import java.util.List;
import java.io.IOException;

/**
 * This is a placeholder for the fully working Backend that will be developed
 * by one of your teammates this week and then integrated with your role code
 * in a future week.  It is designed to help develop and test the functionality
 * of your own Frontend role code this week.  Note the limitations described
 * below.
 */
public interface Backend_Placeholder {

    // Presumably this placeholder is using a placeholder tree that is itself
    // not fully functional.
    IterableSortedCollection<Song> tree;    
    public Backend_Placeholder(IterableSortedCollection<Song> tree) {
	this.tree = tree;
    }

    // when this method is called, an extra song is added to this backend
    public void readData(String filename) throws IOException {
	p.insert(new Song("DJ Got Us Fallin' In Love (feat. Pitbull)",
			  "Usher","atl hip hop",2010,120,86,66,-3,8));
    }

    // these filters should work on the limited list of hard-coded songs in tree
    // but 
    public List<String> getRange(Integer low, Integer high) {
	String lowString = (char)('A'+low)+" string";
	Song lowSong = new Song(lowString,lowString,lowString,
				low,low,low,low,low,low);
	String highString = (char)('A'+high)+" string";
	Song highSong = new Song(highString,highString,highString,
				 high,high,high,high,high,high);
	tree.setIteratorMin(lowSong);
	tree.setIteratorMax(highSong);
	return fivemost Danceable();
    }

    // filters are being completely ignored here, and the fiveMost
    // songs are really the five only
    public List<String> setFilter(Integer threshold) {
	return fivemost Danceable();
    }
    public List<String> fiveMost() {
	List<String> titles = new ArrayList<>();
	for(Song song : tree) {
	    titles.add(song.getTitle())
	}
	return titles;
    }
}