🪢 Fixed schema stitching and added JSDoc

services/graphql.service.ts

@@ -1,3 +1,19 @@
+/**
+ * @fileoverview GraphQL service for schema stitching and query execution
+ * @module services/graphql.service
+ * @description Provides a unified GraphQL API by stitching together local canonical metadata
+ * schema with remote metadata-graphql schema. Handles GraphQL query execution, schema
+ * introspection, and automatic metadata resolution events. Exposes a GraphQL endpoint
+ * via moleculer-web at /graphql.
+ *
+ * The service attempts to connect to a remote metadata GraphQL service and stitch its
+ * schema with the local schema. If the remote service is unavailable, it falls back to
+ * serving only the local schema.
+ *
+ * @see {@link module:models/graphql/typedef} for local schema definitions
+ * @see {@link module:models/graphql/resolvers} for local resolver implementations
+ */
+
 import { ServiceBroker, Context } from "moleculer";
 import { graphql, GraphQLSchema, parse, validate, execute } from "graphql";
 import { makeExecutableSchema } from "@graphql-tools/schema";
@@ -9,38 +25,78 @@ import { typeDefs } from "../models/graphql/typedef";
 import { resolvers } from "../models/graphql/resolvers";
 
 /**
- * Fetch remote GraphQL schema via introspection
+ * Fetch remote GraphQL schema via introspection with timeout handling
+ * @async
+ * @function fetchRemoteSchema
+ * @param {string} url - The URL of the remote GraphQL endpoint
+ * @param {number} [timeout=10000] - Request timeout in milliseconds
+ * @returns {Promise<GraphQLSchema>} The introspected GraphQL schema
+ * @throws {Error} If introspection fails, times out, or returns errors
+ * @description Fetches a GraphQL schema from a remote endpoint using introspection query.
+ * Implements timeout handling with AbortController to prevent hanging requests.
+ * Validates the response and builds a client schema from the introspection result.
+ *
+ * @example
+ * ```typescript
+ * const schema = await fetchRemoteSchema('http://localhost:3080/metadata-graphql', 5000);
+ * ```
  */
-async function fetchRemoteSchema(url: string) {
+async function fetchRemoteSchema(url: string, timeout: number = 10000) {
 	const introspectionQuery = getIntrospectionQuery();
 	
-	const response = await fetch(url, {
+	const controller = new AbortController();
-		method: "POST",
+	const timeoutId = setTimeout(() => controller.abort(), timeout);
-		headers: {
-			"Content-Type": "application/json",
-		},
-		body: JSON.stringify({ query: introspectionQuery }),
-	});
-
-	if (!response.ok) {
-		throw new Error(`Failed to introspect remote schema: ${response.statusText}`);
-	}
-
-	const result = await response.json() as { data?: IntrospectionQuery; errors?: any[] };
 	
-	if (result.errors) {
+	try {
-		throw new Error(`Introspection errors: ${JSON.stringify(result.errors)}`);
+		const response = await fetch(url, {
-	}
+			method: "POST",
+			headers: {
+				"Content-Type": "application/json",
+			},
+			body: JSON.stringify({ query: introspectionQuery }),
+			signal: controller.signal,
+		});
 
-	if (!result.data) {
+		clearTimeout(timeoutId);
-		throw new Error("No data returned from introspection query");
-	}
 
-	return buildClientSchema(result.data);
+		if (!response.ok) {
+			throw new Error(`Failed to introspect remote schema: HTTP ${response.status} ${response.statusText}`);
+		}
+
+		const result = await response.json() as { data?: IntrospectionQuery; errors?: any[] };
+		
+		if (result.errors && result.errors.length > 0) {
+			throw new Error(`Introspection errors: ${JSON.stringify(result.errors)}`);
+		}
+
+		if (!result.data) {
+			throw new Error("No data returned from introspection query");
+		}
+
+		return buildClientSchema(result.data);
+	} catch (error: any) {
+		clearTimeout(timeoutId);
+		if (error.name === 'AbortError') {
+			throw new Error(`Request timeout after ${timeout}ms`);
+		}
+		throw error;
+	}
 }
 
