using System;

using System.Text;

public class Program

{

    public class PasswordOptions

    {

        public bool RequireNonAlphanumeric { get; set; }

        public bool RequireDigit { get; set; }

        public bool RequireLowercase { get; set; }

        public bool RequireUppercase { get; set; }

        public uint RequiredLength { get; set; } = 20;

​

        public static PasswordOptions Strongest() =>

            new()

            {

                RequireDigit = true,

                RequireLowercase = true,

                RequireUppercase = true,

                RequireNonAlphanumeric = true,

                RequiredLength = 50

            };

    }

​

    public class PasswordGenerator

    {

        private readonly PasswordOptions _options;

        private readonly Random _random;

        private uint _currentGenerationLength;

        private bool _currentGenerationShouldIncludeNonAlphanumeric;

        private bool _currentGenerationShouldIncludeDigit;

        private bool _currentGenerationShouldIncludeLowercase;

        private bool _currentGenerationShouldIncludeUppercase;

​

        public PasswordGenerator() : this(PasswordOptions.Strongest())

        {

        }

​

        public PasswordGenerator(PasswordOptions options)

        {

            _options = options;

            _random = new Random();

        }

        public string Generate()

        {

            SetRequirementsBasedOnOptions();

​

            var password = new StringBuilder();

​

            GeneratePasswordOfMinimumSize(password);

​

            AddMissingRequirements(password);

​

            return password.ToString();

        }

​

        private void AddMissingRequirements(StringBuilder password)

        {

            AddNonAlphanumericIfMissing(password);

​

            AddDigitIfMissing(password);

​

            AddLowercaseIfMissing(password);

​

            AddUppercaseIfMissing(password);

        }

​

        private void GeneratePasswordOfMinimumSize(StringBuilder password)

        {

            while (password.Length < _currentGenerationLength)

            {

                var c = RandomAny();

​

                password.Append(c);

​

                updateRequirementsBasedOnCharacter(c);

            }

        }

​

        private void AddUppercaseIfMissing(StringBuilder password)

        {

            if (_currentGenerationShouldIncludeUppercase)

            {

                password.Append(RandomUppercase());

            }

        }

​

        private void AddLowercaseIfMissing(StringBuilder password)

        {

            if (_currentGenerationShouldIncludeLowercase)

            {

                password.Append(RandomLowercase());

            }

        }

​

        private void AddDigitIfMissing(StringBuilder password)

        {

            if (_currentGenerationShouldIncludeDigit)

            {

                password.Append(RandomDigit());

            }

        }

​

        private void AddNonAlphanumericIfMissing(StringBuilder password)

        {

            if (_currentGenerationShouldIncludeNonAlphanumeric)

            {

                password.Append(RandomNonAlphanumeric());

            }

        }

​

        private void SetRequirementsBasedOnOptions()

        {

            _currentGenerationLength = _options.RequiredLength;

            _currentGenerationShouldIncludeNonAlphanumeric = _options.RequireNonAlphanumeric;

            _currentGenerationShouldIncludeDigit = _options.RequireDigit;

            _currentGenerationShouldIncludeLowercase = _options.RequireLowercase;

            _currentGenerationShouldIncludeUppercase = _options.RequireUppercase;

        }

​

        private char RandomAny()

        {

            return (char) _random.Next(32, 126);

        }

​

        private void updateRequirementsBasedOnCharacter(char c)

        {

            if (char.IsDigit(c))

            {

                _currentGenerationShouldIncludeDigit = false;

            }

            else if (char.IsLower(c))

            {

                _currentGenerationShouldIncludeLowercase = false;

            }

            else if (char.IsUpper(c))

            {

                _currentGenerationShouldIncludeUppercase = false;

            }

            else if (!char.IsLetterOrDigit(c))

            {

                _currentGenerationShouldIncludeNonAlphanumeric = false;

            }

        }

​

        private char RandomUppercase()

        {

            return (char) _random.Next(65, 91);

        }

​

        private char RandomLowercase()

        {

            return (char) _random.Next(97, 123);

        }

​

        private char RandomDigit()

        {

            return (char) _random.Next(48, 58);

        }

​

        private char RandomNonAlphanumeric()

        {

            return (char) _random.Next(33, 48);

        }

    }

    public static void Main()

    {

        var generator = new PasswordGenerator();

        var password = generator.Generate();

        Console.WriteLine($"Password is: {password}");

    }

}