X-Git-Url: http://git.giacomolli.uk/onechat/blobdiff_plain/09cde69fdffe2721434392036f98dc241177f5a1..HEAD:/telegram_api.go

diff --git a/telegram_api.go b/telegram_api.go
index 558d006..07d2bf1 100644
--- a/telegram_api.go
+++ b/telegram_api.go
@@ -22,6 +22,9 @@ const (
 	// getUpdates call can take before the bot gives it up.
 	telegramPollSlack = 20 * time.Second
 
+	// telegramPollTimeout is how long one getUpdates call can take.
+	telegramPollTimeout = telegramPollSeconds*time.Second + telegramPollSlack
+
 	// telegramSendTimeout is how long a sendMessage, sendRichMessage, or
 	// sendChatAction call can take. A connection that stops without a
 	// close, such as after a network change, then fails the call, and the
@@ -34,10 +37,6 @@ const (
 	telegramAnswerBytes = 16 << 20
 )
 
-// errTelegramNetwork tells that a Bot API call got no valid answer, such as
-// after a network error. A later call can work.
-var errTelegramNetwork = errors.New("no valid answer from the Bot API")
-
 // newTelegramAPI returns the client of the Bot API at base with token.
 func newTelegramAPI(base, token string) *TelegramAPI {
 	return &TelegramAPI{
@@ -52,11 +51,14 @@ func newTelegramAPI(base, token string) *TelegramAPI {
 // after a network error, HTTP 429, or a server error. It returns the wait that
 // the Bot API asks for, or 0.
 func telegramRetryable(err error) (bool, time.Duration) {
-	if errors.Is(err, errTelegramNetwork) {
+	var network *TelegramNetworkError
+
+	if errors.As(err, &network) {
 		return true, 0
 	}
 
 	var answer *TelegramError
+
 	if errors.As(err, &answer) {
 		return answer.Status == http.StatusTooManyRequests || answer.Status >= 500, answer.RetryAfter
 	}
@@ -70,13 +72,14 @@ func telegramRetryable(err error) (bool, time.Duration) {
 // tell this, so it is not a refusal.
 func telegramRejected(err error) bool {
 	var answer *TelegramError
+
 	return errors.As(err, &answer) && answer.Refused && (answer.Status == http.StatusBadRequest || answer.Status == http.StatusNotFound)
 }
 
 // TelegramAPI calls the Telegram Bot API. The bot token is a part of each URL,
-// so no error of TelegramAPI holds a URL, a net/http error, or the token.
-// SendTimeout limits each sendMessage, sendRichMessage, and sendChatAction
-// call.
+// so no error of TelegramAPI holds a URL, a net/http error, or the token. Its
+// sendTimeout field limits each sendMessage, sendRichMessage, and
+// sendChatAction call.
 type TelegramAPI struct {
 	base        string
 	token       string
@@ -88,11 +91,9 @@ type TelegramAPI struct {
 // and returns them. Telegram forgets each update before offset. Only new
 // messages are asked for.
 func (b *TelegramAPI) GetUpdates(ctx context.Context, offset int64) ([]TelegramUpdate, error) {
-	ctx, cancel := context.WithTimeout(ctx, telegramPollSeconds*time.Second+telegramPollSlack)
-	defer cancel()
-
 	var updates []TelegramUpdate
-	err := b.call(ctx, "getUpdates", map[string]any{
+
+	err := b.call(ctx, telegramPollTimeout, "getUpdates", map[string]any{
 		"offset":          offset,
 		"timeout":         telegramPollSeconds,
 		"allowed_updates": []string{"message"},
@@ -103,12 +104,9 @@ func (b *TelegramAPI) GetUpdates(ctx context.Context, offset int64) ([]TelegramU
 
 // SendMessage sends text to chat with the format of entities, with no parse
 // mode, so the text needs no escaping. With no entities, the text is plain. A
-// call that takes longer than telegramSendTimeout fails with
-// errTelegramNetwork.
+// call that takes longer than telegramSendTimeout fails with a
+// TelegramNetworkError.
 func (b *TelegramAPI) SendMessage(ctx context.Context, chat int64, text string, entities []TelegramEntity) error {
-	ctx, cancel := context.WithTimeout(ctx, b.sendTimeout)
-	defer cancel()
-
 	params := map[string]any{
 		"chat_id": chat,
 		"text":    text,
@@ -118,17 +116,14 @@ func (b *TelegramAPI) SendMessage(ctx context.Context, chat int64, text string,
 		params["entities"] = entities
 	}
 
-	return b.call(ctx, "sendMessage", params, nil)
+	return b.call(ctx, b.sendTimeout, "sendMessage", params, nil)
 }
 
 // SendRichMessage sends markdown to chat as a rich message, which Telegram
 // renders itself, tables included. A call that takes longer than
-// telegramSendTimeout fails with errTelegramNetwork.
+// telegramSendTimeout fails with a TelegramNetworkError.
 func (b *TelegramAPI) SendRichMessage(ctx context.Context, chat int64, markdown string) error {
-	ctx, cancel := context.WithTimeout(ctx, b.sendTimeout)
-	defer cancel()
-
-	return b.call(ctx, "sendRichMessage", map[string]any{
+	return b.call(ctx, b.sendTimeout, "sendRichMessage", map[string]any{
 		"chat_id": chat,
 		"rich_message": map[string]any{
 			"markdown": markdown,
@@ -137,20 +132,22 @@ func (b *TelegramAPI) SendRichMessage(ctx context.Context, chat int64, markdown
 }
 
