eta_data_analysis/services/base_from_ccf/common.go

package base_from_ccf

import (
	"bytes"
	"compress/gzip"
	"encoding/json"
	"eta/eta_data_analysis/utils"
	"fmt"
	"github.com/PuerkitoBio/goquery"
	"golang.org/x/net/html/charset"
	"golang.org/x/text/encoding/simplifiedchinese"
	"golang.org/x/text/transform"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"
)

const (
	CCFSearchPageUrl       = "https://www.ccf.com.cn/newscenter/simplesearch.php" // CCF搜索页地址
	CCFReportDetailBaseUrl = "https://www.ccf.com.cn"                             // CCF报告详情页地址
)

// postEdbLib 调用指标接口
func postEdbLib(param map[string]interface{}, method string) (result []byte, err error) {
	postUrl := utils.EDB_LIB_URL + method
	postData, err := json.Marshal(param)
	if err != nil {
		return
	}
	result, err = httpPost(postUrl, string(postData), "application/json")
	if err != nil {
		return
	}
	return
}

// httpPost HTTP请求
func httpPost(url, postData string, params ...string) ([]byte, error) {
	fmt.Println("httpPost Url:" + url)
	body := ioutil.NopCloser(strings.NewReader(postData))
	client := &http.Client{}
	req, err := http.NewRequest("POST", url, body)
	if err != nil {
		return nil, err
	}
	contentType := "application/x-www-form-urlencoded;charset=utf-8"
	if len(params) > 0 && params[0] != "" {
		contentType = params[0]
	}
	req.Header.Set("Content-Type", contentType)
	req.Header.Set("authorization", utils.MD5(utils.APP_EDB_LIB_NAME_EN+utils.EDB_LIB_Md5_KEY))
	resp, err := client.Do(req)
	if err != nil {
		fmt.Println("client.Do err:" + err.Error())
		return nil, err
	}
	defer resp.Body.Close()
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		fmt.Println("httpPost:" + string(b))
	}
	return b, err
}

// fetchPageHtml 获取网站HTML文本
func fetchPageHtml(baseUrl string) (respBody []byte, err error) {
	defer func() {
		if err != nil {
			tips := fmt.Sprintf("BuildCCFRequest ErrMsg: %s", err.Error())
			utils.FileLog.Info(tips)
			fmt.Println(tips)
		}
	}()
	if baseUrl == "" {
		err = fmt.Errorf("CCF请求地址为空")
		return
	}

	// 读取Cookie
	if utils.CCFCookieFile == "" {
		err = fmt.Errorf("cookie文件未配置")
		return
	}
	cookieByte, e := ioutil.ReadFile(utils.CCFCookieFile)
	if e != nil {
		err = fmt.Errorf("读取cookie文件失败, err: %s", e.Error())
		return
	}
	strCookie := strings.TrimSpace(string(cookieByte))
	if strCookie == "" {
		err = fmt.Errorf("cookie为空")
		return
	}

	// 拉取网站内容
	cli := new(http.Client)
	req, e := http.NewRequest("GET", baseUrl, nil)
	if e != nil {
		err = fmt.Errorf("")
		return
	}

	req.Header.Set("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7")
	req.Header.Set("Accept-Encoding", "gzip, deflate, br")
	req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6")
	req.Header.Set("Connection", "keep-alive")
	req.Header.Set("Cookie", strCookie)
	req.Header.Set("Host", "www.ccf.com.cn")
	req.Header.Set("Referer", baseUrl)
	req.Header.Set("Sec-Ch-Ua", "\"Not A(Brand\";v=\"99\", \"Microsoft Edge\";v=\"121\", \"Chromium\";v=\"121\"")
	req.Header.Set("Sec-Ch-Ua-Mobile", "?0")
	req.Header.Set("Sec-Ch-Ua-Platform", "\"Windows\"")
	req.Header.Set("Sec-Fetch-Dest", "empty")
	req.Header.Set("Sec-Fetch-Mode", "cors")
	req.Header.Set("Sec-Fetch-Site", "same-origin")
	req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36 Edg/121.0.0.0")
	req.Header.Set("X-Requested-With", "XMLHttpRequest")

	resp, e := cli.Do(req)
	if e != nil {
		err = fmt.Errorf("HTTP client Do err: %s", e.Error())
		return
	}
	defer func() {
		_ = resp.Body.Close()
	}()

