feat: 🎸 add API support for user accounts

addons/api/addon/models/user.js

@@ -1,3 +1,82 @@
 import GeneratedUserModel from '../generated/models/user';
+import { attr } from '@ember-data/model';
+import { A } from '@ember/array';
 
-export default class UserModel extends GeneratedUserModel {}
+export default class UserModel extends GeneratedUserModel {
+
+  // =attributes
+
+  /**
+   * Accounts is read-only under normal circumstances.  But accounts can
+   * be persisted via calls to `addAccounts()` or `removeAccounts()`.
+   */
+  @attr({
+    readOnly: true,
+    defaultValue: () => A(),
+    emptyArrayIfMissing: true,
+  })
+  account_ids;
+
+  // =methods
+
+  /**
+   * Adds accounts via the `add-accounts` method.
+   * See serializer and adapter for more information.
+   * @param {[string]} accountIDs
+   * @param {object} options
+   * @param {object} options.adapterOptions
+   * @return {Promise}
+   */
+  addAccounts(accountIDs, options = { adapterOptions: {} }) {
+    const defaultAdapterOptions = {
+      method: 'add-accounts',
+      accountIDs,
+    };
+    // There is no "deep merge" in ES.
+    // All of this nonsense is here to ensure we get
+    // a decent merge of `adapterOptions`.
+    return this.save({
+      ...options,
+      adapterOptions: {
+        ...defaultAdapterOptions,
+        ...options.adapterOptions,
+      },
+    });
+  }
+
+  /**
+   * Remove accounts via the `remove-accounts` method.
+   * See serializer and adapter for more information.
+   * @param {[string]} accountIDs
+   * @param {object} options
+   * @param {object} options.adapterOptions
+   * @return {Promise}
+   */
+  removeAccounts(accountIDs, options = { adapterOptions: {} }) {
+    const defaultAdapterOptions = {
+      method: 'remove-accounts',
+      accountIDs,
+    };
+    // There is no "deep merge" in ES.
+    // All of this nonsense is here to ensure we get
+    // a decent merge of `adapterOptions`.
+    return this.save({
+      ...options,
+      adapterOptions: {
+        ...defaultAdapterOptions,
+        ...options.adapterOptions,
+      },
+    });
+  }
+
+  /**
+   * Remove a single account via the `remove-accounts` method.
+   * @param {number} accountID
+   * @param {object} options
+   * @return {Promise}
+   */
+  removeAccount(accountID, options) {
+    return this.removeAccounts([accountID], options);
+  }
+
+}

addons/api/addon/serializers/user.js

@@ -0,0 +1,33 @@
+import ApplicationSerializer from './application';
+
+export default class UserSerializer extends ApplicationSerializer {
+  // =methods
+
+  /**
+   * If `adapterOptions.accountIDs` is set (to an array of user IDs),
+   * then the payload is serialized via `serializewithAccounts`.
+   * @override
+   * @param {Snapshot} snapshot
+   * @return {object}
+   */
+  serialize(snapshot) {
+    let serialized = super.serialize(...arguments);
+    const accountIDs = snapshot?.adapterOptions?.accountIDs;
+    if (accountIDs) serialized =
+      this.serializewithAccounts(snapshot, accountIDs);
+    return serialized;
+  }
+
+  /**
+   * Returns a payload containing only the `account_ids` array (and version).
+   * @param {Snapshot} snapshot
+   * @param {[string]} account_ids
+   * @return {object}
+   */
+  serializewithAccounts(snapshot, account_ids) {
+    return {
+      version: snapshot.attr('version'),
+      account_ids,
+    };
+  }
+}