graphql-relational-schema-transformer/src/RelationalDBResolverGenerator.ts

import { TemplateContext } from './RelationalDBSchemaTransformer';
import { DocumentNode } from 'graphql';
import { Fn } from 'cloudform';
import AppSync from 'cloudform-types/types/appSync';
import { print, obj, set, str, list, forEach, ref, compoundExpression } from 'graphql-mapping-template';
import { graphqlName, toUpper, plurality } from 'graphql-transformer-common';
import { ResourceConstants } from './ResourceConstants';
import { RelationalDBMappingTemplate } from './RelationalDBMappingTemplate';
import * as fs from 'fs-extra';

const s3BaseUrl = 's3://${S3DeploymentBucket}/${S3DeploymentRootKey}/resolvers/${ResolverFileName}';
const resolverFileName = 'ResolverFileName';
/**
 * This Class is responsible for Generating the RDS Resolvers based on the
 * GraphQL Schema + Metadata of the RDS Cluster (i.e. Primary Keys for Tables).
 *
 * It will generate the CRUDL+Q (Create, Retrieve, Update, Delete, List + Queries) Resolvers as
 * Cloudform Resources so that they may be added on to the base template that the
 * RelationDBTemplateGenerator creates.
 */
export class RelationalDBResolverGenerator {
  document: DocumentNode;
  typePrimaryKeyMap: Map<string, string>;
  stringFieldMap: Map<string, string[]>;
  intFieldMap: Map<string, string[]>;
  resolverFilePath: string;
  typePrimaryKeyTypeMap: Map<string, string>;

  constructor(context: TemplateContext) {
    this.document = context.schemaDoc;
    this.typePrimaryKeyMap = context.typePrimaryKeyMap;
    this.stringFieldMap = context.stringFieldMap;
    this.intFieldMap = context.intFieldMap;
    this.typePrimaryKeyTypeMap = context.typePrimaryKeyTypeMap;
  }

  /**
   * Creates the CRUDL+Q Resolvers as a Map of Cloudform Resources. The output can then be
   * merged with an existing Template's map of Resources.
   */
  public createRelationalResolvers(resolverFilePath: string) {
    let resources = {};
    this.resolverFilePath = resolverFilePath;
    this.typePrimaryKeyMap.forEach((value: string, key: string) => {
      const resourceName = key.replace(/[^A-Za-z0-9]/g, '');
      resources = {
        ...resources,
        ...{ [resourceName + 'CreateResolver']: this.makeCreateRelationalResolver(key) },
        ...{ [resourceName + 'GetResolver']: this.makeGetRelationalResolver(key) },
        ...{ [resourceName + 'UpdateResolver']: this.makeUpdateRelationalResolver(key) },
        ...{ [resourceName + 'DeleteResolver']: this.makeDeleteRelationalResolver(key) },
        ...{ [resourceName + 'ListResolver']: this.makeListRelationalResolver(key) },
      };
      // TODO: Add Guesstimate Query Resolvers
    });

    return resources;
  }

  /**
   * Private Helpers to Generate the CFN Spec for the Resolver Resources
   */

  /**
   * Creates and returns the CFN Spec for the 'Create' Resolver Resource provided
   * a GraphQL Type as the input
   *
   * @param type - the graphql type for which the create resolver will be created
   * @param mutationTypeName - will be 'Mutation'
   */
  private makeCreateRelationalResolver(type: string, mutationTypeName: string = 'Mutation') {
    const fieldName = graphqlName('create' + toUpper(type));
    let createSql = `INSERT INTO ${type} $colStr VALUES $valStr`;
    let selectSql;
    if (this.typePrimaryKeyTypeMap.get(type).includes('String')) {
      selectSql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=\'$ctx.args.create${toUpper(
        type
      )}Input.${this.typePrimaryKeyMap.get(type)}\'`;
    } else {
      selectSql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=$ctx.args.create${toUpper(
        type
      )}Input.${this.typePrimaryKeyMap.get(type)}`;
    }

    const reqFileName = `${mutationTypeName}.${fieldName}.req.vtl`;
    const resFileName = `${mutationTypeName}.${fieldName}.res.vtl`;

    const reqTemplate = print(
      compoundExpression([
        set(ref('cols'), list([])),
        set(ref('vals'), list([])),
        forEach(ref('entry'), ref(`ctx.args.create${toUpper(type)}Input.keySet()`), [
          set(ref('discard'), ref(`cols.add($entry)`)),
          set(ref('discard'), ref(`vals.add("'$ctx.args.create${toUpper(type)}Input[$entry]'")`)),
        ]),
        set(ref('valStr'), ref('vals.toString().replace("[","(").replace("]",")")')),
        set(ref('colStr'), ref('cols.toString().replace("[","(").replace("]",")")')),
        RelationalDBMappingTemplate.rdsQuery({
          statements: list([str(createSql), str(selectSql)]),
        }),
      ])
    );

