CommonUtils

import cn.hutool.core.io.file.FileReader;
import cn.hutool.core.util.StrUtil;
import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.collections.CollectionUtils;


import java.io.File;
import java.lang.reflect.Method;
import java.util.*;

/**
 * 通用工具类
 */
public class CommonUtils {

    public static Boolean checkFileExist(String filePath){
        return new File(filePath).exists();
    }

    /**
     * 读取文件，获取文件中字符串
     *
     * @param filePath 文件路径，相对，绝对都行
     * @return
     */
    public static String readFile(String filePath) {

        FileReader fileReader = new FileReader(filePath);
        return fileReader.readString();

    }

    /**
     * 全量list分页
     *
     * @param list
     * @param page
     * @param pSize
     * @param <E>
     * @return
     */
    public static <E> List<E> safeGetPagination(List<E> list, int page, int pSize) {
        int start = (page - 1) * pSize;
        int offset = page * pSize;
        int size = list.size();
        if (size == 0 || start >= size || offset <= 0) {
            return new ArrayList<E>(0);
        }
        start = Math.max(start, 0);
        List<E> returnList = new ArrayList<E>();
        returnList.addAll(list.subList(start, Math.min(size, offset)));
        return returnList;
    }

    public static <E> List<E> mapLikeKey(Map<String, E> map, String k) {
        List<E> list = new ArrayList<>();
        for (Map.Entry entry : map.entrySet()) {
            String key = (String) entry.getKey();
            if (key.contains(k)) {
                list.add((E) entry.getValue());
            }
        }
        return list;
    }

    /**
     * 对forfind结构进行遍历，propertyname值为value的元素列表并返回，假设找不到，那么返回空集合
     * 不支持target的fieldname为null的情况。
     *
     * @param forFind
     * @return
     */
    public static <T, S> List<T> findMatchingItemsByProperty(Iterable<T> forFind, S value, String propertyName, Class<S> clazz) {
        Object compare1, compare2;
        try {
            compare1 = value;
        } catch (Exception e) {
            throw new IllegalArgumentException("please check all arguments, especially fieldName and its getter method.");
        }
        List<T> returnList = new ArrayList<T>();
        for (Iterator iterator = forFind.iterator(); iterator.hasNext(); ) {
            T temp = (T) iterator.next();
            try {
                compare2 = PropertyUtils.getProperty(temp, propertyName);
                if ((compare1 == null && compare2 == null) || compare1.equals(compare2)) {
                    returnList.add(temp);
                } else {
                    continue;
                }
            } catch (Exception e) {
            }
        }
        //can not find
        return returnList;
    }

    /***
     * 根据bean的某个非空属性propertyName获取数据列表， 其中propertyName首字母必须大写
     *
     * @param list
     * @param propertyName
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <T> List<T> safeGetByPropertyValue(List<? extends Object> list, String propertyName) {
        if (CollectionUtils.isEmpty(list)) {
            return new ArrayList<T>();
        }

        List<T> retList = new ArrayList<T>(list.size());
        Set<T> set = new HashSet<T>(list.size());
        Class<?> clz = list.get(0).getClass();
        Method mth = getPropertyMethod(clz, propertyName);

        for (Object item : list) {
            Object value = null;
            try {
                value = mth.invoke(item);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
            if (value == null) {
                continue;
            }
            set.add((T) value);
        }
        retList.addAll(set);
        return retList;
    }

    private static Method getPropertyMethod(Class clz, String propertyName) {
        Method mth = null;
        propertyName = upperFirstChar(propertyName);

        try {
            mth = clz.getMethod("get" + propertyName);
        } catch (Exception var6) {
            try {
                mth = clz.getMethod("is" + propertyName);
            } catch (Exception var5) {
                throw new RuntimeException(var5);
            }
        }

        return mth;
    }

    /**
     * 第一个首字母大写
     *
     * @param source
     * @return
     */
    private static String upperFirstChar(String source) {
        if (StrUtil.isBlank(source)) {
            return "";
        } else {
            Character firstChar = source.charAt(0);
            return Character.isLowerCase(firstChar) ? Character.toUpperCase(firstChar) + source.substring(1) : source;
        }
    }
}