[core] Improve EventSub API request design

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

botEditor.go

@@ -15,7 +15,7 @@ func getAuthorizationFromRequest(r *http.Request) (string, *twitch.Client, error
 		return "", nil, errors.New("no authorization provided")
 	}
 
-	tc := twitch.New(cfg.TwitchClient, token)
+	tc := twitch.New(cfg.TwitchClient, cfg.TwitchClientSecret, token)
 
 	user, err := tc.GetAuthorizedUsername()
 	return user, tc, errors.Wrap(err, "getting authorized user")

main.go

@@ -140,7 +140,7 @@ func main() {
 	var err error
 
 	cronService = cron.New()
-	twitchClient = twitch.New(cfg.TwitchClient, cfg.TwitchToken)
+	twitchClient = twitch.New(cfg.TwitchClient, cfg.TwitchClientSecret, cfg.TwitchToken)
 
 	twitchWatch := newTwitchWatcher()
 	cronService.AddFunc("@every 10s", twitchWatch.Check) // Query may run that often as the twitchClient has an internal cache
@@ -219,16 +219,12 @@ func main() {
 				log.WithError(err).Fatal("Unable to get or create eventsub secret")
 			}
 
-			twitchEventSubClient = twitch.NewEventSubClient(strings.Join([]string{
+			twitchEventSubClient = twitch.NewEventSubClient(twitchClient, strings.Join([]string{
 				strings.TrimRight(cfg.BaseURL, "/"),
 				"eventsub",
 				handle,
 			}, "/"), secret, handle)
 
-			if err = twitchEventSubClient.Authorize(cfg.TwitchClient, cfg.TwitchClientSecret); err != nil {
-				log.WithError(err).Fatal("Unable to authorize Twitch EventSub client")
-			}
-
 			router.HandleFunc("/eventsub/{keyhandle}", twitchEventSubClient.HandleEventsubPush).Methods(http.MethodPost)
 		}
 	}

plugins/rule_test.go

@@ -75,7 +75,7 @@ func TestAllowExecuteDisableOnOffline(t *testing.T) {
 	r := &Rule{DisableOnOffline: testPtrBool(true)}
 
 	// Fake cache entries to prevent calling the real Twitch API
-	r.twitchClient = twitch.New("", "")
+	r.twitchClient = twitch.New("", "", "")
 	r.twitchClient.APICache().Set([]string{"hasLiveStream", "channel1"}, time.Minute, true)
 	r.twitchClient.APICache().Set([]string{"hasLiveStream", "channel2"}, time.Minute, false)
 

twitch/eventsub.go

@@ -8,9 +8,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
-	"net/url"
 	"strings"
 	"sync"
 	"time"
@@ -55,9 +53,7 @@ type (
 		secret       string
 		secretHandle string
 
-		twitchClientID     string
+		twitchClient *Client
-		twitchClientSecret string
-		twitchAccessToken  string
 
 		subscriptions     map[string]*registeredSubscription
 		subscriptionsLock sync.RWMutex
@@ -151,71 +147,18 @@ func (e EventSubCondition) Hash() (string, error) {
 	return fmt.Sprintf("%x", h), nil
 }
 
-func NewEventSubClient(apiURL, secret, secretHandle string) *EventSubClient {
+func NewEventSubClient(twitchClient *Client, apiURL, secret, secretHandle string) *EventSubClient {
 	return &EventSubClient{
 		apiURL:       apiURL,
 		secret:       secret,
 		secretHandle: secretHandle,
 
+		twitchClient: twitchClient,
+
 		subscriptions: map[string]*registeredSubscription{},
 	}
 }
 
