using System;
using System.Drawing;
using System.Windows.Forms;

namespace GeoSigma.SigmaDrawerStyle
{
    /// <summary>
    /// 线型
    /// </summary>
    public class SymbolListBox : ListBox
    {
        private int padding = 1;
        private int itemHeight = 20;
        private ISymbolListBoxProvider provider;

        public event Action<string> SymbolSelected;

        /// <summary>
        /// Initializes a new instance of the <see cref="SymbolListBox"/> class.
        /// </summary>
        /// <param name="provider">provider</param>
        public SymbolListBox(ISymbolListBoxProvider provider)
        {
            this.DrawMode = DrawMode.OwnerDrawFixed;
            this.ItemHeight = itemHeight;

            this.provider = provider;

            string[] names = this.provider.GetNames();
            this.Items.AddRange(names);
        }

        /// <inheritdoc/>
        protected override void OnSelectedIndexChanged(EventArgs e)
        {
            base.OnSelectedIndexChanged(e);

            if (SelectedIndex >= 0 && SelectedIndex < Items.Count)
            {
                SymbolSelected?.Invoke(SelectedItem.ToString());
            }
        }

        /// <inheritdoc/>
        protected override void OnDrawItem(DrawItemEventArgs e)
        {
            if (e.Index < 0 || e.Index >= Items.Count)
            {
                return;
            }

            string name = Items[e.Index].ToString();
            Rectangle bounds = e.Bounds;

            e.DrawBackground();

            // 图像区域
            int imageSize = bounds.Height - (2 * padding);
            Rectangle imageRect = new Rectangle(
                bounds.Left + padding,
                bounds.Top + padding,
                (bounds.Width - (2 * padding)) / 2,
                imageSize);

            // 获取并绘制图像
            if (!string.IsNullOrWhiteSpace(name))
            {
                using (Bitmap bitmap = GetBitmap(name, imageRect.Width, imageRect.Height))
                {
                    if (bitmap != null)
                    {
                        e.Graphics.DrawImage(bitmap, imageRect);
                    }
                }
            }

            // 文字区域（图像右边，预留间距）
            int textX = imageRect.Right + padding;
            Rectangle textRect = new Rectangle(
                textX,
                bounds.Top,
                bounds.Right - textX,
                bounds.Height);

            TextRenderer.DrawText(
                e.Graphics,
                name,
                this.Font,
                textRect,
                (e.State & DrawItemState.Selected) != 0 ? SystemColors.HighlightText : this.ForeColor,
                TextFormatFlags.VerticalCenter | TextFormatFlags.Left);

            e.DrawFocusRectangle();
        }

        private Bitmap GetBitmap(string name, int width, int height)
        {
            Bitmap bitmap = new Bitmap(width, height);
            using (Graphics image = Graphics.FromImage(bitmap))
            {
                IntPtr hdc = image.GetHdc();
                bool success = false;

                try
                {
                    success = this.provider.Draw(name, hdc, width, height);
                }
                finally
                {
                    image.ReleaseHdc(hdc);
                }

                if (!success)
                {
                    bitmap.Dispose();
                    return null;
                }
            }

            return bitmap;
        }
    }
}