Add JWT authentication.

Add: JWT authentication in Web API. Related configuration and services are added.

OptixServe.Api/Services/TokenService.cs

@@ -0,0 +1,44 @@
+using System.IdentityModel.Tokens.Jwt;
+using System.Security.Claims;
+using System.Text;
+using Microsoft.Extensions.Options;
+using Microsoft.IdentityModel.Tokens;
+using OptixServe.Api.Configuration;
+using OptixServe.Core.Models;
+
+namespace OptixServe.Api.Services;
+
+public interface ITokenService
+{
+    public string GenerateToken(User user);
+}
+
+public class TokenService(IOptions<OptixServeSettings> optixServeSettings) : ITokenService
+{
+    private readonly JwtSettings _jwtSettings = optixServeSettings.Value.Jwt ?? throw new ArgumentNullException(nameof(optixServeSettings), "JWT settings are not configured.");
+
+    public string GenerateToken(User user)
+    {
+        var tokenHandler = new JwtSecurityTokenHandler();
+        var key = Encoding.ASCII.GetBytes(_jwtSettings.Secret);
+
+        var claims = new List<Claim>
+        {
+            new (ClaimTypes.NameIdentifier, user.Id.ToString()),
+            new (ClaimTypes.Name, user.UserName)
+            // Add roles if applicable: new Claim(ClaimTypes.Role, user.Role)
+        };
+
+        var tokenDescriptor = new SecurityTokenDescriptor
+        {
+            Subject = new ClaimsIdentity(claims),
+            Expires = DateTime.UtcNow.AddMinutes(_jwtSettings.TokenExpirationMinutes),
+            Issuer = _jwtSettings.Issuer,
+            Audience = _jwtSettings.Audience,
+            SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
+        };
+
+        var token = tokenHandler.CreateToken(tokenDescriptor);
+        return tokenHandler.WriteToken(token);
+    }
+}