package qyweixin

import (
	"bytes"
	"crypto/hmac"
	"crypto/md5"
	"crypto/sha256"
	"encoding/hex"
	"encoding/xml"
	"fmt"
	"io"
	"sort"
	"strconv"
	"strings"
)

type params map[string]string

func newParams() params {
	return make(params)
}

func (p params) Set(k string, v interface{}) {
	p[k] = fmt.Sprintf("%v", v)
}

func (p params) GetString(k string) string {
	s, _ := p[k]
	return s
}

func (p params) GetUint64(k string) uint64 {
	s, _ := strconv.ParseUint(p[k], 10, 64)
	return s
}

func (p params) GetInt64(k string) int64 {
	i, _ := strconv.ParseInt(p.GetString(k), 10, 64)
	return i
}

func (p params) GetInt(k string) int64 {
	i, _ := strconv.ParseInt(p.GetString(k), 10, 64)
	return i
}

func (p params) GetFloat64(k string) float64 {
	f, _ := strconv.ParseFloat(p.GetString(k), 64)
	return f
}
func (p params) GetBool(k string) bool {
	b, _ := strconv.ParseBool(p.GetString(k))
	return b
}

// XML解码
func (p params) Decode(body []byte) (err error) {
	defer func() {
		if e := recover(); e != nil {
			err = fmt.Errorf("%v", e)
		}
	}()

	var (
		d     *xml.Decoder
		start *xml.StartElement
	)
	buf := bytes.NewBuffer(body)
	d = xml.NewDecoder(buf)
	for {
		tok, err := d.Token()
		if err != nil {
			break
		}
		switch t := tok.(type) {
		case xml.StartElement:
			start = &t
		case xml.CharData:
			if t = bytes.TrimSpace(t); len(t) > 0 {
				p.Set(start.Name.Local, string(t))
			}
		}
	}
	return nil
}

// XML编码
func (p params) Encode() []byte {
	var buf bytes.Buffer
	buf.WriteString(`<xml>`)
	for k, v := range p {
		buf.WriteString(`<`)
		buf.WriteString(k)
		buf.WriteString(`><![CDATA[`)
		buf.WriteString(v)
		buf.WriteString(`]]></`)
		buf.WriteString(k)
		buf.WriteString(`>`)
	}
	buf.WriteString(`</xml>`)
	return buf.Bytes()
}

// 验证签名
func (p params) CheckSign(key string) bool {
	return p.GetString("sign") == p.SignMd5(key)
}

//生成签名
func (p params) getSignStr(key string) string {
	var keys = make([]string, 0, len(p))
	for k, _ := range p {
		if k != "sign" {
			keys = append(keys, k)
		}
	}
	sort.Strings(keys)

	var buf bytes.Buffer
	for _, k := range keys {
		if len(p.GetString(k)) > 0 {
			buf.WriteString(k)
			buf.WriteString(`=`)
			buf.WriteString(p.GetString(k))
			buf.WriteString(`&`)
		}
	}
	buf.WriteString(`key=`)
	buf.WriteString(key)
	return buf.String()
}

func (p params) getQySignStr(secret string) string {
	keys := []string{"act_name", "mch_billno", "mch_id", "nonce_str", "re_openid", "total_amount", "wxappid"}
	sort.Strings(keys)

	var buf bytes.Buffer
	for _, k := range keys {
		buf.WriteString(k)
		buf.WriteString(`=`)
		buf.WriteString(p.GetString(k))
		buf.WriteString(`&`)
	}
	buf.WriteString(`secret=`)
	buf.WriteString(secret)
	return buf.String()
}

// 生成签名
func (p params) QySignMd5(secret string) string {
	sum := md5.Sum([]byte(p.getQySignStr(secret)))
	str := hex.EncodeToString(sum[:])
	return strings.ToUpper(str)
}

// 生成签名
func (p params) SignMd5(key string) string {
	sum := md5.Sum([]byte(p.getSignStr(key)))
	str := hex.EncodeToString(sum[:])
	return strings.ToUpper(str)
}

// 生成签名
func (p params) SignHmacSha256(key string) string {
	h := hmac.New(sha256.New, []byte(key))
	io.WriteString(h, p.getSignStr(key))
	str := hex.EncodeToString(h.Sum(nil))
	return strings.ToUpper(str)
}