-func (e *EventSubClient) Authorize(clientID, clientSecret string) error {
-	e.twitchClientID = clientID
-	e.twitchClientSecret = clientSecret
-
-	_, err := e.getTwitchAppAccessToken()
-	return errors.Wrap(err, "fetching app access token")
-}
-
-func (e *EventSubClient) getTwitchAppAccessToken() (string, error) {
-	if e.twitchAccessToken != "" {
-		return e.twitchAccessToken, nil
-	}
-
-	var rData struct {
-		AccessToken  string        `json:"access_token"`
-		RefreshToken string        `json:"refresh_token"`
-		ExpiresIn    int           `json:"expires_in"`
-		Scope        []interface{} `json:"scope"`
-		TokenType    string        `json:"token_type"`
-	}
-
-	params := make(url.Values)
-	params.Set("client_id", e.twitchClientID)
-	params.Set("client_secret", e.twitchClientSecret)
-	params.Set("grant_type", "client_credentials")
-
-	u, _ := url.Parse("https://id.twitch.tv/oauth2/token")
-	u.RawQuery = params.Encode()
-
-	ctx, cancel := context.WithTimeout(context.Background(), twitchRequestTimeout)
-	defer cancel()
-
-	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, u.String(), nil)
-	resp, err := http.DefaultClient.Do(req)
-	if err != nil {
-		return "", errors.Wrap(err, "fetching response")
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		body, err := ioutil.ReadAll(resp.Body)
-		if err != nil {
-			return "", errors.Wrapf(err, "unexpected status %d and cannot read body", resp.StatusCode)
-		}
-		return "", errors.Errorf("unexpected status %d: %s", resp.StatusCode, body)
-	}
-
-	e.twitchAccessToken = rData.AccessToken
-
-	return rData.AccessToken, errors.Wrap(
-		json.NewDecoder(resp.Body).Decode(&rData),
-		"decoding response",
-	)
-}
-
 func (e *EventSubClient) HandleEventsubPush(w http.ResponseWriter, r *http.Request) {
 	var (
 		body      = new(bytes.Buffer)
@@ -292,7 +235,7 @@ func (e *EventSubClient) HandleEventsubPush(w http.ResponseWriter, r *http.Reque
 	}
 }
 
-//nolint:funlen,gocyclo // Not splitting to keep logic unit
+//nolint:funlen // Not splitting to keep logic unit
 func (e *EventSubClient) RegisterEventSubHooks(event string, condition EventSubCondition, callback func(json.RawMessage) error) (func(), error) {
 	condHash, err := condition.Hash()
 	if err != nil {
@@ -321,39 +264,20 @@ func (e *EventSubClient) RegisterEventSubHooks(event string, condition EventSubC
 		return func() { e.unregisterCallback(cacheKey, cbKey) }, nil
 	}
 
-	accessToken, err := e.getTwitchAppAccessToken()
-	if err != nil {
-		return nil, errors.Wrap(err, "getting app-access-token")
-	}
-
 	ctx, cancel := context.WithTimeout(context.Background(), twitchRequestTimeout)
 	defer cancel()
 
 	// List existing subscriptions
-	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "https://api.twitch.tv/helix/eventsub/subscriptions", nil)
+	subList, err := e.twitchClient.getEventSubSubscriptions(ctx)
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("Client-Id", e.twitchClientID)
-	req.Header.Set("Authorization", "Bearer "+accessToken)
-
-	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
-		return nil, errors.Wrap(err, "requesting subscribscriptions")
+		return nil, errors.Wrap(err, "listing existing subscriptions")
-	}
-	defer resp.Body.Close()
-
-	var subscriptionList struct {
-		Data []eventSubSubscription
-	}
-
-	if err = json.NewDecoder(resp.Body).Decode(&subscriptionList); err != nil {
-		return nil, errors.Wrap(err, "decoding subscription list")
 	}
 
 	// Register subscriptions
 	var (
 		existingSub *eventSubSubscription
 	)
-	for i, sub := range subscriptionList.Data {
+	for i, sub := range subList {
 		existingConditionHash, err := sub.Condition.Hash()
 		if err != nil {
 			return nil, errors.Wrap(err, "hashing existing condition")
@@ -371,7 +295,7 @@ func (e *EventSubClient) RegisterEventSubHooks(event string, condition EventSubC
 				"id":     sub.ID,
 				"status": sub.Status,
 			})
-			existingSub = &subscriptionList.Data[i]
+			existingSub = &subList[i]
 		}
 	}
 
@@ -395,7 +319,10 @@ func (e *EventSubClient) RegisterEventSubHooks(event string, condition EventSubC
 		return func() { e.unregisterCallback(cacheKey, cbKey) }, nil
 	}
 
