Merge feature/split-modes: persist split modes + default-split endpoint

src/main/java/de/zendric/app/xpensely_server/controller/ExpenseListController.java

@@ -98,6 +98,18 @@ public class ExpenseListController {
         return new ResponseEntity<>(renamed, HttpStatus.OK);
     }
 
+    @PutMapping("/{id}/default-split")
+    public ResponseEntity<ExpenseList> updateDefaultSplit(@PathVariable("id") Long id,
+            @RequestBody @Valid DefaultSplitRequest request, Authentication authentication) {
+        AppUser user = authenticatedUserResolver.resolveCurrentUser(authentication);
+        Optional<ExpenseList> listOpt = expenseListService.findById(id);
+        if (listOpt.isEmpty())
+            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
+        assertMember(user, listOpt.get());
+        ExpenseList updated = expenseListService.updateDefaultSplit(id, request.getPercentage());
+        return new ResponseEntity<>(updated, HttpStatus.OK);
+    }
+
     @PostMapping("/{id}/add")
     public ResponseEntity<Expense> addExpenseToList(
             @PathVariable("id") Long expenseListId,

src/main/java/de/zendric/app/xpensely_server/model/DefaultSplitRequest.java

@@ -0,0 +1,17 @@
+package de.zendric.app.xpensely_server.model;
+
+import jakarta.validation.constraints.Max;
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+public class DefaultSplitRequest {
+
+    @NotNull(message = "Percentage is required")
+    @Min(value = 0, message = "Percentage must be between 0 and 100")
+    @Max(value = 100, message = "Percentage must be between 0 and 100")
+    private Integer percentage;
+}

src/main/java/de/zendric/app/xpensely_server/model/Expense.java

@@ -6,6 +6,8 @@ import java.time.LocalDateTime;
 import com.fasterxml.jackson.annotation.JsonBackReference;
 
 import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
@@ -36,6 +38,12 @@ public class Expense {
     private Double personalUseAmount;
     private Double otherPersonAmount;
     private String category;
+
+    @Enumerated(EnumType.STRING)
+    private SplitMode splitMode;
+
+    private Integer splitPercentage;
+
     private LocalDate date;
     private LocalDateTime lastModified;
 

src/main/java/de/zendric/app/xpensely_server/model/ExpenseChangeRequest.java

@@ -3,6 +3,8 @@ package de.zendric.app.xpensely_server.model;
 import java.time.LocalDate;
 
 import jakarta.validation.constraints.DecimalMin;
+import jakarta.validation.constraints.Max;
+import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Size;
@@ -33,6 +35,12 @@ public class ExpenseChangeRequest {
     private Double personalUseAmount;
     private Double otherPersonAmount;
 
+    private SplitMode splitMode;
+
+    @Min(0)
+    @Max(100)
+    private Integer splitPercentage;
+
     @NotNull(message = "Date is required")
     private LocalDate date;
 
@@ -55,6 +63,8 @@ public class ExpenseChangeRequest {
         // The edit dialog sends "" for a missing category; store null so the
         // stub state stays uniform and history diffs don't report null -> "".
         expense.setCategory(category == null || category.isBlank() ? null : category);
+        expense.setSplitMode(splitMode == null ? SplitMode.DETAILED : splitMode);
+        expense.setSplitPercentage(splitPercentage);
 
         return expense;
     }

src/main/java/de/zendric/app/xpensely_server/model/ExpenseInput.java

@@ -3,6 +3,8 @@ package de.zendric.app.xpensely_server.model;
 import java.time.LocalDate;
 
 import jakarta.validation.constraints.DecimalMin;
+import jakarta.validation.constraints.Max;
+import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Size;
@@ -33,6 +35,12 @@ public class ExpenseInput {
     private Double personalUseAmount;
     private Double otherPersonAmount;
 
+    private SplitMode splitMode;
+
+    @Min(0)
+    @Max(100)
+    private Integer splitPercentage;
+
     @NotNull(message = "Date is required")
     private LocalDate date;
 
@@ -56,6 +64,8 @@ public class ExpenseInput {
         expense.setOwner(appUser);
         expense.setTitle(title);
         expense.setCategory(category);
+        expense.setSplitMode(splitMode == null ? SplitMode.DETAILED : splitMode);
+        expense.setSplitPercentage(splitPercentage);
 
         return expense;
     }

src/main/java/de/zendric/app/xpensely_server/model/ExpenseList.java

@@ -31,6 +31,8 @@ public class ExpenseList {
 
     private String name;
 
