using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace UnitTestProject1
{
    public static class WebUnit
    {
        public static string UrlEncode(string value)
        {
            if (value == null)
            {
                return null;
            }

            byte[] bytes = Encoding.UTF8.GetBytes(value);
            return Encoding.UTF8.GetString(UrlEncode(bytes, 0, bytes.Length, alwaysCreateNewReturnValue: false));
        }

        private static byte[] UrlEncode(byte[] bytes, int offset, int count, bool alwaysCreateNewReturnValue)
        {
            byte[] array = UrlEncode(bytes, offset, count);
            if (!alwaysCreateNewReturnValue || array == null || array != bytes)
            {
                return array;
            }

            return (byte[])array.Clone();
        }

        private static byte[] UrlEncode(byte[] bytes, int offset, int count)
        {
            if (!ValidateUrlEncodingParameters(bytes, offset, count))
            {
                return null;
            }

            int num = 0;
            int num2 = 0;
            for (int i = 0; i < count; i++)
            {
                char c = (char)bytes[offset + i];
                if (c == ' ')
                {
                    num++;
                }
                else if (!IsUrlSafeChar(c))
                {
                    num2++;
                }
            }

            if (num == 0 && num2 == 0)
            {
                if (offset == 0 && bytes.Length == count)
                {
                    return bytes;
                }

                byte[] array = new byte[count];
                Buffer.BlockCopy(bytes, offset, array, 0, count);
                return array;
            }

            byte[] array2 = new byte[count + num2 * 2];
            int num3 = 0;
            for (int j = 0; j < count; j++)
            {
                byte b = bytes[offset + j];
                char c2 = (char)b;
                if (IsUrlSafeChar(c2))
                {
                    array2[num3++] = b;
                    continue;
                }

                if (c2 == ' ')
                {
                    array2[num3++] = 43;
                    continue;
                }

                array2[num3++] = 37;
                array2[num3++] = (byte)IntToHex((b >> 4) & 0xF);
                array2[num3++] = (byte)IntToHex(b & 0xF);
            }

            return array2;
        }

        private static char IntToHex(int n)
        {
            if (n <= 9)
            {
                return (char)(n + 48);
            }

            return (char)(n - 10 + 65);
        }

        private static bool ValidateUrlEncodingParameters(byte[] bytes, int offset, int count)
        {
            if (bytes == null && count == 0)
            {
                return false;
            }

            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }

            if (offset < 0 || offset > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("offset");
            }

            if (count < 0 || offset + count > bytes.Length)
            {
                throw new ArgumentOutOfRangeException("count");
            }

            return true;
        }

        private static bool IsUrlSafeChar(char ch)
        {
            if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9'))
            {
                return true;
            }

            switch (ch)
            {
                case '!':
                case '(':
                case ')':
                case '*':
                case '-':
                case '.':
                case '_':
                    return true;
                default:
                    return false;
            }
        }
    }
}