updating and refactoring codebase for improved performance and maintainability

cmdlet/merge_file.py

@@ -40,49 +40,49 @@ except ImportError:
     PdfWriter = None
     PdfReader = None
 
-try:
-    from SYS.metadata import (
-        read_tags_from_file,
-        merge_multiple_tag_lists,
-    )
+# Stub fallbacks used before SYS.metadata is lazily imported (or if unavailable).
+HAS_METADATA_API: bool = False
+_metadata_loaded: bool = False
 
-    HAS_METADATA_API = True
-except ImportError:
-    HAS_METADATA_API = False
 
-    def read_tags_from_file(file_path: Path) -> List[str]:
-        return []
+def read_tags_from_file(file_path: Path) -> List[str]:
+    return []
 
-    def write_tags_to_file(
-        file_path: Path,
-        tags: List[str],
-        source_hashes: Optional[List[str]] = None,
-        url: Optional[List[str]] = None,
-        append: bool = False,
-    ) -> bool:
-        return False
 
-    def dedup_tags_by_namespace(tags: List[str]) -> List[str]:
-        return tags
+def merge_multiple_tag_lists(sources: List[List[str]],
+                              strategy: str = "first") -> List[str]:
+    out: List[str] = []
+    seen: set[str] = set()
+    for src in sources:
+        for t in src or []:
+            s = str(t)
+            if s and s not in seen:
+                out.append(s)
+                seen.add(s)
+    return out
 
-    def merge_multiple_tag_lists(sources: List[List[str]],
-                                 strategy: str = "first") -> List[str]:
-        out: List[str] = []
-        seen: set[str] = set()
-        for src in sources:
-            for t in src or []:
-                s = str(t)
-                if s and s not in seen:
-                    out.append(s)
-                    seen.add(s)
-        return out
 
-    def write_metadata(*_args: Any, **_kwargs: Any) -> None:
-        return None
+def _ensure_metadata_imports() -> None:
+    """Lazily import SYS.metadata to avoid loading Cryptodome (~1s) at startup."""
+    global _metadata_loaded, HAS_METADATA_API, read_tags_from_file, merge_multiple_tag_lists
+    if _metadata_loaded:
+        return
+    _metadata_loaded = True
+    try:
+        from SYS.metadata import (  # type: ignore[assignment]
+            read_tags_from_file as _rtf,
+            merge_multiple_tag_lists as _mml,
+        )
+        read_tags_from_file = _rtf  # type: ignore[assignment]
+        merge_multiple_tag_lists = _mml  # type: ignore[assignment]
+        HAS_METADATA_API = True
+    except ImportError:
+        HAS_METADATA_API = False
 
 
 def _run(result: Any, args: Sequence[str], config: Dict[str, Any]) -> int:
     """Merge multiple files into one."""
+    _ensure_metadata_imports()
 
     # Parse help
     if should_show_help(args):