+    private Integer defaultSplitPercentage = 50;
+
     private String inviteCode;
     @JsonIgnore
     private LocalDateTime inviteCodeExpiration;

src/main/java/de/zendric/app/xpensely_server/model/SplitMode.java

@@ -0,0 +1,6 @@
+package de.zendric.app.xpensely_server.model;
+
+public enum SplitMode {
+    DETAILED,
+    PERCENTAGE
+}

src/main/java/de/zendric/app/xpensely_server/services/ExpenseListService.java

@@ -50,6 +50,13 @@ public class ExpenseListService {
         return repository.save(list);
     }
 
+    public ExpenseList updateDefaultSplit(Long id, int percentage) {
+        ExpenseList list = repository.findById(id)
+                .orElseThrow(() -> new ResourceNotFoundException("ExpenseList not found with id: " + id));
+        list.setDefaultSplitPercentage(percentage);
+        return repository.save(list);
+    }
+
     public Optional<ExpenseList> findById(Long id) {
         return repository.findById(id);
     }
@@ -137,6 +144,8 @@ public class ExpenseListService {
         existingExpense.setDate(updatedExpense.getDate());
         existingExpense.setOwner(updatedExpense.getOwner());
         existingExpense.setCategory(updatedExpense.getCategory());
+        existingExpense.setSplitMode(updatedExpense.getSplitMode());
+        existingExpense.setSplitPercentage(updatedExpense.getSplitPercentage());
         existingExpense.setLastModified(LocalDateTime.now());
 
         Expense saved = expenseRepository.save(existingExpense);
@@ -153,6 +162,8 @@ public class ExpenseListService {
         copy.setPersonalUseAmount(e.getPersonalUseAmount());
         copy.setOtherPersonAmount(e.getOtherPersonAmount());
         copy.setCategory(e.getCategory());
+        copy.setSplitMode(e.getSplitMode());
+        copy.setSplitPercentage(e.getSplitPercentage());
         copy.setDate(e.getDate());
         copy.setOwner(e.getOwner());
         return copy;

src/main/java/de/zendric/app/xpensely_server/services/HistoryService.java

@@ -69,6 +69,10 @@ public class HistoryService {
         addIfChanged(changes, "personalUseAmount", before.getPersonalUseAmount(), after.getPersonalUseAmount());
         addIfChanged(changes, "otherPersonAmount", before.getOtherPersonAmount(), after.getOtherPersonAmount());
         addIfChanged(changes, "category", before.getCategory(), after.getCategory());
+        addIfChanged(changes, "splitMode",
+                before.getSplitMode() == null ? null : before.getSplitMode().name(),
+                after.getSplitMode() == null ? null : after.getSplitMode().name());
+        addIfChanged(changes, "splitPercentage", before.getSplitPercentage(), after.getSplitPercentage());
         addIfChanged(changes, "date", before.getDate(), after.getDate());
         addIfChanged(changes, "owner",
                 before.getOwner() == null ? null : before.getOwner().getUsername(),

src/test/java/de/zendric/app/xpensely_Server/controller/ExpenseListControllerTest.java

@@ -314,6 +314,40 @@ class ExpenseListControllerTest {
                 .andExpect(status().isNotFound());
     }
 
+    // --- Default split ---
+
+    @Test
+    void updateDefaultSplit_setsPercentageForMember() throws Exception {
+        AppUser owner = new AppUser(); owner.setId(1L);
+        ExpenseList list = new ExpenseList(); list.setId(5L); list.setOwner(owner);
+
+        when(expenseListService.findById(5L)).thenReturn(Optional.of(list));
+        when(authenticatedUserResolver.resolveCurrentUser(any())).thenReturn(owner);
+        when(expenseListService.updateDefaultSplit(5L, 60)).thenReturn(list);
+
+        mockMvc.perform(put("/api/expenselist/5/default-split")
+                .contentType(MediaType.APPLICATION_JSON)
+                .content("{\"percentage\":60}"))
+                .andExpect(status().isOk());
+
+        org.mockito.Mockito.verify(expenseListService).updateDefaultSplit(5L, 60);
+    }
+
+    @Test
+    void updateDefaultSplit_nonMember_returns403() throws Exception {
+        AppUser owner = new AppUser(); owner.setId(1L);
+        AppUser stranger = new AppUser(); stranger.setId(2L);
+        ExpenseList list = new ExpenseList(); list.setId(5L); list.setOwner(owner);
+
+        when(expenseListService.findById(5L)).thenReturn(Optional.of(list));
+        when(authenticatedUserResolver.resolveCurrentUser(any())).thenReturn(stranger);
+
+        mockMvc.perform(put("/api/expenselist/5/default-split")
+                .contentType(MediaType.APPLICATION_JSON)
+                .content("{\"percentage\":60}"))
+                .andExpect(status().isForbidden());
+    }
+
     // --- Duplicate-username invite guard ---
 
