Add ReverseString, ToReverseScriptHash method (#281)

* Added
1) ReverseString method to the Uint160 type
2) ToReverseScriptHash method to convert a base58 address to a reverse script hash

* Simplified ToScriptHash method

pkg/wire/util/address/address.go

@@ -1,22 +1,27 @@
 package address
 
 import (
-	"encoding/hex"
-
 	"github.com/CityOfZion/neo-go/pkg/crypto/base58"
 	"github.com/CityOfZion/neo-go/pkg/wire/util"
 )
 
 // ToScriptHash converts an address to a script hash
 func ToScriptHash(address string) string {
-
-	decodedAddressAsBytes, err := base58.Decode(address)
+	a, err := Uint160Decode(address)
 	if err != nil {
 		return ""
 	}
-	decodedAddressAsHex := hex.EncodeToString(decodedAddressAsBytes)
-	scriptHash := (decodedAddressAsHex[2:42])
-	return scriptHash
+	return a.String()
+
+}
+
+// ToReverseScriptHash converts an address to a reverse script hash
+func ToReverseScriptHash(address string) string {
+	a, err := Uint160Decode(address)
+	if err != nil {
+		return ""
+	}
+	return a.ReverseString()
 }
 
 // FromUint160 returns the "NEO address" from the given

pkg/wire/util/address/address_test.go

@@ -0,0 +1,17 @@
+package address
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestScriptHash(t *testing.T) {
+	address := "AJeAEsmeD6t279Dx4n2HWdUvUmmXQ4iJvP"
+
+	hash := ToScriptHash(address)
+	reverseHash := ToReverseScriptHash(address)
+
+	assert.Equal(t, "b28427088a3729b2536d10122960394e8be6721f", reverseHash)
+	assert.Equal(t, "1f72e68b4e39602912106d53b229378a082784b2", hash)
+}

pkg/wire/util/uint160.go

@@ -68,6 +68,11 @@ func (u Uint160) String() string {
 	return hex.EncodeToString(u.Bytes())
 }
 
+// ReverseString implements the stringer interface.
+func (u Uint160) ReverseString() string {
+	return hex.EncodeToString(u.BytesReverse())
+}
+
 // Equals returns true if both Uint256 values are the same.
 func (u Uint160) Equals(other Uint160) bool {
 	for i := 0; i < uint160Size; i++ {

pkg/wire/util/uint160_test.go

@@ -48,3 +48,15 @@ func TestUInt160Equals(t *testing.T) {
 		t.Fatalf("%s and %s must be equal", ua, ua)
 	}
 }
+
+func TestUInt160String(t *testing.T) {
+	hexStr := "b28427088a3729b2536d10122960394e8be6721f"
+	hexRevStr := "1f72e68b4e39602912106d53b229378a082784b2"
+
+	val, err := Uint160DecodeString(hexStr)
+	assert.Nil(t, err)
+
+	assert.Equal(t, hexStr, val.String())
+	assert.Equal(t, hexRevStr, val.ReverseString())
+
+}