[Feature] 다음달의 SalaryBudget 생성하는 기능 추가

Harubee/Sources/Domain/UseCases/Impls/BudgetUseCaseImpl.swift

@@ -95,6 +95,13 @@ final class BudgetUseCaseImpl: BudgetUseCase {
     // 8. Repository에 저장하기
     salaryBudgetRepository.create(salaryBudget)
 
+    // 9. 필요하다면 다음달의 salaryBudget 생성
+    do {
+      try createSalaryBudgetIfNeeded(salaryBudget: salaryBudget)
+    } catch {
+      print(error)
+    }
+
     return salaryBudget
   }
 
@@ -167,9 +174,90 @@ final class BudgetUseCaseImpl: BudgetUseCase {
     // 9. Repository에 저장하기
     salaryBudgetRepository.create(salaryBudget)
 
+    // 10. 필요하다면 다음달의 salaryBudget 생성
+    do {
+      try createSalaryBudgetIfNeeded(salaryBudget: salaryBudget)
+    } catch {
+      print(error)
+    }
+
     return salaryBudget
   }
 
+  func createSalaryBudgetIfNeeded(salaryBudget: SalaryBudget) throws {
+    // 1. 모든 SalaryBudget 가져오기
+    let salaryBudgets = try salaryBudgetRepository.readAll()
+
+    // 2. 이후에 SalaryBudget이 있다면 return
+    guard !salaryBudgets.contains(
+      where: { $0.startDate > salaryBudget.startDate }
+    ) else { return }
+
+    // 3. 기존 startDate, endDate 기준으로 다음달의 날짜 계산하기
+    let nextStartDate = calendar.date(
+      byAdding: .month, value: 1, to: salaryBudget.startDate
+    )!
+    let nextEndDate = calendar.date(
+      byAdding: .month, value: 1, to: salaryBudget.endDate
+    )!
+
+    // 4. 일 수 계산
+    let days = calendar.dateComponents(
+      [.day],
+      from: nextStartDate,
+      to: nextEndDate
+    ).day ?? 0
+
+    // 5. dailyBudget 생성
+    let nextDailyBudgets = (0...days).compactMap { day -> DailyBudget? in
+      guard let date = calendar.date(
+        byAdding: .day,
+        value: day,
+        to: nextStartDate
+      ) else { return nil }
+
+      return DailyBudget(
+        id: UUID().uuidString,
+        date: date,
+        harubee: nil,
+        memo: [],
+        expense: nil,
+        income: nil
+      )
+    }
+
+    // 6. initalBalance 계산
+    let totalExpense = salaryBudget.fixedExpenses.reduce(0) { $0 + $1.price }
+    let initalBalance = salaryBudget.fixedIncome - totalExpense
+
+    let newFixedExpenses = salaryBudget.fixedExpenses.map {
+      let date = $0.date.day.convertDateBetweenStartAndEnd(
+        start: nextStartDate,
+        end: nextEndDate
+      )
+      return TransactionItem(date: date, name: $0.name, price: $0.price)
+    }
+
+    // 7. 새로운 기본 하루비 계산
+    let nextDefaultHarubee = Double(initalBalance) / Double(days + 1)
+
+    // 8. nextSalaryBudget 생성
+    let nextSalaryBudget = SalaryBudget(
+      id: UUID().uuidString,
+      startDate: nextStartDate,
+      endDate: nextEndDate,
+      fixedIncome: salaryBudget.fixedIncome,
+      fixedExpenses: newFixedExpenses,
+      balance: initalBalance,
+      defaultHarubee: nextDefaultHarubee,
+      dailyBudgets: nextDailyBudgets
+    )
+
+
+    // 9. 저장하기
+    salaryBudgetRepository.create(nextSalaryBudget)
+  }
+
   func getAllSalaryBudget() throws -> [SalaryBudget] {
     return try salaryBudgetRepository.readAll()
   }
@@ -249,14 +337,18 @@ final class BudgetUseCaseImpl: BudgetUseCase {
   ) throws -> SalaryBudget {
 
