            }
            else
            {
                _index = _list.Count - 1;
            }
            Refresh();
            SelectedIndexChanged?.Invoke(this);
        }

        #endregion


        #region 事件
        /// <summary>
        /// Index改变时发生
        /// </summary>
        [Browsable(true), Category(""), Description("Index改变时发生")]
        public event Event.SelectedIndexChanged SelectedIndexChanged;

        #endregion


        /// <summary>
        /// 计算大小
        /// </summary>
        protected override void CalcSize()
        {
            int w = 0;

            _borderRect = new Rectangle(BORDER_W / 2, BORDER_W / 2, Width - BORDER_W, Height - BORDER_W);

            _listRect = new Rectangle[_list.Count];
            _listStrRect = new RectangleF[_list.Count];
           

            if (_list.Count == 0) return;
            for (int i = 0; i < _list.Count; i++)
            {
                w = Width - BORDER_W - BORDER_W;
                _listRect[i] = new Rectangle(BORDER_W, BORDER_W + _itemH * i, w, _itemH);
                SizeF sf = CreateGraphics().MeasureString(_list[i], Font);
                _listStrRect[i] = new RectangleF(_listRect[i].X + 6, _listRect[i].Y + (_itemH - sf.Height) / 2, w - 12, sf.Height);
            }

            _allItemH = _listRect[_listRect.Length - 1].Bottom;
            _showItemH = Height - BORDER_W - BORDER_W - BORDER_W;
            if (_allItemH > _showItemH)
            {
                scroll = true;
                for (int i = 0; i < _listRect.Length; i++)
                {
                    _listRect[i].Width -= SCROLL_W;
                    _listStrRect[i].Width -= SCROLL_W;
                }

                int n = _allItemH - _showItemH;
                float m = _showItemH - SCROLL_H;
                _step = n / m;



                _scrollRect = new Rectangle(Width - BORDER_W - SCROLL_W, BORDER_W, SCROLL_W, SCROLL_H);

            }
            else
            {
                scroll = false;
                _scrollRect = new Rectangle();
            }
        }

        private void FlatList_Paint(object sender, PaintEventArgs e)
        {
            //g.SmoothingMode = SmoothingMode.HighQuality;
            //g.CompositingQuality = CompositingQuality.HighQuality;
            //g.InterpolationMode = InterpolationMode.HighQualityBicubic;

            BufferedGraphicsContext current = BufferedGraphicsManager.Current;
            BufferedGraphics bg = current.Allocate(this.CreateGraphics(), this.DisplayRectangle);
            Graphics g = bg.Graphics;




            g.Clear(Common.BACK_COLOR);  //背景

  
            for (int i = 0; i < _list.Count; i++)
            {
                if (_listRect[i].Bottom + offsetY < 0) continue;
                if (_listRect[i].Y + offsetY > Height) break;
                Rectangle rect = _listRect[i];
                rect.Y += offsetY;
                if (_index == i)
                    g.FillRectangle(Common.BLUE_BRUSH, rect);
                else if (_over == i)
                    g.FillRectangle(Common.OVER_BRUSH, rect);
                //else
                //    g.FillRectangle(Common.BACK_BRUSH, rect);

                RectangleF rectf = _listStrRect[i];
                rectf.Y += offsetY;
                g.DrawString(_list[i], Font, Common.FORE_BRUSH, rectf);
            }


            if (Inside)
            {
                g.DrawRectangle(Common.BLUE_PEN, _borderRect);    //进入边框
                if (scroll)
                {
                    float y = Math.Abs(offsetY / _step);
                    g.FillRectangle(_scrollDown ? Common.BLUE_BRUSH : Common.BORDER_BRUSH, _scrollRect.X, _scrollRect.Y + y, _scrollRect.Width, _scrollRect.Height);
                }
            }
            else
                g.DrawRectangle(Common.BORDER_PEN, _borderRect);  //离开边框


            bg.Render();
            bg.Dispose();
        }

        private void FlatList_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left && _scrollDown)
            {
                float n = (e.Y - _scrollY) * _step;
                int h = _allItemH - _showItemH;
                if (Math.Abs(n) > 1)
                {
                    offsetY -= Convert.ToInt32(n);
                    _scrollY = e.Y;
                    if (offsetY > 0)
                        offsetY = 0;
                    else if (Math.Abs(offsetY) > h)
                        offsetY = 0 - h;
                    Refresh();
                }
            }
            else
            {
                int n = -1;
                for (int i = 0; i < _listRect.Length; i++)
                {
                    if (_listRect[i].Contains(e.X, e.Y - offsetY))
                    {
                        n = i;
                        break;
                    }
                }

                if (_over == n) return;
                _over = n;
                Refresh();
            }
        }

        private void FlatList_MouseLeave(object sender, EventArgs e)
        {
            _over = -1;
            Refresh();
        }

        private void FlatList_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button != MouseButtons.Left) return;

            if (_over == -1)
            {
                int y = 0;
                if (_step != 0) y = Convert.ToInt32(Math.Abs(offsetY / _step));
                if (_scrollRect.Contains(e.X, e.Y - y))
                {
                    _scrollDown = true;
                    _scrollY = e.Y;
                    Refresh();
                }
            }
            else if (_over == _index)
            {
                _index = -1;
                Refresh();
                SelectedIndexChanged?.Invoke(this);
            }
            else
            {
                _index = _over;
                Refresh();
                SelectedIndexChanged?.Invoke(this);
            }
        }

        private void FlatList_MouseWheel(object sender, MouseEventArgs e)
        {
            if (!scroll) return;
            int h = _allItemH - _showItemH;
            int y = offsetY + e.Delta;

            if (y > 0)
                y = 0;
            else if (Math.Abs(y) > h)
                y = 0 - h;
            _over = -1;

            if (y != offsetY)
            {
                offsetY = y;
                Refresh();
            }
        }

        private void FlatList_MouseUp(object sender, MouseEventArgs e)
        {
            if (_scrollDown)
            {
                _scrollDown = false;
                Refresh();
            }
        }


    }
}