Music-System-CS151-Fall-2025

1. Overview

Welcome to our music streaming system! 👋🎵

Our project designs and implements a music streaming system for Artists (content creators) and Listeners (consumers). We include user authentication, media management (songs and podcasts), and playback controls (play, pause, stop).

2. Design

We aim to have a clear separate of concerns across authentication, catalog, media items, and the CLI application.

2.1 Architecture:

• Our Catalog acts as the single source of truth for all content, centralizing search functionality and simplifying read-mostly access
• Inheritance allows common fields to reside in abstract classes, with subclasses adding unique attributes
  • MediaItem is extended by concrete types such as Song and Podcast, with shared fields like itemId, title, and durationSec defined in MediaItem
  • User class is extended by Artist and Listener, each inheriting base fields such as userId and displayName
• Searchable interface allows different media objects to share a common search behavior across the system
• State management via the PlayerState enum controls player states PLAYING, PAUSED, and STOPPED for clear playback transitions

2.2 Class Structure

• auth:
  • AuthService: Registers accounts, verifies credentials, validates and creates sessions
  • Session: Holds session metadata (sessionId, accountId, role, linkedId, active flag)
  • Account: User credentials and role binding
• catalog:
  • Catalog: content of all MediaItems; add/list/get and search entry points
  • Library: per-listener collection of saved item IDs
  • DataLoader: Initializes clibrary/catalog information from files
  • data: artists, listeners, song CSV files
• domain:
  • MediaItem (abstract): itemId, title, durationSec, common behavior
  • Song: concrete implmentation of MediaItem
  • Podcast: concrete implmentation of MediaItem
  • Searchable (interface): contract for matching queries (title)
• user:
  • User (abstract): base user identity
  • Artist: can create/publish items to Catalog
  • Listener: maintains a Library, playback state
  • Role: ARTIST, LISTENER for authorization checks in CLI
• app:
  • MusicSystemCLI: text UI, handles auth -> catalog/library -> playback flows
  • ConsoleUI: utility class providing ANSI color-coded console output (success, error, info, warning messages) and formatted input prompts to create a beautified and colorful user experience
• exceptions:
  • InvalidCredentialsException: Custom exception thrown when login fails due to invalid credentials
  • ItemNotFoundException: Custom exception thrown when a requested item cant be found in the catalog
• config:
  • Constants: Enforces maximum number of instances (100) allowed for each class with IllegalStateException
• test:
  • Includes unit test coverage across each package

2.3 Key Design Considerations

• Our single source of truth allows all content to live in the Catalog. Library stores only item IDs (references)
• We designed with extensibility in mind, making implementing new media types and adding more search capabilities easier
• We considered security, deciding our AuthService handles the credential checks, while session carries the role
• We intentionally decided on hashmaps and sets as we considered performance. We have a read-mostly catalog with simple indexing (such as in-memory mapping by itemId and title), and library operations are O(1) on item IDs

2.4 UML Diagram

2.5 Exception Handling

1. NumberFormatException - Catches invalid number input (built-in)
2. InvalidCredentialsException - Catches login failures (custom)
3. ItemNotFoundException - Catches missing songs (custom)
4. File I/O (DataLoader.java) - Catches file-loading errors (e.g., IOException) during CSV reads

2.6 Future Work

• Current file-based persistence via DataLoader keeps setup simple but isn’t realistic for account creation. A future improvement would be migrating to a database to support live updates
• Introduce indexing and metadata filters (e.g., genre, album, artist) to enable more search capabilities
• Implement better authentication practice by implementing password hashing

3. Installation Instructions

1. Clone the repository

git clone https://github.com/juliahusainzada/Music-System-CS151-Fall-2025.git
cd Music-System-CS151-Fall-2025/src

2. Compile the file

javac app/MusicSystemCLI.java

3. Launch the CLI

java app/MusicSystemCLI.java

4. Enjoy the music player!

4. Usage

Once you've launched the CLI, you'll be greeted with the Main Menu, where you can register or log in as a user (User)

4.1 Main Menu Options:

1. Register - Create an account as either an Artist or Listener
2. Login - Access your exist account and session
3. Exit - Close the application

4.2.1 Artist Menu:

If you register/log in as an Artist, you will see the Artist Menu, where you can:

1. Publish Media - Add new music to global Catalog
2. View Published Songs - List all media uploaded by you
3. Remove song - Delete the media from Catalog

4.2.2 Listener Menu

If you register/log in as a Listener, you will see the Listener Menu, where you can:

1. Search Songs - Query the Catalog for available media by title
2. Save/Unsave Songs - Add or remove items in personal Library
3. Play Song - Start playback
4. Pause/ Stop - Manage your playback state
5. View Saved Songs - Display songs saved to your personal library

4.3 Example Workflows:

Artist:

1. Register as Artist
2. Log in → “Publish Song” → Enter title & duration
3. You can verify it appears in the catalog!

Listener:

1. Register as Listener (logs you in)
2. “Search Songs” → View results from catalog
3. “Save Song” to add to your Library
4. “Play Song” → “Pause” → “Stop” and see state transitions
5. “View Saved Songs”

5. Contributions

Together, we designed the overall architecture, high-level design, and project choice.

Team Member	Areas of Contribution
Julia Husainzada	Designed package structure; implemented AuthService, Session, DataLoader, Catalog, Constants, exceptions, unit tests for 7 classes, ReadMe, and CLI flow (ConsoleUI, MusicSystemCLI)
Dushan Siriwardana	Developed UML diagram; Implemented Library, Artist, Podcast functionality; added playback features (Play, Pause, Stop); managed player state transitions with PlayerState enum; Arist unit test
Houmei Li	Implemented Searchable interface, User abstract class