show disc headings in multi-disc album track lists

app/src/main/kotlin/com/subtracks/ui/library/AlbumDetailScreen.kt

@@ -1,11 +1,14 @@
 package com.subtracks.ui.library
 
 import androidx.compose.foundation.clickable
-import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.subtracks.data.model.Album
 import com.subtracks.data.model.CoverArtRef
@@ -64,6 +67,7 @@ fun AlbumDetailScreen(
     playingSongId: String? = null,
     modifier: Modifier = Modifier,
 ) {
+    val multiDisc = songs.map { it.disc ?: 1L }.distinct().size > 1
     HeroDetailScaffold(
         artwork = artwork,
         title = album?.name.orEmpty(),
@@ -88,14 +92,32 @@ fun AlbumDetailScreen(
             )
         },
         content = { rowModifier ->
-            itemsIndexed(songs, key = { _, song -> song.id }) { index, song ->
-                SongRow(
-                    song = song,
-                    isPlaying = song.id == playingSongId,
-                    modifier = rowModifier.clickable { onSongClick(index) },
-                )
+            var lastDisc: Long? = null
+            songs.forEachIndexed { index, song ->
+                val disc = song.disc ?: 1L
+                if (multiDisc && disc != lastDisc) {
+                    item(key = "disc:$disc") { DiscHeader(disc) }
+                }
+                lastDisc = disc
+                item(key = song.id) {
+                    SongRow(
+                        song = song,
+                        isPlaying = song.id == playingSongId,
+                        modifier = rowModifier.clickable { onSongClick(index) },
+                    )
+                }
             }
         },
         modifier = modifier,
     )
 }
+
+@Composable
+private fun DiscHeader(disc: Long) {
+    Text(
+        text = "Disc $disc",
+        style = MaterialTheme.typography.titleSmall,
+        color = MaterialTheme.colorScheme.onSurfaceVariant,
+        modifier = Modifier.padding(start = 16.dp, end = 16.dp, top = 20.dp, bottom = 4.dp),
+    )
+}

app/src/test/kotlin/com/subtracks/ui/AlbumDiscsTest.kt

@@ -0,0 +1,101 @@
+package com.subtracks.ui
+
+import androidx.activity.ComponentActivity
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.junit4.v2.createAndroidComposeRule
+import androidx.compose.ui.test.onAllNodesWithText
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.github.takahirom.roborazzi.RobolectricDeviceQualifiers
+import com.subtracks.data.model.Album
+import com.subtracks.data.model.Song
+import com.subtracks.ui.library.AlbumDetailScreen
+import com.subtracks.ui.theme.SubtracksTheme
+import org.junit.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.annotation.Config
+import org.robolectric.annotation.GraphicsMode
+
+@RunWith(AndroidJUnit4::class)
+@GraphicsMode(GraphicsMode.Mode.NATIVE)
+@Config(qualifiers = RobolectricDeviceQualifiers.PixelXL)
+class AlbumDiscsTest {
+    @get:Rule
+    val composeRule = createAndroidComposeRule<ComponentActivity>()
+
+    @Test
+    fun multiDiscAlbumShowsDiscHeaders() {
+        setContent(listOf(song("s-a", disc = 1, track = 1), song("s-b", disc = 1, track = 2), song("s-c", disc = 2, track = 1)))
+        assertEquals(1, nodesWithText("Disc 1"))
+        assertEquals(1, nodesWithText("Disc 2"))
+    }
+
+    @Test
+    fun singleDiscAlbumShowsNoDiscHeaders() {
+        setContent(listOf(song("s-a", disc = 1, track = 1), song("s-b", disc = 1, track = 2)))
+        assertEquals(0, nodesWithText("Disc 1"))
+    }
+
+    @Test
+    fun discHeadersAreHiddenWhenDiscsAreMissing() {
+        setContent(listOf(song("s-a", disc = null, track = 1), song("s-b", disc = null, track = 2)))
+        assertEquals(0, nodesWithText("Disc 1"))
+    }
+
+    private fun setContent(songs: List<Song>) {
+        composeRule.setContent {
+            SubtracksTheme {
+                AlbumDetailScreen(
+                    album = album(),
+                    songs = songs,
+                    coverArt = { _, _ -> null },
+                    artwork = null,
+                    onBack = {},
+                    onSongClick = {},
+                    modifier = Modifier.fillMaxSize(),
+                )
+            }
+        }
+        composeRule.waitUntil(timeoutMillis = 5_000) { nodesWithText(songs.first().title) == 1 }
+    }
+
+    private fun nodesWithText(text: String) = composeRule.onAllNodesWithText(text).fetchSemanticsNodes().size
+
+    private fun song(
+        id: String,
+        disc: Long?,
+        track: Long,
+    ) = Song(
+        sourceId = 1,
+        id = id,
+        albumId = "al-1",
+        artistId = "ar-1",
+        title = "Song $id",
+        album = "Album",
+        artist = "Artist",
+        duration = 200,
+        track = track,
+        disc = disc,
+        starred = null,
+        genre = null,
+    )
+
+    private fun album() =
+        Album(
+            sourceId = 1,
+            id = "al-1",
+            artistId = "ar-1",
+            name = "Album",
+            albumArtist = "Artist",
+            created = 0,
+            coverArt = null,
+            genre = null,
+            year = null,
+            starred = null,
+            songCount = 3,
+            frequentRank = null,
+            recentRank = null,
+        )
+}

