using AutoMapper;
using DigitalData.Core.Security.Config;
using Microsoft.IdentityModel.Tokens;

namespace DigitalData.Core.Security
{
    internal static class Extension
    {
        internal static string ToBase64String(this byte[] bytes) => Convert.ToBase64String(bytes);

        internal static byte[] Base64ToByte(this string base64String) => Convert.FromBase64String(base64String);

        internal static byte[] ToBytes(this string str) => System.Text.Encoding.UTF8.GetBytes(str);

        internal static string BytesToString(this byte[] bytes) => System.Text.Encoding.UTF8.GetString(bytes);

        /// <summary>
        /// Converts a <see cref="DateTime"/> to a formatted string based on the specified format string.
        /// <br />
        /// - If the format contains the symbol “//”, the method divides the numeric value obtained from the left side of the format
        ///   by one minus the numeric value obtained from the right side of the format string and adds one. For instance:
        /// <br />
        /// - If the date is 02.03.2024 and the format is "MM//2", it extracts the month (02), subtracts one (3), divides it by 2,
        ///   rounds down the outgoing number (1), adds one to the number (resulting in 2).
        ///   <br />
        /// - If the format does not contain "//", the method uses the default <see cref="DateTime.ToString"/> format.
        /// <br />
        /// </summary>
        /// <param name="date">The <see cref="DateTime"/> value to be formatted.</param>
        /// <param name="format">The format string that dictates the formatting of the date. If the format includes the "//" symbol, 
        /// it splits the string at "//" and divides the left-side value by the right-side value. The format string can include standard
        /// <see cref="DateTime.ToString"/> format patterns.</param>
        /// <returns>A string representation of the formatted date, or the result of the division operation if "//" is present in the format.</returns>
        /// <exception cref="ArgumentException">Thrown if the format string is invalid, such as having an incorrect number of parts after "//".</exception>
        /// <exception cref="DivideByZeroException">Thrown if the right side of the "//" contains a zero, resulting in division by zero.</exception>
        /// <exception cref="FormatException">Thrown if either the left-side or right-side value of "//" cannot be parsed as an integer.</exception>
        internal static string ToTag(this DateTime date, string format)
        {
            if (format is not null && format.Contains("//"))
            {
                var subStrings = format.Split("//");

                if (subStrings.Length != 2)
                    throw new ArgumentException($"Date tag format {format} is invalid. It must contain exactly one '//' separator.", nameof(format));

                var formattedLeft = date.ToString(subStrings[0]);

                if (!int.TryParse(formattedLeft, out var dateValue))
                    throw new FormatException($"The left-side value ({formattedLeft}) of the format could not be parsed to an integer.");

                if (!int.TryParse(subStrings[1], out var divisor))
                    throw new FormatException($"The right-side value ({divisor}) of the format could not be parsed to an integer.");

                if (divisor == 0)
                    throw new DivideByZeroException($"Date tag format {format} includes division by zero, which is not allowed.");

                var result = (dateValue - 1) / divisor + 1;
                return result.ToString();
            }

            return date.ToString(format);
        }

        /// <summary>
        /// Converts a <see cref="DateTime"/> to a formatted string based on the specified format string.
        /// <br />
        /// - If the format contains the symbol “//”, the method divides the numeric value obtained from the left side of the format
        ///   by one minus the numeric value obtained from the right side of the format string and adds one. For instance:
        /// <br />
        /// - If the date is 02.03.2024 and the format is "MM//2", it extracts the month (02), subtracts one (3), divides it by 2,
        ///   rounds down the outgoing number (1), adds one to the number (resulting in 2).
        ///   <br />
        /// - If the format does not contain "//", the method uses the default <see cref="DateTime.ToString"/> format.
        /// <br />
        /// This method provides a way to format the date based on typical or customized rules, including mathematical operations like division.
        /// </summary>
        /// <param name="date">The <see cref="DateOnly"/> value to be formatted. It will convert to DateTime to use the method shared with DateTime.</param>
        /// <param name="format">The format string that dictates the formatting of the date. If the format includes the "//" symbol, 
        /// it splits the string at "//" and divides the left-side value by the right-side value. The format string can include standard
        /// <see cref="DateTime.ToString"/> format patterns.</param>
        /// <returns>A string representation of the formatted date, or the result of the division operation if "//" is present in the format.</returns>
        /// <exception cref="ArgumentException">Thrown if the format string is invalid, such as having an incorrect number of parts after "//".</exception>
        /// <exception cref="DivideByZeroException">Thrown if the right side of the "//" contains a zero, resulting in division by zero.</exception>
        /// <exception cref="FormatException">Thrown if either the left-side or right-side value of "//" cannot be parsed as an integer.</exception>
        internal static string ToTag(this DateOnly date, string format) => date.ToDateTime(new()).ToTag(format);

        /// <summary>
        /// Maps a <see cref="TokenDescription"/> to a <see cref="SecurityTokenDescriptor"/>.
        /// </summary>
        /// <param name="mapper">The <see cref="IMapper"/> instance used for mapping.</param>
        /// <param name="description">The <see cref="TokenDescription"/> instance to be mapped.</param>
        /// <returns>A <see cref="SecurityTokenDescriptor"/> instance populated with the mapped values.</returns>
        /// <exception cref="ArgumentNullException">Thrown if <paramref name="mapper"/> or <paramref name="description"/> is <c>null</c>.</exception>
        internal static SecurityTokenDescriptor Map(this IMapper mapper, TokenDescription description)
            => mapper.Map(description, new SecurityTokenDescriptor());
    }
}