	// 读取响应的内容
	reader, e := gzip.NewReader(resp.Body)
	if e != nil {
		err = fmt.Errorf("gzip NewReader err: %s", e.Error())
		return
	}
	body, e := ioutil.ReadAll(reader)
	if e != nil {
		err = fmt.Errorf("read body err: %s", e.Error())
		return
	}

	// 转换编码
	utf8Reader, e := charset.NewReaderLabel("gb2312", bytes.NewReader(body))
	if e != nil {
		err = fmt.Errorf("utf8 reader err: %s", e.Error())
		return
	}
	utf8Body, e := ioutil.ReadAll(utf8Reader)
	if e != nil {
		err = fmt.Errorf("utf8 body err: %s", e.Error())
		return
	}
	respBody = utf8Body
	return
}

// DataRule 数据爬取规则
type DataRule struct {
	Name      string `json:"Name"`
	Frequency string `json:"Frequency"`
	PageDir   string `json:"PageDir"`
	Search    struct {
		ClassId      string `json:"ClassId"`
		SubClassId   string `json:"SubClassId"`
		ProductId    string `json:"ProductId"`
		SubProductId string `json:"SubProductId"`
		SimpleTerms  string `json:"SimpleTerms"`
	} `json:"Search"`
	TableFetch []struct {
		Keyword string `json:"Keyword"`
		Unit    string `json:"Unit"`
	} `json:"TableFetch"`
	EdbMatch   []DataRuleEdbMatch `json:"EdbMatch"`
	StockTable struct {
		ClassifyId int `json:"ClassifyId"`
	} `json:"StockTable"`
}

// DataRuleEdbMatch 数据爬取规则-指标匹配
type DataRuleEdbMatch struct {
	IndexCode  string `json:"IndexCode"`
	IndexName  string `json:"IndexName"`
	ClassifyId int    `json:"ClassifyId"`
	Frequency  string `json:"Frequency"`
	Product    string `json:"Product"`
	Market     string `json:"Market"`
	MatchUnit  string `json:"MatchUnit" description:"匹配单位"`
	Unit       string `json:"Unit" description:"实际单位"`
}

// loadDataRule 从配置中读取爬取规则
func loadDataRule(nameKey string) (fetchRule *DataRule, err error) {
	if utils.CCFDataRuleFile == "" {
		err = fmt.Errorf("rule文件不存在")
		return
	}
	b, e := ioutil.ReadFile(utils.CCFDataRuleFile)
	if e != nil {
		err = fmt.Errorf("读取rule文件失败, err: %v", e)
		return
	}
	rules := make([]*DataRule, 0)
	if e = json.Unmarshal(b, &rules); e != nil {
		err = fmt.Errorf("解析rule文件失败, err: %v", e)
		return
	}
	for _, v := range rules {
		if v.Name != "" && v.Name == nameKey {
			fetchRule = v
			return
		}
	}
	err = fmt.Errorf("rule不存在, nameKey: %s", nameKey)
	return
}

// savePageHtml 拉取历史报告详情
func savePageHtml(nameKey, saveDir string, historyPage bool, reportMax int) (files []string, err error) {
	if nameKey == "" {
		return
	}
	defer func() {
		if err != nil {
			tips := fmt.Sprintf("GetCCFOilEdbHistory ErrMsg: %s", err.Error())
			utils.FileLog.Info(tips)
			fmt.Println(tips)
		}
	}()
	fetchRule, e := loadDataRule(nameKey)
	if e != nil {
		err = fmt.Errorf("loadDataRule, err: %v", e)
		return
	}
	if saveDir == "" {
		saveDir = "static/ccf"
	}

