Dice Roller

DiceRoller.groovy

import javax.swing.JOptionPane

// for: http://www.raymondcamden.com/index.cfm/2014/2/21/Friday-Puzzler-Rolling-the-die
class DiceRoller {

	static Random random = new Random()
	
	static void main( String[] args ) {
		
		String roller = JOptionPane.&showInputDialog "Enter your roll:"
		String message

		if( !validateRoller( roller ) ) {

			message = "Your roll was invalid. Please enter a properly formatted roll."
			JOptionPane.showMessageDialog( null, message, "Error!", 2 )
			main()

		} else {

			Map rolls = roll( roller );

			message = """Total: ${rolls.final}
			Individual rolls: ${rolls.rolls.join(', ')}"""

			JOptionPane.showMessageDialog( null, message, "Roll Results", 1 )

		}
		
	}
	
	static Map roll( String roller ) {
		
		Map rolls = [ final: 0, rolls: [] ]
		ArrayList params = roller.split(/d|\+|-/).collect { Integer.parseInt( it ) }
		Integer count = params[ 0 ]
		Integer sides = params [ 1 ]
		Integer modifier = params[ 2 ] ?: 0;

		if( modifier != 0 ) {
			modifier = roller.contains("-") ? -modifier : modifier
		}

		(1..count).each {
			Integer thisRoll = actualRoll( sides )
			rolls.rolls << thisRoll
			rolls.final += thisRoll
		}
		
		rolls.final += modifier
		
		rolls
		
	}
	
	private static Integer actualRoll( Integer sides ) {
		random.nextInt( sides ) + 1
	}

	private static Boolean validateRoller( String roller ) {
		Integer rollerSize = roller.split(/d|\+|-/).size()
		
		rollerSize > 1 && rollerSize <= 3
	}

}