[#979] added Kakao OAuth2 provider

tools/auth/kakao.go

@@ -0,0 +1,60 @@
+package auth
+
+import (
+	"strconv"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/kakao"
+)
+
+var _ Provider = (*Kakao)(nil)
+
+// NameKakao is the unique name of the Kakao provider.
+const NameKakao string = "kakao"
+
+// Kakao allows authentication via Kakao OAuth2.
+type Kakao struct {
+	*baseProvider
+}
+
+// NewKakaoProvider creates a new Kakao provider instance with some defaults.
+func NewKakaoProvider() *Kakao {
+	return &Kakao{&baseProvider{
+		scopes:     []string{"account_email", "profile_nickname", "profile_image"},
+		authUrl:    kakao.Endpoint.AuthURL,
+		tokenUrl:   kakao.Endpoint.TokenURL,
+		userApiUrl: "https://kapi.kakao.com/v2/user/me",
+	}}
+}
+
+// FetchAuthUser returns an AuthUser instance based on the Kakao's user api.
+func (p *Kakao) FetchAuthUser(token *oauth2.Token) (*AuthUser, error) {
+	// https://developers.kakao.com/docs/latest/en/kakaologin/rest-api#req-user-info-response
+	rawData := struct {
+		Id      int `json:"id"`
+		Profile struct {
+			Nickname string `json:"nickname"`
+			ImageUrl string `json:"profile_image"`
+		} `json:"properties"`
+		KakaoAccount struct {
+			Email           string `json:"email"`
+			IsEmailVerified bool   `json:"is_email_verified"`
+			IsEmailValid    bool   `json:"is_email_valid"`
+		} `json:"kakao_account"`
+	}{}
+
+	if err := p.FetchRawUserData(token, &rawData); err != nil {
+		return nil, err
+	}
+
+	user := &AuthUser{
+		Id:        strconv.Itoa(rawData.Id),
+		Username:  rawData.Profile.Nickname,
+		AvatarUrl: rawData.Profile.ImageUrl,
+	}
+	if rawData.KakaoAccount.IsEmailValid && rawData.KakaoAccount.IsEmailVerified {
+		user.Email = rawData.KakaoAccount.Email
+	}
+
+	return user, nil
+}