-	payload := eventSubSubscription{
+	ctx, cancel = context.WithTimeout(context.Background(), twitchRequestTimeout)
+	defer cancel()
+
+	newSub, err := e.twitchClient.createEventSubSubscription(ctx, eventSubSubscription{
 		Type:      event,
 		Version:   "1",
 		Condition: condition,
@@ -404,43 +331,9 @@ func (e *EventSubClient) RegisterEventSubHooks(event string, condition EventSubC
 			Callback: e.apiURL,
 			Secret:   e.secret,
 		},
-	}
+	})
-
-	buf := new(bytes.Buffer)
-	if err := json.NewEncoder(buf).Encode(payload); err != nil {
-		return nil, errors.Wrap(err, "assemble subscribe payload")
-	}
-
-	ctx, cancel = context.WithTimeout(context.Background(), twitchRequestTimeout)
-	defer cancel()
-
-	req, err = http.NewRequestWithContext(ctx, http.MethodPost, "https://api.twitch.tv/helix/eventsub/subscriptions", buf)
 	if err != nil {
-		return nil, errors.Wrap(err, "creating subscribe request")
+		return nil, errors.Wrap(err, "creating subscription")
-	}
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("Client-Id", e.twitchClientID)
-	req.Header.Set("Authorization", "Bearer "+accessToken)
-
-	resp, err = http.DefaultClient.Do(req)
-	if err != nil {
-		return nil, errors.Wrap(err, "requesting subscribe")
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusAccepted {
-		body, err := ioutil.ReadAll(resp.Body)
-		if err != nil {
-			return nil, errors.Wrapf(err, "unexpected status %d, unable to read body", resp.StatusCode)
-		}
-		return nil, errors.Errorf("unexpected status %d: %s", resp.StatusCode, body)
-	}
-
-	var response struct {
-		Data []eventSubSubscription `json:"data"`
-	}
-	if err = json.NewDecoder(resp.Body).Decode(&response); err != nil {
-		return nil, errors.Wrap(err, "reading eventsub sub response")
 	}
 
 	e.subscriptionsLock.Lock()
@@ -454,7 +347,7 @@ func (e *EventSubClient) RegisterEventSubHooks(event string, condition EventSubC
 		Callbacks: map[string]func(json.RawMessage) error{
 			cbKey: callback,
 		},
-		Subscription: response.Data[0],
+		Subscription: *newSub,
 	}
 
 	logger.Debug("Registered eventsub subscription")
@@ -491,30 +384,13 @@ func (e *EventSubClient) unregisterCallback(cacheKey, cbKey string) {
 		return
 	}
 
-	accessToken, err := e.getTwitchAppAccessToken()
-	if err != nil {
-		log.WithError(err).Error("Unable to get access token")
-		return
-	}
-
 	ctx, cancel := context.WithTimeout(context.Background(), twitchRequestTimeout)
 	defer cancel()
 
-	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, fmt.Sprintf("https://api.twitch.tv/helix/eventsub/subscriptions?id=%s", regSub.Subscription.ID), nil)
+	if err := e.twitchClient.deleteEventSubSubscription(ctx, regSub.Subscription.ID); err != nil {
-	if err != nil {
-		log.WithError(err).Error("Unable to create delete subscription request")
-		return
-	}
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Set("Client-Id", e.twitchClientID)
-	req.Header.Set("Authorization", "Bearer "+accessToken)
-
-	resp, err := http.DefaultClient.Do(req)
-	if err != nil {
 		log.WithError(err).Error("Unable to execute delete subscription request")
 		return
 	}
-	defer resp.Body.Close()
 
 	e.subscriptionsLock.Lock()
 	defer e.subscriptionsLock.Unlock()

twitch/twitch.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net/http"
 	"net/url"
 	"strconv"
@@ -26,6 +27,12 @@ const (
 	twitchRequestTimeout = 2 * time.Second
 )
 
+const (
+	authTypeUnauthorized authType = iota
+	authTypeAppAccessToken
+	authTypeBearerToken
+)
+
 type (
 	Category struct {
 		BoxArtURL string `json:"box_art_url"`
@@ -34,8 +41,11 @@ type (
 	}
 
