import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.Set;

/**
 * Holds a voter's ballot.
 * @author Scot Drysdale
 */
public class Ballot {
	private List<String> ballot;  // Holds the voter's choices (in order given)
	
	/**
	 * Constructs an empty ballot
	 */
	public Ballot() {
		ballot = new ArrayList<String>();
	}
	
	/**
	 * Finds and returns the top choice among candidates.
	 * @param candidates the current set of candidates
	 * @return name of top choice in candidates, or null if none exists.
	 */
	public String getTopChoice(Set<String> candidates) {
		Iterator<String> iter = ballot.iterator();
		while(iter.hasNext()) {
			String candidate = iter.next();
			if(candidates.contains(candidate))
				return candidate;
		}
		return null;  // None of the candidates on ballot were in candidates
	}
	
	
	/**
	 * Returns the first candidate on the ballot
	 * @return the first candidate on the ballot, or null if none exists
	 */
	public String getFirst() {
		if(ballot.size() > 0)
		  return ballot.get(0);
		else
			return null;
	}
	
	/**
	 * Adds candidate to this ballot
	 * @param candidate the candidate to add
	 */
	public void addCandidate(String candidate) {
		ballot.add(candidate);
	}
	
	/**
	 * Returns a string with the candidates
	 */
	public String toString() {
		return ballot.toString();
	}
}