#1: Implemented helper to decode/encode base64 textures value

api/mojang/mojang.go

@@ -15,7 +15,7 @@ var HttpClient = &http.Client{
 type SignedTexturesResponse struct {
 	Id    string      `json:"id"`
 	Name  string      `json:"name"`
-	Props []Property `json:"properties"`
+	Props []*Property `json:"properties"`
 }
 
 type Property struct {

api/mojang/textures.go

@@ -0,0 +1,51 @@
+package mojang
+
+import (
+	"encoding/base64"
+	"encoding/json"
+)
+
+type TexturesProp struct {
+	Timestamp   int64             `json:"timestamp"`
+	ProfileID   string            `json:"profileId"`
+	ProfileName string            `json:"profileName"`
+	Textures    *TexturesResponse `json:"textures"`
+}
+
+type TexturesResponse struct {
+	Skin *SkinTexturesResponse `json:"SKIN,omitempty"`
+	Cape *CapeTexturesResponse `json:"CAPE,omitempty"`
+}
+
+type SkinTexturesResponse struct {
+	Url      string                `json:"url"`
+	Metadata *SkinTexturesMetadata `json:"metadata,omitempty"`
+}
+
+type SkinTexturesMetadata struct {
+	Model string `json:"model"`
+}
+
+type CapeTexturesResponse struct {
+	Url string `json:"url"`
+}
+
+func DecodeTextures(encodedTextures string) (*TexturesProp, error) {
+	jsonStr, err := base64.URLEncoding.DecodeString(encodedTextures)
+	if err != nil {
+		return nil, err
+	}
+
+	var result *TexturesProp
+	err = json.Unmarshal(jsonStr, &result)
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+func EncodeTextures(textures *TexturesProp) string {
+	jsonSerialized, _ := json.Marshal(textures)
+	return base64.URLEncoding.EncodeToString(jsonSerialized)
+}

