Implement strava oauth2 as new auth provider

tools/auth/auth.go

@@ -105,6 +105,8 @@ func NewProviderByName(name string) (Provider, error) {
 		return NewKakaoProvider(), nil
 	case NameTwitch:
 		return NewTwitchProvider(), nil
+	case NameStrava:
+		return NewStravaProvider(), nil
 	default:
 		return nil, errors.New("Missing provider " + name)
 	}

tools/auth/auth_test.go

@@ -108,4 +108,13 @@ func TestNewProviderByName(t *testing.T) {
 	if _, ok := p.(*auth.Twitch); !ok {
 		t.Error("Expected to be instance of *auth.Twitch")
 	}
+
+	// strava
+	p, err = auth.NewProviderByName(auth.NameStrava)
+	if err != nil {
+		t.Errorf("Expected nil, got error %v", err)
+	}
+	if _, ok := p.(*auth.Strava); !ok {
+		t.Error("Expected to be instance of *auth.Strava")
+	}
 }

tools/auth/strava.go

@@ -0,0 +1,70 @@
+package auth
+
+import (
+	"encoding/json"
+	"strconv"
+
+	"golang.org/x/oauth2"
+)
+
+var _ Provider = (*Strava)(nil)
+
+// NameStrava is the unique name of the Strava provider.
+const NameStrava string = "strava"
+
+// Strava allows authentication via Strava OAuth2.
+type Strava struct {
+	*baseProvider
+}
+
+// NewStravaProvider creates new Strava provider instance with some defaults.
+func NewStravaProvider() *Strava {
+	return &Strava{&baseProvider{
+		scopes: []string{
+			"profile:read_all",
+		},
+		authUrl:    "https://www.strava.com/oauth/authorize",
+		tokenUrl:   "https://www.strava.com/api/v3/oauth/token",
+		userApiUrl: "https://www.strava.com/api/v3/athlete",
+	}}
+}
+
+// FetchAuthUser returns an AuthUser instance based on the Strava's user api.
+//
+// API reference: https://developers.strava.com/docs/authentication/
+func (p *Strava) FetchAuthUser(token *oauth2.Token) (*AuthUser, error) {
+	data, err := p.FetchRawUserData(token)
+	if err != nil {
+		return nil, err
+	}
+
+	rawUser := map[string]any{}
+	if err := json.Unmarshal(data, &rawUser); err != nil {
+		return nil, err
+	}
+
+	extracted := struct {
+		Id              int    `json:"id"`
+		FirstName       string `json:"firstname"`
+		LastName        string `json:"lastname"`
+		Username        string `json:"username"`
+		ProfileImageUrl string `json:"profile"`
+
+		// At the time of writing, Strava OAuth2 doesn't support returning the user email address
+		// Email string `json:"email"`
+	}{}
+	if err := json.Unmarshal(data, &extracted); err != nil {
+		return nil, err
+	}
+
+	user := &AuthUser{
+		Id:          strconv.Itoa(extracted.Id),
+		Name:        extracted.FirstName + " " + extracted.LastName,
+		Username:    extracted.Username,
+		AvatarUrl:   extracted.ProfileImageUrl,
+		RawUser:     rawUser,
+		AccessToken: token.AccessToken,
+	}
+
+	return user, nil
+}