download: add method for fetching sticker packs

Author: tulir

download.go

@@ -11,6 +11,7 @@ import (
 	"crypto/hmac"
 	"crypto/sha256"
 	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -28,6 +29,7 @@ import (
 	"go.mau.fi/whatsmeow/proto/waMediaTransport"
 	"go.mau.fi/whatsmeow/proto/waServerSync"
 	"go.mau.fi/whatsmeow/socket"
+	"go.mau.fi/whatsmeow/types"
 	"go.mau.fi/whatsmeow/util/cbcutil"
 	"go.mau.fi/whatsmeow/util/hkdfutil"
 )
@@ -87,6 +89,7 @@ var (
 	_ DownloadableMessage   = (*waE2E.HistorySyncNotification)(nil)
 	_ DownloadableMessage   = (*waServerSync.ExternalBlobReference)(nil)
 	_ DownloadableThumbnail = (*waE2E.ExtendedTextMessage)(nil)
+	_ DownloadableMessage   = (*types.StickerPackItem)(nil)
 )
 
 type downloadableMessageWithLength interface {
@@ -191,15 +194,33 @@ func (cli *Client) DownloadThumbnail(ctx context.Context, msg DownloadableThumbn
 
 // GetMediaType returns the MediaType value corresponding to the given protobuf message.
 func GetMediaType(msg DownloadableMessage) MediaType {
-	protoReflecter, ok := msg.(proto.Message)
-	if !ok {
-		mediaTypeable, ok := msg.(MediaTypeable)
-		if !ok {
-			return ""
-		}
-		return mediaTypeable.GetMediaType()
+	switch typedMsg := msg.(type) {
+	case *types.StickerPackItem:
+		return MediaImage
+	case proto.Message:
+		return classToMediaType[typedMsg.ProtoReflect().Descriptor().Name()]
+	case MediaTypeable:
+		return typedMsg.GetMediaType()
+	default:
+		return ""
+	}
+}
+
+func (cli *Client) FetchStickerPack(ctx context.Context, packID string) (*types.StickerPack, error) {
+	url := fmt.Sprintf("https://static.whatsapp.net/sticker?lottie=1&cat=sticker_pack_data&id=%s&lg=en", packID)
+	resp, err := cli.doMediaDownloadRequest(ctx, url)
+	if err != nil {
+		return nil, err
+	}
+	var packs []types.StickerPack
+	err = json.NewDecoder(resp.Body).Decode(&packs)
+	_ = resp.Body.Close()
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode response: %w", err)
+	} else if len(packs) == 0 {
+		return nil, fmt.Errorf("no sticker pack found in response")
 	}
-	return classToMediaType[protoReflecter.ProtoReflect().Descriptor().Name()]
+	return &packs[0], nil
 }
 
 // Download downloads the attachment from the given protobuf message.

types/sticker.go

@@ -0,0 +1,53 @@
+package types
+
+type StickerPack struct {
+	StickerPackID    string            `json:"sticker-pack-id"`
+	Name             string            `json:"name"`
+	Publisher        string            `json:"publisher"`
+	Description      string            `json:"description"`
+	FileSize         string            `json:"file-size"`
+	ImageDataHash    string            `json:"image-data-hash"`
+	Stickers         []StickerPackItem `json:"stickers"`
+	Animated         int               `json:"animated"`
+	Lottie           int               `json:"lottie"`
+	PreviewImageIDs  []string          `json:"preview-image-ids"`
+	TrayImageID      string            `json:"tray-image-id"`
+	TrayImagePreview string            `json:"tray-image-preview"`
+}
+
+type StickerPackItem struct {
+	MediaKey               []byte   `json:"media-key"`
+	EncFileHash            []byte   `json:"enc-file-hash"`
+	FileHash               []byte   `json:"file-hash"`
+	DirectPath             string   `json:"direct-path"`
+	URL                    string   `json:"url"`
+	FileSize               int64    `json:"file-size"`
+	MimeType               string   `json:"mimetype"`
+	Height                 int      `json:"height"`
+	Width                  int      `json:"width"`
+	Emojis                 []string `json:"emojis"`
+	AccessibilityText      string   `json:"accessibility-text"`
+	Handle                 string   `json:"handle"`
+	StickerHashWithoutMeta []byte   `json:"sticker-hash-without-meta"`
+	PreviewWebpID          string   `json:"preview-webp-id"`
+}
+
+func (spi *StickerPackItem) GetDirectPath() string {
+	return spi.DirectPath
+}
+
+func (spi *StickerPackItem) GetMediaKey() []byte {
+	return spi.MediaKey
+}
+
+func (spi *StickerPackItem) GetFileSHA256() []byte {
+	return spi.FileHash
+}
+
+func (spi *StickerPackItem) GetFileEncSHA256() []byte {
+	return spi.EncFileHash
+}
+
+func (spi *StickerPackItem) GetFileSizeBytes() int64 {
+	return spi.FileSize
+}