Mark the conversations with the blocked user as read and update the blocking user's unread_conversation_count.

Since the conversations with the blocked user are invisible, they are excluded
from the blocking user's `unread_conversation_count`.

lib/pleroma/conversation/participation.ex

@@ -32,11 +32,20 @@ defmodule Pleroma.Conversation.Participation do
 
   def create_for_user_and_conversation(user, conversation, opts \\ []) do
     read = !!opts[:read]
+    invisible_conversation = !!opts[:invisible_conversation]
+
+    update_on_conflict =
+      if(invisible_conversation, do: [], else: [read: read])
+      |> Keyword.put(:updated_at, NaiveDateTime.utc_now())
 
     %__MODULE__{}
-    |> creation_cng(%{user_id: user.id, conversation_id: conversation.id, read: read})
+    |> creation_cng(%{
+      user_id: user.id,
+      conversation_id: conversation.id,
+      read: invisible_conversation || read
+    })
     |> Repo.insert(
-      on_conflict: [set: [read: read, updated_at: NaiveDateTime.utc_now()]],
+      on_conflict: [set: update_on_conflict],
       returning: true,
       conflict_target: [:user_id, :conversation_id]
     )
@@ -69,7 +78,26 @@ defmodule Pleroma.Conversation.Participation do
     end
   end
 
-  def mark_all_as_read(user) do
+  def mark_all_as_read(%User{local: true} = user, %User{} = target_user) do
+    target_conversation_ids =
+      __MODULE__
+      |> where([p], p.user_id == ^target_user.id)
+      |> select([p], p.conversation_id)
+      |> Repo.all()
+
+    __MODULE__
+    |> where([p], p.user_id == ^user.id)
+    |> where([p], p.conversation_id in ^target_conversation_ids)
+    |> update([p], set: [read: true])
+    |> Repo.update_all([])
+
+    {:ok, user} = User.set_unread_conversation_count(user)
+    {:ok, user, []}
+  end
+
+  def mark_all_as_read(%User{} = user, %User{}), do: {:ok, user, []}
+
+  def mark_all_as_read(%User{} = user) do
     {_, participations} =
       __MODULE__
       |> where([p], p.user_id == ^user.id)
@@ -78,8 +106,8 @@ defmodule Pleroma.Conversation.Participation do
       |> select([p], p)
       |> Repo.update_all([])
 
-    User.set_unread_conversation_count(user)
-    {:ok, participations}
+    {:ok, user} = User.set_unread_conversation_count(user)
+    {:ok, user, participations}
   end
 
   def mark_as_unread(participation) do