///////////////////////////////////////////////////////////////////////////////
// For information as to what this class does, see the Javadoc, below.       //
// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
// 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
// Ramsey, and Clark Glymour.                                                //
//                                                                           //
// This program is free software; you can redistribute it and/or modify      //
// it under the terms of the GNU General Public License as published by      //
// the Free Software Foundation; either version 2 of the License, or         //
// (at your option) any later version.                                       //
//                                                                           //
// This program is distributed in the hope that it will be useful,           //
// but WITHOUT ANY WARRANTY; without even the implied warranty of            //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
// GNU General Public License for more details.                              //
//                                                                           //
// You should have received a copy of the GNU General Public License         //
// along with this program; if not, write to the Free Software               //
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
///////////////////////////////////////////////////////////////////////////////

package edu.cmu.tetrad.search;

import edu.cmu.tetrad.graph.Node;

import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.HashSet;
import java.util.Set;

/**
 * Represents a tetrad of variables.
 */
public class Tetrad {
    private Node i;
    private Node j;
    private Node k;
    private Node l;
    private double pValue;

    public Tetrad(Node i, Node j, Node k, Node l) {
//        testDistinctness(i, j, k, l);
        this.i = i;
        this.j = j;
        this.k = k;
        this.l = l;
        this.pValue = Double.NaN;
    }

    public Tetrad(Node i, Node j, Node k, Node l, double pValue) {
//        testDistinctness(i, j, k, l);
        this.i = i;
        this.j = j;
        this.k = k;
        this.l = l;
        this.pValue = pValue;
    }

//    private void testDistinctness(Node i, Node j, Node k, Node l) {
//        if (i == j || i == k || i == l) {
//            throw new IllegalArgumentException("Nodes not distinct.");
//        }
//
//        if (j == k || j == l) {
//            throw new IllegalArgumentException("Nodes not distinct.");
//        }
//
//        if (k == l) {
//            throw new IllegalArgumentException("Nodes not distinct.");
//        }
//    }

    public Node getI() {
        return i;
    }

    public Node getJ() {
        return j;
    }

    public Node getK() {
        return k;
    }

    public Node getL() {
        return l;
    }

    public int hashCode() {
//        int hash = i.hashCode();
//        hash += 17 * hash + j.hashCode();
//        hash += 17 * hash + k.hashCode();
//        hash += 17 * hash + l.hashCode();

        int hash = 17 * i.hashCode() * j.hashCode();
        hash += 29 * k.hashCode() * l.hashCode();

        return hash;
    }

    public boolean equals(Object o) {
        if (o == null) return false;
        Tetrad tetrad = (Tetrad) o;
        return (i == tetrad.i && j == tetrad.j && k == tetrad.k && l == tetrad.l)
                || (i == tetrad.j && j == tetrad.i && k == tetrad.k && l == tetrad.l)
                || (i == tetrad.i && j == tetrad.j && k == tetrad.l && l == tetrad.k)
                || (i == tetrad.j && j == tetrad.i && k == tetrad.l && l == tetrad.k)
                || (i == tetrad.k && j == tetrad.l && k == tetrad.i && l == tetrad.j)
                || (i == tetrad.k && j == tetrad.l && k == tetrad.j && l == tetrad.i)
                || (i == tetrad.l && j == tetrad.k && k == tetrad.i && l == tetrad.j)
                || (i == tetrad.l && j == tetrad.k && k == tetrad.j && l == tetrad.i);
    }

    public String toString() {
        NumberFormat nf = new DecimalFormat("0.0000");

        if (Double.isNaN(pValue)) {
            return "s(" + i + "," + j + ")*s(" + k + "," + l + ")-s(" + i + "," + k + ")*s(" + j + "," + l + ")";
        } else {
            return "<" + i + ", " + j + ", " + k + ", " + l + ", " + nf.format(pValue) + ">";
        }
    }

    public double getPValue() {
        return pValue;
    }

    public Set<Node> getNodes() {
        Set<Node> nodes = new HashSet<>();
        nodes.add(i);
        nodes.add(j);
        nodes.add(k);
        nodes.add(l);
        return nodes;
    }
}