From a85f348fff95e77b846a1175ff030bb32024b7e9 Mon Sep 17 00:00:00 2001
From: Brad Reed <noisyscanner@gmail.com>
Date: Mon, 19 Jun 2017 22:15:04 +0100
Subject: [PATCH] Test and improved, non-stupid camel case conversion

---
 gen/generator.go      | 54 ++++++++++++++++++++++++++++++++++++++++---
 gen/generator_test.go | 22 ++++++++++++++++++
 2 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/gen/generator.go b/gen/generator.go
index 4e8c5b8..cae11b6 100644
--- a/gen/generator.go
+++ b/gen/generator.go
@@ -11,7 +11,6 @@ import (
 	"strconv"
 	"strings"
 	"unicode"
-	"unicode/utf8"
 )
 
 const pkgWriter = "github.com/mailru/easyjson/jwriter"
@@ -382,12 +381,61 @@ func (DefaultFieldNamer) GetJSONFieldName(t reflect.Type, f reflect.StructField)
 
 // LowerCamelCaseFieldNamer
 type LowerCamelCaseFieldNamer struct {}
+
+func isLower(b byte) bool {
+	return b <= 122 && b >= 97
+}
+
+func isUpper(b byte) bool {
+	return b >= 65 && b <= 90
+}
+
+func isNumeric(b byte) bool {
+	return b >= 48 && b <= 57
+}
+// convert HTTPRestClient to httpRestClient
 func lowerFirst(s string) string {
 	if s == "" {
 		return ""
 	}
-	r, n := utf8.DecodeRuneInString(s)
-	return string(unicode.ToLower(r)) + s[n:]
+
+	str := ""
+	strlen := len(s)
+
+	/**
+	  Loop each char
+	  If is uppercase:
+	    If is first char, LOWER it
+	    If the following char is lower, LEAVE it
+	    If the following char is upper OR numeric, LOWER it
+	    If is the end of string, LEAVE it
+	  Else lowercase
+	 */
+
+	foundLower := false
+	for i := range s {
+		ch := s[i]
+		if isUpper(ch) {
+			if i == 0 {
+				str += string(ch + 32)
+			} else if !foundLower { // Currently just a stream of capitals, eg JSONRESTS[erver]
+				if strlen > (i+1) && isLower(s[i+1]) {
+					// Next char is lower, keep this a capital
+					str += string(ch)
+				} else {
+					// Either at end of string or next char is capital
+					str += string(ch + 32)
+				}
+			} else {
+				str += string(ch)
+			}
+		} else {
+			foundLower = true
+			str += string(ch)
+		}
+	}
+
+	return str
 }
 
 func (LowerCamelCaseFieldNamer) GetJSONFieldName(t reflect.Type, f reflect.StructField) string {
diff --git a/gen/generator_test.go b/gen/generator_test.go
index 62c03f0..0c9d278 100644
--- a/gen/generator_test.go
+++ b/gen/generator_test.go
@@ -28,6 +28,28 @@ func TestCamelToSnake(t *testing.T) {
 	}
 }
 
+func TestCamelToLowerCamel(t *testing.T) {
+	for i, test := range []struct {
+		In, Out string
+	}{
+		{"", ""},
+		{"A", "a"},
+		{"SimpleExample", "simpleExample"},
+		{"internalField", "internalField"},
+
+		{"SomeHTTPStuff", "someHTTPStuff"},
+		{"WriteJSON", "writeJSON"},
+		{"HTTP2Server", "http2Server"},
+
+		{"JSONHTTPRPCServer", "jsonhttprpcServer"}, // nothing can be done here without a dictionary
+	} {
+		got := lowerFirst(test.In)
+		if got != test.Out {
+			t.Errorf("[%d] lowerFirst(%s) = %s; want %s", i, test.In, got, test.Out)
+		}
+	}
+}
+
 func TestJoinFunctionNameParts(t *testing.T) {
 	for i, test := range []struct {
 		keepFirst bool