Decode DCS appearance template XML

2026-08-14 12:57:32 +03:00
parent 5615e262a8
commit 8a6610f30c
3 changed files with 79 additions and 0 deletions
@@ -0,0 +1,61 @@
+"""Read-only decoder for 1C DCS appearance-template payloads.
+
+Appearance templates are a distinct XML family (``AppearanceTemplate``), not
+DataCompositionSchema and not a spreadsheet document.  This decoder returns
+only XML-backed rules and preserves the original carrier for any future
+lossless writer work.
+"""
+
+from __future__ import annotations
+
+import xml.etree.ElementTree as ET
+from collections import Counter
+from typing import Any
+
+from .payload import decode_payload_lossless
+
+
+def _local_name(tag: str) -> str:
+    return tag.rsplit("}", 1)[-1]
+
+
+def _child_text(node: ET.Element, name: str) -> str:
+    child = next((item for item in node if _local_name(item.tag) == name), None)
+    return "".join(child.itertext()).strip() if child is not None else ""
+
+
+def inspect_appearance_payload(data: bytes) -> dict[str, Any]:
+    """Decode a compressed appearance-template carrier without changing it."""
+
+    decoded = decode_payload_lossless(data)
+    payload = bytes(decoded.get("payload") or b"")
+    start = payload.find(b"<?xml")
+    if start < 0:
+        start = payload.find(b"<AppearanceTemplate")
+    end_marker = b"</AppearanceTemplate>"
+    end = payload.find(end_marker, start) if start >= 0 else -1
+    if start < 0 or end < 0:
+        return {
+            "status": "undecodable",
+            "container": {"compression": decoded.get("compression"), "raw_bytes": decoded.get("raw_bytes"), "payload_bytes": decoded.get("payload_bytes")},
+            "diagnostics": {"code": "APPEARANCE_XML_NOT_FOUND"},
+        }
+    xml_bytes = payload[start : end + len(end_marker)]
+    try:
+        root = ET.fromstring(xml_bytes.decode("utf-8-sig"))
+    except (UnicodeDecodeError, ET.ParseError) as exc:
+        return {"status": "undecodable", "diagnostics": {"code": "APPEARANCE_XML_INVALID", "message": str(exc)}}
+    if _local_name(root.tag) != "AppearanceTemplate":
+        return {"status": "unsupported", "diagnostics": {"code": "APPEARANCE_ROOT_NOT_CONFIRMED", "xml_root": _local_name(root.tag)}}
+    items = []
+    for ordinal, item in enumerate((node for node in root if _local_name(node.tag) == "item"), start=1):
+        parameter, value = _child_text(item, "parameter"), _child_text(item, "value")
+        items.append({"ordinal": ordinal, "parameter": parameter, "value": value})
+    tag_counts = Counter(_local_name(node.tag) for node in root.iter())
+    return {
+        "status": "ok",
+        "container": {"compression": decoded.get("compression"), "raw_bytes": decoded.get("raw_bytes"), "payload_bytes": decoded.get("payload_bytes"), "xml_offset": start, "xml_bytes": len(xml_bytes), "xml_root": "AppearanceTemplate"},
+        "items": items,
+        "outline": {"tag_counts": dict(sorted(tag_counts.items(), key=lambda item: item[0].casefold()))},
+        "diagnostics": {"write": "unsupported_until_reverse_codec_fixture"},
+    }