ui: add DebugViewModel combining calendars + next 30d instances

app/src/main/java/de/jeanlucmakiola/calendula/ui/debug/DebugUiState.kt

@@ -0,0 +1,14 @@
+package de.jeanlucmakiola.calendula.ui.debug
+
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.domain.FailureReason
+
+sealed interface DebugUiState {
+    data object Loading : DebugUiState
+    data class Failure(val reason: FailureReason) : DebugUiState
+    data class Success(
+        val calendars: List<CalendarSource>,
+        val nextEvents: List<EventInstance>,
+    ) : DebugUiState
+}

app/src/main/java/de/jeanlucmakiola/calendula/ui/debug/DebugViewModel.kt

@@ -0,0 +1,49 @@
+package de.jeanlucmakiola.calendula.ui.debug
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import de.jeanlucmakiola.calendula.data.calendar.CalendarRepository
+import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.domain.FailureReason
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.stateIn
+import kotlin.time.Duration.Companion.days
+import kotlin.time.Instant
+import javax.inject.Inject
+
+private const val MAX_DEBUG_EVENTS = 50
+private val DEBUG_WINDOW = 30.days
+
+@HiltViewModel
+class DebugViewModel @Inject constructor(
+    private val repository: CalendarRepository,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : ViewModel() {
+
+    val state: StateFlow<DebugUiState> = run {
+        val now = Instant.fromEpochMilliseconds(System.currentTimeMillis())
+        val range = now..(now + DEBUG_WINDOW)
+        combine(
+            repository.calendars(),
+            repository.instances(range),
+        ) { calendars, instances ->
+            DebugUiState.Success(
+                calendars = calendars,
+                nextEvents = instances.take(MAX_DEBUG_EVENTS),
+            ) as DebugUiState
+        }
+            .catch { emit(DebugUiState.Failure(FailureReason.ProviderUnavailable)) }
+            .flowOn(io)
+            .stateIn(
+                scope = viewModelScope,
+                started = SharingStarted.WhileSubscribed(5_000L),
+                initialValue = DebugUiState.Loading,
+            )
+    }
+}