@startuml
skinparam BackgroundColor F0F0F0
start

if (currentlyPlayingTrackIndex ⊂ musicFilesCache) then (no) 
partition "**query** newData" {
    : offset = currentlyPlayingTrackIndex - cacheThreshold
     size = cacheMaxSize
     updateMusicFilesList(offset, size);
     }
else (yes)
  if (
   currentlyPlayingTrackIndex >
   musicFilesCache.lastIndex - cacheThreshold
   ) then (yes)
   partition "**query** newBackData" {
    : offset = musicFilesCache.lastIndex + 1
     size = cacheThreshold
     updateMusicFilesList(offset, size);
     }
  else (no)
	 if (
	  currentlyPlayingTrackIndex <
	  musicFilesCache.firstIndex + cacheThreshold
	  ) then (yes)
	  partition "**query** newFrontData" {
	   : offset = musicFilesCache.firstIndex - cacheThreshold
	    size = cacheThreshold
	    updateMusicFilesList(offset, size);
	    } 
	 endif
  endif
endif

stop
@enduml