tsk-3: Add Token support (#10)

Closes #3

Reviewed-on: phoenix/textsender-api#10
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

internal/config/config.go

@@ -16,6 +16,7 @@ type Config struct {
 	DBConnString string
 	ServerPort   string
 	ResetDB      bool
+	JWTSecret    string `env:"JWT_SECRET" required:"true"`
 }
 
 type ConnectionInfo struct {
@@ -68,6 +69,7 @@ func Load() *Config {
 		DBConnString: dbConnString,
 		ServerPort:   *port,
 		ResetDB:      *resetDb,
+		JWTSecret:    os.Getenv("JWT_SECRET"),
 	}
 }
 

internal/middleware/auth.go

@@ -0,0 +1,47 @@
+package middleware
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"git.kundeng.us/phoenix/textsender-api/internal/services"
+)
+
+type contextKey string
+
+const (
+	UserContextKey contextKey = "user"
+)
+
+func AuthMiddleware(authService *services.JWTService) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			authHeader := r.Header.Get("Authorization")
+			if authHeader == "" {
+				http.Error(w, "Authorization header required", http.StatusUnauthorized)
+				return
+			}
+
+			// Extract token from "Bearer <token>"
+			parts := strings.Split(authHeader, " ")
+			if len(parts) != 2 || parts[0] != "Bearer" {
+				http.Error(w, "Invalid authorization header format", http.StatusUnauthorized)
+				return
+			}
+
+			token := parts[1]
+
+			// Validate token with auth service
+			user, err := authService.ValidateToken(token)
+			if err != nil {
+				http.Error(w, "Invalid token", http.StatusUnauthorized)
+				return
+			}
+
+			// Add user to context
+			ctx := context.WithValue(r.Context(), UserContextKey, user)
+			next.ServeHTTP(w, r.WithContext(ctx))
+		})
+	}
+}

internal/services/jwt_service.go

@@ -0,0 +1,50 @@
+package services
+
+import (
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+
+	txtmodels_token "git.kundeng.us/phoenix/textsender-models/pkg/token"
+	txtmodels_user "git.kundeng.us/phoenix/textsender-models/pkg/user"
+)
+
+type JWTService struct {
+	secretKey []byte
+}
+
+func NewJWTService(secretKey string) *JWTService {
+	return &JWTService{
+		secretKey: []byte(secretKey),
+	}
+}
+
+func (s *JWTService) ValidateToken(tokenString string) (*txtmodels_user.User, error) {
+	// TODO: Include more user information in the claims to populate user
+	claims := &txtmodels_token.Claims{}
+
+	token, err := jwt.ParseWithClaims(tokenString, claims, func(token *jwt.Token) (interface{}, error) {
+		// Validate the signing method
+		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, jwt.ErrSignatureInvalid
+		}
+		return s.secretKey, nil
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	if !token.Valid {
+		return nil, jwt.ErrSignatureInvalid
+	}
+
+	// Check token expiration
+	if time.Now().After(claims.ExpiresAt.Time) {
+		return nil, jwt.ErrTokenExpired
+	}
+
+	return &txtmodels_user.User{
+		Id: claims.UserId,
+	}, nil
+}