PlacePanel: Limit max based on unit requirements.

game-app/game-core/src/main/java/games/strategy/triplea/delegate/AbstractPlaceDelegate.java

@@ -38,6 +38,7 @@
 import java.util.Map.Entry;
 import java.util.Objects;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import org.triplea.java.collections.CollectionUtils;
 import org.triplea.java.collections.IntegerMap;
@@ -974,6 +975,11 @@ protected Collection<Unit> getUnitsToBePlaced(
     } else {
       placeableUnits2 = placeableUnits;
     }
+    // Limit count of each unit type to the max that can be placed based on unit requirements.
+    for (UnitType ut : placeableUnits2.stream().map(Unit::getType).collect(Collectors.toSet())) {
+      var unitsOfType = CollectionUtils.getMatches(placeableUnits2, Matches.unitIsOfType(ut));
+      placeableUnits2.removeAll(getUnitsThatCantBePlacedThatRequireUnits(unitsOfType, to));
+    }
     // now check stacking limits
     return UnitStackingLimitFilter.filterUnits(
         placeableUnits2, PLACEMENT_LIMIT, player, to, produced.getOrDefault(to, List.of()));
@@ -1471,20 +1477,25 @@ private Predicate<Unit> unitWhichRequiresUnitsHasRequiredUnits(
 
   private boolean getCanAllUnitsWithRequiresUnitsBePlacedCorrectly(
       final Collection<Unit> units, final Territory to) {
+    return getUnitsThatCantBePlacedThatRequireUnits(units, to).isEmpty();
+  }
+
+  private Collection<Unit> getUnitsThatCantBePlacedThatRequireUnits(
+      final Collection<Unit> units, final Territory to) {
     if (!Properties.getUnitPlacementRestrictions(getData().getProperties())
         || units.stream().noneMatch(Matches.unitRequiresUnitsOnCreation())) {
-      return true;
+      return List.of();
     }
     final IntegerMap<Territory> producersMap = getMaxUnitsToBePlacedMap(units, to, player);
     final List<Territory> producers = getAllProducers(to, player, units);
     if (producers.isEmpty()) {
-      return false;
+      return units;
     }
     producers.sort(getBestProducerComparator(to, units, player));
     final Collection<Unit> unitsLeftToPlace = new ArrayList<>(units);
     for (final Territory t : producers) {
       if (unitsLeftToPlace.isEmpty()) {
-        return true;
+        return List.of();
       }
       final int productionHere = producersMap.getInt(t);
       final List<Unit> canBePlacedHere =
@@ -1499,7 +1510,7 @@ private boolean getCanAllUnitsWithRequiresUnitsBePlacedCorrectly(
           CollectionUtils.getNMatches(canBePlacedHere, productionHere, it -> true);
       unitsLeftToPlace.removeAll(placedHere);
     }
-    return unitsLeftToPlace.isEmpty();
+    return unitsLeftToPlace;
   }
 
   private Comparator<Territory> getBestProducerComparator(

game-app/game-core/src/test/java/games/strategy/triplea/delegate/PlaceDelegateTest.java

@@ -1,5 +1,8 @@
 package games.strategy.triplea.delegate;
 
+import static games.strategy.triplea.Constants.DAMAGE_FROM_BOMBING_DONE_TO_UNITS_INSTEAD_OF_TERRITORIES;
+import static games.strategy.triplea.Constants.UNIT_PLACEMENT_RESTRICTIONS;
+import static games.strategy.triplea.delegate.GameDataTestUtil.unitType;
 import static games.strategy.triplea.delegate.Matches.unitIsOfType;
 import static games.strategy.triplea.delegate.MockDelegateBridge.newDelegateBridge;
 import static games.strategy.triplea.delegate.remote.IAbstractPlaceDelegate.BidMode.NOT_BID;
@@ -145,6 +148,26 @@ void testCanNotProduceThatManyUnits() {
     assertEquals(2, response.getMaxUnits());
   }
 
+  @Test
+  void testCanNotProduceThatManyUnitsDueToRequiresUnits() {
+    gameData.getProperties().set(UNIT_PLACEMENT_RESTRICTIONS, true);
+    // Needed for canProduceXUnits to work. (!)
+    gameData.getProperties().set(DAMAGE_FROM_BOMBING_DONE_TO_UNITS_INSTEAD_OF_TERRITORIES, true);
+    final var factory2 = unitType("factory2", gameData);
+    final var infantry2 = unitType("infantry2", gameData);
+
+    final var threeInfantry2 = create(british, infantry2, 3);
+    final var fourInfantry2 = create(british, infantry2, 4);
+
+    uk.getUnitCollection().clear();
+    assertError(delegate.canUnitsBePlaced(uk, threeInfantry2, british));
+    uk.getUnitCollection().addAll(create(british, factory2, 1));
+    assertValid(delegate.canUnitsBePlaced(uk, threeInfantry2, british));
+    assertError(delegate.canUnitsBePlaced(uk, fourInfantry2, british));
+    final PlaceableUnits response = delegate.getPlaceableUnits(fourInfantry2, uk);
+    assertThat(response.getUnits(), hasSize(3));
+  }
+
   @Test
   void testAlreadyProducedUnits() {
     delegate.setProduced(Map.of(westCanada, create(british, infantry, 2)));

game-app/game-core/src/test/resources/DelegateTest.xml

@@ -459,6 +459,8 @@
         <unit name="submarine"/>
         <unit name="factory"/>
         <unit name="aaGun"/>
+        <unit name="factory2"/>
+        <unit name="infantry2"/>
     </unitList>
 <gamePlay>
         <delegate name="initDelegate" javaClass="games.strategy.triplea.delegate.InitializationDelegate"/>
@@ -718,6 +720,20 @@
             type="unitType">
             <option name="isFactory" value="true"/>
         </attachment>
+
+
+        <attachment name="unitAttachment" attachTo="factory2" javaClass="UnitAttachment" type="unitType">
+            <option name="isFactory" value="true"/>
+            <option name="canProduceXUnits" value="3"/>
+        </attachment>
+        <attachment name="unitAttachment" attachTo="infantry2" javaClass="UnitAttachment" type="unitType">
+            <option name="movement" value="1"/>
+            <option name="transportCost" value="1"/>
+            <option name="attack" value="1"/>
+            <option name="defense" value="2"/>
+            <option name="requiresUnits" value="factory2"/>
+        </attachment>
+
         <attachment name="unitAttachment"
             attachTo="aaGun"
             javaClass="UnitAttachment"