     // 1. 새로운 잔액 = oldBalance - (기존 월급 - 새로운 월급)
+    let totalFixedExpense = salaryBudget.fixedExpenses.reduce(0) {
+      $0 + $1.price
+    }
     let newBalance = salaryBudget.balance - (salaryBudget.fixedIncome - newIncome)
+    let nextNewBalance = newIncome - totalFixedExpense
 
     // 2. 잔액이 음수가 되는지 체크하기
-    guard newBalance >= 0 else {
+    guard newBalance >= 0, nextNewBalance >= 0 else {
       throw DomainError.invalidAmount
     }
 
-    // 5. 기본 하루비 다시 계산하기
+    // 3. 현재 기본 하루비 다시 계산하기
     let defaultHarubee = self.calculateDefaultHarubee(
       salaryBudget: SalaryBudget(
         startDate: salaryBudget.startDate,
@@ -270,7 +362,37 @@ final class BudgetUseCaseImpl: BudgetUseCase {
       anchorDate: .now
     )
 
-    // 6. Repository 통해 저장하기
+    // 4. 현재 SalaryBudget 이후에 SalaryBudgets 가져오기
+    let salaryBudgets = try salaryBudgetRepository.readAll()
+    let afterSalaryBudgets = salaryBudgets.filter {
+      $0.startDate > salaryBudget.startDate
+    }
+
+    for salaryBudget in afterSalaryBudgets {
+      // 5. 기본 하루비 계산
+      let defaultHarubee = self.calculateDefaultHarubee(
+        salaryBudget: SalaryBudget(
+          startDate: salaryBudget.startDate,
+          endDate: salaryBudget.endDate,
+          fixedIncome: newIncome,
+          fixedExpenses: salaryBudget.fixedExpenses,
+          balance: nextNewBalance,
+          defaultHarubee: salaryBudget.defaultHarubee,
+          dailyBudgets: salaryBudget.dailyBudgets
+        ),
+        anchorDate: .now
+      )
+
+      // 6. 반영된 수입과 잔액, 기본하루비 업데이트
+      try salaryBudgetRepository.updateSalaryBudget(
+          salaryBudget.id,
+          fixedIncome: .set(newIncome),
+          fixedExpenses: .keep,
+          balance: .set(nextNewBalance),
+          defaultHarubee: .set(defaultHarubee)
+        )
+    }
+
     do {
       return try salaryBudgetRepository.updateSalaryBudget(
         salaryBudget.id,
@@ -291,6 +413,9 @@ final class BudgetUseCaseImpl: BudgetUseCase {
 
     let today = Date().formattedDate
 
+    // 0. 총 고정지출의 합계
+    let totalExpenses = expenses.reduce(0) { $0 + $1.price }
+
     // 1. 기존 오늘 날짜 이후의 고정 지출의 합계
     let oldPostTodayTotalExpenses = salaryBudget.fixedExpenses
       .filter{ $0.date > today }
@@ -302,9 +427,10 @@ final class BudgetUseCaseImpl: BudgetUseCase {
 
     // 3. 잔액에 반영
     let newBalance = salaryBudget.balance - postTodayDifference
+    let nextNewBalance = salaryBudget.fixedIncome - totalExpenses
 
     // 4. 잔액이 음수가 되는지 체크하기
-    guard newBalance >= 0 else {
+    guard newBalance >= 0, nextNewBalance >= 0 else {
       throw DomainError.invalidAmount
     }
 
@@ -322,7 +448,47 @@ final class BudgetUseCaseImpl: BudgetUseCase {
       anchorDate: .now
     )
 
