package org.optaplanner.examples.cloudbalancing.swingui.realtime;

import java.util.ArrayList;

import org.optaplanner.core.api.solver.change.ProblemChange;
import org.optaplanner.core.api.solver.change.ProblemChangeDirector;
import org.optaplanner.examples.cloudbalancing.domain.CloudBalance;
import org.optaplanner.examples.cloudbalancing.domain.CloudComputer;
import org.optaplanner.examples.cloudbalancing.domain.CloudProcess;

public class DeleteComputerProblemChange implements ProblemChange<CloudBalance> {

    private final CloudComputer computer;

    public DeleteComputerProblemChange(CloudComputer computer) {
        this.computer = computer;
    }

    @Override
    public void doChange(CloudBalance cloudBalance, ProblemChangeDirector problemChangeDirector) {
        CloudComputer workingComputer = problemChangeDirector.lookUpWorkingObjectOrFail(computer);
        if (workingComputer == null) {
            throw new IllegalStateException("A computer " + computer + " does not exist. Maybe it has been already deleted.");
        }
        // First remove the problem fact from all planning entities that use it
        for (CloudProcess process : cloudBalance.getProcessList()) {
            if (process.getComputer() == workingComputer) {
                problemChangeDirector.changeVariable(process, "computer",
                        workingProcess -> workingProcess.setComputer(null));
            }
        }
        // A SolutionCloner does not clone problem fact lists (such as computerList)
        // Shallow clone the computerList so only workingSolution is affected, not bestSolution or guiSolution
        ArrayList<CloudComputer> computerList = new ArrayList<>(cloudBalance.getComputerList());
        cloudBalance.setComputerList(computerList);
        // Remove the problem fact itself
        problemChangeDirector.removeProblemFact(workingComputer, computerList::remove);
    }

}
