Live Football World Cup Scoreboard

How to build

• ./gradlew clean build

N.B. jdk 17 is required

Structure The main interface is Scoreboard, which defines 4 methods for interacting with the library which were mentioned in the requirements document. Respectively, the ScoreboardImpl is its only implementation. Another important interface is ScoreboardStorage which defines contract for storage of matches/scores. It defines 5 basic operations which somewhat resemble java.util.Map's interface The SimpleScoreboardStorage is a naive implementation if that interface which is utilising Java's LinkedHashMap for storing Match vs Score mappings. ScoreboardImpl depends on ScoreboardStorage to store matches information.

• The domain model looks like following

classDiagram
      Match *-- Team
      Team *-- TeamName
      Score : +int homeTeamScore
      Score : +int awayTeamScore
      Match : +Team homeTeam
      Match : +Team awayTeam
      Team : +TeamName teamName
      TeamName : +String value

The model itself is subject to extension/modification, since for the scope of this assignment some simplifications were made. For instance, Score would typically be a part of Match, not a standalone entity (this was done in order to simplify storage structure, since Score is not what Match identity should rely on) Apart from this, Team currently has the only field of TeamName however I'd expect that there could be much more information apart from it

Implementation considerations

• Current implementation does not validate team names, I think, production-ready library would require some validation (e.g. don't allow non-existing country, total amount of countries, etc)
• When updating score, in my opinion it would make sense to throw an exception if the new score for any team is lower than the existing (I'm not a football expert, but I never saw this happening during the game). Also it might make sense to only allow incrementing score (i.e. only allow to increase by 1), but I decided to leave it out as I was not 100% sure if it would bring any value
• The logic for determining which match was started earlier relies on the order of insertion of Match objects in the underlying data structure (I chose LinkedHashMap exactly because of this) However for real-life scenarios I think I'd base this on a timestamp (ideally the Match class should have the information about when it started), since this is generally more standard and reliable approach (insertion order approach seemed to be more simple to implement here)
• Storing Match, Team and Score as Java record makes sense here, as in the scope of this task it's ok to treat those as DTO's as we don't have exact requirements on how to store them. Apparently, the production-ready library should support storing them in some database, hence it would require describing corresponding entities for them.
• Some methods like Scoreboard.updateScore or Scoreboard.finishMatch could declare that they may throw exception. I decided not to complicate it, hence used standard unchecked exception like IllegalStateException or NullPointerException without declaring them. However it may be a good idea to have custom exception for situations like these.