feat(notifications): add login quest counts and claim reminders

src/main/java/games/dmg/spigotquestboard/BukkitIssuerNotifier.java

@@ -1,6 +1,7 @@
 package games.dmg.spigotquestboard;
 
 import java.io.IOException;
+import java.time.Clock;
 import java.util.Objects;
 import java.util.UUID;
 import java.util.logging.Level;
@@ -15,11 +16,17 @@ final class BukkitIssuerNotifier implements IssuerNotifier, Listener {
     private final QuestService quests;
     private final Server server;
     private final Logger logger;
+    private final Clock clock;
 
     BukkitIssuerNotifier(QuestService quests, Server server, Logger logger) {
+        this(quests, server, logger, Clock.systemUTC());
+    }
+
+    BukkitIssuerNotifier(QuestService quests, Server server, Logger logger, Clock clock) {
         this.quests = Objects.requireNonNull(quests, "quests");
         this.server = Objects.requireNonNull(server, "server");
         this.logger = Objects.requireNonNull(logger, "logger");
+        this.clock = Objects.requireNonNull(clock, "clock");
     }
 
     @Override
@@ -32,7 +39,20 @@ final class BukkitIssuerNotifier implements IssuerNotifier, Listener {
 
     @EventHandler
     public void onPlayerJoin(PlayerJoinEvent event) {
-        deliver(event.getPlayer());
+        Player player = event.getPlayer();
+        int count = quests.activeQuests(clock.instant()).size();
+        String summary = switch (count) {
+            case 0 -> "No quests are currently available.";
+            case 1 -> "1 quest is currently available.";
+            default -> count + " quests are currently available.";
+        };
+        player.sendMessage(summary + " Visit the quest board to accept or create a quest.");
+        if (!quests.claimsFor(player.getUniqueId()).isEmpty()) {
+            player.sendMessage(
+                "You have items waiting to be claimed. Visit the quest board to collect them."
+            );
+        }
+        deliver(player);
     }
 
     void deliver(Player player) {

src/main/java/games/dmg/spigotquestboard/SpigotQuestBoardPlugin.java

@@ -41,7 +41,7 @@ public final class SpigotQuestBoardPlugin extends JavaPlugin {
         );
         Clock clock = Clock.systemUTC();
         BukkitIssuerNotifier notifier = new BukkitIssuerNotifier(
-            quests, getServer(), getLogger()
+            quests, getServer(), getLogger(), clock
         );
         QuestCompletionGateway completer = new QuestCompletionController(
             quests, new BukkitQuestCompletionInventory(), notifier

src/test/java/games/dmg/spigotquestboard/BukkitIssuerNotifierTest.java

@@ -4,15 +4,21 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.ArgumentMatchers.contains;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.clearInvocations;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import java.time.Clock;
 import java.time.Instant;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.UUID;
 import java.util.logging.Logger;
 import org.bukkit.Server;
 import org.bukkit.entity.Player;
+import org.bukkit.event.player.PlayerJoinEvent;
 import org.junit.jupiter.api.Test;
 
 final class BukkitIssuerNotifierTest {
@@ -82,6 +88,90 @@ final class BukkitIssuerNotifierTest {
         assertTrue(service.state().notifications().isEmpty());
     }
 
+    @Test
+    void everyLoginReportsAvailableQuestsWithNaturalWordingAndBoardHint() throws Exception {
+        QuestService service = new QuestService(new Repository());
+        Instant now = Instant.EPOCH.plusSeconds(604800);
+        BukkitIssuerNotifier notifier = new BukkitIssuerNotifier(
+            service, mock(Server.class), Logger.getAnonymousLogger(),
+            Clock.fixed(now, ZoneOffset.UTC)
+        );
+        Player player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(UUID.randomUUID());
+        PlayerJoinEvent event = mock(PlayerJoinEvent.class);
+        when(event.getPlayer()).thenReturn(player);
+        String hint = " Visit the quest board to accept or create a quest.";
+
+        // Expired at exactly login time, even before the expiry task runs.
+        createQuest(service, Instant.EPOCH);
+        Quest completed = createQuest(service, now);
+        service.complete(completed.id(), new EscrowItem("STONE", 1, null), now);
+        Quest cancelled = createQuest(service, now);
+        service.cancel(cancelled.id(), cancelled.issuerId(), now);
+        notifier.onPlayerJoin(event);
+        verify(player).sendMessage("No quests are currently available." + hint);
+
+        createQuest(service, now);
+        notifier.onPlayerJoin(event);
+        verify(player).sendMessage("1 quest is currently available." + hint);
+
+        createQuest(service, now);
+        notifier.onPlayerJoin(event);
+        notifier.onPlayerJoin(event);
+        verify(player, times(2)).sendMessage("2 quests are currently available." + hint);
+        verify(player, never()).sendMessage(contains("items waiting"));
+    }
+
+    @Test
+    void claimsAreRemindedOnEveryLoginAcrossReloadsUntilAllCollected() throws Exception {
+        Repository repository = new Repository();
+        QuestService service = completedService(repository);
+        UUID issuer = service.state().notifications().values().iterator().next().recipientId();
+        Quest cancelled = service.create(
+            issuer, "Issuer", "STONE", 1,
+            List.of(new EscrowItem("DIAMOND", 1, null)), Instant.EPOCH
+        );
+        service.cancel(cancelled.id(), issuer, Instant.EPOCH.plusSeconds(1));
+        Player player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(issuer);
+        PlayerJoinEvent event = mock(PlayerJoinEvent.class);
+        when(event.getPlayer()).thenReturn(player);
+        String reminder = "You have items waiting to be claimed. "
+            + "Visit the quest board to collect them.";
+        BukkitIssuerNotifier notifier = new BukkitIssuerNotifier(
+            service, mock(Server.class), Logger.getAnonymousLogger()
+        );
+        notifier.onPlayerJoin(event);
+        notifier.onPlayerJoin(event);
+        verify(player, times(2)).sendMessage(reminder);
+        assertTrue(service.pendingNotifications(issuer).isEmpty());
+        assertEquals(2, service.claimsFor(issuer).size());
+
+        service = new QuestService(repository);
+        notifier = new BukkitIssuerNotifier(service, mock(Server.class), Logger.getAnonymousLogger());
+        notifier.onPlayerJoin(event);
+        verify(player, times(3)).sendMessage(reminder);
+        service.acknowledgeClaim(issuer, service.claimsFor(issuer).getFirst().id());
+        notifier.onPlayerJoin(event);
+        verify(player, times(4)).sendMessage(reminder);
+
+        clearInvocations(player);
+        when(player.getUniqueId()).thenReturn(UUID.randomUUID());
+        notifier.onPlayerJoin(event);
+        verify(player, never()).sendMessage(reminder);
+        when(player.getUniqueId()).thenReturn(issuer);
+        service.acknowledgeClaim(issuer, service.claimsFor(issuer).getFirst().id());
+        notifier.onPlayerJoin(event);
+        verify(player, never()).sendMessage(reminder);
+    }
+
+    private static Quest createQuest(QuestService service, Instant now) throws Exception {
+        return service.create(
+            UUID.randomUUID(), "Issuer", "STONE", 1,
+            List.of(new EscrowItem("DIAMOND", 1, null)), now
+        );
+    }
+
     private static QuestService completedService(Repository repository) throws Exception {
         QuestService service = new QuestService(repository);
         Quest quest = service.create(