Add read-only database V2 parser

serato_doctor/database_parser.py

@@ -0,0 +1,67 @@
+from pathlib import Path
+from typing import Dict, Iterator, Optional, Tuple
+
+from serato_doctor.models.database import DatabaseTrack, SeratoDatabase
+
+
+TEXT_FIELDS = {
+    b"tsng": "title",
+    b"tart": "artist",
+    b"talb": "album",
+    b"tgen": "genre",
+}
+
+
+def iter_records(data: bytes) -> Iterator[Tuple[bytes, bytes]]:
+    """Yield complete big-endian tag-length-value records."""
+
+    offset = 0
+    while offset + 8 <= len(data):
+        tag = data[offset : offset + 4]
+        length = int.from_bytes(data[offset + 4 : offset + 8], "big")
+        payload_start = offset + 8
+        payload_end = payload_start + length
+        if payload_end > len(data):
+            break
+        yield tag, data[payload_start:payload_end]
+        offset = payload_end
+
+
+def decode_text(payload: bytes) -> Optional[str]:
+    value = payload.decode("utf-16-be", errors="ignore").strip("\x00").strip()
+    return value or None
+
+
+def normalize_database_path(value: str) -> Path:
+    if value.startswith(("Users/", "Volumes/")):
+        value = "/" + value
+    return Path(value)
+
+
+def parse_track(payload: bytes) -> Optional[DatabaseTrack]:
+    fields: Dict[str, Optional[str]] = {}
+    path = None
+    for tag, value in iter_records(payload):
+        if tag == b"pfil":
+            decoded_path = decode_text(value)
+            if decoded_path:
+                path = normalize_database_path(decoded_path)
+        elif tag in TEXT_FIELDS:
+            fields[TEXT_FIELDS[tag]] = decode_text(value)
+    if path is None:
+        return None
+    return DatabaseTrack(path=path, filename=path.name, **fields)
+
+
+def parse_database(database_path: Path) -> SeratoDatabase:
+    data = database_path.read_bytes()
+    version = None
+    tracks = []
+    for tag, payload in iter_records(data):
+        if tag == b"vrsn":
+            version = decode_text(payload)
+        elif tag == b"otrk":
+            track = parse_track(payload)
+            if track is not None:
+                tracks.append(track)
+    return SeratoDatabase(database_path, version, tuple(tracks))