implement truncation of a honk

should fix #9.

2 files changed, 44 insertions, 22 deletions

diff --git a/changelog.txt b/changelog.txt
index 69671ff..a2a2a10 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -2,5 +2,6 @@ changelog
 
 === next
 
++ added truncation to long honks and donk descriptions
 + removed TelegramResponse from the honkMap
-+ made gethonks retry 5 times before giving up
\ No newline at end of file
++ made gethonks retry 5 times before giving up
diff --git a/main.go b/main.go
index 1d49c67..965ff69 100644
--- a/main.go
+++ b/main.go
@@ -185,6 +185,7 @@ func NewMess(parseMode string) *Mess {
 
 // NewMessFromHonk creates a slice of Mess objects from existing Honk.
 func NewMessFromHonk(honk *Honk) []*Mess {
+	var truncateWith = "...\n\nfull honk: " + honk.XID // hardcoded == bad
 	// donks should be sent as a separate messages, so need to create all of 'em
 	// cap(messes) = 1 for honk + 1 for each donk
 	var messes = make([]*Mess, 0, 1+len(honk.Donks))
@@ -192,7 +193,7 @@ func NewMessFromHonk(honk *Honk) []*Mess {
 	messes = append(messes, NewMess("html"))
 	for _, donk := range honk.Donks {
 		donkMess := NewMess("MarkdownV2") // donks don't contain html
-		donkMess.Caption = donk.Desc      // FIXME: no check for length
+		donkMess.Caption = TruncateNoise(donk.Desc, truncateWith, 1024)
 		switch {
 		case strings.HasPrefix(donk.Media, "image/"):
 			donkMess.Photo = donk.URL
@@ -214,7 +215,8 @@ func NewMessFromHonk(honk *Honk) []*Mess {
 		messes = messes[:1] // don't donk if editing
 	}
 
-	var noise = calmNoise(honk.Noise)
+	var text = CalmNoise(honk.Noise)
+	text = TruncateNoise(text, truncateWith, 4096)
 	// bonk, then honk back - ok
 	// honk back, then bonk - not gonna sync, is it ok?
 	// upd: bonks work really confusing
@@ -225,15 +227,15 @@ func NewMessFromHonk(honk *Honk) []*Mess {
 		messes[0].ReplyToMessageID = honk.ReplyToID
 	case "bonked":
 		oonker := fmt.Sprintf("<a href=\"%s\">%s</a>:", honk.Oonker, honk.Oondle)
-		noise = oonker + "\n" + noise
+		text = oonker + "\n" + text
 	}
 
 	// danger zone handling
 	if strings.HasPrefix(honk.Precis, "DZ:") {
-		noise = strings.Join([]string{"<tg-spoiler>", "</tg-spoiler>"}, noise)
-		noise = honk.Precis + "\n" + noise
+		text = strings.Join([]string{"<tg-spoiler>", "</tg-spoiler>"}, text)
+		text = honk.Precis + "\n" + text
 	}
-	messes[0].Text = noise
+	messes[0].Text = text
 
 	return messes
 }
@@ -359,25 +361,44 @@ var (
 
 const emptyNoise = "<p></p>\n"
 
-// calmNoise erases and rewrites html tags that are not supported by Telegram.
-func calmNoise(noise string) string {
-	// TODO: check length of a honk
-
+// CalmNoise erases and rewrites html tags that are not supported by Telegram.
+func CalmNoise(s string) string {
 	// delete these
-	noise = rePTags.ReplaceAllString(noise, "")
-	noise = reHlTags.ReplaceAllString(noise, "")
-	noise = reBrTags.ReplaceAllString(noise, "")
-	noise = reImgTags.ReplaceAllString(noise, "")
-	noise = reUlTags.ReplaceAllString(noise, "")
-	noise = reTbTags.ReplaceAllString(noise, "")
+	s = rePTags.ReplaceAllString(s, "")
+	s = reHlTags.ReplaceAllString(s, "")
+	s = reBrTags.ReplaceAllString(s, "")
+	s = reImgTags.ReplaceAllString(s, "")
+	s = reUlTags.ReplaceAllString(s, "")
+	s = reTbTags.ReplaceAllString(s, "")
 
 	// these can be repurposed
-	noise = reHrTags.ReplaceAllString(noise, "---\n")
-	noise = reHnTags.ReplaceAllString(noise, "<b>$1</b>\n\n")
-	noise = reBqTags.ReplaceAllString(noise, "| <i>$1</i>")
-	noise = reLiTags.ReplaceAllString(noise, "* $1\n")
+	s = reHrTags.ReplaceAllString(s, "---\n")
+	s = reHnTags.ReplaceAllString(s, "<b>$1</b>\n\n")
+	s = reBqTags.ReplaceAllString(s, "| <i>$1</i>")
+	s = reLiTags.ReplaceAllString(s, "* $1\n")
+
+	return strings.TrimSpace(s)
+}
 
-	return strings.TrimSpace(noise)
+// TruncateNoise truncates a string up to `length - len(with)` characters long and adds `with` to the end.
+func TruncateNoise(s, with string, length int) string {
+	// telegram can handle posts no longer than 4096 (or 1024) characters _after_ the parsing of entities.
+	// we could be clever and calculate the true length of text, but let's keep it simple and stupid.
+	if len(s) <= length {
+		return s
+	}
+
+	var b strings.Builder
+	b.Grow(length)
+	var end = length - 1 - len(with)
+	for i, r := range s {
+		if i >= end {
+			break
+		}
+		b.WriteRune(r)
+	}
+	b.WriteString(with)
+	return b.String()
 }
 
 func init() {