Show the selection in a contextual top bar (#141)

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/CalendarChrome.kt

@@ -1,6 +1,10 @@
 package de.jeanlucmakiola.calendula.ui.common
 
+import androidx.compose.animation.AnimatedContent
 import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.slideInVertically
+import androidx.compose.animation.slideOutVertically
+import androidx.compose.animation.togetherWith
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
 import androidx.compose.animation.scaleIn
@@ -134,8 +138,10 @@ fun PublishSelection(event: EventInstance?, busy: Boolean, compact: Boolean, onD
     }
 }
 
-/** The top bar every calendar screen shares. */
-@OptIn(ExperimentalMaterial3Api::class)
+/**
+ * The top bar every calendar screen shares — or, while an event is selected,
+ * the selection's own bar in its place (#141).
+ */
 @Composable
 fun CalendarTopBar(
     host: ChromeHost,
@@ -145,6 +151,43 @@ fun CalendarTopBar(
     onOpenDrawer: () -> Unit,
     onOpenSearch: () -> Unit,
     showTodayButton: Boolean,
+) {
+    val effects = MaterialTheme.motionScheme.fastEffectsSpec<Float>()
+    AnimatedContent(
+        targetState = host.selection,
+        contentKey = { it != null },
+        transitionSpec = {
+            (fadeIn(effects) + slideInVertically { -it / 4 })
+                .togetherWith(fadeOut(effects) + slideOutVertically { -it / 4 })
+        },
+        label = "top-bar",
+    ) { selection ->
+        if (selection != null) {
+            SelectionTopBar(selection)
+        } else {
+            ViewTopBar(
+                host = host,
+                selectedView = selectedView,
+                quickSwitchViews = quickSwitchViews,
+                onCycleView = onCycleView,
+                onOpenDrawer = onOpenDrawer,
+                onOpenSearch = onOpenSearch,
+                showTodayButton = showTodayButton,
+            )
+        }
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun ViewTopBar(
+    host: ChromeHost,
+    selectedView: CalendarView,
+    quickSwitchViews: List<CalendarView>,
+    onCycleView: () -> Unit,
+    onOpenDrawer: () -> Unit,
+    onOpenSearch: () -> Unit,
+    showTodayButton: Boolean,
 ) {
     val chrome = host.chrome
     TopAppBar(

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/SelectionTopBar.kt

@@ -0,0 +1,90 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.foundation.layout.Column
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Close
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextOverflow
+import de.jeanlucmakiola.calendula.R
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.floret.locale.currentLocale
+import de.jeanlucmakiola.floret.locale.localizedDateFormatter
+import java.time.ZoneId
+import java.util.Locale
+import kotlin.time.toJavaInstant
+
+/**
+ * The top bar while an event is selected (#141): says which, and when, with a
+ * way out — the selection otherwise only shows on the grid and in the FAB.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SelectionTopBar(selection: EventSelection) {
+    val event = selection.event
+    val use24Hour = LocalUse24HourFormat.current
+    val locale = currentLocale()
+    val whenText = remember(event.start, event.end, use24Hour, locale) {
+        formatSelectionWhen(event, use24Hour, locale)
+    }
+    TopAppBar(
+        navigationIcon = {
+            IconButton(onClick = selection.dismiss) {
+                Icon(
+                    imageVector = Icons.Default.Close,
+                    contentDescription = stringResource(R.string.event_selection_close),
+                )
+            }
+        },
+        title = {
+            Column {
+                Text(
+                    text = event.title.ifBlank { stringResource(R.string.event_untitled) },
+                    style = MaterialTheme.typography.titleMedium,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+                Text(
+                    text = whenText,
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSecondaryContainer,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+            }
+        },
+        colors = TopAppBarDefaults.topAppBarColors(
+            containerColor = MaterialTheme.colorScheme.secondaryContainer,
+            scrolledContainerColor = MaterialTheme.colorScheme.secondaryContainer,
+            navigationIconContentColor = MaterialTheme.colorScheme.onSecondaryContainer,
+            titleContentColor = MaterialTheme.colorScheme.onSecondaryContainer,
+        ),
+    )
+}
+
+/**
+ * "Fri, 9 Oct · 09:00–10:00", or with both days named for an event that runs
+ * into another: "Fri, 9 Oct, 22:00 – Sat, 10 Oct, 02:00".
+ */
+private fun formatSelectionWhen(event: EventInstance, use24Hour: Boolean, locale: Locale): String {
+    val zone = ZoneId.systemDefault()
+    val start = event.start.toJavaInstant().atZone(zone)
+    val end = event.end.toJavaInstant().atZone(zone)
+    val day = localizedDateFormatter(locale, "EEEdMMM")
+    val time = localizedDateFormatter(locale, if (use24Hour) "Hm" else "hm")
+    val endsSameDay = end.toLocalDate() == start.toLocalDate() ||
+        (end.toLocalTime().toSecondOfDay() == 0 && end.toLocalDate() == start.toLocalDate().plusDays(1))
+    return if (endsSameDay) {
+        "${day.format(start)} · ${time.format(start)}–${time.format(end)}"
+    } else {
+        "${day.format(start)}, ${time.format(start)} – ${day.format(end)}, ${time.format(end)}"
+    }
+}

app/src/main/res/values/strings.xml

@@ -101,6 +101,7 @@
     <string name="event_resize_recurring_title">Change recurring event</string>
     <string name="event_selection_actions">Event actions</string>
     <string name="event_selection_hide">Hide event actions</string>
+    <string name="event_selection_close">Deselect event</string>
     <string name="event_action_load_failed">Couldn\'t open the event</string>
     <string name="event_move_undo">Undo</string>
     <string name="event_move_undone">Move undone</string>