app/src/test/kotlin/com/subtracks/ui/AppScreenshotTest.kt

@@ -15,6 +15,8 @@ import androidx.compose.ui.test.junit4.v2.createAndroidComposeRule
 import androidx.compose.ui.test.onAllNodesWithTag
 import androidx.compose.ui.test.onAllNodesWithText
 import androidx.compose.ui.test.onRoot
+import androidx.compose.ui.test.performTouchInput
+import androidx.compose.ui.test.swipeUp
 import androidx.paging.PagingData
 import androidx.paging.compose.collectAsLazyPagingItems
 import androidx.test.core.app.ApplicationProvider
@@ -155,6 +157,36 @@ class AppScreenshotTest {
         composeRule.onRoot().captureRoboImage("src/test/screenshots/album_detail_cool.png")
     }
 
+    @Test
+    fun albumDetailMultiDisc() {
+        val songs =
+            listOf(
+                Fixtures.song("s-eiirp", "al-kid-a", "ar-radiohead", "Everything In Its Right Place", "Kid A", "Radiohead", 1, 251),
+                Fixtures.song("s-kid-a", "al-kid-a", "ar-radiohead", "Kid A", "Kid A", "Radiohead", 2, 274),
+                Fixtures.song("s-anthem", "al-kid-a", "ar-radiohead", "The National Anthem", "Kid A", "Radiohead", 1, 351, disc = 2),
+                Fixtures.song("s-htdc", "al-kid-a", "ar-radiohead", "How to Disappear Completely", "Kid A", "Radiohead", 2, 356, disc = 2),
+            )
+        composeRule.setContent {
+            SubtracksTheme {
+                AlbumDetailScreen(
+                    album = Fixtures.albums.first(),
+                    songs = songs,
+                    coverArt = { id, _ -> id?.let { CoverArtRef(it, "test:$it") } },
+                    artwork = artworkColorsFromSeed(Color.rgb(120, 80, 200)),
+                    onBack = {},
+                    onSongClick = {},
+                    modifier = Modifier.fillMaxSize(),
+                )
+            }
+        }
+        awaitText("Everything In Its Right Place")
+        composeRule.onRoot().performTouchInput { swipeUp(startY = centerY + 600f, endY = centerY - 600f, durationMillis = 400) }
+        composeRule.waitUntil(timeoutMillis = 5_000) {
+            composeRule.onAllNodesWithText("Disc 2").fetchSemanticsNodes().isNotEmpty()
+        }
+        composeRule.onRoot().captureRoboImage("src/test/screenshots/album_detail_multidisc.png")
+    }
+
     @Test
     fun artistDetail() {
         composeRule.setContent {
@@ -489,7 +521,7 @@ private object Fixtures {
         recentRank = null,
     )
 
-    private fun song(
+    fun song(
         id: String,
         albumId: String,
         artistId: String,
@@ -498,6 +530,7 @@ private object Fixtures {
         artist: String,
         track: Long,
         duration: Long,
+        disc: Long? = 1,
     ) = Song(
         sourceId = 1,
         id = id,
@@ -508,7 +541,7 @@ private object Fixtures {
         artist = artist,
         duration = duration,
         track = track,
-        disc = 1,
+        disc = disc,
         starred = null,
         genre = null,
     )