move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/query/messages/specialize.go

@@ -0,0 +1,177 @@
+package messages
+
+import (
+	"fmt"
+	"time"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+// Document returns document object if message has a document attachment (video, voice, audio,
+// basically every type except photo).
+func (e Elem) Document() (*tg.Document, bool) {
+	msg, ok := e.Msg.(*tg.Message)
+	if !ok {
+		return nil, false
+	}
+
+	media, ok := msg.Media.(*tg.MessageMediaDocument)
+	if !ok {
+		return nil, false
+	}
+
+	return media.Document.AsNotEmpty()
+}
+
+// Photo returns photo object if message has a photo attachment.
+func (e Elem) Photo() (*tg.Photo, bool) {
+	msg, ok := e.Msg.(*tg.Message)
+	if !ok {
+		return nil, false
+	}
+
+	media, ok := msg.Media.(*tg.MessageMediaPhoto)
+	if !ok {
+		return nil, false
+	}
+
+	return media.Photo.AsNotEmpty()
+}
+
+// File represents file attachment.
+type File struct {
+	Name     string
+	MIMEType string
+	Location tg.InputFileLocationClass
+}
+
+const dateLayout = "2006-01-02_15-04-05"
+
+func getDocFilename(doc *tg.Document) string {
+	var filename, ext string
+	for _, attr := range doc.Attributes {
+		switch v := attr.(type) {
+		case *tg.DocumentAttributeImageSize:
+			switch doc.MimeType {
+			case "image/png":
+				ext = ".png"
+			case "image/webp":
+				ext = ".webp"
+			case "image/tiff":
+				ext = ".tif"
+			default:
+				ext = ".jpg"
+			}
+		case *tg.DocumentAttributeAnimated:
+			ext = ".gif"
+		case *tg.DocumentAttributeSticker:
+			ext = ".webp"
+		case *tg.DocumentAttributeVideo:
+			switch doc.MimeType {
+			case "video/mpeg":
+				ext = ".mpeg"
+			case "video/webm":
+				ext = ".webm"
+			case "video/ogg":
+				ext = ".ogg"
+			default:
+				ext = ".mp4"
+			}
+		case *tg.DocumentAttributeAudio:
+			switch doc.MimeType {
+			case "audio/webm":
+				ext = ".webm"
+			case "audio/aac":
+				ext = ".aac"
+			case "audio/ogg":
+				ext = ".ogg"
+			default:
+				ext = ".mp3"
+			}
+		case *tg.DocumentAttributeFilename:
+			filename = v.FileName
+		}
+	}
+
+	if filename == "" {
+		filename = fmt.Sprintf(
+			"doc%d_%s%s", doc.GetID(),
+			time.Unix(int64(doc.Date), 0).Format(dateLayout),
+			ext,
+		)
+	}
+
+	return filename
+}
+
+type sizedPhoto interface {
+	GetW() int
+	GetH() int
+	GetType() string
+}
+
+var (
+	_ sizedPhoto = (*tg.PhotoSize)(nil)
+	_ sizedPhoto = (*tg.PhotoCachedSize)(nil)
+	_ sizedPhoto = (*tg.PhotoSizeProgressive)(nil)
+)
+
+// File returns file location if message has a file attachment.
+func (e Elem) File() (File, bool) {
+	msg, ok := e.Msg.(*tg.Message)
+	if !ok {
+		return File{}, false
+	}
+
+	switch media := msg.Media.(type) {
+	case *tg.MessageMediaPhoto:
+		photo, ok := media.Photo.AsNotEmpty()
+		if !ok {
+			return File{}, false
+		}
+
+		filename := fmt.Sprintf(
+			"photo%d_%s.jpg", photo.GetID(),
+			time.Unix(int64(photo.Date), 0).Format(dateLayout),
+		)
+
+		var (
+			thumbSize  string
+			maxW, maxH int
+		)
+		for _, g := range photo.Sizes {
+			// TODO(tdakkota): add helpers to choose photo size.
+			if sz, ok := g.(sizedPhoto); ok && maxW < sz.GetW() && maxH < sz.GetH() {
+				thumbSize = sz.GetType()
+			}
+		}
+
+		if thumbSize == "" {
+			return File{}, false
+		}
+
+		return File{
+			Name:     filename,
+			MIMEType: "image/jpeg",
+			Location: &tg.InputPhotoFileLocation{
+				ID:            photo.ID,
+				AccessHash:    photo.AccessHash,
+				FileReference: photo.FileReference,
+				ThumbSize:     thumbSize,
+			},
+		}, true
+	case *tg.MessageMediaDocument:
+		doc, ok := media.Document.AsNotEmpty()
+		if !ok {
+			return File{}, false
+		}
+
+		return File{
+			Name:     getDocFilename(doc),
+			MIMEType: doc.MimeType,
+			Location: doc.AsInputDocumentFileLocation(),
+		}, true
+	default:
+		return File{}, false
+	}
+}