data: add CalendarRepository + Impl with SharedFlow re-emit on data-source ticks

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/CalendarRepository.kt

@@ -0,0 +1,16 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.coroutines.flow.Flow
+import kotlin.time.Instant
+
+interface CalendarRepository {
+    fun calendars(): Flow<List<CalendarSource>>
+    fun instances(range: ClosedRange<Instant>): Flow<List<EventInstance>>
+    suspend fun eventDetail(eventId: Long): EventDetail
+}
+
+class NoSuchEventException(eventId: Long) :
+    NoSuchElementException("No event with id=$eventId")

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/CalendarRepositoryImpl.kt

@@ -0,0 +1,62 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import de.jeanlucmakiola.calendula.data.di.IoDispatcher
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.onStart
+import kotlinx.coroutines.withContext
+import kotlin.time.Instant
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * One ContentResolver-backed observer for the lifetime of the App process.
+ * Each public flow re-queries on subscribe and after every tick from the
+ * data source.
+ */
+@Singleton
+class CalendarRepositoryImpl @Inject constructor(
+    private val dataSource: CalendarDataSource,
+    @IoDispatcher private val io: CoroutineDispatcher,
+) : CalendarRepository {
+
+    private val ticks = MutableSharedFlow<Unit>(
+        replay = 0,
+        extraBufferCapacity = 1,
+    )
+
+    init {
+        dataSource.registerChangeListener { ticks.tryEmit(Unit) }
+    }
+
+    override fun calendars(): Flow<List<CalendarSource>> =
+        ticks
+            .onStart { emit(Unit) }
+            .reQuery { dataSource.calendars() }
+            .flowOn(io)
+
+    override fun instances(range: ClosedRange<Instant>): Flow<List<EventInstance>> =
+        ticks
+            .onStart { emit(Unit) }
+            .reQuery {
+                dataSource.instances(
+                    beginMillis = range.start.toEpochMillis(),
+                    endMillis = range.endInclusive.toEpochMillis(),
+                )
+            }
+            .flowOn(io)
+
+    override suspend fun eventDetail(eventId: Long): EventDetail = withContext(io) {
+        dataSource.eventDetail(eventId) ?: throw NoSuchEventException(eventId)
+    }
+}
+
+private fun <T> Flow<Unit>.reQuery(block: suspend () -> T): Flow<T> = flow {
+    collect { emit(block()) }
+}

app/src/main/java/de/jeanlucmakiola/calendula/data/di/Qualifiers.kt

@@ -0,0 +1,7 @@
+package de.jeanlucmakiola.calendula.data.di
+
+import javax.inject.Qualifier
+
+@Qualifier
+@Retention(AnnotationRetention.BINARY)
+annotation class IoDispatcher

app/src/test/java/de/jeanlucmakiola/calendula/data/calendar/CalendarRepositoryImplTest.kt

@@ -0,0 +1,111 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import app.cash.turbine.test
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.runTest
+import kotlin.time.Instant
+import org.junit.jupiter.api.Test
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class CalendarRepositoryImplTest {
+
+    private fun makeCal(id: Long, name: String = "Cal $id"): CalendarSource =
+        CalendarSource(id, name, "x@y", "LOCAL", 0xFF112233.toInt(), true)
+
+    private fun makeEvent(id: Long, title: String = "E $id"): EventInstance = EventInstance(
+        instanceId = id, eventId = id, calendarId = 1L,
+        title = title,
+        start = Instant.fromEpochMilliseconds(1_000_000_000L),
+        end = Instant.fromEpochMilliseconds(1_000_003_600L),
+        isAllDay = false, color = 0xFF000000.toInt(), location = null,
+    )
+
+    @Test
+    fun `calendars emits initial query result on subscribe`() = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(makeCal(1L), makeCal(2L))
+        }
+        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+
+        repo.calendars().test {
+            val first = awaitItem()
+            assertThat(first.map { it.id }).containsExactly(1L, 2L).inOrder()
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `calendars re-emits after change listener tick`() = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(makeCal(1L))
+        }
+        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+
+        repo.calendars().test {
+            assertThat(awaitItem().map { it.id }).containsExactly(1L)
+
+            fake.calendarsResult = listOf(makeCal(1L), makeCal(2L))
+            fake.tick()
+
+            assertThat(awaitItem().map { it.id }).containsExactly(1L, 2L).inOrder()
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `instances forwards epoch-millis bounds to data source`() = runTest {
+        var observedBegin: Long? = null
+        var observedEnd: Long? = null
+        val fake = FakeCalendarDataSource().apply {
+            instancesResult = {b, e ->
+                observedBegin = b
+                observedEnd = e
+                listOf(makeEvent(10L))
+            }
+        }
+        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+
+        val range = Instant.fromEpochMilliseconds(1_000L)..Instant.fromEpochMilliseconds(2_000L)
+        repo.instances(range).test {
+            awaitItem()
+            cancelAndIgnoreRemainingEvents()
+        }
+        assertThat(observedBegin).isEqualTo(1_000L)
+        assertThat(observedEnd).isEqualTo(2_000L)
+    }
+
+    @Test
+    fun `instances passes-through whatever the data source returns`() = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            instancesResult = {_, _ -> listOf(makeEvent(10L, "Good")) }
+        }
+        val repo = CalendarRepositoryImpl(fake, UnconfinedTestDispatcher(testScheduler))
+
+        val range = Instant.fromEpochMilliseconds(0)..Instant.fromEpochMilliseconds(10_000L)
+        repo.instances(range).test {
+            val first = awaitItem()
+            assertThat(first.map { it.title }).containsExactly("Good")
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
+    @Test
+    fun `eventDetail throws NoSuchEventException when data source returns null`() = runTest {
+        val fake = FakeCalendarDataSource().apply {
+            eventDetailResult = { null }
+        }
+        val repo = CalendarRepositoryImpl(fake, Dispatchers.Unconfined)
+
+        try {
+            repo.eventDetail(eventId = 999L)
+            error("Expected NoSuchEventException")
+        } catch (expected: NoSuchEventException) {
+            assertThat(expected.message).contains("999")
+        }
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/data/calendar/FakeCalendarDataSource.kt

@@ -0,0 +1,33 @@
+package de.jeanlucmakiola.calendula.data.calendar
+
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventInstance
+
+/**
+ * Test-only fake. Tunable via the three `var` properties; `tick()` simulates
+ * a provider change so the repository re-queries.
+ */
+internal class FakeCalendarDataSource : CalendarDataSource {
+
+    var calendarsResult: List<CalendarSource> = emptyList()
+    var instancesResult: (Long, Long) -> List<EventInstance> = { _, _ -> emptyList() }
+    var eventDetailResult: (Long) -> EventDetail? = { null }
+
+    private val listeners = mutableListOf<() -> Unit>()
+
+    override fun calendars(): List<CalendarSource> = calendarsResult
+    override fun instances(beginMillis: Long, endMillis: Long): List<EventInstance> =
+        instancesResult(beginMillis, endMillis)
+    override fun eventDetail(eventId: Long): EventDetail? = eventDetailResult(eventId)
+    override fun registerChangeListener(listener: () -> Unit) {
+        listeners += listener
+    }
+    override fun unregisterChangeListener(listener: () -> Unit) {
+        listeners -= listener
+    }
+
+    fun tick() {
+        listeners.forEach { it() }
+    }
+}