using AutoMapper;
using DigitalData.Core.Abstractions.Security.Key;
using Microsoft.IdentityModel.Tokens;

namespace DigitalData.Core.Security.Extensions;

internal static class Extension
{
    /// <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="RSATokenDescriptor"/> to a <see cref="SecurityTokenDescriptor"/>.
    /// </summary>
    /// <param name="mapper">The <see cref="IMapper"/> instance used for mapping.</param>
    /// <param name="description">The <see cref="RSATokenDescriptor"/> 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, IAsymmetricTokenDescriptor description)
        => mapper.Map(description, new SecurityTokenDescriptor());
}