Refactored project structure

backend/handlers/jwt.go

@@ -0,0 +1,41 @@
+package handlers
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+var jwtSecret = []byte("supersecretkey") // TODO: move to env variable
+
+func generateToken(userID int, username string) (string, error) {
+	claims := jwt.MapClaims{
+		"user_id":  userID,
+		"username": username,
+		"exp":      time.Now().Add(2 * time.Hour).Unix(),
+	}
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	return token.SignedString(jwtSecret)
+}
+
+func usernameFromJWT(r *http.Request) (string, error) {
+	auth := r.Header.Get("Authorization")
+	parts := strings.SplitN(auth, " ", 2)
+	if len(parts) != 2 || parts[0] != "Bearer" {
+		return "", nil
+	}
+	tokenStr := parts[1]
+
+	token, err := jwt.Parse(tokenStr, func(t *jwt.Token) (interface{}, error) { return jwtSecret, nil })
+	if err != nil || !token.Valid {
+		return "", err
+	}
+	if claims, ok := token.Claims.(jwt.MapClaims); ok {
+		if u, ok := claims["username"].(string); ok {
+			return u, nil
+		}
+	}
+	return "", nil
+}