Made the Player behaviour more consistent

ui/src/audioplayer/keyHandlers.js

@@ -0,0 +1,35 @@
+const keyHandlers = (audioInstance, playerState) => {
+  const nextSong = () => {
+    const idx = playerState.queue.findIndex(
+      (item) => item.uuid === playerState.current.uuid
+    )
+    return idx !== null ? playerState.queue[idx + 1] : null
+  }
+
+  const prevSong = () => {
+    const idx = playerState.queue.findIndex(
+      (item) => item.uuid === playerState.current.uuid
+    )
+    return idx !== null ? playerState.queue[idx - 1] : null
+  }
+
+  return {
+    TOGGLE_PLAY: (e) => {
+      e.preventDefault()
+      audioInstance && audioInstance.togglePlay()
+    },
+    VOL_UP: () =>
+      (audioInstance.volume = Math.min(1, audioInstance.volume + 0.1)),
+    VOL_DOWN: () =>
+      (audioInstance.volume = Math.max(0, audioInstance.volume - 0.1)),
+    PREV_SONG: (e) => {
+      if (!e.metaKey && prevSong()) audioInstance && audioInstance.playPrev()
+    },
+
+    NEXT_SONG: (e) => {
+      if (!e.metaKey && nextSong()) audioInstance && audioInstance.playNext()
+    },
+  }
+}
+
+export default keyHandlers