fix: stop a broken station's site choice from starting a build

src/main/java/net/tfminecraft/vfbuilders/managers/StationManager.java

@@ -240,6 +240,10 @@ public void inventoryClick(InventoryClickEvent e) {
                 return;
             }
             p.closeInventory();
+            if (!isRegistered(h.getStation())) {
+                p.sendMessage("§cThe station was removed, so nothing can be built there.");
+                return;
+            }
 
             ActivePlacement placement = new ActivePlacement(p, h.getStation(), b);
             activePlacements.put(p.getUniqueId(), placement);
@@ -263,6 +267,12 @@ public void onPlayerLeftClick(PlayerInteractEvent e) {
         Location stationLoc = placement.getStation().getLocation();
         Location clickLoc = p.getLocation();
 
+        if (!isRegistered(placement.getStation())) {
+            activePlacements.remove(uuid);
+            p.sendMessage("§cBuilding site choice cancelled: the station was removed.");
+            return;
+        }
+
         if (!java.util.Objects.equals(clickLoc.getWorld(), stationLoc.getWorld())
                 || clickLoc.distanceSquared(stationLoc) > Math.pow(Cache.constructionDistance, 2)) {
             p.sendMessage("§cToo far from the station! (max "+Cache.constructionDistance+" blocks)");
@@ -430,7 +440,17 @@ private boolean remove(Location loc) {
             stations.put(loc, station);
             return false;
         }
+        // A site choice for the removed station must not start a build on it later.
+        activePlacements.values().removeIf(placement -> {
+            if (placement.getStation() != station) return false;
+            placement.getPlayer().sendMessage("§cBuilding site choice cancelled: the station was removed.");
+            return true;
+        });
         return true;
     }
 
+    private boolean isRegistered(ActiveStation station) {
+        return stations.get(station.getLocation()) == station;
+    }
+
 }

src/test/java/net/tfminecraft/vfbuilders/ManagerTest.java

@@ -422,9 +422,9 @@
   void quitAndBreakRemoveOnlyTheirOwnState() throws Exception {
     var s = manager.getStation(block);
     placements().put(player.getUniqueId(), new ActivePlacement(player, s, mock(Blueprint.class)));
     manager.onPlayerQuit(new PlayerQuitEvent(player, "quit"));
     assertTrue(placements().isEmpty());
     manager.onPlayerQuit(new PlayerQuitEvent(player, "quit"));
     manager.onBlockBreak(new BlockBreakEvent(player.getWorld().getBlockAt(50, 64, 50), player));
     manager.onBlockBreak(new BlockBreakEvent(block, player));
     assertNotSame(s, manager.getStation(block));
@@ -504,4 +504,102 @@
     manager.onBlockBreak(new BlockBreakEvent(block, player));
     verify(b).drop(any());
   }
+
+  String drainMessagesUntil(String fragment) {
+    var mock = (org.mockbukkit.mockbukkit.entity.PlayerMock) player;
+    for (String m = mock.nextMessage(); m != null; m = mock.nextMessage()) {
+      if (m.contains(fragment)) return m;
+    }
+    return null;
+  }
+
+  @Test
+  void breakingAnIdleStationDuringSiteChoiceCannotStartABuildOnIt() throws Exception {
+    var s = manager.getStation(block);
+    var b = mock(Blueprint.class);
+    when(b.hasInputs(player)).thenReturn(true);
+    BlueprintLoader.get().put("windrider", b);
+    player.teleport(block.getLocation());
+    manager.inventoryClick(
+        click(s, tagged("vfb_blueprint_id", "windrider"), net.tfminecraft.vfbuilders.enums.VFBGUI.BLUEPRINT));
+    assertNotNull(drainMessagesUntil("and left-click"));
+
+    manager.onBlockBreak(new BlockBreakEvent(block, player));
+
+    assertTrue(placements().isEmpty());
+    assertNotNull(drainMessagesUntil("the station was removed"));
+    manager.onPlayerLeftClick(left());
+    verify(b, never()).takeInputs(player);
+    assertFalse(s.hasBlueprint());
+    assertNull(s.getSpawnLocation());
+  }
+
+  @Test
+  void stalePlacementOnARemovedStationIsDroppedEvenIfAStationReturnsThere() throws Exception {
+    var old = manager.getStation(block);
+    var b = mock(Blueprint.class);
+    when(b.hasInputs(player)).thenReturn(true);
+    manager.onBlockBreak(new BlockBreakEvent(block, player));
+    var replacement = manager.getStation(block);
+    assertNotSame(old, replacement);
+    player.teleport(block.getLocation());
+    placements().put(player.getUniqueId(), new ActivePlacement(player, old, b));
+
+    manager.onPlayerLeftClick(left());
+
+    assertTrue(placements().isEmpty());
+    verify(b, never()).takeInputs(player);
+    assertFalse(old.hasBlueprint());
+    assertFalse(replacement.hasBlueprint());
+    assertNotNull(drainMessagesUntil("the station was removed"));
+  }
+
+  @Test
+  void blueprintMenuLeftOpenOnARemovedStationStartsNoSiteChoice() throws Exception {
+    var s = manager.getStation(block);
+    var b = mock(Blueprint.class);
+    when(b.hasInputs(player)).thenReturn(true);
+    BlueprintLoader.get().put("boat", b);
+    manager.onBlockBreak(new BlockBreakEvent(block, player));
+    assertNotSame(s, manager.getStation(block)); // a new station now stands on the same spot
+
+    manager.inventoryClick(
+        click(s, tagged("vfb_blueprint_id", "boat"), net.tfminecraft.vfbuilders.enums.VFBGUI.BLUEPRINT));
+
+    assertTrue(placements().isEmpty());
+    assertNotNull(drainMessagesUntil("nothing can be built there"));
+  }
+
+  @Test
+  void removingAStationKeepsSiteChoicesForOtherStations() throws Exception {
+    var other = player.getWorld().getBlockAt(2, 64, 1);
+    when(api.getChecker().checkBlock(other, "v.stone")).thenReturn(true);
+    var s = manager.getStation(block);
+    var otherStation = manager.getStation(other);
+    var second = server.addPlayer();
+    var mine = new ActivePlacement(player, s, mock(Blueprint.class));
+    var theirs = new ActivePlacement(second, otherStation, mock(Blueprint.class));
+    placements().put(player.getUniqueId(), mine);
+    placements().put(second.getUniqueId(), theirs);
+
+    manager.onBlockBreak(new BlockBreakEvent(block, player));
+
+    assertNull(placements().get(player.getUniqueId()));
+    assertSame(theirs, placements().get(second.getUniqueId()));
+  }
+
+  @Test
+  void failedRemovalSaveKeepsTheSiteChoiceForTheRestoredStation() throws Exception {
+    var s = manager.getStation(block);
+    var mine = new ActivePlacement(player, s, mock(Blueprint.class));
+    placements().put(player.getUniqueId(), mine);
+    database.when(() -> Database.saveStationsNow(anyMap())).thenReturn(false);
+    var event = new BlockBreakEvent(block, player);
+
+    manager.onBlockBreak(event);
+
+    assertTrue(event.isCancelled());
+    assertSame(s, manager.getStation(block));
+    assertSame(mine, placements().get(player.getUniqueId()));
+  }
 }