package com.ycl.dataListener;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.metadata.data.ReadCellData;
import com.alibaba.excel.read.listener.ReadListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.Consumer;

/**
 * 通用easyexcel数据监听器
 *
 * @author：xp
 * @date：2024/8/6 15:04
 */
public class CurrencyDataListener<T> implements ReadListener<T> {

    private Consumer<List<T>> consumer;

    /**
     * 每隔100条存储数据库，然后清理list ，方便内存回收
     */
    private static final int BATCH_COUNT = 500;

    /**
     * 缓存的数据
     */
    private List<T> cachedDataList = new ArrayList<>(BATCH_COUNT);

    private final static Logger log = LoggerFactory.getLogger(CurrencyDataListener.class);

    public CurrencyDataListener(Consumer<List<T>> consumer) {
        this.consumer = consumer;
    }

    /**
     * 读取出现异常处理
     * @param e
     * @param analysisContext
     * @throws Exception
     */
    @Override
    public void onException(Exception e, AnalysisContext analysisContext) throws Exception {

    }

    /**
     * 处理表头
     * @param map
     * @param analysisContext
     */
    @Override
    public void invokeHead(Map<Integer, ReadCellData<?>> map, AnalysisContext analysisContext) {

    }

    /**
     * 读取数据,每一条数据解析都会来调用
     * @param data
     * @param analysisContext
     */
    @Override
    public void invoke(T data, AnalysisContext analysisContext) {
        cachedDataList.add(data);
        // 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
        if (cachedDataList.size() >= BATCH_COUNT) {
            try {
                saveData();
            } catch(Exception e) {
                // 这里需要捕获异常，否则list无法清空，导致每读一条数据就会执行saveData方法
            }
            // 存储完成清理 list
            cachedDataList = new ArrayList<>(BATCH_COUNT);
        }
    }

    /**
     * 读取完成
     * @param analysisContext
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
        saveData();
        log.info("所有数据解析完成！");
    }

    @Override
    public boolean hasNext(AnalysisContext analysisContext) {
        return true;
    }

    private void saveData() {
        log.info("{}条数据，开始存储数据库！", cachedDataList.size());
        consumer.accept(cachedDataList);
        log.info("存储数据库成功！");
    }

}