/*
 * Copyright (c) 2011-2020, baomidou (jobob@qq.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * <p>
 * https://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.ruoyi.common.numgen;

import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.core.metadata.TableInfoHelper;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.baomidou.mybatisplus.core.toolkit.support.ColumnCache;
import com.baomidou.mybatisplus.core.toolkit.support.SFunction;

import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;

import static java.util.Locale.ENGLISH;

/**
 * Lambda 解析工具类
 *
 * @author HCL, MieMie
 * @since 2018-05-10
 */
public final class LambdaUtils {

    /**
     * 字段映射
     */
    private static final Map<String, Map<String, ColumnCache>> COLUMN_CACHE_MAP = new ConcurrentHashMap<>();

    /**
     * SerializedLambda 反序列化缓存
     */
    private static final Map<String, WeakReference<SerializedLambda>> FUNC_CACHE = new ConcurrentHashMap<>();

    /**
     * 解析 lambda 表达式, 该方法只是调用了 {@link SerializedLambda#resolve(SFunction)} 中的方法，在此基础上加了缓存。
     * 该缓存可能会在任意不定的时间被清除
     *
     * @param func 需要解析的 lambda 对象
     * @param <T>  类型，被调用的 Function 对象的目标类型
     * @return 返回解析后的结果
     * @see SerializedLambda#resolve(SFunction)
     */
    public static <T> SerializedLambda resolve(SFunction<T, ?> func) {
        Class<?> clazz = func.getClass();
        String canonicalName = clazz.getCanonicalName();
        return Optional.ofNullable(FUNC_CACHE.get(canonicalName))
            .map(WeakReference::get)
            .orElseGet(() -> {
                SerializedLambda lambda = SerializedLambda.resolve(func);
                FUNC_CACHE.put(canonicalName, new WeakReference<>(lambda));
                return lambda;
            });
    }

    /**
     * 格式化 key 将传入的 key 变更为大写格式
     *
     * <pre>
     *     Assert.assertEquals("USERID", formatKey("userId"))
     * </pre>
     *
     * @param key key
     * @return 大写的 key
     */
    public static String formatKey(String key) {
        return key.toUpperCase(ENGLISH);
    }

    /**
     * 将传入的表信息加入缓存
     *
     * @param tableInfo 表信息
     */
    public static void installCache(TableInfo tableInfo) {
        COLUMN_CACHE_MAP.put(tableInfo.getEntityType().getName(), createColumnCacheMap(tableInfo));
    }

    /**
     * 缓存实体字段 MAP 信息
     *
     * @param info 表信息
     * @return 缓存 map
     */
    private static Map<String, ColumnCache> createColumnCacheMap(TableInfo info) {
        Map<String, ColumnCache> map = new HashMap<>();

        String kp = info.getKeyProperty();
        if (StringUtils.isNotBlank(kp)) {
            map.put(formatKey(kp), new ColumnCache(info.getKeyColumn(), info.getKeySqlSelect()));
        }

        info.getFieldList().forEach(i ->
            map.put(formatKey(i.getProperty()), new ColumnCache(i.getColumn(), i.getSqlSelect()))
        );
        return map;
    }

    /**
     * 获取实体对应字段 MAP
     *
     * @param clazz 实体类
     * @return 缓存 map
     */
    public static Map<String, ColumnCache> getColumnMap(Class<?> clazz) {
        return COLUMN_CACHE_MAP.computeIfAbsent(clazz.getName(), key -> {
            TableInfo info = TableInfoHelper.getTableInfo(clazz);
            return info == null ? null : createColumnCacheMap(info);
        });
    }

}