Cont. wipmaster

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diff --git a/lib/irc/store.ex b/lib/irc/store.ex
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+defmodule Irc.Store do
+  @moduledoc """
+  Mnesia-based store for `Irc.Client`.
+
+  Tables:
+  * User (transient, in memory): tracks known connected users.
+  * Channel (transient, in memory): tracks known channels.
+
+  ## Setup
+
+  Needs to be ran only once at setup:
+
+  ```elixir
+  # First step: create schemas.
+  Memento.stop()
+  Memento.Schema.create([node()])
+  Memento.start()
+
+  # Second step: create tables
+  Irc.Store.setup()
+  ```
+
+
+  """
+
+  @doc false
+  # Childrens for Irc.Application supervisor tree
+  def childs do
+    [{Irc.Store.OwnerSweeper, []}]
+  end
+
+  @doc "Creates tables in Mnesia. Should only be run once."
+  def setup do
+    Memento.Table.create!(Irc.Store.User)
+  end
+
+  defmodule OwnerSweeper do
+    @moduledoc """
+    Ensures the Store only keeps alive data by monitoring owners and deleting entries when their owner dies.
+    """
+    use GenServer
+    require Logger
+
+    @doc "Register calling process to the `OwnerSweeper` process."
+    def register() do
+      GenServer.call(__MODULE__, {:monitor, self()})
+    end
+
+    @doc "Unregister calling process from the sweeper and delete all its entries."
+    def unregister() do
+      GenServer.call(__MODULE__, {:unregister, self()})
+    end
+
+    @doc false
+    def start_link(_) do
+      GenServer.start_link(__MODULE__, [], name: __MODULE__)
+    end
+
+    @impl true
+    @doc false
+    def init(_) do
+      {:ok, Map.new}
+    end
+
+    @impl true
+    @doc false
+    def handle_call({:register, pid}, _, monitors) do
+      if Map.get(monitors, pid) do
+        {:reply, :ok, monitors}
+      else
+        Logger.debug("Irc.Store.OwnerSweeper: added to sweep list #{inspect(pid)}")
+        monitor = Process.monitor(pid)
+        {:reply, :ok, Map.put(monitors, pid, monitor)}
+      end
+    end
+
+    @impl true
+    @doc false
+    def handle_call({:unregister, pid}, _, monitors) do
+      if ref = Map.get(monitors, pid) do
+        Process.demonitor(ref, [:flush])
+        clear_entries(pid)
+        {:reply, :ok, Map.drop(monitors, pid)}
+      else
+        {:reply, :not_registered, monitors}
+      end
+    end
+
+    @impl true
+    @doc false
+    def handle_info({:DOWN, monitor, :process, pid, _reason}, monitors) do
+      Logger.debug("Irc.Store.OwnerSweeper: removing entries of #{inspect(pid)}")
+      if monitor == Map.get(monitors, pid) do
+        # TODO: Delete all `User` entries where owner == pid
+        clear_entries(pid)
+        {:noreply, Map.drop(monitors, pid)}
+      else
+        {:noreply, monitors}
+      end
+    end
+
+    defp clear_entries(pid) do
+      # TODO: Find some way to use built in mnesia select_delete
+      for table <- [Irc.Store.User] do
+        Memento.transaction fn ->
+          for entry <- Memento.Query.select(table, {:==, :owner, pid}) do
+            Memento.delete(table, entry.id)
+          end
+        end
+      end
+    end
+
+  end
+
+
+  defmodule User do
+    #attributes = Irc.User.__attrs__
+    #|> Enum.map(fn
+    #  ({k, _}) ->  k
+    #  k -> k
+    #end)
+
+    #IO.inspect(attributes)
+
+    #use Memento.Table,
+    #  attributes: attributes,
+    #  index: [:owner, :host, :nick, :account]
+
+  end
+
+end