package org.gcube.informationsystem.tree;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * @author Luca Frosini (ISTI - CNR)
 */
public class Tree<T> {

	private boolean allowMultipleInheritance;
	
	private Node<T> rootNode;
	private NodeInformation<T> ni;
	private Map<String, Node<T>> locate;
	
	public Tree() {
		this.allowMultipleInheritance = true;
		this.locate = new HashMap<>();
	}
	
	public Tree(NodeInformation<T> ni) {
		this();
		setNodeInformation(ni);
	}
	
	public Tree(T root, NodeInformation<T> ni)  {
		this(ni);
		setRoot(root);
	}
	
	/**
	 * Set the NodeInformation if and only if it was not previously set.
	 * Otherwise this function has no effect.
	 * @param ni the NodeInformation to set
	 */
	public void setNodeInformation(NodeInformation<T> ni) {
		if(this.ni==null) {
			this.ni = ni;
		}
	}
	
	/**
	 * Set the root if and only if it was not previously set.
	 * Otherwise this function has no effect.
	 * This function raises a RuntimeException is the
	 * NodeInformation was not previously set.
	 * @param root the root to set
	 */
	public void setRoot(T root) throws RuntimeException {
		if(this.ni==null) {
			throw new RuntimeException("You must set the NodeInformation instance first");
		}
		if(this.rootNode==null) {
			this.rootNode = new Node<>(root);
			this.rootNode.setTree(this);
			String identifier = ni.getIdentifier(root);
			this.locate.put(identifier, rootNode);
		}
	}
	
	public void setAllowMultipleInheritance(boolean allowMultipleInheritance) {
		this.allowMultipleInheritance = allowMultipleInheritance;
	}
	
	public NodeInformation<T> getNodeInformation() {
		return ni;
	}
	
	public Node<T> addNode(T t) {
		String identifier = ni.getIdentifier(t);
		if(locate.containsKey(identifier)) {
			// has been already added
			return locate.get(identifier);
		}
		
		Node<T> node = new Node<>(t);
		node.setTree(this);
		
		Set<String> parentIdentifiers = ni.getParentIdentifiers(rootNode!= null ? rootNode.getNodeElement() : null, t);
		if(parentIdentifiers==null || parentIdentifiers.size()==0) {
			if(this.rootNode==null) {
				this.rootNode = node;
			}else {
				throw new RuntimeException("A Tree cannot have two root. " + t.toString() + " has not parent.");
			}
		} else {
			for(String parentIdentifier : parentIdentifiers) {
				Node<T> parentNode = locate.get(parentIdentifier);
				if(parentNode==null) {
					throw new RuntimeException("I can find parent for " + identifier + ". Missing parent is " + parentIdentifier);
				}
				
				parentNode.addChild(node);
				
				if(!allowMultipleInheritance) {
					break;
				}
			}
		}
		
		this.locate.put(identifier, node);
		
		return node;
	}

	public Node<T> getRootNode() {
		return rootNode;
	}

	@Override
	public String toString() {
		return rootNode.toString();
	}

	public void elaborate(NodeElaborator<T> nodeElaborator) throws Exception {
		rootNode.elaborate(nodeElaborator);
	}
}