using System.Collections.Generic;
using System.Drawing;

namespace ui_elements {
    class DropDown {
        List<string> items;
        Point startPosition;
        Size size;
        int itemHeight;
        int selectedId;
        bool isDropDownVisible;
        string defaultText;

        internal DropDown(Point startPosition, Size size, int itemHeight,
            string defaultText) {
            this.startPosition = startPosition;
            this.size = size;
            this.itemHeight = itemHeight;
            items = new List<string>();
            this.defaultText = defaultText;
        }

        internal List<string> Items {
            get { return items; }
            set { items = value; }
        }

        internal Point StartPosition {
            get { return startPosition; }
            set { startPosition = value; }
        }

        internal Size Size {
            get { return size; }
            set { size = value; }
        }

        internal int ItemHeight {
            get { return itemHeight; }
            set { itemHeight = value; }
        }

        internal int SelectedId {
            get { return selectedId; }
            set {
                if ( value >= 0 && value < items.Count ) {
                    selectedId = value;
                }
            }
        }

        internal bool IsDropDownVisible {
            get { return isDropDownVisible; }
            set { isDropDownVisible = value; }
        }

        internal void ToogleDropDownVisible() {
            isDropDownVisible = !isDropDownVisible;
        }

        internal string DefaultText {
            get { return defaultText; }
            set { defaultText = value; }
        }

        internal void Draw(Graphics g) {
            Rectangle dropDownWrap = new Rectangle(startPosition, size);
            Pen wrapPen = new Pen(new SolidBrush(Color.LightGray));
            g.DrawRectangle(wrapPen, dropDownWrap);

            int trWidth = size.Height / 2;
            int teStartX = startPosition.X - size.Height / 4 + size.Width;
            int teStartY = startPosition.Y + (int) ( size.Height / 2.5F );

            g.FillPolygon(new SolidBrush(Color.LightGray),
                new Point[] {
                    new Point(teStartX, teStartY),
                    new Point(teStartX - trWidth,teStartY),
                    new Point(teStartX - trWidth/2, teStartY + (int)(trWidth * 0.7F)),
                    new Point(teStartX, teStartY)
                });

            int fontSizeInPx = (int) ( g.DpiX / 72.0F * Graphic.MaintFont.SizeInPoints );

            string selectedItemText = defaultText;
            if ( items != null && items.Count > 0 && !isDropDownVisible ) {
                selectedItemText = items[selectedId];
            }

            int textStartPointX = startPosition.X + size.Height / 4;
            int textStartPointY = startPosition.Y + ( size.Height - fontSizeInPx ) / 2;
            Point textStartPoint = new Point(textStartPointX, textStartPointY);
            Brush textBrush = new SolidBrush(Color.DimGray);

            g.DrawString(selectedItemText, Graphic.MaintFont, textBrush, textStartPoint);

            if ( IsDropDownVisible ) {
                drawDropDownOptions(g, fontSizeInPx);
            }
        }

        private void drawDropDownOptions(Graphics g, int fontSizeInPx) {
            Rectangle dropDown = new Rectangle(
                startPosition.X, startPosition.Y + size.Height,
                size.Width, itemHeight * items.Count);
            Pen pen = new Pen(new SolidBrush(Color.LightGray));
            Brush brush = new SolidBrush(Color.White);

            g.FillRectangle(brush, dropDown);

            int x = startPosition.X + itemHeight / 4;
            int y = startPosition.Y + size.Height +
                ( itemHeight - fontSizeInPx ) / 2 - itemHeight;
            int lineX = startPosition.X;
            int lineY = startPosition.Y + size.Height;

            for ( int i = 0; i < items.Count; i++ ) {
                Point itemPt1 = new Point(lineX, lineY += itemHeight);
                Point itemPt2 = new Point(lineX + size.Width, lineY);
                Point textPoint = new Point(x, y += itemHeight);
                Brush textBrush = new SolidBrush(Color.Black);

                g.DrawLine(pen, itemPt1, itemPt2);
                g.DrawString(items[i], Graphic.MaintFont, textBrush, textPoint);
            }

            g.DrawRectangle(pen, dropDown);
        }

        internal bool SelectItem(Point point) {
            if ( isDropDownVisible && point.X > startPosition.X &&
                point.X < startPosition.X + size.Width ) {
                SelectedId = ( point.Y - startPosition.Y - Size.Height ) / itemHeight;

                return true;
            }

            return false;
        }

        internal bool IsHitPoint(Point point) {
            return point.X > startPosition.X &&
                point.X < startPosition.X + size.Width &&
                point.Y > startPosition.Y &&
                point.Y < startPosition.Y + size.Height;
        }

    }
}