Android App Edit: Music to PDF Viewer

I need a proficient Android app developer who can edit my existing music player app and its admin panel to transform it into a PDF viewer while preserving the app's core functionalities.

Key Requirements:
- Retain current music player app functionalities:
* Playlist management: Users should be able to create, modify and manage their own playlists.
* User authentication: The app should maintain its existing user login and account management system.
* Offline access: Users must be able to access their PDFs without an internet connection, just like they would with music.

- Modify the admin panel to accommodate the new PDF viewer:
* The changes to the admin panel will be substantial, requiring a significant level of expertise and understanding of the admin system.

Ideal Skills and Experience:
- Strong proficiency in Android app development.
- Prior experience with music player apps and PDF viewer apps is a plus.
- Excellent understanding of admin panel modifications.
- Ability to maintain app functionality during transition.