package pay

import (
	"crypto"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/base64"
	"encoding/pem"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"strings"
	"time"
	"zhiyuan/models"
	"zhiyuan/pkg/config"
	"zhiyuan/pkg/utils"
	"zhiyuan/services/weixin"
)

const (
	JsapiUrl                  = "https://api.mch.weixin.qq.com/v3/pay/transactions/jsapi"
	HeaderAuthorizationFormat = "WECHATPAY2-SHA256-RSA2048 mchid=\"%s\",nonce_str=\"%s\",timestamp=\"%d\",serial_no=\"%s\",signature=\"%s\""
	Authorization             = "Authorization"
	Accept                    = "Accept"
)

type Client struct {
	Account    *models.Weixin // 支付账号
	SignType   string         // 签名类型
	PrivateKey *rsa.PrivateKey
}

func NewClient(wxID int) (*Client, error) {
	weixinInfo, _ := weixin.GetOne(map[string]interface{}{"id": wxID}, nil, nil)
	private, err := LoadPrivateKey()
	if err != nil {
		return nil, err
	}
	return &Client{
		Account:    weixinInfo,
		SignType:   "RSA",
		PrivateKey: private,
	}, nil
}

func (c *Client) SignRequest(method string, requestUrl string, body string) (string, error) {
	u, err := url.Parse(requestUrl)
	timestamp := time.Now().Unix()
	nonce := utils.RandomStr()
	sign, err := c.Sign([]string{method, u.RequestURI(), utils.ToStr(timestamp), nonce, body})
	if err != nil {
		return "", err
	}
	return fmt.Sprintf(HeaderAuthorizationFormat,
		c.Account.MchID,
		nonce,
		timestamp,
		c.Account.SerialNO,
		sign,
	), nil
}

func (c *Client) Sign(param []string) (string, error) {
	message := strings.Join(param, "\n") + "\n"
	return SignSHA256WithRSA(message, c.PrivateKey)
}

func (c *Client) Prepay(param JsapiParam) (*PrepayResponse, error) {
	if param.Description == "" || param.OutTradeNO == "" || param.Total <= 0 || param.OpenID == "" {
		return nil, errors.New("description,out_trade_no,open_id,money不能为空")
	}
	params := PrepayRequest{
		AppID:       c.Account.AppID,
		MchID:       c.Account.MchID,
		Description: param.Description,
		OutTradeNO:  param.OutTradeNO,
		NotifyUrl:   param.NotifyUrl,
	}
	params.Amount.Total = utils.FloatMul(param.Total, 100, 0)
	params.Payer.OpenID = param.OpenID
	fmt.Println(params)

	authorization, err := c.SignRequest("POST", JsapiUrl, utils.JsonEncode(params))
	if err != nil {
		return nil, err
	}
	header := SetHeaderAuthorization(authorization)
	var res *PrepayResponse
	if err := utils.HttpPostJSON(&http.Client{}, JsapiUrl, header, params, &res); err != nil {
		return nil, err
	}
	if res.PrepayID == "" {
		return nil, errors.New(res.Message)
	}
	return res, nil
}

func (c *Client) JsapiPay(param JsapiParam) (JsapiReturn, error) {
	res, err := c.Prepay(param)
	if err != nil {
		return JsapiReturn{}, err
	}
	retParam := JsapiReturn{
		AppID:     c.Account.AppID,
		Timestamp: utils.ToStr(time.Now().Unix()),
		NonceStr:  utils.RandomStr(),
		Package:   "prepay_id=" + res.PrepayID,
		SignType:  c.SignType,
	}
	if sign, err := c.Sign([]string{retParam.AppID, retParam.Timestamp, retParam.NonceStr, retParam.SignType}); err != nil {
		return JsapiReturn{}, err
	} else {
		retParam.PaySign = sign
		return retParam, nil
	}
}

func SetHeaderAuthorization(authorization string) http.Header {
	header := http.Header{}
	header.Set(Authorization, authorization)
	header.Set(Accept, "*/*")
	return header
}

func LoadPrivateKey() (*rsa.PrivateKey, error) {
	privateKeyStr, err := ioutil.ReadFile(utils.GetRootPath() + config.Cfg.App.WeixinPath + "apiclient_key.pem")
	block, _ := pem.Decode(privateKeyStr)
	if block == nil {
		return nil, fmt.Errorf("decode private key err")
	}
	key, err := x509.ParsePKCS8PrivateKey(block.Bytes)
	if err != nil {
		return nil, fmt.Errorf("parse private key err:%s", err.Error())
	}
	privateKey, ok := key.(*rsa.PrivateKey)
	if !ok {
		return nil, fmt.Errorf("%s is not rsa private key", privateKeyStr)
	}
	return privateKey, nil
}

func SignSHA256WithRSA(source string, privateKey *rsa.PrivateKey) (signature string, err error) {
	if privateKey == nil {
		return "", fmt.Errorf("private key should not be nil")
	}
	h := crypto.Hash.New(crypto.SHA256)
	_, err = h.Write([]byte(source))
	if err != nil {
		return "", nil
	}
	hashed := h.Sum(nil)
	signatureByte, err := rsa.SignPKCS1v15(rand.Reader, privateKey, crypto.SHA256, hashed)
	if err != nil {
		return "", err
	}
	return base64.StdEncoding.EncodeToString(signatureByte), nil
}