 	Client struct {
-		clientID string
+		clientID     string
-		token    string
+		clientSecret string
+		token        string
+
+		appAccessToken string
 
 		apiCache *APICache
 	}
@@ -63,12 +73,25 @@ type (
 		Login           string `json:"login"`
 		ProfileImageURL string `json:"profile_image_url"`
 	}
+
+	authType uint8
+
+	clientRequestOpts struct {
+		AuthType authType
+		Body     io.Reader
+		Context  context.Context
+		Method   string
+		OKStatus int
+		Out      interface{}
+		URL      string
+	}
 )
 
-func New(clientID, token string) *Client {
+func New(clientID, clientSecret, token string) *Client {
 	return &Client{
-		clientID: clientID,
+		clientID:     clientID,
-		token:    token,
+		clientSecret: clientSecret,
+		token:        token,
 
 		apiCache: newTwitchAPICache(),
 	}
@@ -81,13 +104,14 @@ func (c Client) GetAuthorizedUsername() (string, error) {
 		Data []User `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		"https://api.twitch.tv/helix/users",
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      "https://api.twitch.tv/helix/users",
+	}); err != nil {
 		return "", errors.Wrap(err, "request channel info")
 	}
 
@@ -108,13 +132,13 @@ func (c Client) GetDisplayNameForUser(username string) (string, error) {
 		Data []User `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/users?login=%s", username),
+		Method:   http.MethodGet,
-		nil,
+		Out:      &payload,
-		&payload,
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/users?login=%s", username),
-	); err != nil {
+	}); err != nil {
 		return "", errors.Wrap(err, "request channel info")
 	}
 
@@ -149,13 +173,14 @@ func (c Client) GetFollowDate(from, to string) (time.Time, error) {
 		} `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/users/follows?to_id=%s&from_id=%s", toID, fromID),
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/users/follows?to_id=%s&from_id=%s", toID, fromID),
+	}); err != nil {
 		return time.Time{}, errors.Wrap(err, "request follow info")
 	}
 
@@ -188,13 +213,14 @@ func (c Client) GetUserInformation(user string) (*User, error) {
 		param = "id"
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/users?%s=%s", param, user),
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/users?%s=%s", param, user),
+	}); err != nil {
 		return nil, errors.Wrap(err, "request user info")
 	}
 
@@ -224,7 +250,14 @@ func (c Client) SearchCategories(ctx context.Context, name string) ([]Category,
 	}
 
 	for {
-		if err := c.request(ctx, http.MethodGet, fmt.Sprintf("https://api.twitch.tv/helix/search/categories?%s", params.Encode()), nil, &resp); err != nil {
+		if err := c.request(clientRequestOpts{
+			AuthType: authTypeBearerToken,
+			Context:  ctx,
+			Method:   http.MethodGet,
+			OKStatus: http.StatusOK,
+			Out:      &resp,
+			URL:      fmt.Sprintf("https://api.twitch.tv/helix/search/categories?%s", params.Encode()),
+		}); err != nil {
 			return nil, errors.Wrap(err, "executing request")
 		}
 
@@ -255,13 +288,14 @@ func (c Client) HasLiveStream(username string) (bool, error) {
 		} `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/streams?user_login=%s", username),
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/streams?user_login=%s", username),
+	}); err != nil {
 		return false, errors.Wrap(err, "request stream info")
 	}
 
@@ -286,13 +320,14 @@ func (c Client) GetCurrentStreamInfo(username string) (*StreamInfo, error) {
 		Data []*StreamInfo `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/streams?user_id=%s", id),
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/streams?user_id=%s", id),
+	}); err != nil {
 		return nil, errors.Wrap(err, "request channel info")
 	}
 
@@ -316,13 +351,14 @@ func (c Client) GetIDForUsername(username string) (string, error) {
 		Data []User `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/users?login=%s", username),
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/users?login=%s", username),
+	}); err != nil {
 		return "", errors.Wrap(err, "request channel info")
 	}
 
