feat(library): summary endpoint with status counts and a backlog pick

GET /api/library/summary returns the game count per status, the never-started
count and a random backlog game. exclude=<appid> makes a new pick differ from
the current one.

src/test/java/core_service/modules/library/api/LibraryControllerSummaryTest.java

@@ -0,0 +1,100 @@
+package core_service.modules.library.api;
+
+import core_service.modules.library.domain.GameStatus;
+import core_service.modules.library.domain.SteamGame;
+import core_service.modules.library.domain.UserGame;
+import core_service.modules.library.repo.SteamGameRepository;
+import core_service.modules.library.repo.UserGameRepository;
+import core_service.shared.test.AbstractIntegrationTest;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.webmvc.test.autoconfigure.AutoConfigureMockMvc;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.time.Instant;
+import java.util.List;
+
+import static org.hamcrest.Matchers.nullValue;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * The dev profile authenticates every request as user 1.
+ */
+@AutoConfigureMockMvc
+class LibraryControllerSummaryTest extends AbstractIntegrationTest {
+
+    private static final long USER_ID = 1L;
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Autowired
+    private SteamGameRepository steamGameRepository;
+
+    @Autowired
+    private UserGameRepository userGameRepository;
+
+    @BeforeEach
+    void clean() {
+        userGameRepository.deleteAll();
+    }
+
+    @Test
+    void summary_EmptyLibrary_HasAllStatusesWithZeroAndNoSuggestion() throws Exception {
+        mockMvc.perform(get("/api/library/summary"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.total").value(0))
+                .andExpect(jsonPath("$.neverPlayed").value(0))
+                .andExpect(jsonPath("$.byStatus.BACKLOG").value(0))
+                .andExpect(jsonPath("$.byStatus.DROPPED").value(0))
+                .andExpect(jsonPath("$.suggestion").value(nullValue()));
+    }
+
+    @Test
+    void summary_CountsStatusesAndSuggestsABacklogGame() throws Exception {
+        steamGameRepository.saveAll(List.of(
+                new SteamGame(220L, "Half-Life 2", "icon", Instant.now()),
+                new SteamGame(620L, "Portal 2", null, Instant.now())));
+        UserGame finished = new UserGame(USER_ID, 620L, 600, Instant.now(), Instant.now());
+        finished.setStatus(GameStatus.FINISHED);
+        userGameRepository.saveAll(List.of(new UserGame(USER_ID, 220L, 0, Instant.now(), Instant.now()), finished));
+
+        mockMvc.perform(get("/api/library/summary"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.total").value(2))
+                .andExpect(jsonPath("$.neverPlayed").value(1))
+                .andExpect(jsonPath("$.byStatus.BACKLOG").value(1))
+                .andExpect(jsonPath("$.byStatus.FINISHED").value(1))
+                .andExpect(jsonPath("$.byStatus.PLAYING").value(0))
+                .andExpect(jsonPath("$.suggestion.appid").value(220))
+                .andExpect(jsonPath("$.suggestion.name").value("Half-Life 2"))
+                .andExpect(jsonPath("$.suggestion.status").value("BACKLOG"));
+    }
+
+    @Test
+    void summary_Exclude_SuggestsAnotherBacklogGame() throws Exception {
+        steamGameRepository.saveAll(List.of(
+                new SteamGame(220L, "Half-Life 2", null, Instant.now()),
+                new SteamGame(620L, "Portal 2", null, Instant.now())));
+        userGameRepository.saveAll(List.of(
+                new UserGame(USER_ID, 220L, 0, Instant.now(), Instant.now()),
+                new UserGame(USER_ID, 620L, 0, Instant.now(), Instant.now())));
+
+        for (int i = 0; i < 5; i++) {
+            mockMvc.perform(get("/api/library/summary").param("exclude", "220"))
+                    .andExpect(jsonPath("$.suggestion.appid").value(620));
+        }
+    }
+
+    @Test
+    void summary_ExcludeTheOnlyBacklogGame_HasNoSuggestion() throws Exception {
+        steamGameRepository.save(new SteamGame(220L, "Half-Life 2", null, Instant.now()));
+        userGameRepository.save(new UserGame(USER_ID, 220L, 0, Instant.now(), Instant.now()));
+
+        mockMvc.perform(get("/api/library/summary").param("exclude", "220"))
+                .andExpect(jsonPath("$.suggestion").value(nullValue()));
+    }
+}

src/test/java/core_service/modules/library/repo/UserGameRepositoryTest.java

@@ -1,6 +1,7 @@
 package core_service.modules.library.repo;
 
 import core_service.modules.library.domain.GameStatus;
+import core_service.modules.library.domain.StatusCount;
 import core_service.modules.library.domain.SteamGame;
 import core_service.modules.library.domain.UserGame;
 import core_service.modules.library.domain.UserGameId;
@@ -18,9 +19,11 @@ import org.springframework.transaction.support.TransactionTemplate;
 
 import java.time.Instant;
 import java.util.List;
+import java.util.Set;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class UserGameRepositoryTest extends AbstractPersistenceTest {
 
@@ -98,6 +101,47 @@ class UserGameRepositoryTest extends AbstractPersistenceTest {
         assertNull(UserGameRepository.containsPattern(null));
     }
 
+    @Test
+    void countByStatus_CountsOnlyOwnActiveGames() {
+        UserGame dropped = userGameRepository.findById(new UserGameId(USER_ID, 380L)).orElseThrow();
+        dropped.setStatus(GameStatus.DROPPED);
+        UserGame removed = userGameRepository.findById(new UserGameId(USER_ID, 700L)).orElseThrow();
+        removed.setRemovedAt(Instant.now());
+        userGameRepository.flush();
+
+        assertEquals(Set.of(new StatusCount(GameStatus.PLAYING, 2), new StatusCount(GameStatus.DROPPED, 1)),
+                Set.copyOf(userGameRepository.countByStatus(USER_ID)));
+    }
+
+    @Test
+    void countNeverPlayed_CountsOnlyOwnActiveGamesWithoutPlaytime() {
+        UserGame removed = userGameRepository.findById(new UserGameId(USER_ID, 700L)).orElseThrow();
+        removed.setRemovedAt(Instant.now());
+        userGameRepository.save(new UserGame(2L, 380L, 0, Instant.now(), Instant.now()));
+        userGameRepository.flush();
+
+        assertEquals(1, userGameRepository.countByUserIdAndRemovedAtIsNullAndPlaytimeMinutes(USER_ID, 0));
+    }
+
+    @Test
+    void findRandomBacklogGame_PicksOnlyOwnActiveBacklogGames() {
+        UserGame removed = userGameRepository.findById(new UserGameId(USER_ID, 700L)).orElseThrow();
+        removed.setRemovedAt(Instant.now());
+        userGameRepository.flush();
+
+        for (int i = 0; i < 5; i++) {
+            assertEquals(380L, userGameRepository.findRandomBacklogGame(USER_ID, -1).orElseThrow().getAppid());
+        }
+        assertTrue(userGameRepository.findRandomBacklogGame(99L, -1).isEmpty());
+    }
+
+    @Test
+    void findRandomBacklogGame_SkipsTheExcludedGame() {
+        for (int i = 0; i < 5; i++) {
+            assertEquals(700L, userGameRepository.findRandomBacklogGame(USER_ID, 380L).orElseThrow().getAppid());
+        }
+    }
+
     @Test
     @Transactional(propagation = Propagation.NOT_SUPPORTED)
     void syncFlushKeepsBacklogEditCommittedMeanwhile() {