import { GraphQLError } from "graphql";
import { GraphQLExtension } from "graphql-extensions";

export function correlationIdExtension(): GraphQLExtension {
  return {
    willSendResponse(o: any): GraphQLError | any {
      const { context, graphqlResponse } = o;

      if (!graphqlResponse.errors || graphqlResponse.errors.length === 0) {
        return o;
      }

      graphqlResponse.errors = graphqlResponse.errors.map((e: GraphQLError) => {
        const ext = e.extensions || {};

        ext.correlationId = context.req.headers['x-correlation-id'];

        return new GraphQLError(
            e.message,
            e.nodes,
            e.source,
            e.positions,
            e.path,
            e.originalError,
            ext,
        );
      });

      return o;
    },
  }
}