transaction-based music playback managing wip

src/net/torvald/terrarum/TerrarumMusicPlaylist.kt

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+package net.torvald.terrarum
+
+import com.badlogic.gdx.utils.Disposable
+import com.badlogic.gdx.utils.GdxRuntimeException
+import net.torvald.terrarum.App.printdbg
+import net.torvald.terrarum.audio.audiobank.MusicContainer
+import java.io.File
+
+/**
+ * The `musicList` never (read: should not) gets changed, only the `internalIndices` are being changed as
+ * the songs are being played.
+ *
+ * Created by minjaesong on 2024-06-29.
+ */
+class TerrarumMusicPlaylist(
+    /** list of files */
+    val musicList: List<MusicContainer>,
+    /** name of the album/playlist shown in the [net.torvald.terrarum.musicplayer.gui.MusicPlayer] */
+    val name: String,
+    /** canonicalPath with path separators converted to forward slash */
+    val source: String,
+    /** "continuous", "intermittent"; not used by the Playlist itself but by the BackgroundMusicPlayer (aka you are the one who make it actually work) */
+    val diskJockeyingMode: String,
+    /** if set, the `internalIndices` will be shuffled accordingly, and this happens automatically. (aka you don't need to worry about) */
+    val shuffled: Boolean
+): Disposable {
+
+    private val internalIndices = ArrayList<Int>()
+    private var currentIndexCursor = musicList.size
+
+    init {
+        reset()
+    }
+
+    fun reset() {
+        internalIndices.clear()
+        refillInternalIndices()
+        refillInternalIndices()
+        currentIndexCursor = musicList.size
+    }
+
+    private fun checkRefill() {
+        if (internalIndices.size < currentIndexCursor + 1)
+            refillInternalIndices()
+    }
+
+    fun getCurrent(): MusicContainer {
+        checkRefill()
+
+        return musicList[currentIndexCursor]
+    }
+
+    fun getNext(): MusicContainer {
+        checkRefill()
+        currentIndexCursor += 1
+
+        return musicList[currentIndexCursor]
+    }
+
+    fun getPrev(): MusicContainer {
+        if (currentIndexCursor == 0) {
+            if (shuffled) {
+                musicList.indices.toMutableList().also { if (shuffled) it.shuffle() }.reversed().forEach {
+                    internalIndices.add(0, it)
+                }
+                currentIndexCursor += musicList.size
+            }
+            else {
+                musicList.indices.reversed().forEach {
+                    internalIndices.add(0, it)
+                }
+                currentIndexCursor += musicList.size
+            }
+        }
+
+        currentIndexCursor -= 1
+
+        return musicList[currentIndexCursor]
+    }
+
+
+    private fun refillInternalIndices() {
+        internalIndices.addAll(musicList.indices.toMutableList().also { if (shuffled) it.shuffle() })
+    }
+
+    inline fun getNthSong(n: Int) = musicList[n]
+
+    override fun dispose() {
+        musicList.forEach {
+            it.tryDispose()
+        }
+    }
+
+    companion object {
+        /**
+         * Adding songFinishedHook to the songs is a responsibility of the caller.
+         */
+        fun fromDirectory(musicDir: String, shuffled: Boolean, diskJockeyingMode: String, fileToName: ((String) -> String) = { name: String ->
+            name.substringBeforeLast('.').replace('_', ' ').split(" ").map { it.capitalize() }.joinToString(" ")
+        }): TerrarumMusicPlaylist {
+            val musicDir = musicDir.replace('\\', '/')
+            val playlistSource = musicDir
+            printdbg(this, "registerSongsFromDir $musicDir")
+
+            val playlistName = musicDir.substringAfterLast('/')
+
+            val playlist = File(musicDir).listFiles()?.sortedBy { it.name }?.mapNotNull {
+                printdbg(this, "Music: ${it.absolutePath}")
+                try {
+                    MusicContainer(
+                        fileToName(it.name),
+                        it
+                    )/*.also { muscon ->
+
+                        printdbg(this, "MusicTitle: ${muscon.name}")
+
+                        muscon.songFinishedHook =  {
+                            if (App.audioMixer.musicTrack.currentTrack == it) {
+                                stopMusic(this, true, getRandomMusicInterval())
+                            }
+                        }
+                    }*/
+                    // adding songFinishedHook must be done by the caller
+                }
+                catch (e: GdxRuntimeException) {
+                    e.printStackTrace()
+                    null
+                }
+            } ?: emptyList() // TODO test code
+
+            return TerrarumMusicPlaylist(
+                playlist,
+                playlistName,
+                musicDir,
+                diskJockeyingMode,
+                shuffled
+            )
+        }
+    }
+
+
+}