Add token authentication.

Marechai.Server/Services/TokenService.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IdentityModel.Tokens.Jwt;
+using System.Linq;
+using System.Security.Claims;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.IdentityModel.Tokens;
+
+namespace Marechai.Server.Services;
+
+public sealed class TokenService
+{
+    public string CreateToken(IdentityUser user, IList<string> roles)
+    {
+        JwtSecurityToken token        = CreateJwtToken(CreateClaims(user, roles), CreateSigningCredentials());
+        var              tokenHandler = new JwtSecurityTokenHandler();
+
+        return tokenHandler.WriteToken(token);
+    }
+
+    JwtSecurityToken CreateJwtToken(List<Claim> claims, SigningCredentials credentials) =>
+        new("apiWithAuthBackend", "apiWithAuthBackend", claims, expires: null, signingCredentials: credentials);
+
+    List<Claim> CreateClaims(IdentityUser user, IList<string> roles)
+    {
+        try
+        {
+            List<Claim> claims =
+            [
+                new(JwtRegisteredClaimNames.Sub, "TokenForTheApiWithAuth"),
+                new(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
+                new(JwtRegisteredClaimNames.Iat,
+                    EpochTime.GetIntDate(DateTime.UtcNow).ToString(CultureInfo.InvariantCulture)),
+                new(ClaimTypes.Sid, user.Id), new(ClaimTypes.Name, user.UserName), new(ClaimTypes.Email, user.Email)
+            ];
+
+            claims.AddRange(roles.Select(role => new Claim(ClaimTypes.Role, role)));
+
+            return claims;
+        }
+        catch(Exception e)
+        {
+            Console.WriteLine(e);
+
+            throw;
+        }
+    }
+
+    SigningCredentials CreateSigningCredentials() =>
+        new(new SymmetricSecurityKey("!SomethingSecret!!SomethingSecret!!SomethingSecret!!SomethingSecret!"u8
+                                        .ToArray()),
+            SecurityAlgorithms.HmacSha256);
+}