     @Test

src/test/java/de/zendric/app/xpensely_Server/services/ExpenseListServiceTest.java

@@ -3,6 +3,7 @@ package de.zendric.app.xpensely_Server.services;
 import de.zendric.app.xpensely_server.model.AppUser;
 import de.zendric.app.xpensely_server.model.Expense;
 import de.zendric.app.xpensely_server.model.ExpenseList;
+import de.zendric.app.xpensely_server.model.SplitMode;
 import de.zendric.app.xpensely_server.repo.ExpenseListRepository;
 import de.zendric.app.xpensely_server.repo.ExpenseRepository;
 import de.zendric.app.xpensely_server.repo.XpenselyCustomCategoryRepository;
@@ -109,6 +110,29 @@ class ExpenseListServiceTest {
         assertThat(beforeCaptor.getValue().getAmount()).isEqualTo(12.0);
     }
 
+    @Test
+    void updateExpense_persistsSplitModeAndPercentage() {
+        AppUser actor = new AppUser(); actor.setId(1L);
+        ExpenseList list = new ExpenseList(); list.setId(10L); list.setOwner(actor);
+        Expense existing = makeExpense(5L, "Groceries", 100.0);
+        list.setExpenses(new ArrayList<>(List.of(existing)));
+
+        Expense incoming = makeExpense(5L, "Groceries", 100.0);
+        incoming.setDate(LocalDate.now());
+        incoming.setOwner(list.getOwner());
+        incoming.setSplitMode(SplitMode.PERCENTAGE);
+        incoming.setSplitPercentage(70);
+
+        when(repository.findById(10L)).thenReturn(Optional.of(list));
+        when(expenseRepository.findById(5L)).thenReturn(Optional.of(existing));
+        when(expenseRepository.save(any(Expense.class))).thenAnswer(inv -> inv.getArgument(0));
+
+        Expense saved = service.updateExpense(10L, incoming, actor);
+
+        assertThat(saved.getSplitMode()).isEqualTo(SplitMode.PERCENTAGE);
+        assertThat(saved.getSplitPercentage()).isEqualTo(70);
+    }
+
     @Test
     void deleteById_deletesHistoryEntriesBeforeDeletingList() {
         service.deleteById(10L);

src/test/java/de/zendric/app/xpensely_Server/services/HistoryServiceTest.java

@@ -24,6 +24,7 @@ import de.zendric.app.xpensely_server.model.ExpenseHistoryEntry;
 import de.zendric.app.xpensely_server.model.ExpenseList;
 import de.zendric.app.xpensely_server.model.FieldChange;
 import de.zendric.app.xpensely_server.model.HistoryEntryType;
+import de.zendric.app.xpensely_server.model.SplitMode;
 import de.zendric.app.xpensely_server.repo.ExpenseHistoryRepository;
 import de.zendric.app.xpensely_server.services.HistoryService;
 
@@ -86,6 +87,22 @@ class HistoryServiceTest {
         assertThat(changes).containsExactly(new FieldChange("owner", "alice", "ben"));
     }
 
+    @Test
+    void diff_reportsSplitModeAndPercentageChanges() {
+        Expense before = new Expense();
+        before.setSplitMode(SplitMode.DETAILED);
+        before.setSplitPercentage(null);
+
+        Expense after = new Expense();
+        after.setSplitMode(SplitMode.PERCENTAGE);
+        after.setSplitPercentage(70);
+
+        List<FieldChange> changes = service.diff(before, after);
+
+        assertThat(changes).contains(new FieldChange("splitMode", "DETAILED", "PERCENTAGE"));
+        assertThat(changes).contains(new FieldChange("splitPercentage", null, "70"));
+    }
+
     @Test
     void diff_nullToValue_isReported() {
         Expense before = expense("Taxi", 9.0, null, LocalDate.of(2026, 7, 1), user(1L, "alice"));