feat(android,ios): play from Downloads, and say what a download waits for

- A finished download row on the phones plays when tapped and has an
  Open button for its title, as the desktop's does.
- iOS queued downloads say "Waiting for Wi-Fi" or "Waiting for a
  connection", as Android's already do.
- Android download workers post their notifications as one group, each
  named for its episode, under a "Downloading 12 episodes" summary.
  Before, a season made fourteen loose notifications that all said
  "Making episode available offline".

android/app/src/main/java/io/narl/protonstream/download/OfflineDownloadWorker.kt

@@ -1,11 +1,15 @@
 package io.narl.protonstream.download
 
+import android.Manifest
 import android.app.NotificationChannel
 import android.app.NotificationManager
+import android.content.pm.PackageManager
 import android.content.pm.ServiceInfo
 import android.content.Context
+import android.os.Build
 import android.os.SystemClock
 import androidx.core.app.NotificationCompat
+import androidx.core.content.ContextCompat
 import androidx.work.CoroutineWorker
 import androidx.work.Data
 import androidx.work.ForegroundInfo
@@ -25,12 +29,27 @@ class OfflineDownloadWorker(
 ) : CoroutineWorker(appContext, parameters) {
     override suspend fun doWork(): Result {
         createNotificationChannel()
-        setForeground(createForegroundInfo(null))
         val shareId = inputData.getString(KEY_SHARE_ID) ?: return Result.failure(error("missing share"))
         val volumeId = inputData.getString(KEY_VOLUME_ID) ?: return Result.failure(error("missing volume"))
         val linkId = inputData.getString(KEY_LINK_ID) ?: return Result.failure(error("missing link"))
         val label = inputData.getString(KEY_LABEL) ?: linkId
         val store = DownloadStateStore(applicationContext)
+        setForeground(createForegroundInfo(label, null))
+        postSummary(store)
+        try {
+            return transfer(store, shareId, volumeId, linkId, label)
+        } finally {
+            postSummary(store)
+        }
+    }
+
+    private suspend fun transfer(
+        store: DownloadStateStore,
+        shareId: String,
+        volumeId: String,
+        linkId: String,
+        label: String,
+    ): Result {
         // Queued, not running: the engine lets two downloads transfer at once
         // and holds the rest back, and only the first progress report means
         // this one has a slot.
@@ -62,7 +81,7 @@ class OfflineDownloadWorker(
                 reportedAt = now
                 reportedPercent = percent
                 setProgressAsync(workDataOf(KEY_DOWNLOADED to downloaded.toLong(), KEY_TOTAL to total.toLong()))
-                setForegroundAsync(createForegroundInfo(percent))
+                setForegroundAsync(createForegroundInfo(label, percent))
                 // Under the store's lock: `pause()` is a concurrent writer, and
                 // this read-modify-write used to put RUNNING back over the
                 // viewer's PAUSED and then report the download as cancelled.
@@ -120,15 +139,20 @@ class OfflineDownloadWorker(
         )
     }
 
-    /** [progress] is a percentage, or null while waiting for a download slot. */
-    private fun createForegroundInfo(progress: Int?): ForegroundInfo {
+    /**
+     * This episode's line, under [GROUP]: a season is fourteen workers, and
+     * fourteen loose notifications saying the same thing named nothing.
+     * [progress] is a percentage, or null while waiting for a download slot.
+     */
+    private fun createForegroundInfo(label: String, progress: Int?): ForegroundInfo {
         val notification = NotificationCompat.Builder(applicationContext, CHANNEL_ID)
             .setSmallIcon(io.narl.protonstream.R.drawable.ic_launcher_foreground)
-            .setContentTitle(
-                if (progress == null) "Waiting to download" else "Making episode available offline",
-            )
+            .setContentTitle(label)
+            .setContentText(if (progress == null) "Waiting to download" else "$progress %")
             .setProgress(100, progress ?: 0, progress == null || progress == 0)
             .setOngoing(true)
+            .setOnlyAlertOnce(true)
+            .setGroup(GROUP)
             .build()
         return ForegroundInfo(
             stableNotificationId(id),
@@ -137,6 +161,36 @@ class OfflineDownloadWorker(
         )
     }
 
+    /**
+     * The one line the group folds into — "Downloading 12 episodes" — or none
+     * once nothing is left to download. Posted as each worker starts and
+     * ends rather than on progress, which each episode's own line carries.
+     */
+    private fun postSummary(store: DownloadStateStore) {
+        val manager = applicationContext.getSystemService(NotificationManager::class.java)
+        val left = store.records().count {
+            it.status == RetainedDownload.STATUS_QUEUED || it.status == RetainedDownload.STATUS_RUNNING
+        }
+        if (left == 0) {
+            manager.cancel(SUMMARY_ID)
+            return
+        }
+        val allowed = Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU ||
+            ContextCompat.checkSelfPermission(applicationContext, Manifest.permission.POST_NOTIFICATIONS) ==
+            PackageManager.PERMISSION_GRANTED
+        if (!allowed) return
+        manager.notify(
+            SUMMARY_ID,
+            NotificationCompat.Builder(applicationContext, CHANNEL_ID)
+                .setSmallIcon(io.narl.protonstream.R.drawable.ic_launcher_foreground)
+                .setContentTitle(if (left == 1) "Downloading 1 episode" else "Downloading $left episodes")
+                .setOnlyAlertOnce(true)
+                .setGroup(GROUP)
+                .setGroupSummary(true)
+                .build(),
+        )
+    }
+
     private fun error(message: String) = Data.Builder().putString(KEY_ERROR, message).build()
 
     companion object {
@@ -149,6 +203,10 @@ class OfflineDownloadWorker(
         const val KEY_TOTAL = "total"
         private const val MAX_RETRIES = 3
         private const val CHANNEL_ID = "offline-downloads"
+        private const val GROUP = "offline-downloads"
+
+        /** Below [stableNotificationId]'s range, so no episode's line replaces it. */
+        internal const val SUMMARY_ID = 1
 
