using System;
using System.Reflection.Metadata.Ecma335;

namespace NumeralSystems
{
    /// <summary>
    /// Converts a string representations of a numbers to its integer equivalent.
    /// </summary>
    public static class Converter
    {
        /// <summary>
        /// Converts the string representation of a positive number in the octal numeral system to its 32-bit signed integer equivalent.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the octal numeral system.</param>
        /// <returns>A positive decimal value.</returns>
        /// <exception cref="ArgumentException">
        /// Thrown if source string presents a negative number
        /// - or
        /// contains invalid symbols (non-octal alphabetic characters).
        /// Valid octal alphabetic characters: 0,1,2,3,4,5,6,7.
        /// </exception>
        public static int ParsePositiveFromOctal(this string source) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a positive number in the decimal numeral system to its 32-bit signed integer equivalent.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the decimal numeral system.</param>
        /// <returns>A positive decimal value.</returns>
        /// <exception cref="ArgumentException">
        /// Thrown if source string presents a negative number
        /// - or
        /// contains invalid symbols (non-decimal alphabetic characters).
        /// Valid decimal alphabetic characters: 0,1,2,3,4,5,6,7,8,9.
        /// </exception>
        public static int ParsePositiveFromDecimal(this string source) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a positive number in the hex numeral system to its 32-bit signed integer equivalent.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the hex numeral system.</param>
        /// <returns>A positive decimal value.</returns>
        /// <exception cref="ArgumentException">
        /// Thrown if source string presents a negative number
        /// - or
        /// contains invalid symbols (non-hex alphabetic characters).
        /// Valid hex alphabetic characters: 0,1,2,3,4,5,6,7,8,9,A(or a),B(or b),C(or c),D(or d),E(or e),F(or f).
        /// </exception>
        public static int ParsePositiveFromHex(this string source) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a positive number in the octal, decimal or hex numeral system to its 32-bit signed integer equivalent.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the the octal, decimal or hex numeral system.</param>
        /// <param name="radix">The radix.</param>
        /// <returns>A positive decimal value.</returns>
        /// <exception cref="ArgumentException">
        /// Thrown if source string presents a negative number
        /// - or
        /// contains invalid for given numeral system symbols
        /// -or-
        /// the radix is not equal 8, 10 or 16.
        /// </exception>
        public static int ParsePositiveByRadix(this string source, int radix) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a signed number in the octal, decimal or hex numeral system to its 32-bit signed integer equivalent.
        /// </summary>
        /// <param name="source">The string representation of a signed number in the the octal, decimal or hex numeral system.</param>
        /// <param name="radix">The radix.</param>
        /// <returns>A signed decimal value.</returns>
        /// <exception cref="ArgumentException">
        /// Thrown if source contains invalid for given numeral system symbols
        /// -or-
        /// the radix is not equal 8, 10 or 16.
        /// </exception>
        public static int ParseByRadix(this string source, int radix)
        {
            int pow = 1;
            int result = 0;
            int buffer = 0;

            for (int i = source.Length - 1; i >= 0; i--)
            {
                buffer = source[i] switch
                {
                    '0' => 0,
                    '1' => 1,
                    '2' => 2,
                    '3' => 3,
                    '4' => 4,
                    '5' => 5,
                    '6' => 6,
                    '7' => 7,
                    '8' => 8,
                    '9' => 9,
                    'A' => 10,
                    'B' => 11,
                    'C' => 12,
                    'D' => 13,
                    'E' => 14,
                    'F' => 15,
                    _ => 0
                };
                result += buffer * pow;
                pow *= radix;
            }

            return source[0] == '-' ? -result : result;
        }

        /// <summary>
        /// Converts the string representation of a positive number in the octal numeral system to its 32-bit signed integer equivalent.
        /// A return value indicates whether the conversion succeeded.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the octal numeral system.</param>
        /// <param name="value">A positive decimal value.</param>
        /// <returns>true if s was converted successfully; otherwise, false.</returns>
        public static bool TryParsePositiveFromOctal(this string source, out int value) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a positive number in the decimal numeral system to its 32-bit signed integer equivalent.
        /// A return value indicates whether the conversion succeeded.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the decimal numeral system.</param>
        /// <returns>A positive decimal value.</returns>
        /// <param name="value">A positive decimal value.</param>
        /// <returns>true if s was converted successfully; otherwise, false.</returns>
        public static bool TryParsePositiveFromDecimal(this string source, out int value) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a positive number in the hex numeral system to its 32-bit signed integer equivalent.
        /// A return value indicates whether the conversion succeeded.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the hex numeral system.</param>
        /// <returns>A positive decimal value.</returns>
        /// <param name="value">A positive decimal value.</param>
        /// <returns>true if s was converted successfully; otherwise, false.</returns>
        public static bool TryParsePositiveFromHex(this string source, out int value) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a positive number in the octal, decimal or hex numeral system to its 32-bit signed integer equivalent.
        /// A return value indicates whether the conversion succeeded.
        /// </summary>
        /// <param name="source">The string representation of a positive number in the the octal, decimal or hex numeral system.</param>
        /// <param name="radix">The radix.</param>
        /// <returns>A positive decimal value.</returns>
        /// <param name="value">A positive decimal value.</param>
        /// <returns>true if s was converted successfully; otherwise, false.</returns>
        /// <exception cref="ArgumentException">Thrown the radix is not equal 8, 10 or 16.</exception>
        public static bool TryParsePositiveByRadix(this string source, int radix, out int value) => throw new NotImplementedException();

        /// <summary>
        /// Converts the string representation of a signed number in the octal, decimal or hex numeral system to its 32-bit signed integer equivalent.
        /// A return value indicates whether the conversion succeeded.
        /// </summary>
        /// <param name="source">The string representation of a signed number in the the octal, decimal or hex numeral system.</param>
        /// <param name="radix">The radix.</param>
        /// <returns>A positive decimal value.</returns>
        /// <param name="value">A positive decimal value.</param>
        /// <returns>true if s was converted successfully; otherwise, false.</returns>
        /// <exception cref="ArgumentException">Thrown the radix is not equal 8, 10 or 16.</exception>
        public static bool TryParseByRadix(this string source, int radix, out int value) =>
            throw new NotImplementedException();
    }
}