 /**
- * Create executor for remote GraphQL endpoint
+ * Create executor function for remote GraphQL endpoint
+ * @function createRemoteExecutor
+ * @param {string} url - The URL of the remote GraphQL endpoint
+ * @returns {Function} Executor function compatible with schema stitching
+ * @description Creates an executor function that forwards GraphQL operations to a remote
+ * endpoint. The executor handles query printing, variable passing, and error formatting.
+ * Used by schema stitching to delegate queries to the remote schema.
+ *
+ * @example
+ * ```typescript
+ * const executor = createRemoteExecutor('http://localhost:3080/metadata-graphql');
+ * // Used in stitchSchemas configuration
+ * ```
  */
 function createRemoteExecutor(url: string) {
 	return async ({ document, variables }: any) => {
@@ -69,22 +125,71 @@ function createRemoteExecutor(url: string) {
 
 /**
  * GraphQL Service
- * Provides a GraphQL API for canonical metadata queries and mutations
+ * @constant {Object} GraphQLService
- * Standalone service that exposes a graphql action for moleculer-web
+ * @description Moleculer service that provides a unified GraphQL API by stitching together:
- * Stitches remote metadata-graphql schema from port 3080
+ * - Local canonical metadata schema (comics, user preferences, library statistics)
+ * - Remote metadata-graphql schema (weekly pull lists, metadata sources)
+ *
+ * **Features:**
+ * - Schema stitching with automatic fallback to local-only mode
+ * - GraphQL query and mutation execution
+ * - Automatic metadata resolution on import events
+ * - Timeout handling and error recovery
+ * - Debug logging for schema introspection
+ *
+ * **Actions:**
+ * - `graphql.graphql` - Execute GraphQL queries/mutations
+ * - `graphql.getSchema` - Get schema type definitions
+ *
+ * **Events:**
+ * - `metadata.imported` - Triggers auto-resolution if enabled
+ * - `comic.imported` - Triggers auto-resolution on import if enabled
+ *
+ * **Settings:**
+ * - `metadataGraphqlUrl` - Remote metadata GraphQL endpoint URL
+ *
+ * @example
+ * ```typescript
+ * // Execute a GraphQL query via broker
+ * const result = await broker.call('graphql.graphql', {
+ *   query: 'query { comic(id: "123") { id } }',
+ *   variables: {}
+ * });
+ * ```
  */
 export default {
 	name: "graphql",
 	
 	settings: {
-		// Remote metadata GraphQL endpoint
+		/**
+		 * Remote metadata GraphQL endpoint URL
+		 * @type {string}
+		 * @default "http://localhost:3080/metadata-graphql"
+		 * @description URL of the remote metadata GraphQL service to stitch with local schema.
+		 * Can be overridden via METADATA_GRAPHQL_URL environment variable.
+		 */
 		metadataGraphqlUrl: process.env.METADATA_GRAPHQL_URL || "http://localhost:3080/metadata-graphql",
 	},
 
 	actions: {
 		/**
 		 * Execute GraphQL queries and mutations
-		 * This action is called by moleculer-web from the /graphql route
+		 * @action graphql
+		 * @param {string} query - GraphQL query or mutation string
+		 * @param {Object} [variables] - Variables for the GraphQL operation
+		 * @param {string} [operationName] - Name of the operation to execute
+		 * @returns {Promise<Object>} GraphQL execution result with data or errors
+		 * @description Main action for executing GraphQL operations against the stitched schema.
+		 * Called by moleculer-web from the /graphql HTTP endpoint. Provides broker and context
+		 * to resolvers for service communication.
+		 *
+		 * @example
+		 * ```typescript
+		 * await broker.call('graphql.graphql', {
+		 *   query: 'mutation { resolveMetadata(comicId: "123") { id } }',
+		 *   variables: {}
+		 * });
+		 * ```
 		 */
 		graphql: {
 			params: {
@@ -124,7 +229,16 @@ export default {
 		},
 
