package pay

import (
	"errors"
	"encoding/xml"
	"fmt"	
	"github.com/silenceper/wechat/context"
	"github.com/silenceper/wechat/util"
)

var payGateway = "https://api.mch.weixin.qq.com/pay/unifiedorder"

// Pay struct extends context
type Pay struct {
	*context.Context
}

// 传入的参数，用于生成 prepay_id 的必需参数
// PayParams was NEEDED when request unifiedorder
type PayParams struct {
	TotalFee    string
	CreateIP    string
	Body        string
	OutTradeNo  string
	OpenID      string
}

// PayConfig 是传出用于 jsdk 用的参数
type PayConfig struct {
	Timestamp       int64
	NonceStr        string
	PrePayID        string
	SignType        string
	Sign            string
}

// payResult 是 unifie order 接口的返回
type payResult struct {
	ReturnCode      string `xml:"return_code"`
	ReturnMsg       string `xml:"return_msg"`
	AppID           string `xml:"appid,omitempty"`
	MchID           string `xml:"mch_id,omitempty"`
	NonceStr        string `xml:"nonce_str,omitempty"`
	Sign            string `xml:"sign,omitempty"`
	ResultCode      string `xml:"result_code,omitempty"`
	TradeType       string `xml:"trade_type,omitempty"`
	PrePayID        string `xml:"prepay_id,omitempty"`
	CodeURL         string `xml:"code_url,omitempty"`
	ErrCode         string `xml:"err_code,omitempty"`
	ErrCodeDes      string `xml:"err_code_des,omitempty"`
}

//payRequest 接口请求参数
type payRequest struct {
	AppID           string `xml:"appid"`
	MchID           string `xml:"mch_id"`
	DeviceInfo      string `xml:"device_info,omitempty"`
	NonceStr        string `xml:"nonce_str"`
	Sign            string `xml:"sign"`
	SignType        string `xml:"sign_type,omitempty"`
	Body            string `xml:"body"`
	Detail          string `xml:"detail,omitempty"`
	Attach          string `xml:"attach,omitempty"` //附加数据
	OutTradeNo      string `xml:"out_trade_no"` //商户订单号
	FeeType         string `xml:"fee_type,omitempty"` //标价币种
	TotalFee        string `xml:"total_fee"` //标价金额
	SpbillCreateIp  string `xml:"spbill_create_ip"` //终端IP
	TimeStart       string `xml:"time_start,omitempty"`  //交易起始时间
	TimeExpire      string `xml:"time_expire,omitempty"`  //交易结束时间
	GoodsTag        string `xml:"goods_tag,omitempty"`  //订单优惠标记
	NotifyUrl       string `xml:"notify_url"` //通知地址	
	TradeType       string `xml:"trade_type"` //交易类型
	ProductId       string `xml:"product_id,omitempty"`  //商品ID
	LimitPay        string `xml:"limit_pay,omitempty"` //
	OpenID          string `xml:"openid,omitempty"` //用户标识
	SceneInfo       string `xml:"scene_info,omitempty"` //场景信息	
}

// NewPay return an instance of Pay package
func NewPay(ctx *context.Context) *Pay {
	pay := Pay{Context: ctx}
	return &pay
}

// PrePayId will request wechat merchant api and request for a pre payment order id
func (pcf *Pay) PrePayId(p *PayParams) (prePayID string, err error) {
	nonceStr := util.RandomStr(32)
	tradeType := "JSAPI"
	template := "appid=%s&body=%s&mch_id=%s&nonce_str=%s&notify_url=%s&openid=%s&out_trade_no=%s&spbill_create_ip=%s&total_fee=%s&trade_type=%s&key=%s"
	str := fmt.Sprintf(template, pcf.AppID, p.Body, pcf.PayMchID, nonceStr, pcf.PayNotifyURL, p.OpenID, p.OutTradeNo, p.CreateIP, p.TotalFee, tradeType, pcf.PayKey)
	sign := util.MD5Sum(str)
	request := payRequest{
		AppID: pcf.AppID,
		MchID: pcf.PayMchID,
		NonceStr: nonceStr,
		Sign: sign,
		Body: p.Body,
		OutTradeNo: p.OutTradeNo,
		TotalFee: p.TotalFee,
		SpbillCreateIp: p.CreateIP,
		NotifyUrl: pcf.PayNotifyURL,		
		TradeType: tradeType,
		OpenID: p.OpenID,
	}
	rawRet, err := util.PostXML(payGateway, request)
	if err != nil {
		return "", errors.New(err.Error() + " parameters : " + str)
	}
	payRet := payResult{}
	err = xml.Unmarshal(rawRet, &payRet)
	if err != nil {
		return "", errors.New(err.Error())
	}
	if payRet.ReturnCode == "SUCCESS" {
		//pay success
		if payRet.ResultCode == "SUCCESS" {
			return payRet.PrePayID, nil
		}
		return "", errors.New(payRet.ErrCode + payRet.ErrCodeDes)
	} else {
		return "", errors.New("[msg : xmlUnmarshalError] [rawReturn : " + string(rawRet) + "] [params : " + str + "] [sign : " + sign + "]")		
	}
}