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.fight.turn;

import fr.quatrevieux.araknemu.game.fight.Fight;

import fr.quatrevieux.araknemu.game.fight.fighter.Fighter;

import fr.quatrevieux.araknemu.game.fight.turn.event.NextTurnInitiated;

import fr.quatrevieux.araknemu.game.fight.turn.event.TurnListChanged;

import fr.quatrevieux.araknemu.game.fight.turn.order.FighterOrderStrategy;

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

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

import java.util.List;

import java.util.NoSuchElementException;

import java.util.Optional;

import java.util.concurrent.atomic.AtomicBoolean;

/**

 * Handle fight turns

 */

public final class FightTurnList {

    private final Fight fight;

    private final List<Fighter> fighters;

    private Fighter current;

    private @Nullable FightTurn turn;

    private int index;

    private final AtomicBoolean active = new AtomicBoolean(false);

    public FightTurnList(Fight fight, FighterOrderStrategy orderStrategy) {

        this.fight = fight;

        this.fighters = orderStrategy.compute(fight.teams());

        if (fighters.isEmpty()) {

            throw new IllegalStateException("Cannot initialise turn list without fighters");

        }

        current = fighters.get(0); // Always init the first fighter

    }

    /**

     * Get all fighters ordered by their turn order

     */

    /**

     * Remove a fighter from turn list

     *

     * @param fighter Fighter to remove

     *

     * @see TurnListChanged Event triggered after the list is updated

     */

    public void remove(Fighter fighter) {

        if (index == -1) {

            throw new NoSuchElementException("Fighter " + fighter.id() + " is not found on the turn list");

        }

        fighters.remove(index);

        // The removed fighter is the current fighter or before on the list

        // so removing it will shift the list to the left relatively to the cursor (current)

        // which cause that the next fighter will be skipped

        // See: https://github.com/Arakne/Araknemu/issues/127

        if (index <= this.index) {

            // If current is negative, move cursor to the end

            if (--this.index < 0) {

                this.index += fighters.size();

            }

        }

        fight.dispatch(new TurnListChanged(this));

    }

    /**

     * Add a fighter after the current one

     *

     * @param fighter Fighter to add

     *

     * @see TurnListChanged Event triggered after the list is updated

     */

    public void add(Fighter fighter) {

        fighters.add(index + 1, fighter);

        fight.dispatch(new TurnListChanged(this));

    }

    /**

     * Get the current turn

     *

     */

    public Optional<FightTurn> current() {

        return Optional.ofNullable(turn);

    }

    /**

     * Get the current turn fighter

     */

    public Fighter currentFighter() {

        return current;

    }

    /**

     * Start the turn system

     */

    public void start() {

        if (active.getAndSet(true)) {

            throw new IllegalStateException("TurnList already started");

        }

        index = -1;

        next();

    }

    /**

     * Stop the turn system

     */

    public void stop() {

        if (!active.getAndSet(false)) {

            return;

        }

        if (turn != null) {

            turn.stop();

            turn = null;

        }

    }

    /**

     * Stop the current turn and start the next

     *

     */

    void next() {

        // next is called internally by turn system, and fighters if used only with active turn system

        // so fighters is always non-null

        turn = null;

        fight.dispatch(new NextTurnInitiated());

        while (active.get()) {

            if (++index >= fighters.size()) {

                index = 0;

            }

            if (fighters.get(index).dead()) {

                continue;

            }

            current = fighters.get(index);

            turn = new FightTurn(current, fight, fight.type().turnDuration());

            if (turn.start()) {

                break;

            }

        }

    }

}