DigitalData.Core/DigitalData.Core.Security/JwtSignatureHandler.cs

using AutoMapper;
using DigitalData.Core.Abstractions.Security;
using DigitalData.Core.Security.Config;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;

namespace DigitalData.Core.Security
{
    public class JwtSignatureHandler<TPrincipal> : JwtSecurityTokenHandler, IJwtSignatureHandler<TPrincipal>
    {
        private readonly ClaimDescriptor<TPrincipal> _claimDescriptor;

        private readonly IMapper _mapper;

        private readonly IEnumerable<TokenDescription>? _tokenDescriptions;

        private readonly IAsymCryptHandler _cryptHandler;

        public JwtSignatureHandler(IOptions<ClaimDescriptor<TPrincipal>> claimDescriptorOptions, IMapper mapper, IOptions<IEnumerable<TokenDescription>>? tokenDescriptionOptions, IAsymCryptHandler asymCryptHandler)
        {
            _claimDescriptor = claimDescriptorOptions.Value;
            _mapper = mapper;
            _tokenDescriptions = tokenDescriptionOptions?.Value;
            _cryptHandler = asymCryptHandler;
        }

        public SecurityToken CreateToken(TPrincipal subject, TokenDescription description)
        {
            var descriptor = _mapper.Map(description);
            descriptor.Claims = _claimDescriptor.CreateClaims?.Invoke(subject);
            descriptor.Subject = _claimDescriptor.CreateSubject?.Invoke(subject);
            return CreateToken(descriptor);
        }

        public SecurityToken CreateToken(TPrincipal subject, string issuer, string audience)
        {
            var description = _tokenDescriptions?.Get(issuer: issuer, audience: audience)
                ?? throw new InvalidOperationException($"No or multiple token description found for issuer '{issuer}' and audience '{audience}'.");

            description.SigningCredentials = _cryptHandler.Decryptors
                .Get(issuer: issuer, audience: audience)
                .CreateSigningCredentials(algorithm: description.SigningAlgorithm, digest: description.SigningDigest);

            return CreateToken(subject: subject, description: description);
        }

        public SecurityToken CreateToken(TPrincipal subject, string apiRoute)
        {
            var description = _tokenDescriptions?.SingleOrDefault(description => description.ApiRoute == apiRoute)
                ?? throw new InvalidOperationException($"No or multiple token description found for api route '{apiRoute}'.");

            description.SigningCredentials = _cryptHandler.Decryptors
                .Get(issuer: description.Issuer, audience: description.Audience)
                .CreateSigningCredentials(algorithm: description.SigningAlgorithm, digest: description.SigningDigest);

            return CreateToken(subject: subject, description: description);
        }

        public string WriteToken(SecurityTokenDescriptor descriptor) => WriteToken(CreateToken(descriptor));

        public string WriteToken(TPrincipal subject, TokenDescription description) => WriteToken(CreateToken(subject: subject, description: description));

        public string WriteToken(TPrincipal subject, string issuer, string audience) => WriteToken(CreateToken(subject: subject, issuer: issuer, audience: audience));

        public string WriteToken(TPrincipal subject, string apiRoute) => WriteToken(CreateToken(subject: subject, apiRoute: apiRoute));
    }
}