 		/**
-		 * Get GraphQL schema
+		 * Get GraphQL schema type definitions
+		 * @action getSchema
+		 * @returns {Promise<Object>} Object containing schema type definitions as string
+		 * @description Returns the local schema type definitions. Useful for schema
+		 * documentation and introspection.
+		 *
+		 * @example
+		 * ```typescript
+		 * const { typeDefs } = await broker.call('graphql.getSchema');
+		 * ```
 		 */
 		getSchema: {
 			async handler() {
@@ -137,7 +251,18 @@ export default {
 
 	events: {
 		/**
-		 * Trigger metadata resolution when new metadata is imported
+		 * Handle metadata imported event
+		 * @event metadata.imported
+		 * @param {Object} params - Event parameters
+		 * @param {string} params.comicId - ID of the comic with new metadata
+		 * @param {string} params.source - Metadata source that was imported
+		 * @description Triggered when new metadata is imported for a comic. If auto-merge
+		 * is enabled in user preferences, automatically resolves canonical metadata.
+		 *
+		 * @example
+		 * ```typescript
+		 * broker.emit('metadata.imported', { comicId: '123', source: 'COMICVINE' });
+		 * ```
 		 */
 		"metadata.imported": {
 			async handler(ctx: any) {
@@ -179,7 +304,17 @@ export default {
 		},
 
 		/**
-		 * Trigger metadata resolution when comic is imported
+		 * Handle comic imported event
+		 * @event comic.imported
+		 * @param {Object} params - Event parameters
+		 * @param {string} params.comicId - ID of the newly imported comic
+		 * @description Triggered when a new comic is imported into the library. If auto-merge
+		 * on import is enabled in user preferences, automatically resolves canonical metadata.
+		 *
+		 * @example
+		 * ```typescript
+		 * broker.emit('comic.imported', { comicId: '123' });
+		 * ```
 		 */
 		"comic.imported": {
 			async handler(ctx: any) {
@@ -219,6 +354,22 @@ export default {
 		},
 	},
 
+	/**
+	 * Service started lifecycle hook
+	 * @async
+	 * @function started
+	 * @description Initializes the GraphQL service by creating the local schema and attempting
+	 * to stitch it with the remote metadata schema. Implements the following workflow:
+	 *
+	 * 1. Create local executable schema from type definitions and resolvers
+	 * 2. Attempt to introspect remote metadata GraphQL service
+	 * 3. If successful, stitch local and remote schemas together
+	 * 4. If failed, fall back to local schema only
+	 * 5. Log available Query fields for debugging
+	 *
+	 * The service will continue to function with local schema only if remote stitching fails,
+	 * but queries requiring remote types (like WeeklyPullList) will not be available.
+	 */
 	async started() {
 		this.logger.info("GraphQL service starting...");
 		
@@ -237,27 +388,38 @@ export default {
 			
 			this.logger.info("Successfully introspected remote metadata schema");
 			
+			// Log remote schema types for debugging
+			const remoteQueryType = remoteSchema.getQueryType();
+			if (remoteQueryType) {
+				const remoteFields = Object.keys(remoteQueryType.getFields());
+				this.logger.info(`Remote schema Query fields: ${remoteFields.join(', ')}`);
+			}
+			
 			// Create executor for remote schema
 			const remoteExecutor = createRemoteExecutor(this.settings.metadataGraphqlUrl);
 			
-			// Wrap the remote schema with executor
+			// Stitch schemas together with proper configuration
-			const wrappedRemoteSchema = wrapSchema({
-				schema: remoteSchema,
-				executor: remoteExecutor,
-			});
-			
-			// Stitch schemas together
 			this.schema = stitchSchemas({
 				subschemas: [
 					{
 						schema: localSchema,
 					},
 					{
-						schema: wrappedRemoteSchema,
+						schema: remoteSchema,
+						executor: remoteExecutor,
 					},
 				],
+				// Merge types from both schemas
+				mergeTypes: true,
 			});
 			
+			// Log stitched schema types for debugging
+			const stitchedQueryType = this.schema.getQueryType();
+			if (stitchedQueryType) {
+				const stitchedFields = Object.keys(stitchedQueryType.getFields());
+				this.logger.info(`Stitched schema Query fields: ${stitchedFields.join(', ')}`);
+			}
+			
 			this.logger.info("Successfully stitched local and remote schemas");
 		} catch (remoteError: any) {
 			this.logger.warn(
@@ -272,6 +434,11 @@ export default {
 		this.logger.info("GraphQL service started successfully");
 	},
 
+	/**
+	 * Service stopped lifecycle hook
+	 * @function stopped
+	 * @description Cleanup hook called when the service is stopped. Logs service shutdown.
+	 */
 	stopped() {
 		this.logger.info("GraphQL service stopped");
 	},