	// 获取品种第一页
	baseUrl := fmt.Sprintf(`%s?newssubmit=1&sitename=localhost`, CCFSearchPageUrl)
	if fetchRule.Search.ClassId != "" {
		baseUrl = fmt.Sprintf(`%s&ClassID=%s`, baseUrl, fetchRule.Search.ClassId)
	}
	if fetchRule.Search.SubClassId != "" {
		baseUrl = fmt.Sprintf(`%s&SubClassID=%s`, baseUrl, fetchRule.Search.SubClassId)
	}
	if fetchRule.Search.ProductId != "" {
		baseUrl = fmt.Sprintf(`%s&ProductID=%s`, baseUrl, fetchRule.Search.ProductId)
	}
	if fetchRule.Search.SubProductId != "" {
		baseUrl = fmt.Sprintf(`%s&ProductID=%s`, baseUrl, fetchRule.Search.SubProductId)
	}
	if fetchRule.Search.SimpleTerms != "" {
		termsEncode, e := gb2312ToPercentEncoding(fetchRule.Search.SimpleTerms)
		if e != nil {
			err = fmt.Errorf("gb2312ToPercentEncoding err: %v", e)
			return
		}
		baseUrl = fmt.Sprintf(`%s&simpleterms=%s`, baseUrl, termsEncode)
	}
	firstPage := fmt.Sprintf(`%s&cur_pg_num=%d`, baseUrl, 1)

	// 首页报告链接
	firstHtml, e := fetchPageHtml(firstPage)
	if e != nil {
		err = fmt.Errorf("获取首页HTML失败, err: %v", e)
		return
	}
	firstHrefs, e := analysisReportHrefs(firstHtml, 1)
	if e != nil {
		err = fmt.Errorf("读取首页列表报告链接失败, err: %v", e)
		return
	}
	var historyHrefs []ReportHrefs
	historyHrefs = append(historyHrefs, firstHrefs...)

	ticker := time.NewTicker(5 * time.Second)
	defer ticker.Stop()

	// 历史报告
	if historyPage {
		endPage, e := analysisEndPage(firstHtml)
		if e != nil {
			err = fmt.Errorf("解析首页最后页码失败, err: %v", e)
			return
		}
		if endPage > 1 {
			for i := 2; i <= endPage; i++ {
				<-ticker.C
				fmt.Printf("开始读取历史页%d\n", i)

				// 每页28条数据, 需要带上页码*28的偏移量不然始终获取第一页
				pageUrl := fmt.Sprintf(`%s&cur_pg_num=%d&cur_row_pos=%d`, baseUrl, i, i*28)
				fmt.Println("pageUrl: ", pageUrl)
				pageContents, e := fetchPageHtml(pageUrl)
				if e != nil {
					err = fmt.Errorf("获取首页HTML失败, err: %v", e)
					return
				}
				pageHrefs, e := analysisReportHrefs(pageContents, i)
				if e != nil {
					err = fmt.Errorf("读取第%d页列表报告链接失败, err: %v", i, e)
					return
				}
				historyHrefs = append(historyHrefs, pageHrefs...)
				fmt.Printf("结束读取历史页%d\n", i)
			}
		}
		fmt.Println("endPage: ", endPage)
	}
	fmt.Println("historyHrefs len: ", len(historyHrefs))
	fmt.Println("historyHrefs: ", historyHrefs)

	// 拉取报告留档
	strDate := time.Now().Format("20060102")
	reportCount := 0
	for _, v := range historyHrefs {
		<-ticker.C

		if reportMax > 0 {
			reportCount += 1
			if reportCount > reportMax {
				break
			}
		}
		fmt.Printf("拉取报告: %s; url: %s\n", v.Title, v.Href)

		htm, e := fetchPageHtml(fmt.Sprintf("%s%s", CCFReportDetailBaseUrl, v.Href))
		if e != nil {
			err = fmt.Errorf("获取首页HTML失败, err: %v", e)
			return
		}
		outputPath := fmt.Sprintf("%s/%d-%s-%s.html", saveDir, v.Page, strDate, v.Title)
		if e = writeHTMLToFile(string(htm), outputPath); e != nil {
			fmt.Printf("写入html出错, err: %v", e)
			continue
		}
		files = append(files, outputPath)
	}
	fmt.Println("拉取报告 end")
	return
}

// analysisEndPage 读取列表页最后一页页码
func analysisEndPage(contents []byte) (endPage int, err error) {
	doc, e := goquery.NewDocumentFromReader(strings.NewReader(string(contents)))
	if e != nil {
		err = fmt.Errorf("NewDocumentFromReader err: %v", e)
		return
	}

