Properly show upcoming payments in widget same as in the app

app/src/main/kotlin/de/dbauer/expensetracker/widget/UpcomingPaymentsWidgetModel.kt

@@ -1,69 +1,46 @@
 package de.dbauer.expensetracker.widget
 
 import androidx.compose.runtime.mutableStateListOf
-import de.dbauer.expensetracker.shared.data.Recurrence
-import de.dbauer.expensetracker.shared.data.RecurringExpenseData
 import de.dbauer.expensetracker.shared.data.UpcomingPaymentData
-import de.dbauer.expensetracker.shared.model.DateTimeCalculator
+import de.dbauer.expensetracker.shared.model.UpcomingPaymentsExpander
 import de.dbauer.expensetracker.shared.model.database.IExpenseRepository
-import de.dbauer.expensetracker.shared.toLocaleString
-import kotlinx.datetime.DateTimeUnit
-import kotlinx.datetime.LocalDate
+import de.dbauer.expensetracker.shared.model.datastore.IUserPreferencesRepository
+import kotlinx.coroutines.flow.combine
+import kotlinx.datetime.DatePeriod
 import kotlinx.datetime.TimeZone
-import kotlinx.datetime.atStartOfDayIn
-import kotlin.time.Instant
+import kotlinx.datetime.plus
+import kotlinx.datetime.toLocalDateTime
+import kotlin.time.Clock
 
 class UpcomingPaymentsWidgetModel(
     private val expenseRepository: IExpenseRepository,
+    private val userPreferencesRepository: IUserPreferencesRepository,
 ) {
     private val _upcomingPaymentsData = mutableStateListOf<UpcomingPaymentData>()
     val upcomingPaymentsData: List<UpcomingPaymentData>
         get() = _upcomingPaymentsData
 
     suspend fun init() {
-        expenseRepository.allRecurringExpensesByPrice.collect { recurringExpenses ->
-            onDatabaseUpdated(recurringExpenses)
-        }
-    }
-
-    private fun onDatabaseUpdated(recurringExpenses: List<RecurringExpenseData>) {
-        _upcomingPaymentsData.clear()
-        recurringExpenses.forEach { expense ->
-            expense.firstPayment?.let { firstPayment ->
-                val nextPaymentDay =
-                    getNextPaymentDay(firstPayment, expense.everyXRecurrence, expense.recurrence)
-                val nextPaymentRemainingDays = DateTimeCalculator.getDaysFromNowUntil(nextPaymentDay)
-                val nextPaymentDate = nextPaymentDay.atStartOfDayIn(TimeZone.UTC).toLocaleString()
-                _upcomingPaymentsData.add(
-                    UpcomingPaymentData(
-                        id = expense.id,
-                        name = expense.name,
-                        price = expense.price,
-                        nextPaymentRemainingDays = nextPaymentRemainingDays,
-                        nextPaymentDate = nextPaymentDate,
-                        tags = expense.tags,
-                    ),
-                )
+        combine(
+            expenseRepository.allRecurringExpensesByPrice,
+            userPreferencesRepository.upcomingPaymentHorizonMonths.get(),
+        ) { expenses, horizonMonths -> expenses to horizonMonths }
+            .collect { (recurringExpenses, horizonMonths) ->
+                val from =
+                    Clock.System
+                        .now()
+                        .toLocalDateTime(TimeZone.currentSystemDefault())
+                        .date
+                val until = from.plus(DatePeriod(months = horizonMonths))
+                val payments =
+                    UpcomingPaymentsExpander.collectFuturePayments(
+                        expenseRepository = expenseRepository,
+                        recurringExpenses = recurringExpenses,
+                        from = from,
+                        until = until,
+                    )
+                _upcomingPaymentsData.clear()
+                _upcomingPaymentsData.addAll(payments)
             }
-        }
-        _upcomingPaymentsData.sortBy { it.nextPaymentRemainingDays }
-    }
-
-    private fun getNextPaymentDay(
-        firstPayment: Instant,
-        everyXRecurrence: Int,
-        recurrence: Recurrence,
-    ): LocalDate {
-        return DateTimeCalculator.getDayOfNextOccurrenceFromNow(
-            from = firstPayment,
-            everyXRecurrence = everyXRecurrence,
-            recurrence =
-                when (recurrence) {
-                    Recurrence.Daily -> DateTimeUnit.DAY
-                    Recurrence.Weekly -> DateTimeUnit.WEEK
-                    Recurrence.Monthly -> DateTimeUnit.MONTH
-                    Recurrence.Yearly -> DateTimeUnit.YEAR
-                },
-        )
     }
 }