"fmt"
"io"
"log"
+ "net/http"
"os"
"path/filepath"
"strings"
"sync"
"time"
+ "unicode/utf8"
)
const (
// messageUnits is the most UTF-16 code units of one Telegram message.
messageUnits = 4096
+ // richMessageBytes is the most bytes of the Markdown of one rich
+ // message. The Bot API allows 32768 characters of rendered text, and
+ // the Markdown of a text has at least as many bytes as the text has
+ // characters.
+ richMessageBytes = 32768
+
// typingInterval is how often the bot shows the typing action while a
// turn runs. Telegram shows the action for about five seconds.
typingInterval = 4 * time.Second
// telegramBot connects the private chat of the owner with the agent. It polls
// the Bot API for new messages and sends each text message of the owner to the
// agent. It ignores every other update. Its sender sends the replies, the
-// errors, and the user messages of the other clients to the chat as plain text,
-// and shows the typing action while a turn runs. Tool calls do not go to the
-// chat.
+// errors, the notices of the bot, and the user messages of the other clients to
+// the chat, and shows the typing action while a turn runs. Only the replies
+// have a format: their Markdown goes as rich messages, which Telegram renders
+// itself, and as message entities only when Telegram refuses a rich message.
+// The rest is plain text. Tool calls do not go to the chat.
//
// The offset file holds the ID of the next update. It moves past an update
// only after the message of the update is durable in the log, so a restart
ready chan struct{}
}
+// botPart is the text of one message to the chat, at most messageUnits long,
+// and its entities.
+type botPart struct {
+ text string
+ entities []botEntity
+}
+
// offsetFile is the content of the offset file.
type offsetFile struct {
Offset int64 `json:"offset"`
// stop the agent.
func (b *telegramBot) Notify(event Event) {
switch event.Kind {
- case "busy", "idle", "reply", "error":
+ case "busy", "idle", "reply", "error", "notice":
case "user":
if event.Source == telegramSource {
return
case "idle":
busy = false
default:
- for _, part := range splitMessage(botText(event), messageUnits) {
- b.deliver(ctx, part)
- }
+ b.post(ctx, event)
if busy {
b.typing(ctx)
_ = b.api.SendTyping(ctx, b.owner)
}
-// deliver sends text to the chat. It tries again after each failure that a
-// later try can fix, until ctx ends. It drops the text after any other failure.
-func (b *telegramBot) deliver(ctx context.Context, text string) {
+// post sends event to the chat. A reply goes as rich messages of its Markdown,
+// split with splitRich. Every other event goes as plain text, split with
+// splitMessage.
+func (b *telegramBot) post(ctx context.Context, event Event) {
+ if event.Kind != "reply" {
+ for _, text := range splitMessage(botText(event), messageUnits) {
+ b.deliver(ctx, botPart{
+ text: text,
+ })
+ }
+
+ return
+ }
+
+ for _, markdown := range splitRich(event.Text, richMessageBytes) {
+ b.deliverRich(ctx, markdown)
+ }
+}
+
+// deliverRich sends markdown to the chat as a rich message. When the Bot API
+// refuses it with HTTP 400 or 404, the message was not sent, so deliverRich
+// sends the same Markdown once with message entities, and the reply is not
+// lost and does not repeat. It tries again after each failure that a later try
+// can fix, until ctx ends. It drops the message after any other failure.
+func (b *telegramBot) deliverRich(ctx context.Context, markdown string) {
wait := b.minWait
for {
- err := b.api.SendMessage(ctx, b.owner, text)
+ err := b.api.SendRichMessage(ctx, b.owner, markdown)
if err == nil || ctx.Err() != nil {
return
}
+ if rejected(err) {
+ b.logger.Printf("rich message refused, the reply goes with entities: %v", err)
+ for _, part := range replyParts(markdown) {
+ b.deliver(ctx, part)
+ }
+
+ return
+ }
+
+ retry, asked := retryable(err)
+ if !retry {
+ b.logger.Printf("message dropped: %v", err)
+ return
+ }
+
+ wait = b.pause(ctx, err, wait, asked)
+ }
+}
+
+// deliver sends part to the chat. When Telegram refuses a part with entities
+// (HTTP 400), it sends the text of the part again once with no entities, so a
+// reply is not lost to a bad entity. It tries again after each failure that a
+// later try can fix, until ctx ends. It drops the part after any other failure.
