gravityblast
diff --git a/‎client.go
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+96Lines changed: 96 additions & 0 deletions b/‎client.go
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+96Lines changed: 96 additions & 0 deletions
diff --git a/‎types.go
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+7Lines changed: 7 additions & 0 deletions b/‎types.go
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+7Lines changed: 7 additions & 0 deletions
diff --git a/‎utils.go
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+34Lines changed: 34 additions & 0 deletions b/‎utils.go
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+34Lines changed: 34 additions & 0 deletions
@@ -0,0 +1,96 @@
+package etherscan
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+)
+
+type httpClient interface {
+	Get(url string) (resp *http.Response, err error)
+}
+
+type NetworkID = int
+
+const (
+	Mainnet = 1
+	Rinkeby = 3
+
+	baseUrlMainnet = "https://api.etherscan.io/api"
+	baseUrlRinkeby = "https://api-rinkeby.etherscan.io/api"
+)
+
+type Client struct {
+	c       httpClient
+	baseURL string
+	apiKey  string
+}
+
+func NewClient(networkID NetworkID, apiKey string) (*Client, error) {
+	url, err := urlByNetworkID(networkID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Client{
+		c:       http.DefaultClient,
+		baseURL: url,
+		apiKey:  apiKey,
+	}, nil
+}
+
+func (c *Client) Account(address string) (*AccountResponse, error) {
+	params := map[string]string{
+		"module":  "account",
+		"action":  "balance",
+		"address": address,
+		"tag":     "latest",
+	}
+
+	resp, err := c.get(params)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+
+	var accountResp AccountResponse
+
+	decoder := json.NewDecoder(resp.Body)
+	err = decoder.Decode(&accountResp)
+
+	return &accountResp, err
+}
+
+func (c *Client) get(params map[string]string) (*http.Response, error) {
+	query := c.buildQuery(params)
+	url, err := url.Parse(c.baseURL)
+	if err != nil {
+		return nil, err
+	}
+
+	url.RawQuery = query
+	resp, err := c.c.Get(url.String())
+	if err != nil {
+		return resp, err
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode > 299 {
+		resp.Body.Close()
+		return resp, fmt.Errorf("bad status code %d", resp.StatusCode)
+	}
+
+	return resp, nil
+}
+
+func (c *Client) buildQuery(params map[string]string) string {
+	v := url.Values{}
+	for key, value := range params {
+		v.Set(key, value)
+	}
+
+	v.Set("apikey", c.apiKey)
+
+	return v.Encode()
+}
@@ -0,0 +1,7 @@
+package etherscan
+
+type AccountResponse struct {
+	Status  string  `json:"status"`
+	Message string  `json:"message"`
+	Result  *BigInt `json:"result"`
+}
@@ -0,0 +1,34 @@
+package etherscan
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/big"
+)
+
+type BigInt struct {
+	big.Int
+}
+
+func (bigint *BigInt) UnmarshalJSON(b []byte) error {
+	var s string
+	err := json.Unmarshal(b, &s)
+	if err != nil {
+		return err
+	}
+
+	bigint.SetString(s, 10)
+
+	return nil
+}
+
+func urlByNetworkID(id NetworkID) (string, error) {
+	switch id {
+	case Mainnet:
+		return baseUrlMainnet, nil
+	case Rinkeby:
+		return baseUrlRinkeby, nil
+	}
+
+	return "", fmt.Errorf("unknown network id %d", id)
+}