fix: turn the screen on when an alarm or timer goes off

SystemUI launches a full-screen intent only when a notification is first
posted, never on an update. The alarm service went foreground with a
placeholder that had none and added it in the update, so a locked phone
could ring behind a black screen. The placeholder now carries it.

Timers had no full-screen screen at all. A finished timer now opens
TimerRingActivity over the lock screen with Stop and +1 min, posted
under a second notification id so the expiry is a fresh post. It only
does so while the timer is sounding, so it never covers a ringing
alarm's screen or wakes the display for an already auto-silenced timer.

Fixes #15

app/src/test/java/de/jeanlucmakiola/clockula/ui/ring/TimerRingViewModelTest.kt

@@ -0,0 +1,134 @@
+package de.jeanlucmakiola.clockula.ui.ring
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.clockula.domain.TimerState
+import de.jeanlucmakiola.clockula.domain.timer.TimerRing
+import de.jeanlucmakiola.clockula.testing.MainDispatcherExtension
+import de.jeanlucmakiola.clockula.testing.T0
+import de.jeanlucmakiola.clockula.testing.TimerEngineHarness
+import de.jeanlucmakiola.clockula.testing.expiredTimer
+import de.jeanlucmakiola.clockula.testing.runningTimerWith
+import de.jeanlucmakiola.clockula.testing.timerEngineHarness
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.runTest
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.RegisterExtension
+import org.junit.jupiter.api.io.TempDir
+import java.nio.file.Path
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+
+/**
+ * The timer ring screen over the **real** timer engine: which timer it speaks
+ * for, that its buttons are the notification's verbs, and that it closes
+ * whenever the ring ends — including the auto-silence that leaves rows EXPIRED.
+ */
+class TimerRingViewModelTest {
+
+    @JvmField
+    @RegisterExtension
+    val main = MainDispatcherExtension()
+
+    /** Subscribed for the whole test, as the visible screen is: the state is shared while observed. */
+    private fun TestScope.viewModel(harness: TimerEngineHarness) = TimerRingViewModel(
+        timers = harness.timers,
+        ringState = harness.ringState,
+        engine = harness.engine,
+        elapsed = harness.elapsed,
+        wall = harness.wallClock,
+        ticker = harness.ticker,
+    ).also { viewModel -> backgroundScope.launch { viewModel.state.collect {} } }
+
+    @Test
+    fun `an expired timer rings, with the other expired ones counted`(@TempDir tempDir: Path) =
+        runTest(main.dispatcher) {
+            val harness = timerEngineHarness(tempDir)
+            harness.given(expiredTimer(id = 1L, label = "Pasta", sortOrder = 0))
+            harness.given(expiredTimer(id = 2L, label = "Eggs", sortOrder = 1))
+
+            val viewModel = viewModel(harness)
+            advanceUntilIdle()
+
+            assertThat(viewModel.state.value)
+                .isEqualTo(TimerRingUiState.Ringing(timerId = 1L, label = "Pasta", otherExpired = 1))
+        }
+
+    @Test
+    fun `nothing expired finishes the screen`(@TempDir tempDir: Path) = runTest(main.dispatcher) {
+        val harness = timerEngineHarness(tempDir)
+        harness.given(runningTimerWith(id = 1L, left = 3.minutes, elapsedNow = harness.elapsed.value))
+
+        val viewModel = viewModel(harness)
+        advanceUntilIdle()
+
+        assertThat(viewModel.state.value).isEqualTo(TimerRingUiState.Finished)
+    }
+
+    @Test
+    fun `stop resets the timer and the screen moves on to the next expired one`(@TempDir tempDir: Path) =
+        runTest(main.dispatcher) {
+            val harness = timerEngineHarness(tempDir)
+            harness.given(expiredTimer(id = 1L, label = "Pasta", sortOrder = 0))
+            harness.given(expiredTimer(id = 2L, label = "Eggs", sortOrder = 1))
+            val viewModel = viewModel(harness)
+            advanceUntilIdle()
+
+            viewModel.onStop()
+            advanceUntilIdle()
+
+            assertThat(harness.stored(1L)!!.state).isEqualTo(TimerState.IDLE)
+            assertThat(viewModel.state.value)
+                .isEqualTo(TimerRingUiState.Ringing(timerId = 2L, label = "Eggs", otherExpired = 0))
+        }
+
+    @Test
+    fun `stop leaves a timer that is running again alone`(@TempDir tempDir: Path) =
+        runTest(main.dispatcher) {
+            val harness = timerEngineHarness(tempDir)
+            harness.given(expiredTimer(id = 1L))
+            val viewModel = viewModel(harness)
+            advanceUntilIdle()
+
+            // "+1 min" from the shade lands before the screen has re-read the rows.
+            harness.engine.addTime(1L)
+            viewModel.onStop()
+            advanceUntilIdle()
+
+            assertThat(harness.stored(1L)!!.state).isEqualTo(TimerState.RUNNING)
+        }
+
+    @Test
+    fun `plus one minute runs the timer again and finishes the screen`(@TempDir tempDir: Path) =
+        runTest(main.dispatcher) {
+            val harness = timerEngineHarness(tempDir)
+            harness.given(expiredTimer(id = 1L))
+            val viewModel = viewModel(harness)
+            advanceUntilIdle()
+
+            viewModel.onAddMinute()
+            advanceUntilIdle()
+
+            assertThat(harness.stored(1L)!!.state).isEqualTo(TimerState.RUNNING)
+            assertThat(viewModel.state.value).isEqualTo(TimerRingUiState.Finished)
+        }
+
+    @Test
+    fun `an auto-silenced ring finishes the screen though the row stays expired`(@TempDir tempDir: Path) =
+        runTest(main.dispatcher) {
+            val harness = timerEngineHarness(tempDir)
+            harness.given(expiredTimer(id = 1L))
+            harness.ringState.set(T0)
+            val viewModel = viewModel(harness)
+            advanceUntilIdle()
+            assertThat(viewModel.state.value).isInstanceOf(TimerRingUiState.Ringing::class.java)
+
+            harness.wallClock.advance(TimerRing.AUTO_SILENCE_AFTER + 1.seconds)
+            harness.ticker.tick()
+            advanceUntilIdle()
+
+            assertThat(harness.stored(1L)!!.state).isEqualTo(TimerState.EXPIRED)
+            assertThat(viewModel.state.value).isEqualTo(TimerRingUiState.Finished)
+        }
+}