+func (b *telegramBot) deliver(ctx context.Context, part botPart) {
+ wait := b.minWait
+ for {
+ err := b.api.SendMessage(ctx, b.owner, part.text, part.entities)
+ if err == nil || ctx.Err() != nil {
+ return
+ }
+
+ var answer *botError
+ if len(part.entities) > 0 && errors.As(err, &answer) && answer.Status == http.StatusBadRequest {
+ b.logger.Printf("entities refused, the message goes again as plain text: %v", err)
+ part.entities = nil
+
+ continue
+ }
+
retry, asked := retryable(err)
if !retry {
b.logger.Printf("message dropped: %v", err)
// notice queues a short answer of the bot for the chat.
func (b *telegramBot) notice(text string) {
b.Notify(Event{
- Kind: "reply",
+ Kind: "notice",
Text: text,
})
}
return len(text)
}
+
+// splitRich cuts the Markdown of a reply into parts of at most limit bytes. It
+// cuts after a blank line outside a code block, so a table, a code block, or a
+// paragraph stays whole. When no such cut fits in a part, it cuts after the
+// last line break outside a code block, then after the last line break in a
+// code block, which it closes at the end of the part and opens again in the
+// next part with the same fence line. A line longer than limit is cut at the
+// limit. It never cuts a character.
+func splitRich(markdown string, limit int) []string {
+ var parts []string
+ for len(markdown) > limit {
+ cut, fence, opening := richCut(markdown, limit)
+ if fence == "" {
+ parts = append(parts, markdown[:cut])
+ markdown = markdown[cut:]
+
+ continue
+ }
+
+ parts = append(parts, markdown[:cut]+fence+"\n")
+ markdown = opening + "\n" + markdown[cut:]
+ }
+
+ return append(parts, markdown)
+}
+
+// richCut returns where splitRich cuts markdown, which is longer than limit.
+// For a cut in a code block, it also returns the fence that closes the block
+// and the line that opens it. Each part before a cut holds text other than
+// space, and a cut in a code block leaves room for the fence, so each cut makes
+// the rest shorter.
+func richCut(markdown string, limit int) (int, string, string) {
+ blank, line, code := 0, 0, 0
+ var fence, opening, inFence, inOpening string
+ for start := 0; start < limit; {
+ end := strings.IndexByte(markdown[start:], '\n')
+ if end < 0 || start+end+1 > limit {
+ break
+ }
+
+ end += start + 1
+ text := strings.TrimRight(markdown[start:end], "\r\n")
+ _, opens := codeFence(text)
+ switch {
+ case fence != "":
+ if closesFence(text, fence) {
+ fence = ""
+ } else if end > len(opening)+1 && end+len(fence)+1 <= limit {
+ code, inFence, inOpening = end, fence, opening
+ }
+ case opens != "":
+ fence, opening = opens, text
+ case strings.TrimSpace(markdown[:end]) == "":
+ case strings.TrimSpace(text) == "":
+ blank = end
+ }
+
+ if fence == "" && strings.TrimSpace(markdown[:end]) != "" {
+ line = end
+ }
+
+ start = end
+ }
+
+ switch {
+ case blank > 0:
+ return blank, "", ""
+ case line > 0:
+ return line, "", ""
+ case code > 0:
+ return code, inFence, inOpening
+ }
+
+ cut := limit
+ for !utf8.RuneStart(markdown[cut]) {
+ cut--
+ }
+
+ return cut, "", ""
+}
+
+// replyParts returns the messages of the Markdown of a reply with message
+// entities. A reply that has no text left after the conversion, such as an
+// empty code block, goes as its Markdown.
+func replyParts(markdown string) []botPart {
+ text, entities := markdownEntities(markdown)
+ if strings.TrimSpace(text) == "" {
+ text, entities = markdown, nil
+ }
+
+ return splitEntities(text, entities, messageUnits)
+}
+
+// splitEntities cuts text into parts with splitMessage, and gives each part the
+// entities in it, with offsets from the start of the part. An entity that
+// crosses a cut becomes one entity in each part.
+func splitEntities(text string, entities []botEntity, limit int) []botPart {
+ var parts []botPart
+ start := 0
+ for _, part := range splitMessage(text, limit) {
+ end := start + utf16Units(part)
+ var kept []botEntity
+ for _, entity := range entities {
+ from := max(entity.Offset, start)
+ to := min(entity.Offset+entity.Length, end)
+ if to <= from {
+ continue
+ }
+
+ entity.Offset = from - start
+ entity.Length = to - from
+ kept = append(kept, entity)
+ }
+
+ parts = append(parts, botPart{
+ text: part,
+ entities: kept,
+ })
+
+ start = end
+ }
+
+ return parts
+}
projects / onechat / blobdiff