From e6e764320b1b01f49fc7e318721f25bd8f381be5 Mon Sep 17 00:00:00 2001
From: Christopher Allford <christopher.allford@automattic.com>
Date: Wed, 1 Jul 2020 11:07:57 -0700
Subject: [PATCH] Added a registry to hold all of the factories and adapters

---
 tests/e2e/factories/src/framework/adapter.ts  |  3 +
 .../src/framework/factory-registry.spec.ts    | 42 +++++++++
 .../src/framework/factory-registry.ts         | 87 +++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 tests/e2e/factories/src/framework/factory-registry.spec.ts
 create mode 100644 tests/e2e/factories/src/framework/factory-registry.ts

diff --git a/tests/e2e/factories/src/framework/adapter.ts b/tests/e2e/factories/src/framework/adapter.ts
index 85e90dc30ee..e04e45ad714 100644
--- a/tests/e2e/factories/src/framework/adapter.ts
+++ b/tests/e2e/factories/src/framework/adapter.ts
@@ -1,5 +1,8 @@
 import { Model } from '../models/model';
 
+/**
+ * An interface for implementing adapters to create models.
+ */
 export interface Adapter<T extends Model> {
 	/**
 	 * Creates a model or array of models using a service..
diff --git a/tests/e2e/factories/src/framework/factory-registry.spec.ts b/tests/e2e/factories/src/framework/factory-registry.spec.ts
new file mode 100644
index 00000000000..df727595ac6
--- /dev/null
+++ b/tests/e2e/factories/src/framework/factory-registry.spec.ts
@@ -0,0 +1,42 @@
+import { AdapterTypes, FactoryRegistry } from './factory-registry';
+import { ModelFactory } from './model-factory';
+import { Product } from '../models/product';
+import { APIAdapter } from './api-adapter';
+
+describe( 'FactoryRegistry', () => {
+	let factoryRegistry: FactoryRegistry;
+
+	beforeEach( () => {
+		factoryRegistry = new FactoryRegistry();
+	} );
+
+	it( 'should register factories once', () => {
+		const factory = ModelFactory.define<Product, any, ModelFactory<Product>>( ( { params } ) => {
+			return new Product( params );
+		} );
+
+		expect( factoryRegistry.getFactory( Product ) ).toBeNull();
+
+		factoryRegistry.registerFactory( Product, factory );
+
+		expect( () => factoryRegistry.registerFactory( Product, factory ) ).toThrowError( /already been registered/ );
+
+		const loaded = factoryRegistry.getFactory( Product );
+
+		expect( loaded ).toBe( factory );
+	} );
+
+	it( 'should register adapters once', () => {
+		const adapter = new APIAdapter<Product>( '', ( model ) => model );
+
+		expect( factoryRegistry.getAdapter( Product, AdapterTypes.API ) ).toBeNull();
+
+		factoryRegistry.registerAdapter( Product, AdapterTypes.API, adapter );
+
+		expect( () => factoryRegistry.registerAdapter( Product, AdapterTypes.API, adapter ) ).toThrowError( /already been registered/ );
+
+		const loaded = factoryRegistry.getAdapter( Product, AdapterTypes.API );
+
+		expect( loaded ).toBe( adapter );
+	} );
+} );
diff --git a/tests/e2e/factories/src/framework/factory-registry.ts b/tests/e2e/factories/src/framework/factory-registry.ts
new file mode 100644
index 00000000000..615e1541213
--- /dev/null
+++ b/tests/e2e/factories/src/framework/factory-registry.ts
@@ -0,0 +1,87 @@
+import { Adapter } from './adapter';
+import { Model } from '../models/model';
+import { ModelFactory } from './model-factory';
+
+type Registry<T> = { [key: string ]: T };
+
+/**
+ * The types of adapters that can be stored in the registry.
+ *
+ * @typedef AdapterTypes
+ * @property {string} API      "api"
+ * @property {string} Database "database"
+ * @property {string} Custom   "custom"
+ */
+export enum AdapterTypes {
+	API = 'api',
+	Database = 'database',
+	Custom = 'custom'
+}
+
+/**
+ * A registry that allows for us to easily manage all of our factories and related state.
+ */
+export class FactoryRegistry {
+	private readonly registry: Registry<ModelFactory<any>> = {};
+	private readonly adapters: { [key in AdapterTypes]: Registry<Adapter<any>> } = {
+		api: {},
+		database: {},
+		custom: {},
+	};
+
+	/**
+	 * Registers a factory for the class.
+	 *
+	 * @param {Function}     modelClass The class of model we're registering the factory for.
+	 * @param {ModelFactory} factory The factory that we're registering.
+	 */
+	public registerFactory<T extends Model>( modelClass: new () => T, factory: ModelFactory<T> ): void {
+		if ( this.registry.hasOwnProperty( modelClass.name ) ) {
+			throw new Error( 'A factory of this type has already been registered for the model class.' );
+		}
+
+		this.registry[ modelClass.name ] = factory;
+	}
+
+	/**
+	 * Fetches a factory that was registered for the class.
+	 *
+	 * @param {Function} modelClass The class of model for the factory we're fetching.
+	 */
+	public getFactory<T extends Model>( modelClass: new () => T ): ModelFactory<T> | null {
+		if ( this.registry.hasOwnProperty( modelClass.name ) ) {
+			return this.registry[ modelClass.name ];
+		}
+
+		return null;
+	}
+
+	/**
+	 * Registers an adapter for the class.
+	 *
+	 * @param {Function}     modelClass The class of model that we're registering the adapter for.
+	 * @param {AdapterTypes} type The type of adapter that we're registering.
+	 * @param {Adapter}      adapter The adapter that we're registering.
+	 */
+	public registerAdapter<T extends Model>( modelClass: new () => T, type: AdapterTypes, adapter: Adapter<T> ): void {
+		if ( this.adapters[ type ].hasOwnProperty( modelClass.name ) ) {
+			throw new Error( 'An adapter of this type has already been registered for the model class.' );
+		}
+
+		this.adapters[ type ][ modelClass.name ] = adapter;
+	}
+
+	/**
+	 * Fetches an adapter registered for the class.
+	 *
+	 * @param {Function}     modelClass The class of the model for the adapter we're fetching.
+	 * @param {AdapterTypes} type The type of adapter we're fetching.
+	 */
+	public getAdapter<T extends Model>( modelClass: new () => T, type: AdapterTypes ): Adapter<T> | null {
+		if ( this.adapters[ type ].hasOwnProperty( modelClass.name ) ) {
+			return this.adapters[ type ][ modelClass.name ];
+		}
+
+		return null;
+	}
+}