From 64e23a8d0ced5a34de8f4b9a69c360777e73266d Mon Sep 17 00:00:00 2001
From: Jim Myhrberg <contact@jimeh.me>
Date: Wed, 29 Jun 2016 01:27:37 +0100
Subject: [PATCH] Simplify exposed method API

This package serves a single purpose, convert between integers and
base58 strings the same as a Flickr does. It has no need for supporting
custom alphabets passed in a runtime.
---
 base58.go      | 50 +++++++++++++-------------------------------------
 base58_test.go | 35 -----------------------------------
 2 files changed, 13 insertions(+), 72 deletions(-)

diff --git a/base58.go b/base58.go
index 3d9f4f2..dd1c181 100644
--- a/base58.go
+++ b/base58.go
@@ -8,46 +8,32 @@ import (
 
 // Alphabet is the default alphabet.
 const Alphabet = "123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ"
+const base = len(Alphabet)
 
 // Encode converts a base10 integer to a base58 string using the default
 // alphabet.
 func Encode(num int) string {
-	return EncodeWithAlphabet(num, Alphabet)
+	str := ""
+	for num >= base {
+		mod := num % base
+		str = string(Alphabet[mod]) + str
+		num = (num - mod) / base
+	}
+
+	return string(Alphabet[num]) + str
 }
 
 // Decode converts a base58 string to a base10 integer using the default
 // alphabet.
 func Decode(str string) (int, error) {
-	return DecodeWithAlphabet(str, Alphabet)
-}
-
-// EncodeWithAlphabet converts a base10 integer to a base58 string with the
-// given alphabet.
-func EncodeWithAlphabet(num int, alphabet string) string {
-	base := len(alphabet)
-
-	str := ""
-	for num >= base {
-		mod := num % base
-		str = string(alphabet[mod]) + str
-		num = (num - mod) / base
-	}
-
-	return string(alphabet[num]) + str
-}
-
-// DecodeWithAlphabet converts a base58 string to a base10 integer with the
-// given alphabet.
-func DecodeWithAlphabet(str string, alphabet string) (int, error) {
-	base := len(alphabet)
 	num := 0
 	multi := 1
 
 	for i := len(str); i > 0; i-- {
 		char := string(str[i-1])
-		index := strings.Index(alphabet, char)
+		index := strings.Index(Alphabet, char)
 		if index == -1 {
-			return -1, decodeError(str, alphabet)
+			return -1, decodeError(str)
 		}
 		num += multi * index
 		multi = multi * base
@@ -56,17 +42,7 @@ func DecodeWithAlphabet(str string, alphabet string) (int, error) {
 	return num, nil
 }
 
-func decodeError(str string, alphabet string) error {
-	var msg string
-
-	if alphabet == Alphabet {
-		msg = fmt.Sprintf("\"%s\" is not a valid base58 string.", str)
-	} else {
-		msg = fmt.Sprintf(
-			"\"%s\" is not a valid input for alphabet \"%s\".",
-			str, alphabet,
-		)
-	}
-
+func decodeError(str string) error {
+	msg := fmt.Sprintf("\"%s\" is not a valid base58 string.", str)
 	return errors.New(msg)
 }
diff --git a/base58_test.go b/base58_test.go
index 72f89b1..0e53eaf 100644
--- a/base58_test.go
+++ b/base58_test.go
@@ -177,13 +177,6 @@ var examples = map[string]int{
 	"6hJPEq": 3471202816, "6hGMH7": 3470806020, "6hGp5L": 3470729904,
 }
 
-var myAlphabet = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ123456789"
-var myExamples = map[string]int{
-	"frMj9u": 3469905409, "fr3bSF": 3472804260, "frYrT8": 3472074356,
-	"frUXLH": 3471394398, "frTYPz": 3471202816, "frRWSg": 3470806020,
-	"frRyeV": 3470729904, "frQp15": 3470507135, "frP2SC": 3470432637,
-}
-
 type Base58Suite struct {
 	suite.Suite
 }
@@ -225,34 +218,6 @@ func (s *Base58Suite) TestDecodeError() {
 	assert.Equal(errors.New(errMsg), err)
 }
 
-func (s *Base58Suite) TestEncodeWithAlphabet() {
-	assert := assert.New(s.T())
-
-	for str, num := range myExamples {
-		assert.Equal(str, EncodeWithAlphabet(num, myAlphabet))
-	}
-}
-
-func (s *Base58Suite) TestDecodeWithAlphabet() {
-	assert := assert.New(s.T())
-
-	for str, num := range myExamples {
-		result, _ := DecodeWithAlphabet(str, myAlphabet)
-		assert.Equal(num, result)
-	}
-}
-
-func (s *Base58Suite) TestDecodeWithAlphabetError() {
-	assert := assert.New(s.T())
-	errMsg := "\"AaBbCc\" is not a valid input for alphabet " +
-		"\"abcdefghjklmnpqrstuvwxyz\"."
-
-	result, err := DecodeWithAlphabet("AaBbCc", "abcdefghjklmnpqrstuvwxyz")
-
-	assert.Equal(-1, result)
-	assert.Equal(errors.New(errMsg), err)
-}
-
 func TestBase58Suite(t *testing.T) {
 	suite.Run(t, new(Base58Suite))
 }