	// 查找页码元素并遍历a标签
	sectionDigg := doc.Find(".digg")
	aElements := sectionDigg.Find("a")

	// 获取倒数第二个a标签中的页码
	totalAElements := aElements.Length()
	targetIndex := totalAElements - 2
	if targetIndex >= 0 && targetIndex < totalAElements {
		targetA := aElements.Eq(targetIndex)
		txt := targetA.Text()
		endPage, e = strconv.Atoi(txt)
		if e != nil {
			err = fmt.Errorf("页码文本有误, %s", txt)
			return
		}
		fmt.Println(endPage)
		return
	}
	endPage = 1
	return
}

// ReportHrefs 报告链接
type ReportHrefs struct {
	Title string `description:"报告标题"`
	Href  string `description:"报告详情链接"`
	Page  int    `description:"页码"`
}

// analysisReportHrefs 解析列表页报告链接
func analysisReportHrefs(contents []byte, page int) (hrefs []ReportHrefs, err error) {
	doc, e := goquery.NewDocumentFromReader(strings.NewReader(string(contents)))
	if e != nil {
		err = fmt.Errorf("NewDocumentFromReader err: %v", e)
		return
	}
	doc.Find("ul.newslist li a").Each(func(_ int, s *goquery.Selection) {
		href, exists := s.Attr("href")
		if exists {
			title := s.Text()
			hrefs = append(hrefs, ReportHrefs{
				Title: title,
				Href:  href,
				Page:  page,
			})
		}
	})
	return
}

// writeHTMLToFile 将HTML内容写入指定的文件中
func writeHTMLToFile(content string, filePath string) error {
	// 使用os.Create创建文件，如果文件已存在则会被截断
	file, err := os.Create(filePath)
	if err != nil {
		return err
	}
	defer file.Close()

	// 将HTML内容写入文件
	_, err = file.WriteString(content)
	if err != nil {
		return err
	}

	return nil
}

// extractReportPublishTime 提取报告发布时间
func extractReportPublishTime(text string) (time.Time, error) {
	datePattern := `(\d{4}年\d{1,2}月\d{1,2}日\d{1,2}:\d{2})`
	re := regexp.MustCompile(datePattern)

	var strTime string
	match := re.FindStringSubmatch(text)
	if len(match) <= 0 {
		return time.Time{}, fmt.Errorf("没有读取出日期")
	}
	strTime = match[0]

	// 转为时间格式
	dateFormat := "2006年01月02日15:04"
	parsedDate, e := time.ParseInLocation(dateFormat, strTime, time.Local)
	if e != nil {
		return time.Time{}, fmt.Errorf("日期转换失败, str: %s, err: %v", strTime, e)
	}
	return parsedDate, nil
}

// calculateDataHalfVal 取出数据区间的折中值, 如"7-9天"返回结果为"8"
func calculateDataHalfVal(duration string) (result string, err error) {
	re := regexp.MustCompile(`\d+`)
	matches := re.FindAllString(duration, -1)
	if len(matches) != 2 {
		err = fmt.Errorf("未找到两个数字, Num: %d", len(matches))
		return
	}

	a, e := strconv.Atoi(matches[0])
	if e != nil {
		err = e
		return
	}
	b, e := strconv.Atoi(matches[1])
	if e != nil {
		err = e
		return
	}
	average := float64(a+b) / 2.0

	// 格式化结果
	if average == float64(int(average)) {
		result = strconv.Itoa(int(average))
	} else {
		result = fmt.Sprintf("%.1f", average)
	}
	return
}

// gb2312ToPercentEncoding 中文字符转码
func gb2312ToPercentEncoding(input string) (string, error) {
	// 创建GB18030编码转换器（兼容GB2312）
	encoder := simplifiedchinese.GB18030.NewEncoder()

	// 使用转换器将字符串转换为GB18030编码的字节流，并写入bytes.Buffer
	var buf bytes.Buffer
	writer := transform.NewWriter(&buf, encoder)
	_, err := writer.Write([]byte(input))
	if err != nil {
		return "", err
	}
	err = writer.Close()
	if err != nil {
		return "", err
	}

