.env.example

@@ -26,3 +26,7 @@ REACT_APP_SSH_PORT=42069
 
 REDIS_HOST=localhost
 REDIS_PORT=6379
+
+NEW_GAME_PINGABLE_ROLE_ID=1123232
+NEW_GAME_CHANNEL_WEBHOOK=https://discordapp.com/api/webhooks/
+REMIND_MOVE_CHANNEL_WEBHOOK=https://discordapp.com/api/webhooks/

config/config.exs

@@ -14,14 +14,19 @@ config :chessh, RateLimits,
   player_session_message_burst_rate: 8,
   player_public_keys: 15,
   create_game_ms: 60 * 1000,
-  create_game_rate: 3
+  create_game_rate: 3,
+  discord_notification_rate: 3,
+  discord_notification_rate_ms: 1000
 
 config :chessh, Web,
   discord_oauth_login_url: "https://discord.com/api/oauth2/token",
   discord_user_api_url: "https://discord.com/api/users/@me",
   discord_scope: "identify"
 
-config :chessh, DiscordNotifications, looking_for_games_mention: "<@&1070084105796075550>"
+config :chessh, DiscordNotifications,
+  game_move_notif_delay_ms: 3 * 60 * 1000,
+  game_created_notif_delay_ms: 30 * 1000,
+  reschedule_delay: 5 * 1000
 
 config :joken, default_signer: "secret"
 

config/runtime.exs

@@ -3,6 +3,11 @@ import Config
 config :chessh,
   ssh_port: String.to_integer(System.get_env("SSH_PORT", "34355"))
 
+config :chessh, DiscordNotifications,
+  looking_for_games_role_mention: "<@&#{System.get_env("NEW_GAME_PINGABLE_ROLE_ID")}>",
+  discord_game_move_notif_webhook: System.get_env("REMIND_MOVE_CHANNEL_WEBHOOK"),
+  discord_new_game_notif_webhook: System.get_env("NEW_GAME_CHANNEL_WEBHOOK")
+
 config :chessh, Web,
   discord_client_id: System.get_env("DISCORD_CLIENT_ID"),
   discord_client_secret: System.get_env("DISCORD_CLIENT_SECRET"),

lib/chessh/application.ex

@@ -18,6 +18,7 @@ defmodule Chessh.Application do
     children = [
       Chessh.Repo,
       Chessh.SSH.Daemon,
+      Chessh.DiscordNotifier,
       Plug.Cowboy.child_spec(
         scheme: :http,
         plug: Chessh.Web.Endpoint,

