status-im/status-go

package fourbytegithub

import (
    "errors"
    "fmt"
    "io/ioutil"
    "net/http"
    "regexp"
    "strings"
    "time"

    "github.com/ethereum/go-ethereum/accounts/abi"
    "github.com/status-im/status-go/services/wallet/thirdparty"
)

type Signature struct {
    ID   int    `json:"id"`
    Text string `json:"text_signature"`
}

type ByID []Signature

func (s ByID) Len() int           { return len(s) }
func (s ByID) Less(i, j int) bool { return s[i].ID > s[j].ID }
func (s ByID) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

type SignatureList struct {
    Count   int         `json:"count"`
    Results []Signature `json:"results"`
}

type Client struct {
    Client *http.Client
    URL    string
}

func NewClient() *Client {
    return &Client{Client: &http.Client{Timeout: time.Minute}, URL: "https://raw.githubusercontent.com"}
}

func (c *Client) DoQuery(url string) (*http.Response, error) {
    resp, err := c.Client.Get(url)

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

func (c *Client) Run(data string) (*thirdparty.DataParsed, error) {
    if len(data) < 10 || !strings.HasPrefix(data, "0x") {
        return nil, errors.New("input is badly formatted")
    }
    methodSigData := data[2:10]
    url := fmt.Sprintf("%s/ethereum-lists/4bytes/master/signatures/%s", c.URL, methodSigData)
    resp, err := c.DoQuery(url)
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return nil, err
    }
    signature := string(body)
    rgx := regexp.MustCompile(`\((.*?)\)`)

    id := fmt.Sprintf("0x%s", methodSigData)
    name := strings.Split(signature, "(")[0]
    rs := rgx.FindStringSubmatch(signature)
    inputsMapString := make(map[string]string)

    if len(rs[1]) > 0 {
        inputs := make([]string, 0)
        rawInputs := strings.Split(rs[1], ",")
        for index, typ := range rawInputs {
            if index == len(rawInputs)-1 && typ == "bytes" {
                continue
            }
            inputs = append(inputs, fmt.Sprintf("{\"name\":\"%d\",\"type\":\"%s\"}", index, typ))
        }

        functionABI := fmt.Sprintf("[{\"constant\":true,\"inputs\":[%s],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\", \"name\": \"%s\"}], ", strings.Join(inputs, ","), name)
        contractABI, err := abi.JSON(strings.NewReader(functionABI))
        if err != nil {
            return nil, err
        }
        method := contractABI.Methods[name]
        inputsMap := make(map[string]interface{})
        if err := method.Inputs.UnpackIntoMap(inputsMap, []byte(data[10:])); err != nil {
            return nil, err
        }
        for key, value := range inputsMap {
            inputsMapString[key] = fmt.Sprintf("%v", value)
        }
    }

    return &thirdparty.DataParsed{
        Name:      name,
        ID:        id,
        Signature: signature,
        Inputs:    inputsMapString,
    }, nil
}