using System.Security.Cryptography;
using System.Text;

namespace DigitalData.Core.Abstractions.Security
{
    public static class SecurityExtensions
    {
        public static IEnumerable<TUniqueSecurityContext> GetByIssuer<TUniqueSecurityContext>(this IEnumerable<TUniqueSecurityContext> contextes, string issuer) where TUniqueSecurityContext: IUniqueSecurityContext
            => contextes.Where(c => c.Issuer == issuer);

        public static IEnumerable<TUniqueSecurityContext> GetByAudience<TUniqueSecurityContext>(this IEnumerable<TUniqueSecurityContext> contextes, string audience) where TUniqueSecurityContext : IUniqueSecurityContext
            => contextes.Where(c => c.Audience == audience);

        public static TUniqueSecurityContext Get<TUniqueSecurityContext>(this IEnumerable<TUniqueSecurityContext> contextes, string issuer, string audience) where TUniqueSecurityContext : IUniqueSecurityContext
            => contextes.Where(c => c.Issuer == issuer && c.Audience == audience).SingleOrDefault()
            ?? throw new InvalidOperationException($"Exactly one {typeof(TUniqueSecurityContext).Name} must exist with Issuer: '{issuer}' and Audience: '{audience}'.");

        public static bool TryGet<TUniqueSecurityContext>(this IEnumerable<TUniqueSecurityContext> contextes, string issuer, string audience, out TUniqueSecurityContext context) where TUniqueSecurityContext : IUniqueSecurityContext
        {
#pragma warning disable CS8601 // Possible null reference assignment.
            context = contextes.SingleOrDefault(c => c.Issuer == issuer && c.Audience == audience);
#pragma warning restore CS8601 // Possible null reference assignment.
            return context is not null;
        }

        public static TUniqueSecurityContext Match<TUniqueSecurityContext>(this IEnumerable<TUniqueSecurityContext> contextes, IUniqueSecurityContext lookupContext) where TUniqueSecurityContext : IUniqueSecurityContext
            => contextes.Get(lookupContext.Issuer, lookupContext.Audience);

        public static bool TryMatch<TUniqueSecurityContext>(this IEnumerable<TUniqueSecurityContext> contextes, IUniqueSecurityContext lookupContext, out TUniqueSecurityContext context) where TUniqueSecurityContext : IUniqueSecurityContext
            => contextes.TryGet(lookupContext.Issuer, lookupContext.Audience, out context);

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

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

        internal static string ToBase64String(this byte[] bytes) => Convert.ToBase64String(bytes);

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

        public static string Decrypt(this IAsymmetricDecryptor decryptor, string data) => decryptor
            .Decrypt(data.Base64ToByte()).BytesToString();

        public static string Encrypt(this IAsymmetricEncryptor encryptor, string data) => encryptor.Encrypt(data.ToBytes()).ToBase64String();
    }
}