use auth service for validating user in competitions service

internal/competition/middleware/auth.go

@@ -0,0 +1,67 @@
+package middleware
+
+import (
+	"context"
+	"strings"
+
+	authpb "datarush/pkg/api/auth"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+type contextKey string
+
+const (
+	UserIDKey    contextKey = "user_id"
+	authHeader              = "authorization"
+	bearerScheme            = "bearer"
+)
+
+type AuthInterceptor struct {
+	authClient authpb.AuthServiceClient
+}
+
+func NewAuthInterceptor(authClient authpb.AuthServiceClient) *AuthInterceptor {
+	return &AuthInterceptor{authClient: authClient}
+}
+
+func (i *AuthInterceptor) Unary() grpc.UnaryServerInterceptor {
+	return func(
+		ctx context.Context,
+		req interface{},
+		info *grpc.UnaryServerInfo,
+		handler grpc.UnaryHandler,
+	) (interface{}, error) {
+		md, ok := metadata.FromIncomingContext(ctx)
+		if !ok {
+			return nil, status.Error(codes.Unauthenticated, "metadata is not provided")
+		}
+
+		authHeaders := md.Get(authHeader)
+		if len(authHeaders) == 0 {
+			return nil, status.Error(codes.Unauthenticated, "authorization token is not provided")
+		}
+
+		header := authHeaders[0]
+		parts := strings.Split(header, " ")
+		if len(parts) != 2 || !strings.EqualFold(parts[0], bearerScheme) {
+			return nil, status.Errorf(codes.Unauthenticated, "invalid authorization header format")
+		}
+
+		token := parts[1]
+
+		validateResp, err := i.authClient.ValidateToken(ctx, &authpb.ValidateTokenRequest{
+			Token: token,
+		})
+		if err != nil {
+			return nil, status.Errorf(codes.Unauthenticated, "failed to validate token: %v", err)
+		}
+
+		newCtx := context.WithValue(ctx, UserIDKey, validateResp.GetUserId())
+
+		return handler(newCtx, req)
+	}
+}