chore(appsync): reorganize code base to improve readability

packages/@aws-cdk/aws-appsync/lib/dataSource.ts

@@ -0,0 +1,251 @@
+import { Table } from '@aws-cdk/aws-dynamodb';
+import { IGrantable, IPrincipal, IRole, Role, ServicePrincipal } from '@aws-cdk/aws-iam';
+import { IFunction } from '@aws-cdk/aws-lambda';
+import { Construct, IResolvable } from '@aws-cdk/core';
+import { CfnDataSource } from './appsync.generated';
+import { GraphQLApi } from './graphqlapi';
+import { BaseResolverProps, Resolver } from './resolver';
+
+/**
+ * Base properties for an AppSync datasource
+ */
+export interface BaseDataSourceProps {
+  /**
+   * The API to attach this data source to
+   */
+  readonly api: GraphQLApi;
+  /**
+   * The name of the data source
+   */
+  readonly name: string;
+  /**
+   * the description of the data source
+   *
+   * @default - None
+   */
+  readonly description?: string;
+}
+
+/**
+ * properties for an AppSync datasource backed by a resource
+ */
+export interface BackedDataSourceProps extends BaseDataSourceProps {
+  /**
+   * The IAM service role to be assumed by AppSync to interact with the data source
+   *
+   * @default -  Create a new role
+   */
+  readonly serviceRole?: IRole;
+}
+
+/**
+ * props used by implementations of BaseDataSource to provide configuration. Should not be used directly.
+ */
+export interface ExtendedDataSourceProps {
+  /**
+   * the type of the AppSync datasource
+   */
+  readonly type: string;
+  /**
+   * configuration for DynamoDB Datasource
+   *
+   * @default - No config
+   */
+  readonly dynamoDbConfig?: CfnDataSource.DynamoDBConfigProperty | IResolvable;
+  /**
+   * configuration for Elasticsearch Datasource
+   *
+   * @default - No config
+   */
+  readonly elasticsearchConfig?: CfnDataSource.ElasticsearchConfigProperty | IResolvable;
+  /**
+   * configuration for HTTP Datasource
+   *
+   * @default - No config
+   */
+  readonly httpConfig?: CfnDataSource.HttpConfigProperty | IResolvable;
+  /**
+   * configuration for Lambda Datasource
+   *
+   * @default - No config
+   */
+  readonly lambdaConfig?: CfnDataSource.LambdaConfigProperty | IResolvable;
+  /**
+   * configuration for RDS Datasource
+   *
+   * @default - No config
+   */
+  readonly relationalDatabaseConfig?: CfnDataSource.RelationalDatabaseConfigProperty | IResolvable;
+}
+
+/**
+ * Abstract AppSync datasource implementation. Do not use directly but use subclasses for concrete datasources
+ */
+export abstract class BaseDataSource extends Construct {
+  /**
+   * the name of the data source
+   */
+  public readonly name: string;
+  /**
+   * the underlying CFN data source resource
+   */
+  public readonly ds: CfnDataSource;
+
+  protected api: GraphQLApi;
+  protected serviceRole?: IRole;
+
+  constructor(scope: Construct, id: string, props: BackedDataSourceProps, extended: ExtendedDataSourceProps) {
+    super(scope, id);
+
+    if (extended.type !== 'NONE') {
+      this.serviceRole = props.serviceRole || new Role(this, 'ServiceRole', { assumedBy: new ServicePrincipal('appsync') });
+    }
+
+    this.ds = new CfnDataSource(this, 'Resource', {
+      apiId: props.api.apiId,
+      name: props.name,
+      description: props.description,
+      serviceRoleArn: this.serviceRole?.roleArn,
+      ...extended,
+    });
+    this.name = props.name;
+    this.api = props.api;
+  }
+
+  /**
+   * creates a new resolver for this datasource and API using the given properties
+   */