         /** Shortest gap between two identical-looking progress reports. */
         private const val PROGRESS_INTERVAL_MS = 1_000L
@@ -186,4 +244,4 @@ internal class TransferRate {
 }
 
 internal fun stableNotificationId(workId: UUID): Int =
-    (workId.hashCode() and Int.MAX_VALUE).coerceAtLeast(1)
+    (workId.hashCode() and Int.MAX_VALUE).coerceAtLeast(OfflineDownloadWorker.SUMMARY_ID + 1)

android/app/src/main/java/io/narl/protonstream/ui/DownloadsScreen.kt

@@ -3,6 +3,7 @@ package io.narl.protonstream.ui
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.aspectRatio
 import androidx.compose.foundation.layout.fillMaxSize
@@ -16,6 +17,7 @@ import androidx.compose.material.icons.filled.Close
 import androidx.compose.material.icons.filled.Pause
 import androidx.compose.material.icons.filled.PlayArrow
 import androidx.compose.material.icons.outlined.Delete
+import androidx.compose.material.icons.outlined.Info
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -58,6 +60,8 @@ internal fun DownloadsScreen(
     onResume: (RetainedDownload) -> Unit,
     onDeletePartial: (RetainedDownload) -> Unit,
     padding: PaddingValues,
+    onPlay: (TitleRecord, Int) -> Unit = { _, _ -> },
+    onOpen: (TitleRecord) -> Unit = {},
 ) {
     val context = LocalContext.current
     val work = WorkManager.getInstance(context).getWorkInfosByTagLiveData(DownloadCoordinator.TAG)
@@ -122,7 +126,7 @@ internal fun DownloadsScreen(
                     )
                 }
                 items(group.files, key = { "${it.shareId}/${it.linkId}" }) { file ->
-                    SavedRow(file, group.title, onDelete = { deleting = file })
+                    SavedRow(file, group.title, onDelete = { deleting = file }, onPlay = onPlay, onOpen = onOpen)
                 }
             }
         }
@@ -160,9 +164,23 @@ private fun SectionHeading(title: String, caption: String? = null) {
 
 /** A saved episode: its still, what it is, its size, and a way to remove it. */
 @Composable
-private fun SavedRow(file: OfflineRecord, title: TitleRecord?, onDelete: () -> Unit) {
+private fun SavedRow(
+    file: OfflineRecord,
+    title: TitleRecord?,
+    onDelete: () -> Unit,
+    onPlay: (TitleRecord, Int) -> Unit,
+    onOpen: (TitleRecord) -> Unit,
+) {
     val episode = file.episode
+    // What a download is for: tapping it plays it, from where it was left,
+    // without going back through the library to find it.
+    val index = title?.seasons?.flatMap(SeasonRecord::episodes)?.indexOfFirst { it.linkId == file.linkId } ?: -1
     ListItem(
+        modifier = if (title != null && index >= 0) {
+            Modifier.clickable(onClickLabel = "Play") { onPlay(title, index) }
+        } else {
+            Modifier
+        },
         leadingContent = {
             RemoteArtwork(
                 episode?.stillUrl ?: title?.backdropUrl,
@@ -179,8 +197,15 @@ private fun SavedRow(file: OfflineRecord, title: TitleRecord?, onDelete: () -> U
             Text(listOfNotNull(episode?.label, formatBytes(file.size)).joinToString(" · "))
         },
         trailingContent = {
-            IconButton(onClick = onDelete) {
-                Icon(Icons.Outlined.Delete, contentDescription = "Delete download")
+            Row {
+                title?.let {
+                    IconButton(onClick = { onOpen(it) }) {
+                        Icon(Icons.Outlined.Info, contentDescription = "Open ${it.displayName}")
+                    }
+                }
+                IconButton(onClick = onDelete) {
+                    Icon(Icons.Outlined.Delete, contentDescription = "Delete download")
+                }
             }
         },
         colors = ListItemDefaults.colors(containerColor = Color.Transparent),

android/app/src/main/java/io/narl/protonstream/ui/ProtonStreamApp.kt

@@ -329,6 +329,15 @@ fun ProtonStreamApp(
                         model::resumeDownload,
                         model::deletePartial,
                         body,
+                        onPlay = { title, index ->
+                            playingTitleKey = title.key
+                            playingIndex = index
+                            playerMinimized = false
+                        },
+                        onOpen = { title ->
+                            destination = Destination.Library
+                            selectedTitleKey = title.key
+                        },
                     )
                     Destination.Settings -> SettingsScreen(
                         state,