implement /tournament/featured API endpoint - closes #3791

It uses the same algorithm already in place for the website homepage,
selecting best upcoming and ongoing tournaments for the user tastes,
and highlighting official tournaments.

app/controllers/Tournament.scala

@@ -220,4 +220,14 @@ object Tournament extends LilaController {
       env.socketHandler.join(id, uid, ctx.me)
     }
   }
+
+  def featured = Open { implicit ctx =>
+    negotiate(
+      html = notFound,
+      api = _ =>
+        Env.tournament.cached.promotable.get.nevermind map {
+          lila.tournament.Spotlight.select(_, ctx.me, 4)
+        } flatMap env.scheduleJsonView.featured map { Ok(_) }
+    )
+  }
 }

app/views/lobby/home.scala.html

@@ -18,7 +18,7 @@
 @events.map { e =>
 @event.homepageSpotlight(e)
 }
-@lila.tournament.Spotlight.select(tours, ctx.me).map { tour =>
+@lila.tournament.Spotlight.select(tours, ctx.me, 3).map { tour =>
 @tournament.homepageSpotlight(tour)
 }
 @simuls.find(_.spotlightable).take(2).map { s =>

conf/routes

@@ -224,6 +224,7 @@ GET   /$gameId<\w{8}>/$color<white|black>/text   controllers.Round.watcherText(g
 
 # Tournament
 GET   /tournament                             controllers.Tournament.home(page: Int ?= 1)
+GET   /tournament/featured                    controllers.Tournament.featured
 GET   /tournament/new                         controllers.Tournament.form
 POST  /tournament/new                         controllers.Tournament.create
 GET   /tournament/$id<\w{8}>                  controllers.Tournament.show(id: String)

modules/tournament/src/main/ScheduleJsonView.scala

@@ -19,9 +19,14 @@ final class ScheduleJsonView(lightUser: LightUser.Getter) {
     "finished" -> finished
   )
 
+  def featured(tournaments: List[Tournament]): Fu[JsObject] =
+    tournaments.map(tournamentJson).sequenceFu map { objs =>
+      Json.obj("featured" -> objs)
+    }
+
   private def tournamentJson(tour: Tournament): Fu[JsObject] = for {
-    owner <- tour.nonLichessCreatedBy.??(lightUser)
-    winner <- tour.winnerId.??(lightUser)
+    owner <- tour.nonLichessCreatedBy ?? lightUser
+    winner <- tour.winnerId ?? lightUser
   } yield Json.obj(
     "id" -> tour.id,
     "createdBy" -> tour.createdBy,

modules/tournament/src/main/Spotlight.scala

@@ -16,11 +16,11 @@ object Spotlight {
 
   import Schedule.Freq._
 
-  def select(tours: List[Tournament], user: Option[User]): List[Tournament] =
-    user.fold(sort(tours) take 3) { select(tours, _) }
+  def select(tours: List[Tournament], user: Option[User], max: Int): List[Tournament] =
+    user.fold(sort(tours) take max) { select(tours, _, max) }
 
-  def select(tours: List[Tournament], user: User): List[Tournament] =
-    sort(tours.filter { select(_, user) }) take 3
+  def select(tours: List[Tournament], user: User, max: Int): List[Tournament] =
+    sort(tours.filter { select(_, user) }) take max
 
   private def sort(tours: List[Tournament]) = tours.sortBy { t =>
     -(t.schedule.??(_.freq.importance))