Arakne / Araknemu

 * This file is part of Araknemu.

 *

 * Araknemu is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * Araknemu 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with Araknemu.  If not, see <https://www.gnu.org/licenses/>.

 *

 * Copyright (c) 2017-2019 Vincent Quatrevieux

 */

package fr.quatrevieux.araknemu.game.handler.object;

import fr.quatrevieux.araknemu.core.network.exception.ErrorPacket;

import fr.quatrevieux.araknemu.core.network.parser.PacketHandler;

import fr.quatrevieux.araknemu.game.exploration.ExplorationPlayer;

import fr.quatrevieux.araknemu.game.exploration.creature.ExplorationCreature;

import fr.quatrevieux.araknemu.game.exploration.creature.Operation;

import fr.quatrevieux.araknemu.game.exploration.map.ExplorationMap;

import fr.quatrevieux.araknemu.game.exploration.map.cell.ExplorationMapCell;

import fr.quatrevieux.araknemu.game.item.type.UsableItem;

import fr.quatrevieux.araknemu.game.player.GamePlayer;

import fr.quatrevieux.araknemu.game.player.inventory.InventoryEntry;

import fr.quatrevieux.araknemu.network.game.GameSession;

import fr.quatrevieux.araknemu.network.game.in.object.ObjectUseRequest;

import fr.quatrevieux.araknemu.network.game.out.basic.Noop;

import fr.quatrevieux.araknemu.network.game.out.info.Error;

import org.checkerframework.checker.nullness.qual.Nullable;

import org.checkerframework.checker.nullness.util.NullnessUtil;

/**

 * Use an object

 */

public final class UseObject implements PacketHandler<GameSession, ObjectUseRequest> {

    @Override

    public void handle(GameSession session, ObjectUseRequest packet) throws Exception {

        final GamePlayer player = NullnessUtil.castNonNull(session.player());

        if (!player.restrictions().canUseObject()) {

            throw new ErrorPacket(Error.cantDoOnCurrentState());

        }

        final InventoryEntry entry = player.inventory().get(packet.objectId());

        final UsableItem item = UsableItem.class.cast(entry.item());

        boolean result = true;

        try {

            result = packet.isTarget()

                ? handleForTarget(NullnessUtil.castNonNull(session.exploration()), item, packet)

                : handleForSelf(NullnessUtil.castNonNull(session.exploration()), item)

            ;

        } finally {

            if (result) {

                entry.remove(1);

            } else {

                session.send(new Noop());

            }

        }

    }

    private boolean handleForSelf(ExplorationPlayer exploration, UsableItem item) {

        if (!item.check(exploration)) {

            return false;

        }

        item.apply(exploration);

        return true;

    }

    private boolean handleForTarget(ExplorationPlayer exploration, UsableItem item, ObjectUseRequest packet) {

        final ExplorationMap map = exploration.map();

        if (map == null || packet.cell() >= map.size()) {

            return false;

        }

        final ExplorationMapCell cell = packet.cell() != -1 ? map.get(packet.cell()) : null;

        final ApplyItemOperation operation = new ApplyItemOperation(item, exploration, cell);

        return map.has(packet.target())

            ? NullnessUtil.castNonNull(map.creature(packet.target()).apply(operation)) // The implementation ensure that the return value is never null

            : operation.onNull()

        ;

    }

    private static class ApplyItemOperation implements Operation<Boolean> {

        private final UsableItem item;

        private final ExplorationPlayer caster;

        private final @Nullable ExplorationMapCell targetCell;

        public ApplyItemOperation(UsableItem item, ExplorationPlayer caster, @Nullable ExplorationMapCell targetCell) {

            this.item = item;

            this.caster = caster;

            this.targetCell = targetCell;

        }

        @Override

        public Boolean onExplorationPlayer(@Nullable ExplorationPlayer target) {

            if (!item.checkTarget(caster, target, targetCell)) {

                return false;

            }

            item.applyToTarget(caster, target, targetCell);

            return true;

        }

        @Override

        public Boolean onCreature(ExplorationCreature creature) {

            return onNull();

        }

        public Boolean onNull() {

            return onExplorationPlayer(null);

        }

    }

}