lib/chessh/discord/notifier.ex

@@ -0,0 +1,129 @@
+defmodule Chessh.DiscordNotifier do
+  use GenServer
+
+  @name :discord_notifier
+
+  alias Chessh.{Game, Player, Repo}
+
+  def start_link(state \\ []) do
+    GenServer.start_link(__MODULE__, state, name: @name)
+  end
+
+  @impl true
+  def init(state) do
+    {:ok, state}
+  end
+
+  @impl true
+  def handle_cast(x, state), do: handle_info(x, state)
+
+  @impl true
+  def handle_info({:attempt_notification, notification} = body, state) do
+    [discord_notification_rate, discord_notification_rate_ms] =
+      Application.get_env(:chessh, RateLimits)
+      |> Keyword.take([:discord_notification_rate, :discord_notification_rate_ms])
+      |> Keyword.values()
+
+    reschedule_delay = Application.get_env(:chessh, RateLimits)[:reschedule_delay]
+
+    case Hammer.check_rate_inc(
+           :redis,
+           "discord-webhook-message-rate",
+           discord_notification_rate_ms,
+           discord_notification_rate,
+           1
+         ) do
+      {:allow, _count} ->
+        send_notification(notification)
+
+      {:deny, _limit} ->
+        Process.send_after(self(), body, reschedule_delay)
+    end
+
+    {:noreply, state}
+  end
+
+  @impl true
+  def handle_info({:schedule_notification, notification, delay}, state) do
+    Process.send_after(self(), {:attempt_notification, notification}, delay)
+    {:noreply, state}
+  end
+
+  defp send_notification({:move_reminder, game_id}) do
+    [min_delta_t, discord_game_move_notif_webhook] =
+      Application.get_env(:chessh, DiscordNotifications)
+      |> Keyword.take([:game_move_notif_delay_ms, :discord_game_move_notif_webhook])
+      |> Keyword.values()
+
+    case Repo.get(Game, game_id) do
+      nil ->
+        nil
+
+      game ->
+        %Game{
+          dark_player: %Player{discord_id: dark_player_discord_id},
+          light_player: %Player{discord_id: light_player_discord_id},
+          turn: turn,
+          updated_at: last_updated,
+          moves: move_count
+        } = Repo.preload(game, [:dark_player, :light_player])
+
+        delta_t = NaiveDateTime.diff(NaiveDateTime.utc_now(), last_updated, :millisecond)
+
+        if delta_t >= min_delta_t do
+          post_discord(
+            discord_game_move_notif_webhook,
+            "<@#{if turn == :light, do: light_player_discord_id, else: dark_player_discord_id}> it is your move in Game #{game_id} (move #{move_count})."
+          )
+        end
+    end
+  end
+
+  defp send_notification({:game_created, game_id}) do
+    [pingable_mention, discord_game_created_notif_webhook] =
+      Application.get_env(:chessh, DiscordNotifications)
+      |> Keyword.take([:looking_for_games_role_mention, :discord_new_game_notif_webhook])
+      |> Keyword.values()
+
+    case Repo.get(Game, game_id) do
+      nil ->
+        nil
+
+      game ->
+        %Game{
+          dark_player: dark_player,
+          light_player: light_player
+        } = Repo.preload(game, [:dark_player, :light_player])
+
+        message =
+          case {is_nil(light_player), is_nil(dark_player)} do
+            {true, false} ->
+              "#{pingable_mention}, <@#{dark_player.discord_id}> is looking for an opponent to play as light in Game #{game_id}"
+
+            {false, true} ->
+              "#{pingable_mention}, <@#{light_player.discord_id}> is looking for an opponent to play as dark in Game #{game_id}"
+
+            _ ->
+              false
+          end
+
+        if message do
+          post_discord(discord_game_created_notif_webhook, message)
+        end
+    end
+  end
+
+  defp post_discord(webhook, message) do
+    :httpc.request(
+      :post,
+      {
+        String.to_charlist(webhook),
+        [],
+        'application/json',
+        %{content: message} |> Jason.encode!() |> String.to_charlist()
+      },
+      [],
+      []
+    )
+  end
+end

lib/chessh/ssh/client/game/game.ex

@@ -77,7 +77,7 @@ defmodule Chessh.SSH.Client.Game do
          ) do
       {:allow, _count} ->
         # Starting a new game
-        {:ok, %Game{} = game} =
+        {:ok, %Game{id: game_id} = game} =
           Game.changeset(
             %Game{},
             Map.merge(
@@ -92,6 +92,12 @@ defmodule Chessh.SSH.Client.Game do
           )
           |> Repo.insert()
 
+        GenServer.cast(
+          :discord_notifier,
+          {:schedule_notification, {:game_created, game_id},
+           Application.get_env(:chessh, DiscordNotifications)[:game_created_notif_delay_ms]}
+        )
+
         init([
           %State{
             state
@@ -403,6 +409,12 @@ defmodule Chessh.SSH.Client.Game do
 
         :syn.publish(:games, {:game, game_id}, {:new_move, attempted_move})
 
+        GenServer.cast(
+          :discord_notifier,
+          {:schedule_notification, {:move_reminder, game_id},
+           Application.get_env(:chessh, DiscordNotifications)[:game_move_notif_delay_ms]}
+        )
+
       _ ->
         nil
     end

priv/repo/migrations/20221219082326_create_player.exs

@@ -2,11 +2,9 @@ defmodule Chessh.Repo.Migrations.CreatePlayer do
   use Ecto.Migration
 
   def change do
-    execute("CREATE EXTENSION IF NOT EXISTS citext", "")
-
     create table(:players) do
       add(:discord_id, :string, null: false)
-      add(:username, :citext, null: false)
+      add(:username, :string, null: false)
       add(:hashed_password, :string, null: true)
       timestamps()
     end