Use yaneuraou for positions that could be reached from default starti…

…ng position

modules/game/src/main/EngineConfig.scala

@@ -1,8 +1,8 @@
 package lila.game
 
 import shogi.format.forsyth.Sfen
-import shogi.variant.Variant
-import shogi.Handicap
+import shogi.variant.{ Standard, Variant }
+import shogi.{ Handicap, Role }
 
 case class EngineConfig(
     level: Int,
@@ -41,7 +41,7 @@ object EngineConfig {
       if (
         variant.standard && level.fold(true)(_ > 1) && initialSfen
           .filterNot(_.initialOf(variant))
-          .fold(true)(sf => Handicap.isHandicap(sf, variant))
+          .fold(true)(sf => Handicap.isHandicap(sf, variant) || reachableFromStandardInitialPosition(sf))
       ) YaneuraOu
       else Fairy
   }
@@ -52,4 +52,15 @@ object EngineConfig {
       engine = Engine(sfen, variant, level.some)
     )
 
+  def reachableFromStandardInitialPosition(sfen: Sfen): Boolean =
+    sfen.toSituation(Standard).exists { sit =>
+      val default = Standard.pieces.values.map(_.role)
+      def countHands(r: Role): Int =
+        ~Standard.handRoles.find(_ == r).map(hr => sit.hands.sente(hr) + sit.hands.gote(hr))
+      sit.playable(strict = true, withImpasse = true) &&
+      Standard.allRoles.filterNot(r => Standard.unpromote(r).isDefined).forall { r =>
+        default
+          .count(_ == r) == (sit.board.count(r) + ~Standard.promote(r).map(sit.board.count) + countHands(r))
+      }
+    }
 }

ui/@types/lishogi/index.d.ts

@@ -251,8 +251,6 @@ interface Variant {
   name: string;
 }
 
-declare type EngineCode = 'yn' | 'fs';
-
 interface Paginator<A> {
   currentPage: number;
   maxPerPage: number;

ui/ceval/src/ctrl.ts

@@ -1,12 +1,11 @@
 import { Result } from '@badrap/result';
 import { prop } from 'common/common';
-import { engineName } from 'common/engineName';
+import { EngineCode, engineCode, engineName } from 'common/engineName';
 import { isImpasse } from 'common/impasse';
 import { isAndroid, isIOS, isIPad } from 'common/mobile';
 import { storedProp } from 'common/storage';
 import throttle from 'common/throttle';
 import { parseSfen } from 'shogiops/sfen';
-import { Position } from 'shogiops/variant/position';
 import { defaultPosition } from 'shogiops/variant/variant';
 import { Cache } from './cache';
 import { CevalCtrl, CevalOpts, CevalTechnology, Hovering, PvBoard, Started, Step, Work } from './types';
@@ -58,22 +57,6 @@ function enabledAfterDisable() {
   return enabledAfter === disable;
 }
 
-function isStandardMaterial(pos: Position) {
-  const board = pos.board,
-    hands = pos.hands.color('sente').combine(pos.hands.color('gote'));
-  return (
-    board.role('pawn').size() + board.role('tokin').size() + hands.get('pawn') <= 18 &&
-    board.role('lance').size() + board.role('promotedlance').size() + hands.get('lance') <= 4 &&
-    board.role('knight').size() + board.role('promotedknight').size() + hands.get('knight') <= 4 &&
-    board.role('silver').size() + board.role('promotedsilver').size() + hands.get('silver') <= 4 &&
-    board.role('gold').size() + hands.get('gold') <= 4 &&
-    board.role('rook').size() + board.role('dragon').size() + hands.get('rook') <= 2 &&
-    board.role('bishop').size() + board.role('horse').size() + hands.get('bishop') <= 2 &&
-    board.role('king').size() == 2 &&
-    board.role('king').intersect(board.color('sente')).size() === 1
-  );
-}
-
 export default function (opts: CevalOpts): CevalCtrl {
   const storageKey = (k: string) => {
     return opts.storageKeyPrefix ? `${opts.storageKeyPrefix}.${k}` : k;
@@ -87,7 +70,9 @@ export default function (opts: CevalOpts): CevalCtrl {
   const analysable = pos.isOk && !unsupportedVariants.includes(opts.variant.key);
 
