From 91a534142deaea27908d4bf6d63f811bc2c71625 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Fri, 1 Sep 2023 15:04:18 +0200
Subject: [PATCH] frontend-app-api: store attachemnts on extension instances
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Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/frontend-app-api/src/createApp.tsx    |  2 +-
 .../src/createExtensionInstance.ts             | 18 +++++++++++++-----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/packages/frontend-app-api/src/createApp.tsx b/packages/frontend-app-api/src/createApp.tsx
index b3704fea4f..192e2485c6 100644
--- a/packages/frontend-app-api/src/createApp.tsx
+++ b/packages/frontend-app-api/src/createApp.tsx
@@ -83,7 +83,7 @@ export function createApp(options: { plugins: BackstagePlugin[] }): {
       return existingInstance;
     }
 
-    const attachments = Object.fromEntries(
+    const attachments = new Map(
       Array.from(
         attachmentMap.get(instanceParams.extension.id)?.entries() ?? [],
       ).map(([inputName, attachmentConfigs]) => [
diff --git a/packages/frontend-app-api/src/createExtensionInstance.ts b/packages/frontend-app-api/src/createExtensionInstance.ts
index 911955f50a..a7c49d48cb 100644
--- a/packages/frontend-app-api/src/createExtensionInstance.ts
+++ b/packages/frontend-app-api/src/createExtensionInstance.ts
@@ -19,9 +19,16 @@ import mapValues from 'lodash/mapValues';
 
 /** @internal */
 export interface ExtensionInstance {
-  id: string;
-  data: Map<string, unknown>;
-  $$type: 'extension-instance';
+  readonly id: string;
+  /**
+   * Maps extension data ref IDs to extensions produced.
+   */
+  readonly data: Map<string, unknown>;
+  /**
+   * Maps input names to the actual instances given to them.
+   */
+  readonly attachments: Map<string, ExtensionInstance[]>;
+  readonly $$type: 'extension-instance';
 }
 
 /** @internal */
@@ -29,7 +36,7 @@ export function createExtensionInstance(options: {
   extension: Extension<unknown>;
   config: unknown;
   source?: BackstagePlugin;
-  attachments: Record<string, ExtensionInstance[]>;
+  attachments: Map<string, ExtensionInstance[]>;
 }): ExtensionInstance {
   const { extension, config, source, attachments } = options;
   const extensionData = new Map<string, unknown>();
@@ -54,7 +61,7 @@ export function createExtensionInstance(options: {
         extension.inputs,
         ({ extensionData: pointData }, inputName) => {
           // TODO: validation
-          return (attachments[inputName] ?? []).map(attachment =>
+          return (attachments.get(inputName) ?? []).map(attachment =>
             mapValues(pointData, ref => attachment.data.get(ref.id)),
           );
         },
@@ -69,6 +76,7 @@ export function createExtensionInstance(options: {
   return {
     id: options.extension.id,
     data: extensionData,
+    attachments,
     $$type: 'extension-instance',
   };
 }