    const resTemplate = print(ref('utils.toJson($utils.parseJson($utils.rds.toJsonString($ctx.result))[1][0])'));

    fs.writeFileSync(`${this.resolverFilePath}/${reqFileName}`, reqTemplate, 'utf8');
    fs.writeFileSync(`${this.resolverFilePath}/${resFileName}`, resTemplate, 'utf8');

    let resolver = new AppSync.Resolver({
      ApiId: Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId),
      DataSourceName: Fn.GetAtt(ResourceConstants.RESOURCES.RelationalDatabaseDataSource, 'Name'),
      TypeName: mutationTypeName,
      FieldName: fieldName,
      RequestMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: reqFileName,
      }),
      ResponseMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: resFileName,
      }),
    }).dependsOn([ResourceConstants.RESOURCES.RelationalDatabaseDataSource]);
    return resolver;
  }

  /**
   * Creates and Returns the CFN Spec for the 'Get' Resolver Resource provided
   * a GraphQL type
   *
   * @param type - the graphql type for which the get resolver will be created
   * @param queryTypeName  - will be 'Query'
   */
  private makeGetRelationalResolver(type: string, queryTypeName: string = 'Query') {
    const fieldName = graphqlName('get' + toUpper(type));
    let sql;
    if (this.typePrimaryKeyTypeMap.get(type).includes('String')) {
      sql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=\'$ctx.args.${this.typePrimaryKeyMap.get(type)}\'`;
    } else {
      sql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=$ctx.args.${this.typePrimaryKeyMap.get(type)}`;
    }
    const reqFileName = `${queryTypeName}.${fieldName}.req.vtl`;
    const resFileName = `${queryTypeName}.${fieldName}.res.vtl`;

    const reqTemplate = print(
      compoundExpression([
        RelationalDBMappingTemplate.rdsQuery({
          statements: list([str(sql)]),
        }),
      ])
    );

    const resTemplate = print(ref('utils.toJson($utils.rds.toJsonObject($ctx.result)[0][0])'));

    fs.writeFileSync(`${this.resolverFilePath}/${reqFileName}`, reqTemplate, 'utf8');
    fs.writeFileSync(`${this.resolverFilePath}/${resFileName}`, resTemplate, 'utf8');

    let resolver = new AppSync.Resolver({
      ApiId: Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId),
      DataSourceName: Fn.GetAtt(ResourceConstants.RESOURCES.RelationalDatabaseDataSource, 'Name'),
      FieldName: fieldName,
      TypeName: queryTypeName,
      RequestMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: reqFileName,
      }),
      ResponseMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: resFileName,
      }),
    }).dependsOn([ResourceConstants.RESOURCES.RelationalDatabaseDataSource]);
    return resolver;
  }

  /**
   * Creates and Returns the CFN Spec for the 'Update' Resolver Resource provided
   * a GraphQL type
   *
   * @param type - the graphql type for which the update resolver will be created
   * @param mutationTypeName - will be 'Mutation'
   */
  private makeUpdateRelationalResolver(type: string, mutationTypeName: string = 'Mutation') {
    const fieldName = graphqlName('update' + toUpper(type));
    const updateSql = `UPDATE ${type} SET $update WHERE ${this.typePrimaryKeyMap.get(type)}=$ctx.args.update${toUpper(
      type
    )}Input.${this.typePrimaryKeyMap.get(type)}`;
    let selectSql;
    if (this.typePrimaryKeyTypeMap.get(type).includes('String')) {
      selectSql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=\'$ctx.args.update${toUpper(
        type
      )}Input.${this.typePrimaryKeyMap.get(type)}\'`;
    } else {
      selectSql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=$ctx.args.update${toUpper(
        type
      )}Input.${this.typePrimaryKeyMap.get(type)}`;
    }
    const reqFileName = `${mutationTypeName}.${fieldName}.req.vtl`;
    const resFileName = `${mutationTypeName}.${fieldName}.res.vtl`;

    const reqTemplate = print(
      compoundExpression([
        set(ref('updateList'), obj({})),
        forEach(ref('entry'), ref(`ctx.args.update${toUpper(type)}Input.keySet()`), [
          set(ref('discard'), ref(`updateList.put($entry, "'$ctx.args.update${toUpper(type)}Input[$entry]'")`)),
        ]),
        set(ref('update'), ref(`updateList.toString().replace("{","").replace("}","")`)),
        RelationalDBMappingTemplate.rdsQuery({
          statements: list([str(updateSql), str(selectSql)]),
        }),
      ])
    );

    const resTemplate = print(ref('utils.toJson($utils.parseJson($utils.rds.toJsonString($ctx.result))[1][0])'));

    fs.writeFileSync(`${this.resolverFilePath}/${reqFileName}`, reqTemplate, 'utf8');
    fs.writeFileSync(`${this.resolverFilePath}/${resFileName}`, resTemplate, 'utf8');

    let resolver = new AppSync.Resolver({
      ApiId: Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId),
      DataSourceName: Fn.GetAtt(ResourceConstants.RESOURCES.RelationalDatabaseDataSource, 'Name'),
      TypeName: mutationTypeName,
      FieldName: fieldName,
      RequestMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: reqFileName,
      }),
      ResponseMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: resFileName,
      }),
    }).dependsOn([ResourceConstants.RESOURCES.RelationalDatabaseDataSource]);
    return resolver;
  }