   // select nnue > hce > none
-  const useYaneuraou = opts.variant.key === 'standard' && (!analysable || isStandardMaterial(pos.value)),
+  const useYaneuraou =
+      (!analysable && opts.variant.key === 'standard') ||
+      engineCode('standard', opts.initialSfen) === EngineCode.YaneuraOu,
     fairySupports = !useYaneuraou && analysable;
   let supportsNnue = false,
     technology: CevalTechnology = 'none',

ui/common/src/engineName.ts

@@ -1,28 +1,48 @@
 import { Rules } from 'shogiops';
 import { isHandicap } from 'shogiops/handicaps';
-import { initialSfen } from 'shogiops/sfen';
+import { initialSfen, parseSfen } from 'shogiops/sfen';
 
 const useJp = document.documentElement.lang === 'ja-JP';
 
+export const enum EngineCode {
+  YaneuraOu = 'yn',
+  Fairy = 'fs',
+}
+
 // modules/game/src/main/EngineConfig.scala
-export function engineName(
-  rules: Rules,
-  sfen: Sfen | undefined,
-  level?: number,
-  withLevel?: boolean,
-  trans?: Trans
-): string {
-  const code: EngineCode =
-    rules === 'standard' &&
+export function engineCode(rules: Rules, sfen: Sfen | undefined, level?: number): EngineCode {
+  return rules === 'standard' &&
     (!level || level > 1) &&
-    (!sfen || initialSfen(rules) === sfen || isHandicap({ sfen, rules }))
-      ? 'yn'
-      : 'fs';
-  return engineNameFromCode(code, withLevel ? level : undefined, trans);
+    (!sfen || initialSfen(rules) === sfen || isHandicap({ sfen, rules }) || isStandardMaterial(sfen))
+    ? EngineCode.YaneuraOu
+    : EngineCode.Fairy;
+}
+
+export function engineName(rules: Rules, sfen: Sfen | undefined, level?: number, trans?: Trans): string {
+  const code = engineCode(rules, sfen, level);
+  return engineNameFromCode(code, level, trans);
 }
 
 export function engineNameFromCode(code?: EngineCode, level?: number, trans?: Trans): string {
   const name = code === 'fs' ? 'Fairy Stockfish' : useJp ? 'やねうら王' : 'YaneuraOu';
   if (level && trans) return name + ' - ' + trans('levelX', level);
   else return name;
 }
+
+function isStandardMaterial(sfen: Sfen): boolean {
+  const pos = parseSfen('standard', sfen);
+  if (pos.isErr) return false;
+  const board = pos.value.board,
+    hands = pos.value.hands.color('sente').combine(pos.value.hands.color('gote'));
+  return (
+    board.role('pawn').size() + board.role('tokin').size() + hands.get('pawn') <= 18 &&
+    board.role('lance').size() + board.role('promotedlance').size() + hands.get('lance') <= 4 &&
+    board.role('knight').size() + board.role('promotedknight').size() + hands.get('knight') <= 4 &&
+    board.role('silver').size() + board.role('promotedsilver').size() + hands.get('silver') <= 4 &&
+    board.role('gold').size() + hands.get('gold') <= 4 &&
+    board.role('rook').size() + board.role('dragon').size() + hands.get('rook') <= 2 &&
+    board.role('bishop').size() + board.role('horse').size() + hands.get('bishop') <= 2 &&
+    board.role('king').size() == 2 &&
+    board.role('king').intersect(board.color('sente')).size() === 1
+  );
+}

ui/game/src/interfaces.ts

@@ -1,3 +1,5 @@
+import { EngineCode } from 'common/engineName';
+
 export interface GameData {
   game: Game;
   player: Player;

ui/puzzle/src/interfaces.ts

@@ -1,6 +1,7 @@
 import { CevalCtrl, NodeEvals } from 'ceval';
 import { Prop } from 'common/common';
 import { Deferred } from 'common/defer';
+import { EngineCode } from 'common/engineName';
 import { StoredBooleanProp } from 'common/storage';
 import { Api as SgApi } from 'shogiground/api';
 import { Config as SgConfig } from 'shogiground/config';