package main

import (
	"encoding/xml"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"strings"
	"time"

	"golang.org/x/text/encoding/charmap"
)

type ValCurs struct {
	XMLName xml.Name `xml:"ValCurs"`
	Text    string   `xml:",chardata"`
	Date    string   `xml:"Date,attr"`
	Name    string   `xml:"name,attr"`
	Valute  []struct {
		Text     string `xml:",chardata"`
		ID       string `xml:"ID,attr"`
		NumCode  string `xml:"NumCode"`
		CharCode string `xml:"CharCode"`
		Nominal  string `xml:"Nominal"`
		Name     string `xml:"Name"`
		Value    string `xml:"Value"`
	} `xml:"Valute"`
}
type result struct {
	name     string
	value    float64
	CharCode string
	date     string
}

func CharsetReader(char string, data io.Reader) (io.Reader, error) {
	if char == "windows-1251" {
		return charmap.Windows1251.NewDecoder().Reader(data), nil
	}
	return nil, fmt.Errorf("Кодировка не поддерживается")
}

func MaxMinAvg(Curss []*ValCurs) (map[string]result, *float64) {
	var min, max result
	var agv, summ float64
	var summItem int
	res := make(map[string]result)
	for i := 0; i < len(Curss); i++ {
		for j := 0; j < len(Curss[i].Valute); j++ {
			val, err := strconv.ParseFloat(strings.Replace(Curss[i].Valute[j].Value, ",", ".", 1), 64)
			if err != nil {
				fmt.Println(err)
				return nil, nil
			}

			if val < min.value || min.value == 0 {
				min.value = val
				min.name = Curss[i].Valute[j].Name
				min.CharCode = Curss[i].Valute[j].CharCode
				min.date = Curss[i].Date
			}
			if val > max.value {
				max.value = val
				max.name = Curss[i].Valute[j].Name
				max.CharCode = Curss[i].Valute[j].CharCode
				max.date = Curss[i].Date
			}
			summ += val
			summItem += i
		}
	}
	res["Min"] = min
	res["Max"] = max
	agv = summ / float64(summItem)
	return res, &agv
}

func main() {
	Curss := []*ValCurs{}
	Client := http.Client{
		Timeout: time.Second * 10,
	}
	t := time.Now()
	fmt.Println("Пожалуйста подождите....")
	for i := 0; i <= 90; i++ {
		buff := ValCurs{}
		data := fmt.Sprint(t.Add((-2160 + 24*time.Duration(i)) * time.Hour).Format("02/01/2006"))
		req, err := http.NewRequest("GET", "http://www.cbr.ru/scripts/XML_daily_eng.asp?date_req="+data, nil)
		if err != nil {
			fmt.Println(err)
		}
		req.Header.Add("User-Agent", "PostmanRuntime/7.31.3")
		res, err := Client.Do(req)
		if err != nil {
			fmt.Println(err)
		}
		defer res.Body.Close()
		dacoder := xml.NewDecoder(res.Body)
		dacoder.CharsetReader = CharsetReader
		err = dacoder.Decode(&buff)

		if err != nil {
			fmt.Println(err)
		}
		Curss = append(Curss, &buff)
	}
	MaxMin, avg := MaxMinAvg(Curss)
	fmt.Println("Минимальный Курс")
	fmt.Println(MaxMin["Min"].value, " ", MaxMin["Min"].name, " ", MaxMin["Min"].CharCode, " ", MaxMin["Min"].date)
	fmt.Println("Максимальный Курс")
	fmt.Println(MaxMin["Max"].value, " ", MaxMin["Max"].name, " ", MaxMin["Max"].CharCode, " ", MaxMin["Max"].date)
	fmt.Println("Среднее значение курса", float32(*avg))

}