initial commit

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) <year> <copyright holders>
+Copyright (c) 2022 Yiyang Kang
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 

go.mod

@@ -0,0 +1,13 @@
+module git.gensokyo.cafe/kkyy/mycurrencynet
+
+go 1.19
+
+require (
+	github.com/PuerkitoBio/goquery v1.8.0
+	github.com/go-resty/resty/v2 v2.7.0
+)
+
+require (
+	github.com/andybalholm/cascadia v1.3.1 // indirect
+	golang.org/x/net v0.2.0 // indirect
+)

go.sum

@@ -0,0 +1,15 @@
+github.com/PuerkitoBio/goquery v1.8.0 h1:PJTF7AmFCFKk1N6V6jmKfrNH9tV5pNE6lZMkG0gta/U=
+github.com/PuerkitoBio/goquery v1.8.0/go.mod h1:ypIiRMtY7COPGk+I/YbZLbxsxn9g5ejnI2HSMtkjZvI=
+github.com/andybalholm/cascadia v1.3.1 h1:nhxRkql1kdYCc8Snf7D5/D3spOX+dBgjA6u8x004T2c=
+github.com/andybalholm/cascadia v1.3.1/go.mod h1:R4bJ1UQfqADjvDa4P6HZHLh/3OxWWEqc0Sk8XGwHqvA=
+github.com/go-resty/resty/v2 v2.7.0 h1:me+K9p3uhSmXtrBZ4k9jcEAfJmuC8IivWHwaLZwPrFY=
+github.com/go-resty/resty/v2 v2.7.0/go.mod h1:9PWDzw47qPphMRFfhsyk0NnSgvluHcljSMVIq3w7q0I=
+golang.org/x/net v0.0.0-20210916014120-12bc252f5db8/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211029224645-99673261e6eb/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.2.0 h1:sZfSu1wtKLGlWI4ZZayP0ck9Y73K1ynO6gqzTdBVdPU=
+golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

iso/currency.go

@@ -0,0 +1,10 @@
+package iso
+
+type ISOCurrency struct {
+	Name      string
+	Code      string
+	Number    string
+	MinorUnit string
+}
+
+//go:generate go run generate.go

iso/generate.go

@@ -0,0 +1,98 @@
+//go:build ignore
+
+package main
+
+import (
+	"bytes"
+	"encoding/xml"
+	"fmt"
+	"os"
+	"os/exec"
+	"time"
+
+	"github.com/go-resty/resty/v2"
+)
+
+const (
+	xmlFileURL = "https://www.six-group.com/dam/download/financial-information/data-center/iso-currrency/lists/list-one.xml"
+)
+
+type iso4217 struct {
+	XMLName       xml.Name `xml:"ISO_4217"`
+	Published     string   `xml:"Pblshd,attr"`
+	CurrencyTable struct {
+		XMLName         xml.Name               `xml:"CcyTbl"`
+		CurrencyEntries []iso4217CurrencyEntry `xml:"CcyNtry"`
+	} `xml:"CcyTbl"`
+}
+
+type iso4217CurrencyEntry struct {
+	XMLName            xml.Name `xml:"CcyNtry"`
+	CountryName        string   `xml:"CtryNm"`
+	CurrencyName       string   `xml:"CcyNm"`
+	Currency           string   `xml:"Ccy"`
+	CurrencyNumber     string   `xml:"CcyNbr"`
+	CurrencyMinorUnits string   `xml:"CcyMnrUnts"`
+}
+
+func main() {
+	resp, err := resty.New().
+		SetTimeout(time.Second * 10).
+		R().Get(xmlFileURL)
+
+	if err != nil {
+		panic(err)
+	}
+	if resp.StatusCode() != 200 {
+		panic(fmt.Sprintf("response from %q: %d %q", xmlFileURL, resp.StatusCode(), string(resp.Body())))
+	}
+
+	var parsed iso4217
+
+	err = xml.Unmarshal(resp.Body(), &parsed)
+	if err != nil {
+		panic(err)
+	}
+
+	buf := bytes.NewBuffer(nil)
+
+	_, _ = fmt.Fprint(buf, "// Code generated with `go generate`. DO NOT EDIT.\n\n")
+	_, _ = fmt.Fprint(buf, "package iso\n\n")
+	_, _ = fmt.Fprint(buf, "var Currencies = map[string]ISOCurrency {\n")
+
+	sean := map[string]struct{}{}
+	for _, entry := range parsed.CurrencyTable.CurrencyEntries {
+		if entry.Currency == "" {
+			continue
+		}
+		if _, ok := sean[entry.Currency]; ok {
+			continue
+		}
+		sean[entry.Currency] = struct{}{}
+
+		_, _ = fmt.Fprintf(buf, "\t%q: {\n", entry.Currency)
+		_, _ = fmt.Fprintf(buf, "\t\t%s: %q,\n", "Name", entry.CurrencyName)
+		_, _ = fmt.Fprintf(buf, "\t\t%s: %q,\n", "Code", entry.Currency)
+		_, _ = fmt.Fprintf(buf, "\t\t%s: %q,\n", "Number", entry.CurrencyNumber)
+		_, _ = fmt.Fprintf(buf, "\t\t%s: %q,\n", "MinorUnit", entry.CurrencyMinorUnits)
+		_, _ = fmt.Fprint(buf, "\t},\n")
+	}
+
+	_, _ = fmt.Fprint(buf, "}\n")
+
+	oF, err := os.OpenFile("currencies.go", os.O_WRONLY|os.O_TRUNC, 0644)
+	if err != nil {
+		panic(err)
+	}
+
+	fmtCmd := exec.Command("gofmt", "-s")
+	fmtCmd.Stdin = bytes.NewReader(buf.Bytes())
+	fmtCmd.Stdout = oF
+	if err = fmtCmd.Start(); err != nil {
+		panic(err)
+	}
+
+	if err = fmtCmd.Wait(); err != nil {
+		panic(err)
+	}
+}