  /**
   * Creates and Returns the CFN Spec for the 'Delete' Resolver Resource provided
   * a GraphQL type
   *
   * @param type - the graphql type for which the delete resolver will be created
   * @param mutationTypeName - will be 'Mutation'
   */
  private makeDeleteRelationalResolver(type: string, mutationTypeName: string = 'Mutation') {
    const fieldName = graphqlName('delete' + toUpper(type));
    let selectSql;
    if (this.typePrimaryKeyTypeMap.get(type).includes('String')) {
      selectSql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=\'$ctx.args.${this.typePrimaryKeyMap.get(type)}\'`;
    } else {
      selectSql = `SELECT * FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=$ctx.args.${this.typePrimaryKeyMap.get(type)}`;
    }
    const deleteSql = `DELETE FROM ${type} WHERE ${this.typePrimaryKeyMap.get(type)}=$ctx.args.${this.typePrimaryKeyMap.get(type)}`;
    const reqFileName = `${mutationTypeName}.${fieldName}.req.vtl`;
    const resFileName = `${mutationTypeName}.${fieldName}.res.vtl`;
    const reqTemplate = print(
      compoundExpression([
        RelationalDBMappingTemplate.rdsQuery({
          statements: list([str(selectSql), str(deleteSql)]),
        }),
      ])
    );
    const resTemplate = print(ref('utils.toJson($utils.rds.toJsonObject($ctx.result)[0][0])'));

    fs.writeFileSync(`${this.resolverFilePath}/${reqFileName}`, reqTemplate, 'utf8');
    fs.writeFileSync(`${this.resolverFilePath}/${resFileName}`, resTemplate, 'utf8');

    let resolver = new AppSync.Resolver({
      ApiId: Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId),
      DataSourceName: Fn.GetAtt(ResourceConstants.RESOURCES.RelationalDatabaseDataSource, 'Name'),
      TypeName: mutationTypeName,
      FieldName: fieldName,
      RequestMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: reqFileName,
      }),
      ResponseMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: resFileName,
      }),
    }).dependsOn([ResourceConstants.RESOURCES.RelationalDatabaseDataSource]);

    return resolver;
  }

  /**
   * Creates and Returns the CFN Spec for the 'List' Resolver Resource provided
   * a GraphQL type
   *
   * @param type - the graphql type for which the list resolver will be created
   * @param queryTypeName - will be 'Query'
   */
  private makeListRelationalResolver(type: string, queryTypeName: string = 'Query') {
    const fieldName = graphqlName('list' + plurality(toUpper(type)));
    const sql = `SELECT * FROM ${type}`;
    const reqFileName = `${queryTypeName}.${fieldName}.req.vtl`;
    const resFileName = `${queryTypeName}.${fieldName}.res.vtl`;
    const reqTemplate = print(
      RelationalDBMappingTemplate.rdsQuery({
        statements: list([str(sql)]),
      })
    );
    const resTemplate = print(ref('utils.toJson($utils.rds.toJsonObject($ctx.result)[0])'));

    fs.writeFileSync(`${this.resolverFilePath}/${reqFileName}`, reqTemplate, 'utf8');
    fs.writeFileSync(`${this.resolverFilePath}/${resFileName}`, resTemplate, 'utf8');

    let resolver = new AppSync.Resolver({
      ApiId: Fn.Ref(ResourceConstants.PARAMETERS.AppSyncApiId),
      DataSourceName: Fn.GetAtt(ResourceConstants.RESOURCES.RelationalDatabaseDataSource, 'Name'),
      TypeName: queryTypeName,
      FieldName: fieldName,
      RequestMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: reqFileName,
      }),
      ResponseMappingTemplateS3Location: Fn.Sub(s3BaseUrl, {
        [ResourceConstants.PARAMETERS.S3DeploymentBucket]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentBucket),
        [ResourceConstants.PARAMETERS.S3DeploymentRootKey]: Fn.Ref(ResourceConstants.PARAMETERS.S3DeploymentRootKey),
        [resolverFileName]: resFileName,
      }),
    }).dependsOn([ResourceConstants.RESOURCES.RelationalDatabaseDataSource]);

    return resolver;
  }
}