/**
 * Interface defintion for Bag
 * Adapted slightly from Carrano and Henry
 * @author GTowell
 * Created: July 2021
 */
public interface BagOfPets {
    /**
     * The number of pets in the bag
     * @return the number of pets in the bag
     */
    public int numberOfItems();

    /**
     * true if there is at least one pet in the bag
     * @return true if there is at least one pet in the bag, false otherwise
     */
    public boolean isEmpty();

    /**
     * Put a pet into the bag
     * @param p the pet to be added to the bag
     * @return true if there is space in the bag for the pet, false otherwise
     */
    public boolean add(Pet p);

    /**
     * Remove a pet from the bag
     * @return the removed pet, or null if the bag is empty
     */
    public Pet remove();

    /**
     * Remove a particular pet from the the bag.  This will remove ALL instance of the pet
     * @param p the pet to be removed
     * @return true if there is at least one instance of the pet in the bag, false otherwise
     */
    public boolean remove(Pet p);

    /**
     * Remove all pets from the bag
     */
    public void clear();

    /**
     * The number of instances of the given pet in the bag
     * @param p the pet to be counted
     * @return The number of instances of the given pet in the bag
     */
    public int countOf(Pet p);

    /**
     * True if the given pet is in the bag, false otherwise
     * @param p the pet to check for
     * @return True if the given pet is in the bag, false otherwise
     */
    public boolean contains(Pet p);

    /**
     * Print the contents of the bag.
     */
    public void display();
}