Added support for querying blocknumber by timestamp

Author: avislash

block.go

@@ -7,6 +7,8 @@
 
 package etherscan
 
+import "strconv"
+
 // BlockReward gets block and uncle rewards by block number
 func (c *Client) BlockReward(blockNum int) (rewards BlockRewards, err error) {
 	param := M{
@@ -16,3 +18,22 @@ func (c *Client) BlockReward(blockNum int) (rewards BlockRewards, err error) {
 	err = c.call("block", "getblockreward", param, &rewards)
 	return
 }
+
+// BlockReward gets closest block number by UNIX timestamp
+func (c *Client) BlockNumber(timestamp int64, closest string) (blockNumber BlockNumberFromTimestamp, err error) {
+	var result string
+	param := M{
+		"timestamp": strconv.Itoa(int(timestamp)),
+		"closest":   closest,
+	}
+
+	err = c.call("block", "getblocknobytime", param, &result)
+
+	if err != nil {
+		return
+	}
+
+	blockNum, err := strconv.ParseInt(result, 10, 64)
+	blockNumber.BlockNumber = int(blockNum)
+	return
+}

response.go

@@ -129,6 +129,11 @@ type BlockRewards struct {
 	UncleInclusionReward *BigInt `json:"uncleInclusionReward"`
 }
 
+// BlockNumberFromTimestamp holds info from query for block by UNIX timestamp
+type BlockNumberFromTimestamp struct {
+	BlockNumber int
+}
+
 // LatestPrice holds info from query for latest ether price
 type LatestPrice struct {
 	ETHBTC          float64 `json:"ethbtc,string"`