Convert webp images to png when sending to WhatsApp (#346)

WhatsApp doesn't seem to like webp images

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/mattn/go-sqlite3 v1.14.8
 	github.com/prometheus/client_golang v1.11.0
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
+	golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d
 	gopkg.in/yaml.v2 v2.4.0
 	maunium.net/go/mauflag v1.0.0
 	maunium.net/go/maulogger/v2 v2.3.0

go.sum

@@ -148,6 +148,8 @@ golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
 golang.org/x/crypto v0.0.0-20210506145944-38f3c27a63bf h1:B2n+Zi5QeYRDAEodEu72OS36gmTWjgpXr2+cWcBW90o=
 golang.org/x/crypto v0.0.0-20210506145944-38f3c27a63bf/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
+golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d h1:RNPAfi2nHY7C2srAV8A49jpsYr0ADedCk1wq6fTMTvs=
+golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -184,6 +186,7 @@ golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9sn
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

portal.go

@@ -42,6 +42,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"golang.org/x/image/webp"
 	"github.com/Rhymen/go-whatsapp"
 	waProto "github.com/Rhymen/go-whatsapp/binary/proto"
 
@@ -1889,6 +1890,20 @@ func (portal *Portal) downloadThumbnail(content *event.MessageEventContent, id i
 	return buf.Bytes()
 }
 
+func (portal *Portal) convertWebPtoPNG(webpImage []byte) ([]byte, error) {
+	webpDecoded, err := webp.Decode(bytes.NewReader(webpImage))
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode webp image: %w", err)
+	}
+
+	var pngBuffer bytes.Buffer
+	if err := png.Encode(&pngBuffer, webpDecoded); err != nil {
+		return nil, fmt.Errorf("failed to encode png image: %w", err)
+	}
+
+	return pngBuffer.Bytes(), nil
+}
+
 func (portal *Portal) convertGifToVideo(gif []byte) ([]byte, error) {
 	dir, err := ioutil.TempDir("", "gif-convert-*")
 	if err != nil {
@@ -1974,7 +1989,14 @@ func (portal *Portal) preprocessMatrixMedia(sender *User, relaybotFormatted bool
 		}
 		content.Info.MimeType = "video/mp4"
 	}
-
+	if mediaType == whatsapp.MediaImage && content.GetInfo().MimeType == "image/webp" {
+		data, err = portal.convertWebPtoPNG(data)
+		if err != nil {
+			portal.log.Errorfln("Failed to convert webp to png in %s: %v", eventID, err)
+			return nil
+		}
+		content.Info.MimeType = "image/png"
+	}
 	url, mediaKey, fileEncSHA256, fileSHA256, fileLength, err := sender.Conn.Upload(bytes.NewReader(data), mediaType)
 	if err != nil {
 		portal.log.Errorfln("Failed to upload media in %s: %v", eventID, err)