byufen

Solution to the BYU FEN coding challenge (http://files.lib.byu.edu/webdev-hire/instructions/)

Instructions

1. mvn clean
2. mvn install
3. mvn test for testing
4. mvn spring-boot:run

Endpoints

Running mvn spring-boot:run will spin up the application on localhost:8081. All endpoints are accessed with the HTTP GET request.

• \ping - A sanity endpoint to ensure that the server is up and running
• \validate?fen=[FEN] - An endpoint to check the validity of the FEN string passed in as a query parameter
• \task1?fen=[FEN] - Prints out a board based on the provided FEN string. The FEN string must be valid or an error message will display instead
• \task2?fen=[FEN] - Calls the syzygy.info API and updates the FEN string based on the suggested move. If a bestmove is specified, it will be used instead. This endpoint handles castling, en passant, and pawn promotion.
• \stretch?fen=[FEN] - Prints out a board of an updated FEN, a combination of task 1 and task 2

Why Spring Boot?

Most Java-based services use Java EE or some sort of framework. I chose Spring because it was the Java framework I was most familiar with. This also allows me to showcase my skills with developing a RESTful service.

How can I improve this?

• These are the steps to move a piece and update the FEN representation
  • Convert current FEN piece data representation to a 64 character string, replacing numbers with that number of dashes:
    • e.g. rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR becomes rnbqkbnrpppppppp--------------------------------PPPPPPPPRNBQKBNR
  • Determine the "from" square and the "to" square.
    • e.g. a2a3. a2 is the from square. a3 is the to square.
  • Calculate the character positions of the given squares
    • character position = 8 * (8 - row number) + column number, where a = 0 -> h = 7
    • a2 = 48, a3 = 40
  • Set the to square = character in from square
  • Set the from square character to '-'
  • Convert the 64 character string representation back to FEN notation I would like to be able to work out a solution that didn't affect the entire board; just the rows that are affected by the move
• Only the piece placement data is updated. Improvements could include changing the active color each move, remove castling ability flags if the king or rooks move without castling, detect if a pawn moves in such a way that it can be captured by en passant, etc...
• As part of the FEN validation process, I could check to see if there are too many pieces of one type, such as checking to ensure that each side has only one king.
• Ensure moves are valid before completing the movement action. This would include
  • Check to see if the "from" square is within reach of the piece in the "to" square.
  • Check to make sure that a move doesn't put the active player's king in check