api/mojang/textures_test.go

@@ -0,0 +1,112 @@
+package mojang
+
+import (
+	testify "github.com/stretchr/testify/assert"
+	"testing"
+)
+
+type texturesTestCase struct {
+	Name    string
+	Encoded string
+	Decoded *TexturesProp
+}
+
+var texturesTestCases = []*texturesTestCase{
+	{
+		Name:    "property without textures",
+		Encoded: "eyJ0aW1lc3RhbXAiOjE1NTU4NTYwMTA0OTQsInByb2ZpbGVJZCI6IjNlM2VlNmMzNWFmYTQ4YWJiNjFlOGNkOGM0MmZjMGQ5IiwicHJvZmlsZU5hbWUiOiJFcmlja1NrcmF1Y2giLCJ0ZXh0dXJlcyI6e319",
+		Decoded: &TexturesProp{
+			ProfileID:   "3e3ee6c35afa48abb61e8cd8c42fc0d9",
+			ProfileName: "ErickSkrauch",
+			Timestamp:   int64(1555856010494),
+			Textures:    &TexturesResponse{},
+		},
+	},
+	{
+		Name:    "property with classic skin textures",
+		Encoded: "eyJ0aW1lc3RhbXAiOjE1NTU4NTYzMDc0MTIsInByb2ZpbGVJZCI6IjNlM2VlNmMzNWFmYTQ4YWJiNjFlOGNkOGM0MmZjMGQ5IiwicHJvZmlsZU5hbWUiOiJFcmlja1NrcmF1Y2giLCJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvZmMxNzU3NjMzN2ExMDZkOWMyMmFjNzgyZTM2MmMxNmM0ZTBlNDliZTUzZmFhNDE4NTdiZmYzMzJiNzc5MjgxZSJ9fX0=",
+		Decoded: &TexturesProp{
+			ProfileID:   "3e3ee6c35afa48abb61e8cd8c42fc0d9",
+			ProfileName: "ErickSkrauch",
+			Timestamp:   int64(1555856307412),
+			Textures: &TexturesResponse{
+				Skin: &SkinTexturesResponse{
+					Url: "http://textures.minecraft.net/texture/fc17576337a106d9c22ac782e362c16c4e0e49be53faa41857bff332b779281e",
+				},
+			},
+		},
+	},
+	{
+		Name:    "property with alex skin textures",
+		Encoded: "eyJ0aW1lc3RhbXAiOjE1NTU4NTY0OTQ3OTEsInByb2ZpbGVJZCI6IjNlM2VlNmMzNWFmYTQ4YWJiNjFlOGNkOGM0MmZjMGQ5IiwicHJvZmlsZU5hbWUiOiJFcmlja1NrcmF1Y2giLCJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvNjlmNzUzNWY4YzNhMjE1ZDFkZTc3MmIyODdmMTc3M2IzNTg5OGVmNzUyZDI2YmRkZjRhMjVhZGFiNjVjMTg1OSIsIm1ldGFkYXRhIjp7Im1vZGVsIjoic2xpbSJ9fX19",
+		Decoded: &TexturesProp{
+			ProfileID:   "3e3ee6c35afa48abb61e8cd8c42fc0d9",
+			ProfileName: "ErickSkrauch",
+			Timestamp:   int64(1555856494791),
+			Textures: &TexturesResponse{
+				Skin: &SkinTexturesResponse{
+					Url: "http://textures.minecraft.net/texture/69f7535f8c3a215d1de772b287f1773b35898ef752d26bddf4a25adab65c1859",
+					Metadata: &SkinTexturesMetadata{
+						Model: "slim",
+					},
+				},
+			},
+		},
+	},
+	{
+		Name:    "property with skin and cape textures",
+		Encoded: "eyJ0aW1lc3RhbXAiOjE1NTU4NTc2NzUzMzUsInByb2ZpbGVJZCI6ImQ5MGI2OGJjODE3MjQzMjlhMDQ3ZjExODZkY2Q0MzM2IiwicHJvZmlsZU5hbWUiOiJha3Jvbm1hbjEiLCJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvM2U2ZGVmY2I3ZGU1YTBlMDVjNzUyNWM2Y2Q0NmU0YjliNDE2YjkyZTBjZjRiYWExZTBhOWUyMTJhODg3ZjNmNyJ9LCJDQVBFIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvNzBlZmZmYWY4NmZlNWJjMDg5NjA4ZDNjYjI5N2QzZTI3NmI5ZWI3YThmOWYyZmU2NjU5YzIzYTJkOGIxOGVkZiJ9fX0=",
+		Decoded: &TexturesProp{
+			ProfileID:   "d90b68bc81724329a047f1186dcd4336",
+			ProfileName: "akronman1",
+			Timestamp:   int64(1555857675335),
+			Textures: &TexturesResponse{
+				Skin: &SkinTexturesResponse{
+					Url: "http://textures.minecraft.net/texture/3e6defcb7de5a0e05c7525c6cd46e4b9b416b92e0cf4baa1e0a9e212a887f3f7",
+				},
+				Cape: &CapeTexturesResponse{
+					Url: "http://textures.minecraft.net/texture/70efffaf86fe5bc089608d3cb297d3e276b9eb7a8f9f2fe6659c23a2d8b18edf",
+				},
+			},
+		},
+	},
+}
+
+func TestDecodeTextures(t *testing.T) {
+	for _, testCase := range texturesTestCases {
+		t.Run("decode "+testCase.Name, func(t *testing.T) {
+			assert := testify.New(t)
+
+			result, err := DecodeTextures(testCase.Encoded)
+			assert.Nil(err)
+			assert.Equal(testCase.Decoded, result)
+		})
+	}
+
+	t.Run("should return error if invalid base64 passed", func(t *testing.T) {
+		assert := testify.New(t)
+
+		result, err := DecodeTextures("invalid base64")
+		assert.Error(err)
+		assert.Nil(result)
+	})
+
+	t.Run("should return error if invalid json found inside base64", func(t *testing.T) {
+		assert := testify.New(t)
+
+		result, err := DecodeTextures("aW52YWxpZCBqc29u") // encoded "invalid json"
+		assert.Error(err)
+		assert.Nil(result)
+	})
+}
+
+func TestEncodeTextures(t *testing.T) {
+	for _, testCase := range texturesTestCases {
+		t.Run("encode "+testCase.Name, func(t *testing.T) {
+			assert := testify.New(t)
+
+			result := EncodeTextures(testCase.Decoded)
+			assert.Equal(testCase.Encoded, result)
+		})
+	}
+}