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index.js

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+const { ApolloServer, gql } = require('apollo-server');
+const { SchemaDirectiveVisitor } = require('graphql-tools');
+
+const { createError } = require('apollo-errors');
+
+const { ApolloProjector, IncludeAll, IgnoreField, default: makeProjection } = require('graphql-db-projection');
+
+const AuthorizationError = createError('AuthorizationError', {
+	message: 'You are not authorized.'
+});
+
+const { DirectiveLocation, GraphQLDirective, GraphQLList, GraphQLString, GraphQLNonNull } = require('graphql');
+
+
+class AuthDirective extends SchemaDirectiveVisitor {
+	static getDirectiveDeclaration(directiveName, schema) {
+		return new GraphQLDirective({
+			name: 'auth',
+			locations: [ DirectiveLocation.FIELD_DEFINITION, DirectiveLocation.OBJECT ],
+			args: {
+				roles: {
+					type: new GraphQLList(new GraphQLNonNull(schema.getType('Role'))),
+					defaultValue: 'reader'
+				}
+			}
+		});
+	}
+
+	visitFieldDefinition(field, x) {
+		const { resolve = defaultFieldResolver } = field;
+
+		field.resolve = async (root, args, context, info) => {
+			const allowedRoles = this.args.roles || [];
+
+			const user = await context.getUser();
+
+			if (!user || !user.roles.some((role) => allowedRoles.includes(role))) {
+				throw new Error('Unauthorized');
+			}
+
+			return resolve.call(this, root, args, context, info);
+		};
+	}
+
+	visitObject(obj) {
+		const fields = obj.getFields();
+		const expectedRoles = this.args.roles;
+
+		Object.keys(fields).forEach((fieldName) => {
+			const field = fields[fieldName];
+			const next = field.resolve;
+
+			this.visitFieldDefinition(field);
+		});
+	}
+}
+
+class ModelDirective extends SchemaDirectiveVisitor {
+	static getDirectiveDeclaration(directiveName, schema) {
+		return new GraphQLDirective({
+			name: 'model',
+			locations: [ DirectiveLocation.FIELD_DEFINITION ],
+			args: {
+				table: {
+					type: GraphQLString,
+					defaultValue: null
+				}
+			}
+		});
+	}
+
+	visitFieldDefinition(field) {
+		for (const [ name, subfield ] of Object.entries(field.type.ofType._fields)) {
+			field.args.push({
+				name,
+				description: '',
+				type: subfield.type instanceof GraphQLNonNull ? subfield.type.ofType : subfield.type,
+				defaultValue: undefined
+			});
+		}
+		const { resolve = defaultFieldResolver } = field;
+
+		field.resolve = async (root, args, context, info) => {
+			const { table } = this.args;
+
+			const projection = makeProjection(info);
+
+			debugger;
+
+			return resolve.call(this, root, args, context, info);
+		};
+	}
+}
+// The GraphQL schema
+const typeDefs = gql`
+	enum Role {
+		ADMIN
+		USER
+	}
+
+	type Hero {
+		name: String!
+	}
+
+	directive @auth(roles: [Role!]) on FIELD_DEFINITION | OBJECT
+
+	directive @model(table: String!) on FIELD_DEFINITION
+
+	directive @project(projection: String, projections: [String], nameInDB: String) on FIELD_DEFINITION
+
+	directive @all on FIELD_DEFINITION
+
+	directive @ignore on FIELD_DEFINITION
+
+	type Query {
+		heroes(x: Int): [Hero] @model(table: "hero")
+	}
+`;
+
+// A map of functions which return data for the schema.
+const resolvers = {
+	Query: {
+		heroes: () => 'world'
+	}
+};
+
+const server = new ApolloServer({
+	typeDefs,
+	resolvers,
+	schemaDirectives: {
+		project: ApolloProjector,
+		all: IncludeAll,
+		ignore: IgnoreField,
+		auth: AuthDirective,
+		model: ModelDirective
+	}
+});
+
+server.listen().then(({ url }) => {
+	console.log(`🚀 Server ready at ${url}`);
+});