Reduce Telegram tool message noise

internal/telegram/render.go

@@ -66,6 +66,108 @@ func SummaryDetailsHTMLLimited(summary, details string, limit int) string {
 	return SummaryDetailsHTML(summary, suffix)
 }
 
+func FitHTMLMessage(htmlText string, limit int) string {
+	if limit <= 0 {
+		limit = TelegramHTMLMessageLimit
+	}
+	htmlText = strings.TrimSpace(htmlText)
+	if len([]rune(htmlText)) <= limit {
+		return htmlText
+	}
+
+	const open = "<blockquote expandable>"
+	const close = "</blockquote>"
+	const truncatedQuote = "...[truncated]"
+	for len([]rune(htmlText)) > limit {
+		contentStart, contentEnd, content := largestBlockquoteContent(htmlText, open, close)
+		if contentStart < 0 {
+			return truncateHTMLText(htmlText, limit)
+		}
+
+		contentRunes := []rune(strings.TrimSpace(html.UnescapeString(content)))
+		over := len([]rune(htmlText)) - limit
+		keep := len(contentRunes) - over - 80
+		if keep < 0 {
+			keep = 0
+		}
+		if keep >= len(contentRunes) {
+			keep = len(contentRunes) - 1
+		}
+		replacementText := truncatedQuote
+		if keep > 0 {
+			replacementText = strings.TrimSpace(string(contentRunes[:keep])) + "\n" + truncatedQuote
+		}
+		replacement := EscapeHTML(replacementText)
+		if replacement == content {
+			return summaryOnlyHTML(htmlText, limit)
+		}
+		htmlText = htmlText[:contentStart] + replacement + htmlText[contentEnd:]
+	}
+	return htmlText
+}
+
+func largestBlockquoteContent(htmlText, open, close string) (int, int, string) {
+	bestStart := -1
+	bestEnd := -1
+	bestContent := ""
+	searchFrom := 0
+	for {
+		start := strings.Index(htmlText[searchFrom:], open)
+		if start < 0 {
+			break
+		}
+		start += searchFrom
+		contentStart := start + len(open)
+		end := strings.Index(htmlText[contentStart:], close)
+		if end < 0 {
+			break
+		}
+		end += contentStart
+		content := htmlText[contentStart:end]
+		if bestStart < 0 || len([]rune(content)) > len([]rune(bestContent)) {
+			bestStart = contentStart
+			bestEnd = end
+			bestContent = content
+		}
+		searchFrom = end + len(close)
+	}
+	return bestStart, bestEnd, bestContent
+}
+
+func summaryOnlyHTML(htmlText string, limit int) string {
+	const open = "<blockquote expandable>"
+	const close = "</blockquote>"
+	for {
+		start := strings.Index(htmlText, open)
+		if start < 0 {
+			break
+		}
+		end := strings.Index(htmlText[start+len(open):], close)
+		if end < 0 {
+			break
+		}
+		end += start + len(open) + len(close)
+		htmlText = strings.TrimRight(htmlText[:start], "\n") + "\n" + strings.TrimLeft(htmlText[end:], "\n")
+	}
+	return truncateHTMLText(strings.TrimSpace(htmlText), limit)
+}
+
+func truncateHTMLText(htmlText string, limit int) string {
+	if limit <= 0 {
+		limit = TelegramHTMLMessageLimit
+	}
+	suffix := "\n...[truncated]"
+	runes := []rune(htmlText)
+	if len(runes) <= limit {
+		return htmlText
+	}
+	keep := limit - len([]rune(suffix))
+	if keep < 0 {
+		keep = 0
+	}
+	return string(runes[:keep]) + suffix
+}
+
 func ChunkText(text string, max int) []string {
 	if max <= 0 {
 		max = TelegramMessageLimit