using CPRNIMS.Domain.UIContracts.CaptCha;
using System;
using System.Collections.Generic;
using System.Drawing.Imaging;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CPRNIMS.Domain.UIServices.CaptCha
{
    public class CaptchaService : ICaptchaService
    {
        private readonly Random _random = new Random();

        public (string code, byte[] image) GenerateCaptcha()
        {
            // Generate random code
            string captchaCode = GenerateRandomCode();

            // Create image from code
            using (var bitmap = new Bitmap(150, 50))
            using (var graphics = Graphics.FromImage(bitmap))
            using (var memoryStream = new MemoryStream())
            {
                graphics.Clear(Color.White);

                // Add noise and pattern
                AddNoise(graphics, bitmap.Width, bitmap.Height);

                // Draw the text
                using (var font = new Font("Arial", 20, FontStyle.Bold))
                {
                    graphics.DrawString(captchaCode, font, Brushes.Black, 10, 10);
                }

                // Add some random lines for more security
                AddRandomLines(graphics, bitmap.Width, bitmap.Height);

                // Save to memory stream as PNG
                bitmap.Save(memoryStream, ImageFormat.Png);
                return (captchaCode, memoryStream.ToArray());
            }
        }

        private string GenerateRandomCode()
        {
            // Generate a code of 6 characters (letters and numbers)
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
            return new string(Enumerable.Repeat(chars, 6)
                .Select(s => s[_random.Next(s.Length)]).ToArray());
        }

        private void AddNoise(Graphics graphics, int width, int height)
        {
            // Add random pixels
            for (int i = 0; i < 50; i++)
            {
                int x = _random.Next(width);
                int y = _random.Next(height);
                graphics.DrawRectangle(Pens.LightGray, x, y, 1, 1);
            }
        }

        private void AddRandomLines(Graphics graphics, int width, int height)
        {
            // Add random lines
            for (int i = 0; i < 5; i++)
            {
                int x1 = _random.Next(width);
                int y1 = _random.Next(height);
                int x2 = _random.Next(width);
                int y2 = _random.Next(height);
                graphics.DrawLine(Pens.Gray, x1, y1, x2, y2);
            }
        }
    }
}