Implement getting external token info for BEP20 (#23)

* Tweak validation text

* Implement getting external token info for BEP20

go.sum

@@ -272,8 +272,6 @@ github.com/subosito/gotenv v1.2.0 h1:Slr1R9HxAlEKefgq5jn9U+DnETlIUa6HfgEzj0g5d7s
 github.com/subosito/gotenv v1.2.0/go.mod h1:N0PQaV/YGNqwC0u51sEeR/aUtSLEXKX9iv69rRypqCw=
 github.com/trustwallet/go-libs v0.2.17 h1:l2zr5Ow19GTPnoWbhjExAhTbz7xLcYPXBa10EIgItjI=
 github.com/trustwallet/go-libs v0.2.17/go.mod h1:gBDrDkN5wOY+8kwlU6pnv3l/seGJy2qH1OpTKe7NnXA=
-github.com/trustwallet/go-primitives v0.0.11 h1:uVjm1IssSrur5MjnSbl+LerljnaU8pvgoBxq7krjNvI=
-github.com/trustwallet/go-primitives v0.0.11/go.mod h1:XPY046lWNrCZ67ZsCeQlJYbKTMDpulc9y7hiRjnL9R4=
 github.com/trustwallet/go-primitives v0.0.14-0.20211130135322-c76db95f1406 h1:lezUwyiPYCChVu12XPGlc51cG4GE6hE0ONrKNG/UDQ8=
 github.com/trustwallet/go-primitives v0.0.14-0.20211130135322-c76db95f1406/go.mod h1:jLqd7rm+4EYG5JdpxhngM9HwbqfEXzKy/wK4vUB7STs=
 github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=

pkg/validation/info/external/bep20.go

@@ -0,0 +1,67 @@
+package external
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	holdersRegexp  = regexp.MustCompile(`(\d+)\saddresses`)
+	decimalsRegexp = regexp.MustCompile(`(\d+)\s<\/div>`)
+	symbolRegexp   = regexp.MustCompile(`<b>(\w+)<\/b>\s<span`)
+)
+
+func GetTokenInfoForBEP20(tokenID string) (*TokenInfo, error) {
+	url := fmt.Sprintf("https://bscscan.com/token/%s", tokenID)
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	dataInBytes, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	// Remove all "," from content
+	pageContent := strings.ReplaceAll(string(dataInBytes), ",", "")
+
+	var holders, decimals int
+	var symbol string
+
+	match := symbolRegexp.FindStringSubmatch(pageContent)
+	if len(match) > 1 {
+		symbol = match[1]
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	match = decimalsRegexp.FindStringSubmatch(pageContent)
+	if len(match) > 1 {
+		decimals, err = strconv.Atoi(match[1])
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	match = holdersRegexp.FindStringSubmatch(pageContent)
+	if len(match) > 1 {
+		holders, err = strconv.Atoi(match[1])
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return &TokenInfo{
+		Symbol:       symbol,
+		Decimals:     decimals,
+		HoldersCount: holders,
+	}, nil
+}

pkg/validation/info/external/erc20.go

@@ -0,0 +1,35 @@
+package external
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/trustwallet/assets-go-libs/pkg"
+)
+
+type TokenInfoERC20 struct {
+	Symbol       string `json:"symbol"`
+	Decimals     string `json:"decimals"`
+	HoldersCount int    `json:"holdersCount"`
+}
+
+func GetTokenInfoForERC20(tokenID string) (*TokenInfo, error) {
+	url := fmt.Sprintf("https://api.ethplorer.io/getTokenInfo/%s?apiKey=freekey", tokenID)
+
+	var result TokenInfoERC20
+	err := pkg.GetHTTPResponse(url, &result)
+	if err != nil {
+		return nil, err
+	}
+
+	decimals, err := strconv.Atoi(result.Decimals)
+	if err != nil {
+		return nil, err
+	}
+
+	return &TokenInfo{
+		Symbol:       result.Symbol,
+		Decimals:     decimals,
+		HoldersCount: result.HoldersCount,
+	}, nil
+}

pkg/validation/info/external/external.go

@@ -0,0 +1,22 @@
+package external
+
+import (
+	"strings"
+)
+
+type TokenInfo struct {
+	Symbol       string
+	Decimals     int
+	HoldersCount int
+}
+
+func GetTokenInfo(tokenID, tokentType string) (*TokenInfo, error) {
+	switch strings.ToLower(tokentType) {
+	case "erc20":
+		return GetTokenInfoForERC20(tokenID)
+	case "bep20":
+		return GetTokenInfoForBEP20(tokenID)
+	}
+
+	return nil, nil
+}

pkg/validation/info/fields_validators.go

@@ -143,7 +143,7 @@ func ValidateCoinLinks(links []Link) error {
 		prefix := allowedLinkKeys[*l.Name]
 		if prefix != "" {
 			if !strings.HasPrefix(*l.URL, prefix) {
-				return fmt.Errorf("ivalid value for links.url field, allowed only with prefixes - %s",
+				return fmt.Errorf("invalid value for links.url field, allowed only with prefixes - %s",
 					strings.Join(supportedLinkValues(), ", "))
 			}
 		}

pkg/validation/info/values.go

@@ -78,6 +78,10 @@ func supportedLinkNames() []string {
 func supportedLinkValues() []string {
 	values := make([]string, 0, len(allowedLinkKeys))
 	for _, v := range allowedLinkKeys {
+		if v == "" {
+			continue
+		}
+
 		values = append(values, v)
 	}