import { type GraphQLSchema } from 'graphql';
import { type ApplicationConfig } from 'graphql-modules';
import { authDirective } from './authenticated-directive';
import { makeExecutableSchema } from '@graphql-tools/schema';
import { mergeResolvers, mergeTypeDefs } from '@graphql-tools/merge';
import { type IResolvers, type Maybe, type TypeSource } from '@graphql-tools/utils';

export const buildSchema =
  <TSource, TContext>({
    typeDefs,
    resolvers,
    authDirective: { authDirectiveTypeDefs, authDirectiveTransformer } = authDirective('auth'),
    directives = [],
  }: {
    typeDefs?: TypeSource;
    resolvers?:
      | Maybe<IResolvers<TSource, TContext>>
      | Maybe<Maybe<IResolvers<TSource, TContext>>[]>;
    authDirective?: {
      authDirectiveTypeDefs: string;
      authDirectiveTransformer: (schema: GraphQLSchema) => GraphQLSchema;
    };
    directives?: Array<[TypeSource | undefined, (schema: GraphQLSchema) => GraphQLSchema]>;
  } = {}): ApplicationConfig['schemaBuilder'] =>
  ({ typeDefs: accountsTypeDefs, resolvers: accountsResolvers }) => {
    let schema = makeExecutableSchema({
      typeDefs: mergeTypeDefs([
        ...accountsTypeDefs,
        ...(typeDefs ? [typeDefs] : []),
        authDirectiveTypeDefs,
        ...directives.reduce<TypeSource[]>((acc, [directiveTypeDefs]) => {
          if (directiveTypeDefs != null) {
            acc.push(directiveTypeDefs);
          }
          return acc;
        }, []),
      ]),
      resolvers: resolvers
        ? mergeResolvers([resolvers, ...accountsResolvers] as Maybe<
            Maybe<IResolvers<TSource, TContext>>[]
          >)
        : accountsResolvers,
    });
    for (const [, directiveTransformer] of directives) {
      schema = directiveTransformer(schema);
    }
    return authDirectiveTransformer(schema);
  };