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) 2017-2020 Vincent Quatrevieux

 */

package fr.quatrevieux.araknemu.game.fight.ai;

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

import fr.quatrevieux.araknemu.game.fight.ai.action.ActionGenerator;

import fr.quatrevieux.araknemu.game.fight.ai.action.FightAiActionFactoryAdapter;

import fr.quatrevieux.araknemu.game.fight.ai.util.AIHelper;

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

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

import fr.quatrevieux.araknemu.game.fight.map.BattlefieldMap;

import fr.quatrevieux.araknemu.game.fight.turn.Turn;

import fr.quatrevieux.araknemu.game.fight.turn.action.Action;

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

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

import java.time.Duration;

import java.util.Optional;

import java.util.stream.Stream;

/**

 * Base class to handle AI actions

 *

 * Note: The AI execution is deferred, each action is executed by the fight executor,

 *       and the next action is scheduled after the last one.

 *       So the AI execution is not blocking, and executed in parallel of the turn timer.

 */

public final class FighterAI implements Runnable, AI<Fighter> {

    private final Fighter fighter;

    private final Fight fight;

    private final ActionGenerator<Fighter> generator;

    private final AIHelper helper;

    private @Nullable Turn turn;

    /**

     * Creates the AI

     *

     * @param fighter The fighter to control

     * @param generator The action generator

     */

    @SuppressWarnings({"argument", "assignment"})

    public FighterAI(Fighter fighter, Fight fight, ActionGenerator<Fighter> generator) {

        this.fighter = fighter;

        this.fight = fight;

        this.generator = generator;

        this.helper = new AIHelper(this);

    }

    @Override

    public void start(Turn turn) {

        this.turn = turn;

        generator.initialize(this);

        fight.execute(this);

    }

    @Override

    public void run() {

        if (turn == null) {

            throw new IllegalStateException("AI#start() must be called before run()");

        }

        final Turn currentTurn = turn;

        if (!currentTurn.active()) {

            turn = null;

            return;

        }

        final Optional<Action> action = generator.generate(

            this,

            new FightAiActionFactoryAdapter(

                fighter,

                fight,

                fight.actions()

            )

        );

        if (action.isPresent()) {

            currentTurn.perform(action.get());

            currentTurn.later(() -> fight.schedule(this, Duration.ofMillis(800)));

            return;

        }

        turn = null;

        currentTurn.stop();

    }

    @Override

    public BattlefieldMap map() {

        return fight.map();

    }

    @Override

    public @NonNull Turn turn() {

        if (turn == null) {

            throw new IllegalStateException("AI must be started");

        }

        return turn;

    }

    @Override

    public Stream<? extends FighterData> fighters() {

        return fight.fighters().stream().filter(other -> !other.dead());

    }

    @Override

    public Optional<? extends FighterData> enemy() {

        return helper.enemies().nearest();

    }

    @Override

    public AIHelper helper() {

        return helper;

    }

}