RandomEffectNode.java

package com.hearthsim.util.tree;

import com.hearthsim.model.PlayerSide;
import com.hearthsim.util.HearthAction;

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

/**
 * Random effect node
 *
 * This node signifies that the immediate children of the node are all outcomes of a random event.
 * Each random outcome can have a weighting associated to it.  The total expected score of this node
 * is computed as a weighted average of the scores of all outcomes.
 *
 */
public class RandomEffectNode extends StopNode {

    private final ArrayList<Double> childWeighting_ = new ArrayList<>();

    public RandomEffectNode(HearthTreeNode origNode,
                            HearthAction action) {
        super(origNode);
        this.setAction(action);
        for (int indx = 0; indx < numChildren(); ++indx) {
            childWeighting_.add(1.0);
        }
    }

    @Override
    public HearthTreeNode finishAllEffects() {
        if (this.numChildren() > 0) {
            return this.getChildren().get((int)(Math.random() * this.numChildren()));
        }

        return null;
    }

    @Override
    public HearthTreeNode addChild(HearthTreeNode node) {
        node.setAction(new HearthAction(HearthAction.Verb.RNG, PlayerSide.CURRENT_PLAYER, this.numChildren()));
        HearthTreeNode toRet = super.addChild(node);
        childWeighting_.add(1.0);
        return toRet;
    }

    @Override
    public void setChildren(List<HearthTreeNode> children) {
        super.setChildren(children);
        childWeighting_.clear();
        for (int indx = 0; indx < children.size(); ++indx) {
            childWeighting_.add(1.0);
        }
    }

    @Override
    public void clearChildren() {
        super.clearChildren();
        childWeighting_.clear();
    }

    //If you are going to play a random effect card, it's usually better to play it when you have more mana
    private double getManaBenefit() {
        return 1.e-2 * data_.getCurrentPlayer().getMana();
    }

    public double weightedAverageScore() {
        double toRet = 0.0;
        for (int index = 0; index < children_.size(); ++index) {
            toRet += childWeighting_.get(index) * children_.get(index).getScore();
        }
        toRet = toRet / children_.size();
        toRet += this.getManaBenefit();
        return toRet;
    }

    public double weightedAverageBestChildScore() {
        double toRet = 0.0;
        for (int index = 0; index < children_.size(); ++index) {
            toRet += childWeighting_.get(index) * children_.get(index).getBestChildScore();
        }
        toRet = toRet / children_.size();
        toRet += this.getManaBenefit();
        return toRet;
    }
}