+  public createResolver(props: BaseResolverProps): Resolver {
+    return new Resolver(this, `${props.typeName}${props.fieldName}Resolver`, {
+      api: this.api,
+      dataSource: this,
+      ...props,
+    });
+  }
+}
+
+/**
+ * Abstract AppSync datasource implementation. Do not use directly but use subclasses for resource backed datasources
+ */
+export abstract class BackedDataSource extends BaseDataSource implements IGrantable {
+  /**
+   * the principal of the data source to be IGrantable
+   */
+  public readonly grantPrincipal: IPrincipal;
+
+  constructor(scope: Construct, id: string, props: BackedDataSourceProps, extended: ExtendedDataSourceProps) {
+    super(scope, id, props, extended);
+
+    this.grantPrincipal = this.serviceRole!;
+  }
+}
+
+/**
+ * Properties for an AppSync dummy datasource
+ */
+export interface NoneDataSourceProps extends BaseDataSourceProps {
+}
+
+/**
+ * An AppSync dummy datasource
+ */
+export class NoneDataSource extends BaseDataSource {
+  constructor(scope: Construct, id: string, props: NoneDataSourceProps) {
+    super(scope, id, props, {
+      type: 'NONE',
+    });
+  }
+}
+
+/**
+ * Properties for an AppSync DynamoDB datasource
+ */
+export interface DynamoDbDataSourceProps extends BackedDataSourceProps {
+  /**
+   * The DynamoDB table backing this data source
+   * [disable-awslint:ref-via-interface]
+   */
+  readonly table: Table;
+  /**
+   * Specify whether this DS is read only or has read and write permissions to the DynamoDB table
+   *
+   * @default false
+   */
+  readonly readOnlyAccess?: boolean;
+  /**
+   * use credentials of caller to access DynamoDB
+   *
+   * @default false
+   */
+  readonly useCallerCredentials?: boolean;
+}
+
+/**
+ * An AppSync datasource backed by a DynamoDB table
+ */
+export class DynamoDbDataSource extends BackedDataSource {
+  constructor(scope: Construct, id: string, props: DynamoDbDataSourceProps) {
+    super(scope, id, props, {
+      type: 'AMAZON_DYNAMODB',
+      dynamoDbConfig: {
+        tableName: props.table.tableName,
+        awsRegion: props.table.stack.region,
+        useCallerCredentials: props.useCallerCredentials,
+      },
+    });
+    if (props.readOnlyAccess) {
+      props.table.grantReadData(this);
+    } else {
+      props.table.grantReadWriteData(this);
+    }
+  }
+}
+
+/**
+ * Properties for an AppSync http datasource
+ */
+export interface HttpDataSourceProps extends BaseDataSourceProps {
+  /**
+   * The http endpoint
+   */
+  readonly endpoint: string;
+}
+
+/**
+ * An AppSync datasource backed by a http endpoint
+ */
+export class HttpDataSource extends BaseDataSource {
+  constructor(scope: Construct, id: string, props: HttpDataSourceProps) {
+    super(scope, id, props, {
+      httpConfig: {
+        endpoint: props.endpoint,
+      },
+      type: 'HTTP',
+    });
+  }
+}
+
+/**
+ * Properties for an AppSync Lambda datasource
+ */
+export interface LambdaDataSourceProps extends BackedDataSourceProps {
+  /**
+   * The Lambda function to call to interact with this data source
+   */
+  readonly lambdaFunction: IFunction;
+}
+
+/**
+ * An AppSync datasource backed by a Lambda function
+ */
+export class LambdaDataSource extends BackedDataSource {
+  constructor(scope: Construct, id: string, props: LambdaDataSourceProps) {
+    super(scope, id, props, {
+      type: 'AWS_LAMBDA',
+      lambdaConfig: {
+        lambdaFunctionArn: props.lambdaFunction.functionArn,
+      },
+    });
+    props.lambdaFunction.grantInvoke(this);
+  }
+}