	// 将字节流转换为百分号编码
	percentEncoded := url.QueryEscape(buf.String())

	return percentEncoded, nil
}

// AnalysisNoneMergeTablePars 解析无合并单元格的简单表格入参
type AnalysisNoneMergeTablePars struct {
	DocTable  *goquery.Selection
	MarketCol struct {
		HasCol   bool `description:"是否有市场列"`
		ColIndex int  `description:"市场列"`
	}
	DateCol struct {
		StartIndex  int       `description:"日期开始列"`
		EndIndex    int       `description:"日期结束列"`
		PublishTime time.Time `description:"报告发布时间"`
		//PublishYear   int       `description:"报告发布年份"`
		StrTimeFormat string   `description:"数据日期格式-需拼接日期列中的变量"`
		TimeFormat    []string `description:"标准日期格式, 可能存在多种分别进行遍历"`
		SplitLast     bool     `description:"是否分隔日期: 如1.24-1.28"`
		SplitFlag     string   `description:"分隔日期分隔符: 如-"`
	}
	ValCol struct {
		SplitHalfVal bool `description:"是否取折中值: 如8-10天, 9-12天"`
	}
}

// TableRow 读取Table的行信息
type TableRow struct {
	Product  string
	Market   string
	DateData map[string]string
	Unit     string
}

// analysisNoneMergeTable 解析无合并单元格的简单表格
func analysisNoneMergeTable(params AnalysisNoneMergeTablePars) (items []TableRow) {
	if params.DocTable != nil && params.DocTable.Length() <= 0 {
		return
	}

	attemptDates := []string{"2006/1/2", "2006/01/02", "2006/01/2", "2006/1/02", "2006-1-2", "2006-01-02", "2006-01-2", "2006-1-02", "2006.01.02", "2006.1.2", "2006.1.02", "2006.01.2", "2006年01月02日", "2006年1月2日", "2006年1月02日", "2006年01月2日"}
	colDate := make(map[int]string)
	params.DocTable.Find("tbody").Children().Each(func(i int, s *goquery.Selection) {
		cells := s.Find("td")

		// 表头取出日期
		if i == 0 {
			cells.Each(func(ii int, ss *goquery.Selection) {
				cellTxt := strings.TrimSpace(ss.Text())
				//fmt.Println("cellTxt", cellTxt)
				if ii >= params.DateCol.StartIndex && ii <= params.DateCol.EndIndex {
					//strTime := fmt.Sprintf("%d.%s", publishYear, cellTxt)
					//var strTimeFormat string
					completeTime := cellTxt
					// 是否需要拼接年份
					if params.DateCol.StrTimeFormat != "" {
						strDate := cellTxt
						// 是否取分隔日期的后一个日期
						if params.DateCol.SplitLast && params.DateCol.SplitFlag != "" {
							dateArr := strings.Split(cellTxt, params.DateCol.SplitFlag)
							if len(dateArr) > 1 {
								strDate = dateArr[len(dateArr)-1]
							}
						}
						completeTime = fmt.Sprintf(params.DateCol.StrTimeFormat, params.DateCol.PublishTime.Year(), strDate)
					}
					//fmt.Println("completeTime: ", completeTime)

					// 遍历多种可能的日期格式
					var colTime time.Time
					for _, f := range params.DateCol.TimeFormat {
						t, e := time.ParseInLocation(f, completeTime, time.Local)
						if e != nil {
							continue
						}
						colTime = t
						break
					}
					// 统一判断一次, 入参的日期格式可能不全
					if colTime.IsZero() {
						utils.FileLog.Info(fmt.Sprintf("日期格式异常: cellTxt-%s; completeTime-%s", cellTxt, completeTime))
						for _, f := range attemptDates {
							t, e := time.ParseInLocation(f, completeTime, time.Local)
							if e != nil {
								continue
							}
							colTime = t
							break
						}
					}
					// 判断报告是否跨年
					if colTime.AddDate(0, -6, 0).After(params.DateCol.PublishTime) {
						utils.FileLog.Info(fmt.Sprintf("跨年判断: ColTime-%v; PublishTime-%v", colTime, params.DateCol.PublishTime))
						colTime = colTime.AddDate(-1, 0, 0)
					}
					if !colTime.IsZero() {
						colDate[ii] = colTime.Format(utils.FormatDate)
					}
					fmt.Println("日期：", colTime.Format(utils.FormatDate))
				}
			})
		}

