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package org.aoju.bus.mapper.genid;

import org.aoju.bus.core.exception.InternalException;
import org.aoju.bus.mapper.reflect.MetaObject;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 不提供具体的实现，这里提供一个思路
 * 在 Spring 集成环境中，可以通过配置静态方式获取 Spring 的 context 对象
 * 如果使用 vesta(https://gitee.com/robertleepeak/vesta-id-generator) 来生成 ID，假设已经提供了 vesta 的 idService
 *
 * @author Kimi Liu
 * @since Java 17+
 */
public interface GenId {

    Map, GenId> CACHE = new ConcurrentHashMap<>();
    ReentrantLock LOCK = new ReentrantLock();

    /**
     * 生成 Id
     *
     * @param target   目标对象
     * @param property 属性
     * @param genClass class
     * @param table    表
     * @param column   列
     * @throws InternalException 异常
     */
    static void genId(Object target, String property, Class genClass, String table, String column) throws InternalException {
        try {
            GenId genId;
            if (CACHE.containsKey(genClass)) {
                genId = CACHE.get(genClass);
            } else {
                LOCK.lock();
                try {
                    if (!CACHE.containsKey(genClass)) {
                        CACHE.put(genClass, genClass.getConstructor().newInstance());
                    }
                    genId = CACHE.get(genClass);
                } finally {
                    LOCK.unlock();
                }
            }
            org.apache.ibatis.reflection.MetaObject metaObject = MetaObject.forObject(target);
            if (metaObject.getValue(property) == null) {
                Object id = genId.genId(table, column);
                metaObject.setValue(property, id);
            }
        } catch (Exception e) {
            throw new InternalException("生成 ID 失败!", e);
        }
    }

    T genId(String table, String column);

    class NULL implements GenId {
        @Override
        public Object genId(String table, String column) {
            throw new UnsupportedOperationException();
        }
    }

}