package com.jsowell.common.util;

import lombok.extern.slf4j.Slf4j;

import java.math.BigDecimal;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.text.DecimalFormat;
import java.util.Base64;

/**
 * 汇付支付的工具类
 */
@Slf4j
public class AdapayUtil {

	public static void main(String[] args) {
		String amount = "1110.5309";
		String s = formatAmount(amount);
		System.out.println(s);

		BigDecimal bigDecimal = new BigDecimal(amount);
		String s2 = formatAmount(bigDecimal);
		System.out.println(s2);
	}

	/**
	 * 格式化数字  保留两位小数，不足补0
	 * @param amount
	 * @return
	 */
	public static String formatAmount(String amount) {
		//保留2位小数
		double d = new BigDecimal(amount).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
		//不足两位则补0
		DecimalFormat decimalFormat = new DecimalFormat("0.00#");
		return decimalFormat.format(d);
	}

	/**
	 * 格式化数字  保留两位小数，不足补0
	 * @param amount
	 * @return
	 */
	public static String formatAmount(BigDecimal amount) {
		return formatAmount(amount.toString());
	}

	/**
	 * RSA私钥签名：签名方式SHA256WithRSA
	 * @param data 待签名字符串
	 * @param privateKeyBase64 私钥（Base64编码）
	 * @return 签名byte[]
	 * @throws Exception
	 */
	public static String sign(String data, String privateKeyBase64) {
		// Base64 --> Key
		try {
			byte[] bytes = Base64.getDecoder().decode(privateKeyBase64);
			PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(bytes);
			KeyFactory keyFactory;
			keyFactory = KeyFactory.getInstance("RSA");
			PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
			// Sign
			Signature signature = Signature.getInstance("SHA256WithRSA");
			signature.initSign(privateKey);
			signature.update(data.getBytes(StandardCharsets.UTF_8));
			return Base64.getEncoder().encodeToString(signature.sign());
		} catch (Exception e) {
			log.error("sign Exception", e);
			return null;
		}
	}

	/**
	 * 使用汇付RSA公钥验签
	 * @param data 待签名字符串
	 * @param publicKeyBase64 公钥（Base64编码）
	 * @return 验签结果
	 * @throws Exception
	 */
	public static boolean verify(String data, String publicKeyBase64, String sign) {
		// Base64 --> Key
		try {
			byte[] bytes = Base64.getDecoder().decode(publicKeyBase64);
			X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes);
			KeyFactory keyFactory;
			keyFactory = KeyFactory.getInstance("RSA");
			PublicKey publicKey = keyFactory.generatePublic(keySpec);
			// verify
			Signature signature = Signature.getInstance("SHA256WithRSA");
			signature.initVerify(publicKey);
			signature.update(data.getBytes(StandardCharsets.UTF_8));
			return signature.verify(Base64.getDecoder().decode(sign));
		} catch (Exception e) {
			log.error("verify Exception", e);
			return false;
		}
	}

}