-    // 6. Repository 통해 저장하기
+    // 6. 현재 SalaryBudget 이후에 SalaryBudgets 가져오기
+    let salaryBudgets = try salaryBudgetRepository.readAll()
+    let afterSalaryBudgets = salaryBudgets.filter {
+      $0.startDate > salaryBudget.startDate
+    }
+
+    for salaryBudget in afterSalaryBudgets {
+
+      let newFixedExpenses = expenses.map {
+        let date = $0.date.day.convertDateBetweenStartAndEnd(
+          start: salaryBudget.startDate,
+          end: salaryBudget.endDate
+        )
+        return TransactionItem(date: date, name: $0.name, price: $0.price)
+      }
+
+      // 7. 기본 하루비 계산
+      let defaultHarubee = self.calculateDefaultHarubee(
+        salaryBudget: SalaryBudget(
+          startDate: salaryBudget.startDate,
+          endDate: salaryBudget.endDate,
+          fixedIncome: salaryBudget.fixedIncome,
+          fixedExpenses: newFixedExpenses,
+          balance: nextNewBalance,
+          defaultHarubee: salaryBudget.defaultHarubee,
+          dailyBudgets: salaryBudget.dailyBudgets
+        ),
+        anchorDate: .now
+      )
+
+      // 8. 반영된 수입과 잔액, 기본하루비 업데이트
+      try salaryBudgetRepository.updateSalaryBudget(
+          salaryBudget.id,
+          fixedIncome: .keep,
+          fixedExpenses: .set(newFixedExpenses),
+          balance: .set(nextNewBalance),
+          defaultHarubee: .set(defaultHarubee)
+        )
+    }
+
+    // 9. Repository 통해 저장하기
     do {
       return try salaryBudgetRepository.updateSalaryBudget(
         salaryBudget.id,
@@ -501,10 +667,21 @@ final class BudgetUseCaseImpl: BudgetUseCase {
 
     let (startDate, endDate) = Date.calculateStartAndEndDate(from: day)
 
-    // 4.  기존 salaryBudget 삭제하기
+    // 4. 기존 salaryBudget 삭제하기
     try salaryBudgetRepository.deleteById(salaryBudget.id)
 
-    // 5. 새로운 SalaryBudget 생성
+    // 5. 현재 salaryBudgte 이후에 salaryBudget 가져오기
+    let salaryBudgets = try salaryBudgetRepository.readAll()
+    let afterSalaryBudgets = salaryBudgets.filter {
+      $0.startDate > salaryBudget.startDate
+    }
+
+    // 6. 아이디 찾아서 삭제하기
+    for salaryBudget in afterSalaryBudgets {
+      try salaryBudgetRepository.deleteById(salaryBudget.id)
+    }
+
+    // 7. 새로운 SalaryBudget 생성
     return try self.createSalaryBudget(
       startDate: startDate,
       endDate: endDate,

Harubee/Sources/Domain/UseCases/Interfaces/BudgetUseCase.swift

@@ -35,6 +35,11 @@ protocol BudgetUseCase {
     fixedExpenses: [TransactionItem]
   ) throws -> SalaryBudget
 
+  /// 다음 salaryBudget이 없다면, 생성합니다.
+  /// - Parameter salaryBudget: 초기 생성시에 사용했던 SalaryBudget
+  func createSalaryBudgetIfNeeded(
+    salaryBudget: SalaryBudget
+  ) throws
 
   /// 모든 SalaryBudget을 가져옵니다.
   /// - Returns: 저장된 모든 SalaryBudget

Harubee/Sources/Presentation/Today/ViewModels/TodayViewModel.swift

@@ -64,18 +64,21 @@ extension TodayViewModel {
         date: state.todayDate
       )
 
+      // 2. 다음달의 SalaryBudget이 없다면 생성합니다.
+      try budgetUseCase.createSalaryBudgetIfNeeded(salaryBudget: salaryBudget)
+
       initializeState(salaryBudget: salaryBudget)
 
     } catch DomainError.dataNotFound {
 
-      // 2. 없다면 가장 최근 SalaryBudget을 기반으로 새 SalaryBudget 생성
+      // 3. 없다면 가장 최근 SalaryBudget을 기반으로 새 SalaryBudget 생성
       let salaryBudgets = try? budgetUseCase.getAllSalaryBudget()
 
       guard let recentSalaryBudget = salaryBudgets?.max(
         by: { $0.endDate < $1.endDate }
       ) else { return }
 
-      // 3. 새로운 시작일과 종료일 계산
+      // 4. 새로운 시작일과 종료일 계산
       let (newStartDate, newEndDate) = calculateNewSalaryBudgetDates(
         referenceStartDay: Calendar.current.component(
           .day,