Ma Harpers Creole Gumbo

Name: Ma Harper's Creole Gumbo
Ingredients: 2 cups all-purpose flour; 1 pound chicken meat, light or dark, cut into pieces; 2 teaspoons oil; 1 pound smoked or hot sausage, sliced; 2 large onions, chopped; 1 large bell pepper, chopped; 1 head garlic, chopped; 6 whole blue crabs, cleaned and back shell removed; 2 teaspoons thyme; 1 teaspoon cayenne pepper; 5 ribs celery, chopped; 3 small bay leaves; 1 bunch green onion, chopped; 3 quarts chicken or seafood stock; 2 teaspoons salt; 1 teaspoon black pepper; Cajun seasoning, to taste; 1/4 cup chopped fresh parsley; Rice, for serving; Gumbo file powder, for serving