/**
 * Model of a copy machine.
 *
 * @author Jeff Raab
 */
public class CopyMachine {

    /** 
     * Number of copies to make. 
     * @invariant copies >= 0
     */
    protected int copies = 0;
    
    /** 
     * Darkness of copies. 
     * @invariant 1 <= darkness <= 10
     */
    protected int darkness = 5;
    
    /**
     * Copy mode.
     * @invariant 1 <= mode <= 3
     */
    protected int mode = 1;

    /** 
     * Constructs a new copy machine 
     * ready to make 0 copies in mode 1 with darkness 5.
     */
    public CopyMachine() {}

    /** Sets the number of copies to make to 0. */
    public void clear() {
        copies = 0;
    }
    
    /** Adds 1 to the number of copies. */
    public void plus1() {
        copies++;
    }
    
    /** 
     * Adds 1 to the darkness level.
     *
     * If the darkness level is already 10,
     * this method does nothing.
     */
    public void darker() {
        if (darkness == 10)
            return;
        
        darkness++;
    }
    
    /** 
     * Subtracts 1 from the darkness level. 
     *
     * If the darkness level is already 1,
     * this method does nothing.
     */
    public void lighter() {
        if (darkness == 1)
            return;
        
        darkness--;
    }
    
    /** Selects the next copy mode. */
    public void mode() {
        if (mode == 3)
            mode = 1;
        else
            mode++;
    }
    
    /** Returns the number of copies to make. */
    public int getCopies() {
        return copies;
    }
    
    /** Returns the darkness level. */
    public int getDarkness() {
        return darkness;
    }
    
    /** Returns the copy mode. */
    public int getMode() {
        return mode;
    }
}