directive @core(feature: String!) repeatable on SCHEMA

directive @join__owner(graph: join__Graph!) on OBJECT

directive @join__type(
    graph: join__Graph!
    key: String!
    resolvable: Boolean = true
) repeatable on OBJECT | INTERFACE

directive @join__field(
    graph: join__Graph
    requires: String
    provides: String
) on FIELD_DEFINITION

directive @join__graph(name: String!, url: String!) on ENUM_VALUE

enum join__Graph {
    COURSES @join__graph(name: "courses", url: "http://example.com/courses")
    RATINGS @join__graph(name: "ratings", url: "http://example.com/ratings")
    STUDENTS @join__graph(name: "students", url: "http://example.com/students")
}

type Course
    @join__type(graph: COURSES, key: "id")
    @join__type(graph: STUDENTS, key: "id")
{
    description: String @join__field(graph: COURSES)
    enrolledStudents: [Student] @join__field(graph: STUDENTS, requires: "id")
    id: ID!
    name: String @join__field(graph: COURSES)
}

type Enrollment
    @join__type(graph: COURSES, key: "studentId courseId")
    @join__type(graph: RATINGS, key: "studentId courseId")
    @join__type(graph: STUDENTS, key: "studentId courseId")
{
    course: Course @join__field(graph: STUDENTS)
    courseId: ID!
    enrollmentDate: String @join__field(graph: STUDENTS)
    enrollmentDetails: Enrollment @join__field(graph: COURSES, requires: "studentId courseId")
    rating: CourseRating @join__field(graph: RATINGS)
    studentId: ID!
}

type CourseRating
    @join__type(graph: RATINGS, key: "courseId")
{
    comments: String @join__field(graph: RATINGS)
    courseId: ID!
    rating: Float @join__field(graph: RATINGS)
}

type Student
    @join__type(graph: STUDENTS, key: "id")
{
    enrollments: [Enrollment] @join__field(graph: STUDENTS)
    id: ID!
    name: String @join__field(graph: STUDENTS)
}

type Query {
    course(id: ID!): Course @join__field(graph: COURSES)
    courseRating(courseId: ID!): [CourseRating] @join__field(graph: RATINGS)
    courses: [Course] @join__field(graph: COURSES)
    student(id: ID!): Student @join__field(graph: STUDENTS)
    students: [Student] @join__field(graph: STUDENTS)
}