 // SendTyping shows the typing action in chat for about five seconds. A call
-// that takes longer than telegramSendTimeout fails with errTelegramNetwork.
+// that takes longer than telegramSendTimeout fails with a TelegramNetworkError.
 func (b *TelegramAPI) SendTyping(ctx context.Context, chat int64) error {
-	ctx, cancel := context.WithTimeout(ctx, b.sendTimeout)
-	defer cancel()
-
-	return b.call(ctx, "sendChatAction", map[string]any{
+	return b.call(ctx, b.sendTimeout, "sendChatAction", map[string]any{
 		"chat_id": chat,
 		"action":  "typing",
 	}, nil)
 }
 
 // call sends one call of method with the JSON params and decodes its result
-// into result, when result is not nil.
-func (b *TelegramAPI) call(ctx context.Context, method string, params, result any) error {
+// into result, when result is not nil. The call can take up to timeout. Its
+// errors tell the cause in plain words, with no method name, so that a log line
+// can say first what the call was for.
+func (b *TelegramAPI) call(ctx context.Context, timeout time.Duration, method string, params, result any) error {
+	ctx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
 	body, err := json.Marshal(params)
 	if err != nil {
 		return fmt.Errorf("%s: encode request: %w", method, err)
@@ -162,34 +159,34 @@ func (b *TelegramAPI) call(ctx context.Context, method string, params, result an
 	}
 
 	request.Header.Set("Content-Type", "application/json")
+
 	response, err := b.http.Do(request)
 	if err != nil {
-		return fmt.Errorf("%s: %w: %s", method, errTelegramNetwork, b.redact(err))
+		return b.networkError("no answer", err, timeout)
 	}
 
 	data, err := io.ReadAll(io.LimitReader(response.Body, telegramAnswerBytes))
 	err = errors.Join(err, response.Body.Close())
 	if err != nil {
-		return fmt.Errorf("%s: %w: read answer: %s", method, errTelegramNetwork, b.redact(err))
+		return b.networkError("answer cut off", err, timeout)
 	}
 
 	var answer TelegramAnswer
+
 	err = json.Unmarshal(data, &answer)
 	if err != nil && response.StatusCode != http.StatusOK {
 		return &TelegramError{
-			Method:      method,
 			Status:      response.StatusCode,
 			Description: http.StatusText(response.StatusCode),
 		}
 	}
 
 	if err != nil {
-		return fmt.Errorf("%s: %w: decode answer: %s", method, errTelegramNetwork, b.redact(err))
+		return b.networkError("invalid JSON", err, timeout)
 	}
 
 	if !answer.OK {
 		return &TelegramError{
-			Method:      method,
 			Status:      response.StatusCode,
 			Description: b.redact(errors.New(answer.Description)),
 			RetryAfter:  time.Duration(answer.Parameters.RetryAfter) * time.Second,
@@ -203,17 +200,34 @@ func (b *TelegramAPI) call(ctx context.Context, method string, params, result an
 
 	err = json.Unmarshal(answer.Result, result)
 	if err != nil {
-		return fmt.Errorf("%s: %w: decode result: %s", method, errTelegramNetwork, b.redact(err))
+		return b.networkError("invalid result", err, timeout)
 	}
 
 	return nil
 }
 
+// networkError returns the TelegramNetworkError of err, which happened at the
+// step that what names. When the call used all of its time timeout, the cause
+// is "no answer in TIMEOUT", because the Go text of a deadline does not tell
+// how long the wait was.
+func (b *TelegramAPI) networkError(what string, err error, timeout time.Duration) error {
+	if errors.Is(err, context.DeadlineExceeded) {
+		return &TelegramNetworkError{
+			Cause: "no answer in " + timeout.String(),
+		}
+	}
+
+	return &TelegramNetworkError{
+		Cause: what + ": " + b.redact(err),
+	}
+}
+
 // redact returns the text of err without a URL and without the token. A
 // *url.Error holds the URL of the call, which holds the token, so only its
 // cause is kept.
 func (b *TelegramAPI) redact(err error) string {
 	var urlError *url.Error
+
 	if errors.As(err, &urlError) {
 		err = urlError.Err
 	}
@@ -221,12 +235,23 @@ func (b *TelegramAPI) redact(err error) string {
 	return strings.ReplaceAll(err.Error(), b.token, "TOKEN")
 }
 
-// TelegramError is an answer of the Bot API that tells of a failure. RetryAfter
-// is the wait that the Bot API asks for after HTTP 429. Refused tells that the
-// answer is a Bot API answer with ok false, not a page of a proxy or of a
-// server error.
+// TelegramNetworkError tells that a Bot API call got no valid answer, such as
+// after a network error. A later call can work. Cause tells why in plain words,
+// with no URL and no token.
+type TelegramNetworkError struct {
+	Cause string
+}
+
+func (e *TelegramNetworkError) Error() string {
+	return e.Cause
+}
+
+// TelegramError is an answer of the Bot API that tells of a failure. Its text
+// gives the HTTP status and the description, such as "502 Bad Gateway".
+// RetryAfter is the wait that the Bot API asks for after HTTP 429. Refused
+// tells that the answer is a Bot API answer with ok false, not a page of a
+// proxy or of a server error.
 type TelegramError struct {
-	Method      string
 	Status      int
 	Description string
 	RetryAfter  time.Duration
@@ -234,7 +259,7 @@ type TelegramError struct {
 }
 
 func (e *TelegramError) Error() string {
-	return fmt.Sprintf("%s: Bot API answered %d: %s", e.Method, e.Status, e.Description)
+	return fmt.Sprintf("%d %s", e.Status, e.Description)
 }
 
 // TelegramUpdate is one update of getUpdates. Message is nil for the kinds of