2 files changed, 59 insertions, 8 deletions

diff --git a/bridge/telegram/handlers.go b/bridge/telegram/handlers.go
index 5c60f74b..ee087524 100644
--- a/bridge/telegram/handlers.go
+++ b/bridge/telegram/handlers.go
@@ -217,6 +217,46 @@ func (b *Btelegram) handleDownloadAvatar(userid int, channel string) {
 	}
 }
 
+func (b *Btelegram) maybeConvertTgs(name *string, data *[]byte) {
+	var format string
+	switch b.GetString("MediaConvertTgs") {
+	case FormatWebp:
+		b.Log.Debugf("Tgs to WebP conversion enabled, converting %v", name)
+		format = FormatWebp
+	case FormatPng:
+		// The WebP to PNG converter can't handle animated webp files yet,
+		// and I'm not going to write a path for x/image/webp.
+		// The error message would be:
+		//     conversion failed: webp: non-Alpha VP8X is not implemented
+		// So instead, we tell lottie to directly go to PNG.
+		b.Log.Debugf("Tgs to PNG conversion enabled, converting %v", name)
+		format = FormatPng
+	default:
+		// Otherwise, no conversion was requested. Trying to run the usual webp
+		// converter would fail, because '.tgs.webp' is actually a gzipped JSON
+		// file, and has nothing to do with WebP.
+		return
+	}
+	err := helper.ConvertTgsToX(data, format, b.Log)
+	if err != nil {
+		b.Log.Errorf("conversion failed: %v", err)
+	} else {
+		*name = strings.Replace(*name, "tgs.webp", format, 1)
+	}
+}
+
+func (b *Btelegram) maybeConvertWebp(name *string, data *[]byte) {
+	if b.GetBool("MediaConvertWebPToPNG") {
+		b.Log.Debugf("WebP to PNG conversion enabled, converting %v", name)
+		err := helper.ConvertWebPToPNG(data)
+		if err != nil {
+			b.Log.Errorf("conversion failed: %v", err)
+		} else {
+			*name = strings.Replace(*name, ".webp", ".png", 1)
+		}
+	}
+}
+
 // handleDownloadFile handles file download
 func (b *Btelegram) handleDownload(rmsg *config.Message, message *tgbotapi.Message) error {
 	size := 0
@@ -264,15 +304,13 @@ func (b *Btelegram) handleDownload(rmsg *config.Message, message *tgbotapi.Messa
 	if err != nil {
 		return err
 	}
-	if strings.HasSuffix(name, ".webp") && b.GetBool("MediaConvertWebPToPNG") {
-		b.Log.Debugf("WebP to PNG conversion enabled, converting %s", name)
-		err := helper.ConvertWebPToPNG(data)
-		if err != nil {
-			b.Log.Errorf("conversion failed: %s", err)
-		} else {
-			name = strings.Replace(name, ".webp", ".png", 1)
-		}
+
+	if strings.HasSuffix(name, ".tgs.webp") {
+		b.maybeConvertTgs(&name, data)
+	} else if strings.HasSuffix(name, ".webp") {
+		b.maybeConvertWebp(&name, data)
 	}
+
 	helper.HandleDownloadData(b.Log, rmsg, name, message.Caption, "", data, b.General)
 	return nil
 }
diff --git a/bridge/telegram/telegram.go b/bridge/telegram/telegram.go
index 29f2f291..f1c7168c 100644
--- a/bridge/telegram/telegram.go
+++ b/bridge/telegram/telegram.go
@@ -2,6 +2,7 @@ package btelegram
 
 import (
 	"html"
+	"log"
 	"strconv"
 	"strings"
 
@@ -16,6 +17,8 @@ const (
 	HTMLFormat  = "HTML"
 	HTMLNick    = "htmlnick"
 	MarkdownV2  = "MarkdownV2"
+	FormatPng   = "png"
+	FormatWebp  = "webp"
 )
 
 type Btelegram struct {
@@ -25,6 +28,16 @@ type Btelegram struct {
 }
 
 func New(cfg *bridge.Config) bridge.Bridger {
+	tgsConvertFormat := cfg.GetString("MediaConvertTgs")
+	if tgsConvertFormat != "" {
+		err := helper.CanConvertTgsToX()
+		if err != nil {
+			log.Fatalf("Telegram bridge configured to convert .tgs files to '%s', but lottie does not appear to work:\n%#v", tgsConvertFormat, err)
+		}
+		if tgsConvertFormat != FormatPng && tgsConvertFormat != FormatWebp {
+			log.Fatalf("Telegram bridge configured to convert .tgs files to '%s', but only '%s' and '%s' are supported.", FormatPng, FormatWebp, tgsConvertFormat)
+		}
+	}
 	return &Btelegram{Config: cfg, avatarMap: make(map[string]string)}
 }