expose delayed PGN for all live games

app/controllers/Round.scala

@@ -2,6 +2,7 @@ package controllers
 
 import play.api.libs.json._
 import play.api.mvc._
+import scala.concurrent.duration._
 
 import lila.api.Context
 import lila.app._
@@ -320,4 +321,23 @@ final class Round(
       html.game.bits.mini
     )
   }
+
+  private val delayedPgnCache = env.memo.cacheApi[GameModel.ID, Result](32, "round.delayedPgn") {
+    _.expireAfterWrite(3 seconds)
+      .buildAsyncFuture { gameId =>
+        env.round.proxyRepo.game(gameId) flatMap {
+          case None => NotFound("No such game").fuccess
+          case Some(game) =>
+            env.game.gameRepo initialFen game flatMap { fen =>
+              env.game.pgnDump(game, fen, lila.game.PgnDump.WithFlags().copy(delayMoves = 3)) map { pgn =>
+                Ok(pgn.toString).as(pgnContentType)
+              }
+            }
+        }
+      }
+  }
+
+  def delayedPgn(gameId: GameModel.ID) = Action.async {
+    delayedPgnCache.get(gameId)
+  }
 }

conf/routes

@@ -189,6 +189,7 @@ GET   /streamer/:username              controllers.Streamer.show(username: Strin
 GET   /$gameId<\w{8}>                            controllers.Round.watcher(gameId: String, color: String = "white")
 GET   /$gameId<\w{8}>/$color<white|black>        controllers.Round.watcher(gameId: String, color: String)
 GET   /$fullId<\w{12}>                           controllers.Round.player(fullId: String)
+GET   /$gameId<\w{8}>.pgn                        controllers.Round.delayedPgn(gameId: String)
 GET   /$gameId<\w{8}>/$color<white|black>/sides  controllers.Round.sides(gameId: String, color: String)
 GET   /$gameId<\w{8}>/continue/:mode             controllers.Round.continue(gameId: String, mode: String)
 GET   /$gameId<\w{8}>/note                       controllers.Round.readNote(gameId: String)

modules/game/src/main/PgnDump.scala

@@ -26,9 +26,13 @@ final class PgnDump(
       val turns = flags.moves ?? {
         val fenSituation = ts.fen.map(_.value) flatMap Forsyth.<<<
         val moves2 =
-          if (fenSituation.exists(_.situation.color.black)) ".." +: game.pgnMoves else game.pgnMoves
+          if (fenSituation.exists(_.situation.color.black)) ".." +: game.pgnMoves
+          else game.pgnMoves
+        val moves3 =
+          if (flags.delayMoves > 0) moves2 dropRight flags.delayMoves
+          else moves2
         makeTurns(
-          moves2,
+          moves3,
           fenSituation.map(_.fullMoveNumber) | 1,
           flags.clocks ?? ~game.bothClockStates,
           game.startColor
@@ -164,7 +168,8 @@ object PgnDump {
       evals: Boolean = true,
       opening: Boolean = true,
       literate: Boolean = false,
-      pgnInJson: Boolean = false
+      pgnInJson: Boolean = false,
+      delayMoves: Int = 0
   )
 
   def result(game: Game) =