/*
 * Copyright 2020 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.optaplanner.examples.cloudbalancing.optional.score;

import java.util.function.Function;

import org.optaplanner.core.api.score.buildin.hardsoft.HardSoftScore;
import org.optaplanner.core.api.score.stream.Constraint;
import org.optaplanner.core.api.score.stream.ConstraintFactory;
import org.optaplanner.core.api.score.stream.ConstraintProvider;
import org.optaplanner.examples.cloudbalancing.domain.CloudComputer;
import org.optaplanner.examples.cloudbalancing.domain.CloudProcess;

import static org.optaplanner.core.api.score.stream.ConstraintCollectors.sum;
import static org.optaplanner.core.api.score.stream.Joiners.equal;

public class CloudBalancingConstraintProvider implements ConstraintProvider {

    @Override
    public Constraint[] defineConstraints(ConstraintFactory constraintFactory) {
        return new Constraint[]{
                requiredCpuPowerTotal(constraintFactory),
                requiredMemoryTotal(constraintFactory),
                requiredNetworkBandwidthTotal(constraintFactory),
                computerCost(constraintFactory)
        };
    }

    // ************************************************************************
    // Hard constraints
    // ************************************************************************

    private Constraint requiredCpuPowerTotal(ConstraintFactory constraintFactory) {
        return constraintFactory.from(CloudProcess.class)
                .groupBy(CloudProcess::getComputer, sum(CloudProcess::getRequiredCpuPower))
                .filter((computer, requiredCpuPower) -> requiredCpuPower > computer.getCpuPower())
                .penalize("requiredCpuPowerTotal",
                        HardSoftScore.ONE_HARD,
                        (computer, requiredCpuPower) -> requiredCpuPower - computer.getCpuPower());
    }

    private Constraint requiredMemoryTotal(ConstraintFactory constraintFactory) {
        return constraintFactory.from(CloudProcess.class)
                .groupBy(CloudProcess::getComputer, sum(CloudProcess::getRequiredMemory))
                .filter((computer, requiredMemory) -> requiredMemory > computer.getMemory())
                .penalize("requiredMemoryTotal",
                        HardSoftScore.ONE_HARD,
                        (computer, requiredMemory) -> requiredMemory - computer.getMemory());
    }

    private Constraint requiredNetworkBandwidthTotal(ConstraintFactory constraintFactory) {
        return constraintFactory.from(CloudProcess.class)
                .groupBy(CloudProcess::getComputer, sum(CloudProcess::getRequiredNetworkBandwidth))
                .filter((computer, requiredNetworkBandwidth) -> requiredNetworkBandwidth > computer.getNetworkBandwidth())
                .penalize("requiredNetworkBandwidthTotal",
                        HardSoftScore.ONE_HARD,
                        (computer, requiredNetworkBandwidth) -> requiredNetworkBandwidth - computer.getNetworkBandwidth());
    }

    // ************************************************************************
    // Soft constraints
    // ************************************************************************

    private Constraint computerCost(ConstraintFactory constraintFactory) {
        return constraintFactory.from(CloudComputer.class)
                .ifExists(CloudProcess.class, equal(Function.identity(), CloudProcess::getComputer))
                .penalize("computerCost",
                        HardSoftScore.ONE_SOFT,
                        CloudComputer::getCost);
    }

}
