From d3c16dd7aa429f1ab4b9f7cffceb69715e3694ce Mon Sep 17 00:00:00 2001
From: Pim Kunis <pim@kunis.nl>
Date: Sun, 25 Jul 2021 17:39:22 +0200
Subject: [PATCH] Save state set in database

---
 lib/matrix_server/room_server.ex              | 33 +++++++++++--------
 lib/matrix_server/state_resolution.ex         | 21 +++++++++++-
 .../20210725151601_add_state_to_room.exs      |  9 +++++
 3 files changed, 48 insertions(+), 15 deletions(-)
 create mode 100644 priv/repo/migrations/20210725151601_add_state_to_room.exs

diff --git a/lib/matrix_server/room_server.ex b/lib/matrix_server/room_server.ex
index 1a1c811..7436c93 100644
--- a/lib/matrix_server/room_server.ex
+++ b/lib/matrix_server/room_server.ex
@@ -9,11 +9,6 @@ defmodule MatrixServer.RoomServer do
   @registry MatrixServer.RoomServer.Registry
   @supervisor MatrixServer.RoomServer.Supervisor
 
-  def start_link(opts) do
-    {name, opts} = Keyword.pop(opts, :name)
-    GenServer.start_link(__MODULE__, opts, name: name)
-  end
-
   def create_room(input, account) do
     %Room{id: room_id} = room = Repo.insert!(Room.create_changeset(input))
 
@@ -27,6 +22,11 @@ defmodule MatrixServer.RoomServer do
     DynamicSupervisor.start_child(@supervisor, {__MODULE__, opts})
   end
 
+  def start_link(opts) do
+    {name, opts} = Keyword.pop(opts, :name)
+    GenServer.start_link(__MODULE__, opts, name: name)
+  end
+
   @impl true
   def init(opts) do
     %Room{id: room_id} = Keyword.fetch!(opts, :room)
@@ -36,6 +36,8 @@ defmodule MatrixServer.RoomServer do
     Repo.transaction(fn ->
       with {:ok, state_set} <- insert_create_room_event(account, input, room_id) do
         {:ok, %{room_id: room_id, state_set: state_set}}
+      else
+        _ -> {:error, :something}
       end
     end)
   end
@@ -47,27 +49,30 @@ defmodule MatrixServer.RoomServer do
        ) do
     create_room_event = Event.create_room(room_id, MatrixServer.get_mxid(localpart), room_version)
 
-    verify_and_insert_event(create_room_event)
-
-    {:ok, %{}}
+    verify_and_insert_event(create_room_event, %{})
   end
 
-  defp verify_and_insert_event(event) do
+  defp verify_and_insert_event(event, current_state_set) do
     # Check the following things:
     # 1. TODO: Is a valid event, otherwise it is dropped.
     # 2. TODO: Passes signature checks, otherwise it is dropped.
     # 3. TODO: Passes hash checks, otherwise it is redacted before being processed further.
     # 4. Passes authorization rules based on the event's auth events, otherwise it is rejected.
     # 5. Passes authorization rules based on the state at the event, otherwise it is rejected.
-    # 6. TODO: Passes authorization rules based on the current state of the room, otherwise it is "soft failed".
+    # 6. Passes authorization rules based on the current state of the room, otherwise it is "soft failed".
     if StateResolution.is_authorized_by_auth_events(event) do
       state_set = StateResolution.resolve(event, false)
 
       if StateResolution.is_authorized(event, state_set) do
-        # TODO: Assume the event is a forward extremity, should check this actually.
-        Room.update_forward_extremities(event)
-        {:ok, event} = Repo.insert(event)
-        {:ok, state_set}
+        if StateResolution.is_authorized(event, current_state_set) do
+          # TODO: Assume the event is a forward extremity, should check this actually.
+          Room.update_forward_extremities(event)
+          {:ok, event} = Repo.insert(event)
+          state_set = StateResolution.resolve_forward_extremities(event)
+          {:ok, state_set}
+        else
+          {:error, :soft_failed}
+        end
       else
         {:error, :rejected}
       end
diff --git a/lib/matrix_server/state_resolution.ex b/lib/matrix_server/state_resolution.ex
index 094cf16..8591664 100644
--- a/lib/matrix_server/state_resolution.ex
+++ b/lib/matrix_server/state_resolution.ex
@@ -1,7 +1,9 @@
 defmodule MatrixServer.StateResolution do
   import Ecto.Query
 
-  alias MatrixServer.{Repo, Event}
+  alias MatrixServer.{Repo, Event, Room}
+
+  def resolve(event), do: resolve(event, true)
 
   def resolve(%Event{room_id: room_id} = event, apply_state) do
     room_events =
@@ -322,6 +324,23 @@ defmodule MatrixServer.StateResolution do
     is_authorized(event, state_set)
   end
 
+  def resolve_forward_extremities(%Event{room_id: room_id}) do
+    room_events =
+      Event
+      |> where([e], e.room_id == ^room_id)
+      |> select([e], {e.event_id, e})
+      |> Repo.all()
+      |> Enum.into(%{})
+
+    Event
+    |> where([e], e.room_id == ^room_id)
+    |> join(:inner, [e], r in Room, on: e.room_id == r.id)
+    |> where([e, r], e.event_id == fragment("ANY(?)", r.forward_extremities))
+    |> Repo.all()
+    |> Enum.map(&resolve/1)
+    |> do_resolve(room_events)
+  end
+
   def testing do
     %Event{content: content} = event = Event.power_levels("room1", "charlie")
     event = %Event{event | content: %{content | "ban" => 0}}
diff --git a/priv/repo/migrations/20210725151601_add_state_to_room.exs b/priv/repo/migrations/20210725151601_add_state_to_room.exs
new file mode 100644
index 0000000..f7bc549
--- /dev/null
+++ b/priv/repo/migrations/20210725151601_add_state_to_room.exs
@@ -0,0 +1,9 @@
+defmodule MatrixServer.Repo.Migrations.AddStateToRoom do
+  use Ecto.Migration
+
+  def change do
+    alter table(:rooms) do
+      add :state, :map, default: %{}, null: false
+    end
+  end
+end