@@ -356,13 +392,14 @@ func (c Client) GetRecentStreamInfo(username string) (string, string, error) {
 		} `json:"data"`
 	}
 
-	if err := c.request(
+	if err := c.request(clientRequestOpts{
-		context.Background(),
+		AuthType: authTypeBearerToken,
-		http.MethodGet,
+		Context:  context.Background(),
-		fmt.Sprintf("https://api.twitch.tv/helix/channels?broadcaster_id=%s", id),
+		Method:   http.MethodGet,
-		nil,
+		OKStatus: http.StatusOK,
-		&payload,
+		Out:      &payload,
-	); err != nil {
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/channels?broadcaster_id=%s", id),
+	}); err != nil {
 		return "", "", errors.Wrap(err, "request channel info")
 	}
 
@@ -429,28 +466,172 @@ func (c Client) ModifyChannelInformation(ctx context.Context, broadcasterName st
 	}
 
 	return errors.Wrap(
-		c.request(ctx, http.MethodPatch, fmt.Sprintf("https://api.twitch.tv/helix/channels?broadcaster_id=%s", broadcaster), body, nil),
+		c.request(clientRequestOpts{
+			AuthType: authTypeBearerToken,
+			Body:     body,
+			Context:  ctx,
+			Method:   http.MethodPatch,
+			OKStatus: http.StatusOK,
+			URL:      fmt.Sprintf("https://api.twitch.tv/helix/channels?broadcaster_id=%s", broadcaster),
+		}),
 		"executing request",
 	)
 }
 
-func (c Client) request(ctx context.Context, method, url string, body io.Reader, out interface{}) error {
+func (c *Client) createEventSubSubscription(ctx context.Context, sub eventSubSubscription) (*eventSubSubscription, error) {
+	var (
+		buf  = new(bytes.Buffer)
+		resp struct {
+			Total      int64                  `json:"total"`
+			Data       []eventSubSubscription `json:"data"`
+			Pagination struct {
+				Cursor string `json:"cursor"`
+			} `json:"pagination"`
+		}
+	)
+
+	if err := json.NewEncoder(buf).Encode(sub); err != nil {
+		return nil, errors.Wrap(err, "assemble subscribe payload")
+	}
+
+	if err := c.request(clientRequestOpts{
+		AuthType: authTypeAppAccessToken,
+		Body:     buf,
+		Context:  ctx,
+		Method:   http.MethodPost,
+		OKStatus: http.StatusAccepted,
+		Out:      &resp,
+		URL:      "https://api.twitch.tv/helix/eventsub/subscriptions",
+	}); err != nil {
+		return nil, errors.Wrap(err, "executing request")
+	}
+
+	return &resp.Data[0], nil
+}
+
+func (c *Client) deleteEventSubSubscription(ctx context.Context, id string) error {
+	return errors.Wrap(c.request(clientRequestOpts{
+		AuthType: authTypeAppAccessToken,
+		Context:  ctx,
+		Method:   http.MethodDelete,
+		OKStatus: http.StatusNoContent,
+		URL:      fmt.Sprintf("https://api.twitch.tv/helix/eventsub/subscriptions?id=%s", id),
+	}), "executing request")
+}
+
+func (c *Client) getEventSubSubscriptions(ctx context.Context) ([]eventSubSubscription, error) {
+	var (
+		out    []eventSubSubscription
+		params = make(url.Values)
+		resp   struct {
+			Total      int64                  `json:"total"`
+			Data       []eventSubSubscription `json:"data"`
+			Pagination struct {
+				Cursor string `json:"cursor"`
+			} `json:"pagination"`
+		}
+	)
+
+	for {
+		if err := c.request(clientRequestOpts{
+			AuthType: authTypeAppAccessToken,
+			Context:  ctx,
+			Method:   http.MethodGet,
+			OKStatus: http.StatusOK,
+			Out:      &resp,
+			URL:      fmt.Sprintf("https://api.twitch.tv/helix/eventsub/subscriptions?%s", params.Encode()),
+		}); err != nil {
+			return nil, errors.Wrap(err, "executing request")
+		}
+
+		out = append(out, resp.Data...)
+
+		if resp.Pagination.Cursor == "" {
+			break
+		}
+
+		params.Set("after", resp.Pagination.Cursor)
+		resp.Pagination.Cursor = "" // Clear from struct as struct is reused
+	}
+
+	return out, nil
+}
+
+func (c *Client) getTwitchAppAccessToken() (string, error) {
+	if c.appAccessToken != "" {
+		return c.appAccessToken, nil
+	}
+
+	var rData struct {
+		AccessToken  string        `json:"access_token"`
+		RefreshToken string        `json:"refresh_token"`
+		ExpiresIn    int           `json:"expires_in"`
+		Scope        []interface{} `json:"scope"`
+		TokenType    string        `json:"token_type"`
+	}
+
+	params := make(url.Values)
+	params.Set("client_id", c.clientID)
+	params.Set("client_secret", c.clientSecret)
+	params.Set("grant_type", "client_credentials")
+
+	u, _ := url.Parse("https://id.twitch.tv/oauth2/token")
+	u.RawQuery = params.Encode()
+
+	ctx, cancel := context.WithTimeout(context.Background(), twitchRequestTimeout)
+	defer cancel()
+
+	if err := c.request(clientRequestOpts{
+		AuthType: authTypeUnauthorized,
+		Context:  ctx,
+		Method:   http.MethodPost,
+		OKStatus: http.StatusOK,
+		Out:      &rData,
+		URL:      u.String(),
+	}); err != nil {
+		return "", errors.Wrap(err, "fetching token response")
+	}
+
+	c.appAccessToken = rData.AccessToken
+	return rData.AccessToken, nil
+}
+
+func (c *Client) request(opts clientRequestOpts) error {
 	log.WithFields(log.Fields{
-		"method": method,
+		"method": opts.Method,
-		"url":    url,
+		"url":    opts.URL,
 	}).Trace("Execute Twitch API request")
 
