Schema.ts

import globby from 'globby';
import fs from 'fs';
import path from 'path';
import { CfnResources } from '../types/cloudFormation';
import { Api } from './Api';
import { flatten } from 'lodash';
import { parse, print } from 'graphql';
import { validateSDL } from 'graphql/validation/validate';
import { mergeTypeDefs } from '@graphql-tools/merge';

const AWS_TYPES = `
directive @aws_iam on FIELD_DEFINITION | OBJECT
directive @aws_oidc on FIELD_DEFINITION | OBJECT
directive @aws_api_key on FIELD_DEFINITION | OBJECT
directive @aws_lambda on FIELD_DEFINITION | OBJECT
directive @aws_auth(cognito_groups: [String]) on FIELD_DEFINITION | OBJECT
directive @aws_cognito_user_pools(
  cognito_groups: [String]
) on FIELD_DEFINITION | OBJECT
directive @aws_subscribe(mutations: [String]) on FIELD_DEFINITION
directive @canonical on OBJECT
directive @hidden on OBJECT
directive @renamed on OBJECT
scalar AWSDate
scalar AWSTime
scalar AWSDateTime
scalar AWSTimestamp
scalar AWSEmail
scalar AWSJSON
scalar AWSURL
scalar AWSPhone
scalar AWSIPAddress
`;

export class Schema {
  constructor(private api: Api, private schemas: string[]) {}

  compile(): CfnResources {
    const logicalId = this.api.naming.getSchemaLogicalId();

    return {
      [logicalId]: {
        Type: 'AWS::AppSync::GraphQLSchema',
        Properties: {
          Definition: this.generateSchema(),
          ApiId: this.api.getApiId(),
        },
      },
    };
  }

  valdiateSchema(schema: string) {
    const errors = validateSDL(parse(schema));
    if (errors.length > 0) {
      throw new this.api.plugin.serverless.classes.Error(
        'Invalid GraphQL schema:\n' +
          errors.map((error) => `     ${error.message}`).join('\n'),
      );
    }
  }

  generateSchema() {
    const schemaFiles = flatten(
      globby.sync(
        this.schemas.map((schema) =>
          path
            .join(this.api.plugin.serverless.config.servicePath, schema)
            .replace(/\\/g, '/'),
        ),
      ),
    );

    const schemas = schemaFiles.map((file) => {
      return fs.readFileSync(file, 'utf8');
    });

    this.valdiateSchema(AWS_TYPES + '\n' + schemas.join('\n'));

    // Return single files as-is.
    if (schemas.length === 1) {
      return schemas[0];
    }

    // AppSync does not support Object extensions
    // https://spec.graphql.org/October2021/#sec-Object-Extensions
    // Merge the schemas
    return print(
      mergeTypeDefs(schemas, {
        forceSchemaDefinition: false,
        useSchemaDefinition: false,
        sort: true,
        throwOnConflict: true,
      }),
    );
  }
}