package ca.uhn.hl7v2.model;

import java.io.Serializable;
import java.util.ArrayList;

/**
 * A set of "extra" components (sub-components) that are not a standard part 
 * of a field (component) but have been added at runtime.  The purpose is to allow 
 * processing of locally-defined extensions to datatypes without the need for a 
 * custom message definition.  
 * Extra components are not treated uniformly with standard components (e.g. 
 * they are not accessible through methods like Primitive.getValue() and 
 * Composite.getComponent()).  To do so would blur the distinction between 
 * primitive and composite types (i.e. leaf and non-leaf nodes), which seems 
 * nice and polymorphic for a moment but actually isn't helpful.  
 * Furthermore, the auto-generated classes do not define accessors to extra 
 * components, because they are meant to encourage and enforce use of the standard 
 * message structure -- stepping outside the standard structure must be 
 * deliberate. 
 * Note that a uniformity of access to standard and extra components is provided
 * by Terser.   
 * @author Bryan Tripp
 */
public class ExtraComponents implements Serializable {
    
    private static final long serialVersionUID = -2614683870975956395L;
    
    private ArrayList comps;
    private Message message;
    
    /** Creates a new instance of ExtraComponents */
    public ExtraComponents(Message message) {
        this.comps = new ArrayList();
        this.message = message; 
    }
    
    /** Returns the number of existing extra components */
    public int numComponents() {
        return comps.size();
    }
    
    /** Returns the number of existing reps of a given extra component */
    /*public int numReps(int comp) {
        return ((ArrayList) this.comps.get(comp)).size();
    }*/
    
    /** 
     * Returns the component at the given location, creating it 
     * and all preceeding components if necessary.  
     * @param comp the extra component number starting at 0 (i.e. 0 is the first 
     *      extra component)
     */
    public Varies getComponent(int comp) {
        ensureComponentAndPredecessorsExist(comp);
        return (Varies) this.comps.get(comp);
    }
    
    /**
     * Checks that the component at the given location exists, and that 
     * all preceding components exist, creating any missing ones.  
     */
    private void ensureComponentAndPredecessorsExist(int comp) {
        for (int i = this.comps.size(); i <= comp; i++) {
            this.comps.add(new Varies(message));
        }
        /*ArrayList reps = (ArrayList) this.comps.get(comp);
        for (int j = reps.size(); j <= rep; j++) {
            addRep(comp, j);
        }*/
    }


	/**
	 * Clears all extra components
	 */
	void clear() {
		comps.clear();
	}


    /*private void addComp(int comp) {
    }*/
    
    /*private void addRep(int comp, int rep) {
        ArrayList l = (ArrayList) this.comps.get(comp);
        l.add(rep, new Varies());
    }*/
}