 	return backoff.NewBackoff().WithMaxIterations(twitchRequestRetries).Retry(func() error {
-		reqCtx, cancel := context.WithTimeout(ctx, twitchRequestTimeout)
+		reqCtx, cancel := context.WithTimeout(opts.Context, twitchRequestTimeout)
 		defer cancel()
 
-		req, err := http.NewRequestWithContext(reqCtx, method, url, body)
+		req, err := http.NewRequestWithContext(reqCtx, opts.Method, opts.URL, opts.Body)
 		if err != nil {
 			return errors.Wrap(err, "assemble request")
 		}
 		req.Header.Set("Content-Type", "application/json")
-		req.Header.Set("Client-Id", c.clientID)
+
-		req.Header.Set("Authorization", "Bearer "+c.token)
+		switch opts.AuthType {
+		case authTypeUnauthorized:
+			// Nothing to do
+
+		case authTypeAppAccessToken:
+			accessToken, err := c.getTwitchAppAccessToken()
+			if err != nil {
+				return errors.Wrap(err, "getting app-access-token")
+			}
+
+			req.Header.Set("Authorization", "Bearer "+accessToken)
+			req.Header.Set("Client-Id", c.clientID)
+
+		case authTypeBearerToken:
+			req.Header.Set("Authorization", "Bearer "+c.token)
+			req.Header.Set("Client-Id", c.clientID)
+
+		default:
+			return errors.New("invalid auth type specified")
+		}
 
 		resp, err := http.DefaultClient.Do(req)
 		if err != nil {
@@ -458,12 +639,20 @@ func (c Client) request(ctx context.Context, method, url string, body io.Reader,
 		}
 		defer resp.Body.Close()
 
-		if out == nil {
+		if opts.OKStatus != 0 && resp.StatusCode != opts.OKStatus {
+			body, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				return errors.Wrapf(err, "unexpected status %d and cannot read body", resp.StatusCode)
+			}
+			return errors.Errorf("unexpected status %d: %s", resp.StatusCode, body)
+		}
+
+		if opts.Out == nil {
 			return nil
 		}
 
 		return errors.Wrap(
-			json.NewDecoder(resp.Body).Decode(out),
+			json.NewDecoder(resp.Body).Decode(opts.Out),
 			"parse user info",
 		)
 	})