media: make all media direct downloadable

The only exception is emojis.

Also changed direct download encoding field names to be more generic
when used in mixed manner depending on peer type.

Direct downloads are still somewhat inefficient as they require an API
round trip to succeed but we can cache things in the database if needed.

pkg/connector/ids/media.go

@@ -17,6 +17,8 @@
 package ids
 
 import (
+	"bytes"
+	"crypto/sha256"
 	"encoding/binary"
 	"fmt"
 
@@ -33,59 +35,94 @@ import (
 //
 // 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)
-// rrrrrrrr (int64) = the receiver ID (big endian)
+// cccccccc (int64) = the Telegram peer ID (big endian)
+// rrrrrrrr (int64) = the Telegram user ID (big endian)
 // mmmmmmmm (int64) = the Telegram message ID (big endian)
-// MMMMMMMM (int64) = the Telegram media ID (big endian)
+// MMMMMMMM (int64) = the Telegram photo/file/document ID (big endian)
 // T (byte) = 0 or 1 depending on whether it's a thumbnail
 type DirectMediaInfo struct {
-	PeerType        PeerType
-	ChatID          int64
-	ReceiverID      int64
-	MessageID       int64
-	TelegramMediaID int64
-	Thumbnail       bool
+	// Type of PeerID
+	PeerType PeerType
+
+	// Peer ID, may be channel, chat or user
+	PeerID int64
+
+	// Telegram user ID of the client that downloads this media
+	UserID int64
+
+	// Telegram message ID if related to a message
+	MessageID int64
+
+	// Telegram photo/file/document ID, depends on PeerType
+	ID int64
+
+	// Is this a thumbnail?
+	Thumbnail bool
 }
 
 func (m DirectMediaInfo) AsMediaID() (networkid.MediaID, error) {
-	mediaID := []byte{
-		0x00,                // Version
-		m.PeerType.AsByte(), // Peer Type
+	var mediaID networkid.MediaID
+	buf := &bytes.Buffer{}
+
+	// version byte
+	if err := binary.Write(buf, binary.BigEndian, byte(0)); err != nil {
+		return mediaID, err
 	}
-	mediaID = binary.BigEndian.AppendUint64(mediaID, uint64(m.ChatID))          // Telegram Chat ID
-	mediaID = binary.BigEndian.AppendUint64(mediaID, uint64(m.ReceiverID))      // Telegram Chat ID
-	mediaID = binary.BigEndian.AppendUint64(mediaID, uint64(m.MessageID))       // Telegram Message ID
-	mediaID = binary.BigEndian.AppendUint64(mediaID, uint64(m.TelegramMediaID)) // Telegram Media ID
-	if m.Thumbnail {
-		mediaID = append(mediaID, 0x01)
-	} else {
-		mediaID = append(mediaID, 0x00)
+
+	// v0
+	if err := binary.Write(buf, binary.BigEndian, m.PeerType.AsByte()); err != nil {
+		return mediaID, err
+	} else if err := binary.Write(buf, binary.BigEndian, m.PeerID); err != nil {
+		return mediaID, err
+	} else if err := binary.Write(buf, binary.BigEndian, m.UserID); err != nil {
+		return mediaID, err
+	} else if err := binary.Write(buf, binary.BigEndian, m.MessageID); err != nil {
+		return mediaID, err
+	} else if err := binary.Write(buf, binary.BigEndian, m.ID); err != nil {
+		return mediaID, err
+	} else if err := binary.Write(buf, binary.BigEndian, m.Thumbnail); err != nil {
+		return mediaID, err
 	}
-	return mediaID, nil
+
+	return networkid.MediaID(buf.Bytes()), 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) != 35 {
-		err = fmt.Errorf("invalid media ID")
-		return
+		return info, fmt.Errorf("empty media ID")
 	}
 
-	info.PeerType, err = PeerTypeFromByte(mediaID[1])
-	if err != nil {
-		return
+	buf := bytes.NewBuffer(mediaID)
+
+	// version byte
+	var version byte
+	if err := binary.Read(buf, binary.BigEndian, &version); err != nil {
+		return info, err
+	} else if version != 0 {
+		return info, fmt.Errorf("invalid version %d", version)
 	}
-	info.ChatID = int64(binary.BigEndian.Uint64(mediaID[2:]))
-	info.ReceiverID = int64(binary.BigEndian.Uint64(mediaID[10:]))
-	info.MessageID = int64(binary.BigEndian.Uint64(mediaID[18:]))
-	info.TelegramMediaID = int64(binary.BigEndian.Uint64(mediaID[26:]))
-	info.Thumbnail = mediaID[34] == 1
-	return
+
+	// v0
+	var peerType byte
+	if err := binary.Read(buf, binary.BigEndian, &peerType); err != nil {
+		return info, fmt.Errorf("failed to read peer type: %w", err)
+	} else if info.PeerType, err = PeerTypeFromByte(peerType); err != nil {
+		return info, fmt.Errorf("failed to convert peer type: %w", err)
+	} else if err := binary.Read(buf, binary.BigEndian, &info.PeerID); err != nil {
+		return info, fmt.Errorf("failed to read peer id: %w", err)
+	} else if err := binary.Read(buf, binary.BigEndian, &info.UserID); err != nil {
+		return info, fmt.Errorf("failed to read user id: %w", err)
+	} else if err := binary.Read(buf, binary.BigEndian, &info.MessageID); err != nil {
+		return info, fmt.Errorf("failed to message id: %w", err)
+	} else if err := binary.Read(buf, binary.BigEndian, &info.ID); err != nil {
+		return info, fmt.Errorf("failed to media id: %w", err)
+	} else if err := binary.Read(buf, binary.BigEndian, &info.Thumbnail); err != nil {
+		return info, fmt.Errorf("failed to thumbnail flag: %w", err)
+	}
+
+	return info, nil
+}
+
+func HashMediaID(mediaID networkid.MediaID) [32]byte {
+	return sha256.Sum256(mediaID)
 }