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package cn.schoolwow.quickdao.util;

import cn.schoolwow.quickdao.module.database.dql.condition.domain.SFunction;

import java.lang.invoke.SerializedLambda;
import java.lang.reflect.Method;
import java.util.Locale;

/**
 * lambda表达式工具类
 */
public class LambdaUtils {
    /**
     * 转换参数类型并调用实例方法
     *
     * @param args     方法参数
     * @param method   调用方法
     * @param instance 实例
     */
    public static Object invokeMethod(Object[] args, Method method, Object instance) throws Exception {
        //转换lambda参数
        Class[] parameterTypes = method.getParameterTypes();
        for (int i = 0; i < parameterTypes.length; i++) {
            Class parameterType = parameterTypes[i];
            if (parameterType.isArray() && parameterType.getComponentType().getName().equals(SFunction.class.getName())) {
                SFunction[] sFunctions = (SFunction[]) args[i];
                String[] convertParameterValues = new String[sFunctions.length];
                for (int j = 0; j < sFunctions.length; j++) {
                    convertParameterValues[j] = resolveLambdaProperty(sFunctions[j]);
                }
                args[i] = convertParameterValues;
                parameterTypes[i] = String[].class;
            } else if (parameterType.getName().equals(SFunction.class.getName())) {
                args[i] = resolveLambdaProperty((SFunction) args[i]);
                parameterTypes[i] = String.class;
            }
        }
        Method invokeMethod = instance.getClass().getMethod(method.getName(), parameterTypes);
        Object result = invokeMethod.invoke(instance, args);
        return result;
    }

    /**
     * 将Lambda表达式转化为属性名称
     *
     * @param sFunction lambda表达式
     */
    public static String resolveLambdaProperty(SFunction sFunction) {
        SerializedLambda serializedLambda = null;
        try {
            Method writeReplace = sFunction.getClass().getDeclaredMethod("writeReplace");
            writeReplace.setAccessible(true);
            serializedLambda = (SerializedLambda) writeReplace.invoke(sFunction);
        } catch (Exception e) {
            throw new RuntimeException("获取lambda表达式对应字段名失败!");
        }

        String methodName = serializedLambda.getImplMethodName();
        if (methodName.startsWith("is")) {
            methodName = methodName.substring(2);
        } else if (methodName.startsWith("get") || methodName.startsWith("set")) {
            methodName = methodName.substring(3);
        } else {
            throw new IllegalArgumentException("lambda参数错误,方法名需以is,get,set开头!当前方法名:" + methodName);
        }
        if (methodName.length() == 1 || (methodName.length() > 1 && !Character
                .isUpperCase(methodName.charAt(1)))) {
            methodName = methodName.substring(0, 1).toLowerCase(Locale.ENGLISH) + methodName.substring(1);
        }
        return methodName;
    }
}