docs: add v1.0 chat docs

architecture/v1.0/chat.md

@@ -0,0 +1,66 @@
+# Chat
+
+## Chat rooms management
+
+- When the user is connected to the server, we find all his rooms and _join_ his socket to it.
+- When the user is disconnected from the server, we find all his rooms and _remove_ his socket from these rooms.
+  - Notify his room members in these rooms that the user is offline ([related](#onlineoffline))
+
+## Online/Offline
+
+> Depends on (blocked by) [chat rooms management](#chat-rooms-management).
+
+##### Requirements
+
+When the user is connected/disconnected to/from the server
+
+- He should be marked as `online` / `offline`
+- All the other users that share a room with the current user should be notified.
+- Logic should be tested.
+
+## Mark messages as read
+
+> Depends on (blocked by) [chat rooms management](#chat-rooms-management).
+
+##### Requirements
+
+- When the message first created it should be marked as unread by default.
+- Onwership must be verified.
+- Ensure the the messages was not already deleted.
+- Client can emit an event to mark message as read.
+- Upon failure, a revert event should be sent back to the same client to notify that the action was reverted.
+- Logic should be tested.
+
+## Delete message
+
+> Depends on (blocked by) [chat rooms management](#chat-rooms-management).
+
+##### Requirements
+
+- Client can emit an event to delete a room message in case he is the owner.
+  - Event should contain the message id only.
+- Onwership must be verified.
+- Ensure that messages was not already deleted.
+- Messages should be never be deleted from the database but it should be _marked as deleted_ instead.
+- Ensure that deleted messages is not included in the the find room messages api handler.
+- Upon deletion failure, an event should be sent back to the same client with the revert reason.
+  ```ts
+  // event emitted by the server to the chat room associated with the deleted messages.
+  type MessageDeletionReverted = {
+    messageId: number;
+    reason: string;
+  };
+  ```
+- Other members in the room should notified that the message was deleted.
+  ```ts
+  // event emitted by the server to the chat room associated with deleted message.
+  type MessagedDeleted = { messageId: number };
+  ```
+
+## Tasks
+
+- [ ] Write full-test coverage for the `messages` model. @mmoehabb
+- [ ] Chat room management ([info](#chat-rooms-management)). @mmoehabb
+- [ ] Online/Offline ([info](#onlineoffline)) @mmoehabb
+- [ ] Mark message as read ([info](#mark-messages-as-read)). @mmoehabb
+- [ ] Delete messages ([info](#delete-message)). @mmoehabb