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package net.sf.tweety.commons.util.rules;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import net.sf.tweety.commons.Formula;
import net.sf.tweety.commons.util.Digraph;
import net.sf.tweety.commons.util.DigraphNode;

/**
 * 
 * @author Nils Geilen
 * expands a set of formulae to a graph where nodes are formulae and edges show, which forumla can be composed of which formulae
 * @param  a formula type
 * @param  a rule type F^n -> F
 */


public class DerivationGraph> extends Digraph {
	
	public DerivationGraph() {
		super(false);
	}
	
	/**
	 * expands the rule set 
	 * @param rules a collection of rules
	 */
	public void allDerivations (Collection rules) {
		Collection open = new ArrayList<>();
		open.addAll(rules);
		for(R r:open) 
			if (r.isFact())
				this.addNode(r);
		open.removeAll(getValues());
		
		
		while(true) {
			int noe = this.numberOfEdges();
			rule_loop: for(R r: open) {
				List params = new ArrayList<>();
				params.addAll(r.getPremise());
				List>> pre = new ArrayList<>();
				for(int i = 0 ; i < params.size() ; i++) {
					pre.add(new ArrayList<>());
					F param = params.get(i);
					for(DigraphNode n:this)
						if(n.getValue().getConclusion().equals(param))
							pre.get(i).add(n);
				}
				
				for(List> l:pre) {
					if(l.isEmpty())
						continue rule_loop;
				}
				
				
				Digraph> param_tree = new Digraph<>(false);
				param_tree.addNode(null);
				for(List> l:pre) {
					Collection>> leafs = param_tree.getLeafs();
					for(DigraphNode> leaf:leafs)
						for(DigraphNode n:l){
							leaf.addEdge(param_tree.addNode(n));
						}
				}
				
				
				for(DigraphNode> leaf: param_tree.getLeafs()) {
					
					List> path = new ArrayList<>();
					do {
						path.add(leaf.getValue());
						leaf = leaf.getParent();
					} while (! leaf.isRoot());
					
					if(containsNode(r, path))
						continue;
					
					DigraphNode new_node = this.addNode(r);
					for(DigraphNode node: path)
						node.addEdge(new_node);
					
				}
				
			}
			
			//printTrees(System.out);
			
			//System.out.println(size());
			//System.out.println(numberOfEdges());
			if(noe == this.numberOfEdges())
				break;
		}
	}
	
	private boolean containsNode(R value, List> parents) {
		next_node : for(DigraphNode node:this) {
			if(node.getValue().equals(value)) {
				for(DigraphNode n:parents) {
					if(!node.getParents().contains(n))
						continue next_node;
				}
				return true;
			}
		}
		return false;
	}

}