BauSystem2.0/BauSystem_Main/src/de/steamwar/bausystem/linkage/LinkageUtils.java

/*
 * This file is a part of the SteamWar software.
 *
 * Copyright (C) 2021  SteamWar.de-Serverteam
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package de.steamwar.bausystem.linkage;

import de.steamwar.bausystem.BauSystem;
import lombok.experimental.UtilityClass;
import org.bukkit.Bukkit;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.*;
import java.util.logging.Level;

@UtilityClass
public class LinkageUtils {

    private Map<Class<?>, Object> objectMap = new HashMap<>();
    private Set<Field> fieldsToLink = new HashSet<>();

    public void link() {
        internalLinkOrUnlink(false, Linked.class);
        internalLinkOrUnlink(false, Linked.Linkages.class);
        internalLinkFields();
    }

    public void unlink() {
        internalLinkOrUnlink(true, Linked.Linkages.class);
        internalLinkOrUnlink(true, Linked.class);
    }

    private void internalLinkOrUnlink(boolean unlink, Class<?> toLink) {
        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(BauSystem.class.getResourceAsStream("/de.steamwar.bausystem/" + toLink.getTypeName().replace("$", "."))))) {
            bufferedReader.lines().forEach(s -> {
                try {
                    linkOrUnlink(Class.forName(s), unlink);
                } catch (ClassNotFoundException e) {
                    // ignored
                } catch (Exception e) {
                    Bukkit.getLogger().log(Level.WARNING, e.getMessage(), e);
                }
            });
        } catch (IOException e) {
            Bukkit.shutdown();
        } catch (NullPointerException e) {
            // Ignored
        }
    }

    private void internalLinkFields() {
        for (Field field : fieldsToLink) {
            LinkedInstance linkedInstance = field.getDeclaredAnnotation(LinkedInstance.class);
            if (linkedInstance == null) {
                continue;
            }
            Object object = objectMap.getOrDefault(linkedInstance.value(), null);
            Object source = objectMap.getOrDefault(field.getDeclaringClass(), null);
            try {
                field.setAccessible(true);
                field.set(source, object);
            } catch (IllegalAccessException e) {
                // Ignored
            }
        }
    }

    private void linkOrUnlink(Class<?> clazz, boolean unlink) {
        Linked[] linkages = clazz.getDeclaredAnnotationsByType(Linked.class);
        if (linkages.length == 0) {
            return;
        }

        List<LinkageType> linkageTypeList = new ArrayList<>();
        for (Linked linked : linkages) {
            if (linked == null) {
                continue;
            }
            LinkageType linkageType = linked.value();
            if (linkageType.getLinkagePredicate().test(clazz)) {
                linkageTypeList.add(linked.value());
            }
        }

        linkageTypeList.removeIf(linkageType -> linkageType.isUnlink() != unlink);
        if (linkageTypeList.isEmpty()) {
            return;
        }

        linkageTypeList.sort(Comparator.comparingInt(LinkageType::getOrder));
        if (unlink) {
            Object object = objectMap.remove(clazz);
            if (object == null) {
                return;
            }
            linkageTypeList.forEach(linkageType -> linkageType.getLinkageConsumer().accept(object));
        } else {
            Object object = objectMap.computeIfAbsent(clazz, LinkageUtils::constructInstance);
            linkageTypeList.forEach(linkageType -> linkageType.getLinkageConsumer().accept(object));

            for (Field field : clazz.getDeclaredFields()) {
                LinkedInstance linkedInstance = field.getDeclaredAnnotation(LinkedInstance.class);
                if (linkedInstance == null) {
                    continue;
                }
                if (!field.getType().isAssignableFrom(linkedInstance.value())) {
                    continue;
                }
                fieldsToLink.add(field);
            }
        }
    }

    private Object constructInstance(Class<?> clazz) {
        try {
            Constructor<?> constructor = clazz.getDeclaredConstructor();
            constructor.setAccessible(true); //NOSONAR
            return constructor.newInstance();
        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException | InstantiationException e) {
            throw new SecurityException(e.getMessage(), e.getCause());
        }
    }
}