mycurrencynet.go

@@ -0,0 +1,181 @@
+package mycurrencynet
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/PuerkitoBio/goquery"
+	"github.com/go-resty/resty/v2"
+
+	"git.gensokyo.cafe/kkyy/mycurrencynet/iso"
+)
+
+var (
+	updateUrl = "https://www.mycurrency.net/=US"
+
+	client = resty.New()
+)
+
+type Currency struct {
+	Code      string
+	Name      string
+	Countries []string // TODO fill this
+	Rate      float64
+}
+
+func (c *Currency) To(t *Currency) float64 {
+	if c == nil || t == nil || c.Rate == 0 {
+		return 0
+	}
+	return t.Rate / c.Rate
+}
+
+func init() {
+	client.
+		SetTimeout(5*time.Second).
+		SetRetryCount(1).
+		SetHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0")
+}
+
+func fetch() (html []byte, err error) {
+	resp, err := client.R().Get(updateUrl)
+	if err != nil {
+		return
+	}
+	if resp.StatusCode() != 200 {
+		return nil, fmt.Errorf("HTTP %d %s: %q", resp.StatusCode(), resp.Status(), resp.String())
+	}
+
+	return resp.Body(), nil
+}
+
+func parse(body []byte) (map[string]*Currency, error) {
+	doc, err := goquery.NewDocumentFromReader(bytes.NewReader(body))
+	if err != nil {
+		return nil, err
+	}
+	ret := make(map[string]*Currency)
+
+	doc.Find("tr.country").Each(func(_ int, s *goquery.Selection) {
+		var (
+			c    Currency
+			isoC iso.ISOCurrency
+			ok   bool
+			err  error
+			rate string
+		)
+		if c.Code, ok = s.Attr("data-currency-code"); !ok {
+			return
+		}
+		if _, exist := ret[c.Code]; exist {
+			return
+		}
+
+		if isoC, ok = iso.Currencies[c.Code]; !ok {
+			return
+		}
+		c.Name = isoC.Name
+
+		if rate, ok = s.Find(".money[data-rate]").Attr("data-rate"); !ok {
+			return
+		}
+		if c.Rate, err = strconv.ParseFloat(rate, 64); err != nil {
+			return
+		}
+
+		ret[c.Code] = &c
+	})
+
+	return ret, nil
+}
+
+func Fetch() (map[string]*Currency, error) {
+	html, err := fetch()
+	if err != nil {
+		return nil, err
+	}
+	rates, err := parse(html)
+	if err != nil {
+		return nil, err
+	}
+	// add base currency
+	rates["USD"] = &Currency{
+		Code: "USD",
+		Name: iso.Currencies["USD"].Name,
+		Rate: 1,
+	}
+	return rates, nil
+}
+
+type MyCurrencyNet struct {
+	rates      map[string]*Currency
+	lastUpdate time.Time
+
+	mu sync.RWMutex
+}
+
+func New() *MyCurrencyNet {
+	return &MyCurrencyNet{}
+}
+
+func (m *MyCurrencyNet) Get(codes ...string) ([]*Currency, error) {
+	if m.rates == nil {
+		return nil, fmt.Errorf("not initialized.")
+	}
+
+	ret := make([]*Currency, len(codes))
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	var (
+		errors []string
+		err    error = nil
+	)
+	for i, code := range codes {
+		rate, ok := m.rates[strings.ToUpper(code)]
+		if !ok {
+			errors = append(errors, "unknown currency code: "+code)
+			continue
+		}
+		var cp Currency = *rate
+		ret[i] = &cp
+	}
+	if len(errors) > 0 {
+		err = fmt.Errorf(strings.Join(errors, ", "))
+	}
+	return ret, err
+}
+
+func (m *MyCurrencyNet) Update() error {
+	currencies, err := Fetch()
+	if err != nil {
+		return err
+	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.rates = currencies
+	m.lastUpdate = time.Now()
+
+	return nil
+}
+
+func (m *MyCurrencyNet) UpdateEvery(interval time.Duration, onErr func(error), onSuccess func()) {
+	for {
+		<-time.After(interval)
+
+		if err := m.Update(); err != nil {
+			if onErr != nil {
+				onErr(err)
+			}
+		} else {
+			if onSuccess != nil {
+				onSuccess()
+			}
+		}
+	}
+}