Sync with recycled items

[pyphilia]

Since the introduction of the recycled-bin, the recycled items are no more moved/deleted from the table.
This lead to the fact that recycled items are not sync with websockets.

I don't think updating the plugin accordingly is a good idea.
Would there be a way to extend the plugin? Create a graasp-plugin-websockets-recycle-bin? Or should recycle-bin export a plugin for supporting its feature?

[mochiruntime]

In my opinion, you should be able to integrate additional websockets interactions for this use case in a rather straightforward manner. Would adding the related websocket functionalities directly into graasp-recycle-bin work?

You can refer to https://github.com/graasp/graasp-plugin-chatbox for an example.

Here's an implementation sketch (for more details, please refer to: https://github.com/graasp/graasp-websockets/blob/master/USAGE.md#consuming-the-graasp-websockets-plugin-to-extend-real-time-capabilities):

1. Retrieve the injected websockets service from the main fastify instance. It should be typed as optional, as such you can simply ignore any behaviour registration if the property is unavailable (i.e. websockets are disabled).

   In https://github.com/graasp/graasp-recycle-bin/blob/5cf8d760b52683e493e54ee0c0b9198b925261e0/src/plugin.ts#L38-L44:

   const plugin: FastifyPluginAsync<RecycleBinOptions> = async (fastify, options) => {
     const {
       items: { taskManager: itemTaskManager },
       members: { taskManager: memberTaskManager },
       itemMemberships: { taskManager: itemMembershipTaskManager },
       taskRunner: runner,
   +   websockets,
     } = fastify;

   you can then check if websockets are available:

   if (websockets) {
       // ... do stuff with websockets
   }

   Note that you may need to repeat the module augmentation type beforehand somewhere in this file. See Property 'websockets' does not exist on type 'FastifyInstance<Server, IncomingMessage, ServerResponse, FastifyLoggerInstance>' #19 and https://github.com/graasp/graasp-websockets/blob/master/USAGE.md#registering-real-time-behaviour-on-the-server

2. You can probably reuse the item topic which is already registered by the core item service at https://github.com/graasp/graasp/blob/master/src/services/items/ws/hooks.ts#L35. However, you could also register a dedicated topic if you want to.

3. Define your websocket events, for instance in a new file at graasp-recycle-bin/src/ws/events.ts. Have a look at https://github.com/graasp/graasp/blob/master/src/services/items/ws/events.ts, I guess your use case will extend SelfItemEvent, ChildItemEvent, OwnItemsEvent (maybe SharedItemsEvent also?), as well as a new RecycleBinEvent if you need to monitor the recycle bin itself.

   // if you can extend the interface from https://github.com/graasp/graasp/blob/master/src/services/items/ws/events.ts directly, otherwise define your own custom events:
   interface SelfRecycledEvent = {
       kind: 'self';
       op: 'recycle';
       item: Item;
   }
   
   // factory...
   export SelfRecycledEvent = (): SelfRecycledEvent => ({ ... })
   
   // etc...

4. Define when you publish your events based on the hook handlers in for instance graasp-recycle-bin/src/ws/hooks.ts (the tricky part is not forgetting edge cases). Have a look at https://github.com/graasp/graasp/blob/master/src/services/items/ws/hooks.ts, since I guess you will add special cases to the existing implementations. You may want to implement your own service machinery, similar to https://github.com/graasp/graasp-plugin-chatbox/blob/main/src/task-manager.ts so that you can identify your own tasks if you need to perform DB calls transactionally, and also benefit from getting hook handlers for free from the task runner. Otherwise, you can also simply add your publish call in recycleItem directly (although I guess you will need transactional DB calls anyway to query the item, its parent, etc):

   async function recycleItem(itemId: string, member: Member<RecycleExtra>,
   recycleBinItemId: string, log: FastifyLoggerInstance): Promise<void> {
       // ... existing implementation
   
      if (websockets) {
         // notify parent of child getting recycled if it exists
         parentId = ... // from item path
         if (parentId) { websockets.publish(itemTopic, parentId, ChildRecycledEvent() }
         // notify user if own (root item)
         else { websocket.publish(memberItemsTopic, item.creator, OwnRecycledEvent()) }
         // notify item itself
         websockets.publish(itemTopic, itemId, SelfRecycledEvent())
         // ... etc. for your other events cases (such as memberships, the recycle bin itself, ...)
      }
   }

5. Finally you'll need to modify the query client hooks (https://github.com/graasp/graasp-query-client/blob/675f46fae900aa5f59b5e7952d8bbdae83159918/src/ws/hooks/item.ts, https://github.com/graasp/graasp-query-client/blob/675f46fae900aa5f59b5e7952d8bbdae83159918/src/ws/hooks/membership.ts) to handle the above events. You may need to add additional hooks (for instance to monitor the recycle bin), which will be called from your consumer-facing hook (similarly to https://github.com/graasp/graasp-query-client/blob/675f46fae900aa5f59b5e7952d8bbdae83159918/src/hooks/item.ts)

I'm probably forgetting many edge cases, so the actual implementation will have to be done with more care.

WDYT?