[twitchclient] Reduce retries and errors when banning banned user

Signed-off-by: Knut Ahlers <knut@ahlers.me>

pkg/twitch/http.go

@@ -4,44 +4,55 @@ import (
 	"fmt"
 )
 
-type httpError struct {
-	body []byte
-	code int
-	err  error
+// HTTPError represents an HTTP error containing the response body (or
+// the wrapped error occurred while readiny the body) and the status
+// code returned by the server
+type HTTPError struct {
+	Body []byte
+	Code int
+	Err  error
 }
 
-var errAnyHTTPError = newHTTPError(0, nil, nil)
+// ErrAnyHTTPError can be used in errors.Is() to match an HTTPError
+// with any status code
+var ErrAnyHTTPError = newHTTPError(0, nil, nil)
 
-func newHTTPError(status int, body []byte, wrappedErr error) httpError {
-	return httpError{
-		body: body,
-		code: status,
-		err:  wrappedErr,
+func newHTTPError(status int, body []byte, wrappedErr error) HTTPError {
+	return HTTPError{
+		Body: body,
+		Code: status,
+		Err:  wrappedErr,
 	}
 }
 
-func (h httpError) Error() string {
-	selfE := fmt.Sprintf("unexpected status %d", h.code)
-	if h.body != nil {
-		selfE = fmt.Sprintf("%s (%s)", selfE, h.body)
+// Error implements the error interface and returns a formatted version
+// of the error including the body, might therefore leak confidential
+// information when included in the response body
+func (h HTTPError) Error() string {
+	selfE := fmt.Sprintf("unexpected status %d", h.Code)
+	if h.Body != nil {
+		selfE = fmt.Sprintf("%s (%s)", selfE, h.Body)
 	}
 
-	if h.err == nil {
+	if h.Err == nil {
 		return selfE
 	}
 
-	return fmt.Sprintf("%s: %s", selfE, h.err)
+	return fmt.Sprintf("%s: %s", selfE, h.Err)
 }
 
-func (h httpError) Is(target error) bool {
-	ht, ok := target.(httpError)
+// Is checks whether the given error is an HTTPError and the status
+// code matches the given error
+func (h HTTPError) Is(target error) bool {
+	ht, ok := target.(HTTPError)
 	if !ok {
 		return false
 	}
 
-	return ht.code == 0 || ht.code == h.code
+	return ht.Code == 0 || ht.Code == h.Code
 }
 
-func (h httpError) Unwrap() error {
-	return h.err
+// Unwrap returns the wrapped error occurred when reading the body
+func (h HTTPError) Unwrap() error {
+	return h.Err
 }

pkg/twitch/moderation.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
 	"strings"
@@ -13,7 +14,10 @@ import (
 	"github.com/pkg/errors"
 )
 
-const maxTimeoutDuration = 1209600 * time.Second
+const (
+	errMessageAlreadyBanned = "The user specified in the user_id field is already banned."
+	maxTimeoutDuration      = 1209600 * time.Second
+)
 
 // BanUser bans or timeouts a user in the given channel. Setting the
 // duration to 0 will result in a ban, setting if greater than 0 will
@@ -65,6 +69,26 @@ func (c *Client) BanUser(channel, username string, duration time.Duration, reaso
 				"https://api.twitch.tv/helix/moderation/bans?broadcaster_id=%s&moderator_id=%s",
 				channelID, botID,
 			),
+			ValidateFunc: func(opts ClientRequestOpts, resp *http.Response) error {
+				if resp.StatusCode == http.StatusBadRequest {
+					// The user might already be banned, lets check the error in detail
+					body, err := io.ReadAll(resp.Body)
+					if err != nil {
+						return newHTTPError(resp.StatusCode, nil, err)
+					}
+
+					var payload ErrorResponse
+					if err = json.Unmarshal(body, &payload); err == nil && payload.Message == errMessageAlreadyBanned {
+						// The user is already banned, that's fine as that was
+						// our goal!
+						return nil
+					}
+
+					return newHTTPError(resp.StatusCode, body, nil)
+				}
+
+				return ValidateStatus(opts, resp)
+			},
 		}),
 		"executing ban request",
 	)

pkg/twitch/twitch.go

@@ -50,6 +50,12 @@ type (
 		apiCache *APICache
 	}
 
+	ErrorResponse struct {
+		Error   string `json:"error"`
+		Status  int    `json:"status"`
+		Message string `json:"message"`
+	}
+
 	OAuthTokenResponse struct {
 		AccessToken  string   `json:"access_token"`
 		RefreshToken string   `json:"refresh_token"`
@@ -78,9 +84,29 @@ type (
 		OKStatus        int
 		Out             interface{}
 		URL             string
+		ValidateFunc    func(ClientRequestOpts, *http.Response) error
 	}
 )
 
+// ValidateStatus is the default validation function used when no
+// ValidateFunc is given in the ClientRequestOpts and checks for the
+// returned HTTP status is equal to the OKStatus
+//
+// When wrapping this function the body should not have been read
+// before in order to have the response body available in the returned
+// HTTPError
+func ValidateStatus(opts ClientRequestOpts, resp *http.Response) error {
+	if opts.OKStatus != 0 && resp.StatusCode != opts.OKStatus {
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return newHTTPError(resp.StatusCode, nil, err)
+		}
+		return newHTTPError(resp.StatusCode, body, nil)
+	}
+
+	return nil
+}
+
 func New(clientID, clientSecret, accessToken, refreshToken string) *Client {
 	return &Client{
 		clientID:     clientID,
@@ -132,7 +158,7 @@ func (c *Client) RefreshToken() error {
 	case err == nil:
 		// That's fine, just continue
 
-	case errors.Is(err, errAnyHTTPError):
+	case errors.Is(err, ErrAnyHTTPError):
 		// Retried refresh failed, wipe tokens
 		log.WithError(err).Warning("resetting tokens after refresh-failure")
 		c.UpdateToken("", "")
@@ -249,7 +275,7 @@ func (c *Client) getTwitchAppAccessToken() (string, error) {
 	return rData.AccessToken, nil
 }
 
-//nolint:gocognit,gocyclo // Not gonna split to keep as a logical unit
+//nolint:gocyclo // Not gonna split to keep as a logical unit
 func (c *Client) Request(opts ClientRequestOpts) error {
 	log.WithFields(log.Fields{
 		"method": opts.Method,
@@ -262,6 +288,10 @@ func (c *Client) Request(opts ClientRequestOpts) error {
 		retries = 1
 	}
 
+	if opts.ValidateFunc == nil {
+		opts.ValidateFunc = ValidateStatus
+	}
+
 	return backoff.NewBackoff().WithMaxIterations(retries).Retry(func() error {
 		reqCtx, cancel := context.WithTimeout(opts.Context, twitchRequestTimeout)
 		defer cancel()
@@ -313,12 +343,8 @@ func (c *Client) Request(opts ClientRequestOpts) error {
 			return errors.New("app-access-token is invalid")
 		}
 
-		if opts.OKStatus != 0 && resp.StatusCode != opts.OKStatus {
-			body, err := io.ReadAll(resp.Body)
-			if err != nil {
-				return newHTTPError(resp.StatusCode, nil, err)
-			}
-			return newHTTPError(resp.StatusCode, body, nil)
+		if err = opts.ValidateFunc(opts, resp); err != nil {
+			return err
 		}
 
 		if opts.Out == nil {