public class Album implements Comparable<Album> {
  private final String title;
  private final String artist;
  private final int year;
  private double price;
  private int unitsSold;

  /**
   * Construct a Album object with the given title, artist, year, price, and unitsSold.
   * @param title
   * @param artist
   * @param year
   * @param price
   * @param unitsSold
   * 
   * @throws IllegalArgumentException if title or artist is null, year, price, or unitsSold is negative.
   */
  public Album(String title, String artist, int year, double price, int unitsSold) {
    if (title == null || artist == null || year < 0 || price < 0 || unitsSold < 0) {
      throw new IllegalArgumentException("Invalid input");
    }

    this.title = title;
    this.artist = artist;
    this.year = year;
    this.price = price;
    this.unitsSold = unitsSold;
  }

  /**
   * Compares two Album objects based on their titles in ascending order.
   */
  @Override
  public int compareTo(Album o) {
    int titleComp = this.title.compareTo(o.title);
    return titleComp;
  }

  public String getTitle() {
    return this.title;
  }

  public String getArtist() {
    return this.artist;
  }

  public int getYear() {
    return this.year;
  }

  public double getPrice() {
    return this.price;
  }

  public void setPrice(double price) {
    if (price < 0) {
      throw new IllegalArgumentException("Invalid input");
    }

    this.price = price;
  }

  public int getUnitsSold() {
    return this.unitsSold;
  }

  public void increaseUnitsSold(int unitsSold) {
    if (unitsSold < 0) {
      throw new IllegalArgumentException("Invalid input");
    }

    this.unitsSold += unitsSold;
  }
}