direct media: implement direct download for photos

Signed-off-by: Sumner Evans <sumner.evans@automattic.com>

pkg/connector/ids/ids.go

@@ -0,0 +1,101 @@
+package ids
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/gotd/td/tg"
+	"maunium.net/go/mautrix/bridgev2/networkid"
+)
+
+func MakeUserID(userID int64) networkid.UserID {
+	return networkid.UserID(strconv.FormatInt(userID, 10))
+}
+
+func ParseUserID(userID networkid.UserID) (int64, error) {
+	return strconv.ParseInt(string(userID), 10, 64)
+}
+
+func MakeUserLoginID(userID int64) networkid.UserLoginID {
+	return networkid.UserLoginID(strconv.FormatInt(userID, 10))
+}
+
+func MakeMessageID(messageID int) networkid.MessageID {
+	return networkid.MessageID(strconv.Itoa(messageID))
+}
+
+type PeerType string
+
+const (
+	PeerTypeUser    PeerType = "user"
+	PeerTypeChat    PeerType = "chat"
+	PeerTypeChannel PeerType = "channel"
+)
+
+func PeerTypeFromByte(pt byte) (PeerType, error) {
+	switch pt {
+	case 0x01:
+		return PeerTypeUser, nil
+	case 0x02:
+		return PeerTypeChat, nil
+	case 0x03:
+		return PeerTypeChannel, nil
+	default:
+		return "", fmt.Errorf("unknown peer type %d", pt)
+	}
+}
+
+func (pt PeerType) AsByte() byte {
+	switch pt {
+	case PeerTypeUser:
+		return 0x01
+	case PeerTypeChat:
+		return 0x02
+	case PeerTypeChannel:
+		return 0x03
+	default:
+		panic(fmt.Errorf("unknown peer type %s", pt))
+	}
+}
+
+func (pt PeerType) AsPortalKey(chatID int64) networkid.PortalKey {
+	return networkid.PortalKey{ID: networkid.PortalID(fmt.Sprintf("%s:%d", pt, chatID))}
+}
+
+func MakePortalID(peer tg.PeerClass) networkid.PortalKey {
+	switch v := peer.(type) {
+	case *tg.PeerUser:
+		return networkid.PortalKey{ID: networkid.PortalID(fmt.Sprintf("%s:%d", PeerTypeUser, v.UserID))}
+	case *tg.PeerChat:
+		return networkid.PortalKey{ID: networkid.PortalID(fmt.Sprintf("%s:%d", PeerTypeChat, v.ChatID))}
+	case *tg.PeerChannel:
+		return networkid.PortalKey{ID: networkid.PortalID(fmt.Sprintf("%s:%d", PeerTypeChannel, v.ChannelID))}
+	default:
+		panic(fmt.Errorf("unknown peer class type %T", v))
+	}
+}
+
+func ParsePortalID(portalID networkid.PortalID) (pt PeerType, id int64, err error) {
+	parts := strings.Split(string(portalID), ":")
+	pt = PeerType(parts[0])
+	id, err = strconv.ParseInt(parts[1], 10, 64)
+	return
+}
+
+func InputPeerForPortalID(portalID networkid.PortalID) (tg.InputPeerClass, error) {
+	peerType, id, err := ParsePortalID(portalID)
+	if err != nil {
+		return nil, err
+	}
+	switch peerType {
+	case PeerTypeUser:
+		return &tg.InputPeerUser{UserID: id}, nil
+	case PeerTypeChat:
+		return &tg.InputPeerChat{ChatID: id}, nil
+	case PeerTypeChannel:
+		return &tg.InputPeerChannel{ChannelID: id}, nil
+	default:
+		panic("invalid peer type")
+	}
+}

pkg/connector/ids/media.go

@@ -0,0 +1,59 @@
+package ids
+
+import (
+	"encoding/binary"
+	"fmt"
+
+	"maunium.net/go/mautrix/bridgev2/networkid"
+)
+
+// DirectMediaInfo is the information that is encoded in the media ID when
+// using direct media.
+//
+// The format of the media ID is as follows (each character represents a single
+// byte, |'s added for clarity):
+//
+// v|p|CCCCCCCC|TTTTTTTT
+//
+// v (int8) = binary encoding format version. Should be 0.
+// p (byte) = the peer type of the Telegram chat ID
+// CCCCCCCC (int64) = the Telegram chat ID (big endian)
+// TTTTTTTT (int64) = the Telegram message ID (big endian)
+type DirectMediaInfo struct {
+	PeerType  PeerType
+	ChatID    int64
+	MessageID int64
+}
+
+func (m DirectMediaInfo) AsMediaID() (networkid.MediaID, error) {
+	mediaID := []byte{
+		0x00,                // Version
+		m.PeerType.AsByte(), // Peer Type
+	}
+	mediaID = binary.BigEndian.AppendUint64(mediaID, uint64(m.ChatID))    // Telegram Chat ID
+	mediaID = binary.BigEndian.AppendUint64(mediaID, uint64(m.MessageID)) // Telegram Message ID
+	return mediaID, nil
+}
+
+func ParseDirectMediaInfo(mediaID networkid.MediaID) (info DirectMediaInfo, err error) {
+	if len(mediaID) == 0 {
+		err = fmt.Errorf("empty media ID")
+		return
+	}
+	if mediaID[0] != 0x00 {
+		err = fmt.Errorf("invalid version %d", mediaID[0])
+		return
+	}
+	if len(mediaID) != 18 {
+		err = fmt.Errorf("invalid media ID")
+		return
+	}
+	fmt.Printf("%v\n", mediaID)
+	info.PeerType, err = PeerTypeFromByte(mediaID[1])
+	if err != nil {
+		return
+	}
+	info.ChatID = int64(binary.BigEndian.Uint64(mediaID[2:]))
+	info.MessageID = int64(binary.BigEndian.Uint64(mediaID[10:]))
+	return
+}