		// 取指标
		if i > 0 {
			row := TableRow{
				DateData: make(map[string]string),
			}
			cells.Each(func(ii int, ss *goquery.Selection) {
				cellTxt := filterInvalidVal(ss.Text())
				//fmt.Println("cellTxt", cellTxt)
				if ii == 0 {
					row.Product = cellTxt
				}
				if params.MarketCol.HasCol && ii == params.MarketCol.ColIndex {
					row.Market = cellTxt
				}
				if ii >= params.DateCol.StartIndex && ii <= params.DateCol.EndIndex {
					d, ok := colDate[ii]
					if !ok {
						return
					}
					// 是否取折中值
					if params.ValCol.SplitHalfVal {
						val, e := calculateDataHalfVal(cellTxt)
						if e != nil {
							fmt.Printf("calculateDataHalfVal err: %v\n", e)
							return
						}
						cellTxt = val
					}
					if cellTxt != "" {
						row.DateData[d] = cellTxt
					}
				}
			})
			//fmt.Println(row)
			items = append(items, row)
		}
	})
	return
}

// formatTableRow2ValidEdb 表格行转换为有效指标
func formatTableRow2ValidEdb(rows []TableRow, edbMatch []DataRuleEdbMatch) (indexes []*HandleIndexData) {
	indexes = make([]*HandleIndexData, 0)
	for _, m := range edbMatch {
		for _, v := range rows {
			fmt.Printf("产品: %s, 市场: %s, 日期数据: %v, 单位: %s\n", v.Product, v.Market, v.DateData, v.Unit)
			var productOk, marketOk, unitOk bool
			if (m.Product == "" && v.Product == "") || (m.Product != "" && strings.Contains(v.Product, m.Product)) {
				productOk = true
			}
			if (m.Market == "" && v.Market == "") || (m.Market != "" && strings.Contains(v.Market, m.Market)) {
				marketOk = true
			}
			if (m.MatchUnit == "" && v.Unit == "") || (m.MatchUnit != "" && strings.Contains(v.Unit, m.MatchUnit)) {
				unitOk = true
			}
			if productOk && marketOk && unitOk {
				edb := new(HandleIndexData)
				edb.IndexCode = m.IndexCode
				edb.IndexName = m.IndexName
				edb.ClassifyId = m.ClassifyId
				edb.Frequency = m.Frequency
				edb.Unit = m.Unit
				edb.DateData = v.DateData
				edb.TerminalCode = utils.TerminalCode
				indexes = append(indexes, edb)
			}
		}
	}
	return
}

// listFiles 列出目录下所有文件名
func listFiles(dirPath string) ([]string, error) {
	var files []string

	err := filepath.Walk(dirPath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() {
			files = append(files, info.Name())
		}
		return nil
	})

	if err != nil {
		return nil, err
	}
	return files, nil
}

// filterInvalidVal 过滤无效值
func filterInvalidVal(cellTxt string) string {
	cellTxt = strings.TrimSpace(cellTxt)
	if cellTxt == "休市" || cellTxt == "/" || cellTxt == "-" || cellTxt == "—" {
		return ""
	}
	return cellTxt
}

// formatIntervalData 格式化区间值
func formatIntervalData(cellTxt, flag string) string {
	cellTxt = filterInvalidVal(cellTxt)

	if flag == "" {
		flag = "-"
	}
	matches := strings.Split(cellTxt, flag)
	if len(matches) < 2 {
		return cellTxt
	}
	if len(matches) != 2 {
		return ""
	}

	// 转换不了直接返回空值
	a, e := strconv.ParseFloat(matches[0], 64)
	if e != nil {
		return ""
	}
	b, e := strconv.ParseFloat(matches[1], 64)
	if e != nil {
		return ""
	}
	average := (a + b) / 2

	return fmt.Sprint(average)
}