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

namespace Flags
{
    public partial class Flags : Form
    {
        enum Countries { Sudan = 1, Congo };
        Countries country;

        public Flags()
        {
            InitializeComponent();
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            Invalidate();
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            if (country == Countries.Sudan)
                DrawFlag_Sudan(ClientRectangle, e.Graphics);
            else if (country == Countries.Congo)
                DrawFlag_Congo(ClientRectangle, e.Graphics);
        }

        private void DrawFlag_Sudan(Rectangle r, Graphics g)
        {
            const int prop_x = 1, prop_y = 2;
            int H = r.Height - menuStrip1.Height, W = r.Width;
            Point WN = new Point(0, menuStrip1.Height);

            if (prop_x * r.Width > prop_y * r.Height)
            {
                W = H * prop_y / prop_x;
                WN.X = (r.Width - W) / 2;
            }

            else if (prop_x * r.Width < prop_y * r.Height)
            {
                H = W * prop_x / prop_y;
                WN.Y = (r.Height - H) / 2;
            }

            SolidBrush brush = new SolidBrush(Color.Black);
            g.FillRectangle(brush, WN.X, WN.Y, W, H);
            Point a = new Point(WN.X, WN.Y + H / 3);
            Point b = new Point(WN.X + W, WN.Y + H / 3);
            Point c = new Point(WN.X, WN.Y + 2 * H / 3);
            Point d = new Point(WN.X + W, WN.Y + 2 * H / 3);
            Point CenterL = new Point(WN.X, WN.Y + H / 2);
            Point CenterR = new Point(WN.X + W, WN.Y + H / 2);
            Point BottomL = new Point(WN.X, WN.Y + 6 * H / 7);
            Point BottomR = new Point(WN.X + W, WN.Y + 6 * H / 7);

            Pen pen = new Pen(Color.White, W / 38);
            g.DrawLine(pen, a, b);
            g.DrawLine(pen, c, d);
            pen.Color = System.Drawing.ColorTranslator.FromHtml("#da121a");
            pen.Width = W / 7;
            g.DrawLine(pen, CenterL, CenterR);
            pen.Color = System.Drawing.ColorTranslator.FromHtml("#078930");
            pen.Width = W / 6;
            g.DrawLine(pen, BottomL, BottomR);

            Point Center = new Point(WN.X + 2 * W / 5, WN.Y + H / 2);
            Point LeftBottom = new Point(WN.X, WN.Y + H);
            Point[] fillpoints = { WN, Center, LeftBottom };
            brush.Color = System.Drawing.ColorTranslator.FromHtml("#0f47af");
            g.FillPolygon(brush, fillpoints);
            brush.Color = System.Drawing.ColorTranslator.FromHtml("#f7d618");
            g.FillPolygon(brush, Draw_Star(WN.X + W / 7, WN.Y + H / 2, W / 12, H / 16, 0));

            Font font = new Font("Underlined", W / 71, FontStyle.Underline);
            StringFormat drawFormat = new System.Drawing.StringFormat();
            g.DrawString("Южный Судан", font, brush, WN.X + 3 * W / 4, WN.Y + H / 18, drawFormat);

            pen.Dispose();
            brush.Dispose();
        }

        private void DrawFlag_Congo(Rectangle r, Graphics g)
        {
            const int prop_x = 3, prop_y = 4;
            int H = r.Height - menuStrip1.Height, W = r.Width;
            Point WN = new Point(0, menuStrip1.Height);

            if (prop_x * r.Width > prop_y * r.Height)
            {
                W = H * prop_y / prop_x;
                WN.X = (r.Width - W) / 2;
            }

            else if (prop_x * r.Width < prop_y * r.Height)
            {
                H = W * prop_x / prop_y;
                WN.Y = (r.Height - H) / 2;
            }

            SolidBrush brush = new SolidBrush(Color.Blue);
            brush.Color = System.Drawing.ColorTranslator.FromHtml("#007fff");
            g.FillRectangle(brush, WN.X, WN.Y, W, H);
            brush.Color = System.Drawing.ColorTranslator.FromHtml("#f7d618");
            Point a = new Point(WN.X, WN.Y + 4 * H / 5);
            Point b = new Point(WN.X, WN.Y + H);
            Point c = new Point(WN.X + W / 17, WN.Y + H);
            Point d = new Point(WN.X + W, WN.Y + H / 5);
            Point e = new Point(WN.X + W, WN.Y);
            Point f = new Point(WN.X + 19 * W / 20, WN.Y);
            Point[] fillpoints1 = { a, b, c, d, e, f };
            g.FillPolygon(brush, fillpoints1);

            brush.Color = System.Drawing.ColorTranslator.FromHtml("#ce1021");
            Point r1 = new Point(WN.X, WN.Y + 21 * H / 25);
            Point r2 = new Point(WN.X + W, WN.Y + 4 * H / 25);
            Point[] fillpoints2 = { r1, b, r2, e };
            g.FillPolygon(brush, fillpoints2);
            brush.Color = System.Drawing.ColorTranslator.FromHtml("#f7d618");
            g.FillPolygon(brush, Draw_Star(WN.X + W / 6, WN.Y + H / 3, W / 7.2, H / 14.5, 4.084));

            Font font = new Font("Underlined", W / 50, FontStyle.Underline);
            StringFormat drawFormat = new System.Drawing.StringFormat();
            g.DrawString("Демократическая Республика Конго", font,
                brush, WN.X + W / 3, WN.Y + H / 18, drawFormat);
            brush.Dispose();
        }

        private PointF[] Draw_Star(double center_x, double center_y, double R, double r, double alpha)
        {
            int num = 5;
            PointF[] points = new PointF[2 * num + 1];
            double a = Math.PI / num, rads;
            for (int i = 0; i < 2 * num + 1; i++)
            {
                rads = (i % 2 == 0) ? r : R;
                points[i] = new PointF((float)(center_x + rads * Math.Cos(alpha)),
                    (float)(center_y + rads * Math.Sin(alpha)));
                alpha += a;
            }
            return points;
        }

        private void SudanMenu_Click(object sender, EventArgs e)
        {
            country = Countries.Sudan;
            Invalidate();
        }

        private void CongoMenu_Click(object sender, EventArgs e)
        {
            country = Countries.Congo;
            Invalidate();
        }
    }
}