1 files changed, 98 insertions, 0 deletions
diff --git a/generat3d/library.py b/generat3d/library.py
new file mode 100644
index 0000000..ea12794
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+++ b/generat3d/library.py
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+# generat3D - evaluate Daz DSON scenes and write .dbz files
+# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+import gzip
+import json
+import os
+from pathlib import Path
+from urllib.parse import unquote
+
+from . import Error
+
+
+def parse_url(url):
+    """Split a DSON URL "node:/path/file.dsf#id?prop" into (node, path, id, prop)."""
+    node = ""
+    if not url.startswith(("/", "#")) and ":" in url:
+        node, url = url.split(":", 1)
+    url, _, prop = url.partition("?")
+    path, _, ident = url.partition("#")
+    return unquote(node), unquote(path), unquote(ident), prop
+
+
+def read_dson(path):
+    """Parse a plain or gzipped DSON file."""
+    try:
+        data = Path(path).read_bytes()
+        if data[:2] == b"\x1f\x8b":
+            data = gzip.decompress(data)
+        return json.loads(data)
+    except (OSError, EOFError, ValueError) as e:
+        raise Error(f"{path}: {e}") from None
+
+
+def _find_nocase(base, parts, want_dir=False):
+    for part in parts:
+        try:
+            names = {n.lower(): n for n in os.listdir(base)}
+        except OSError:
+            return None
+        name = names.get(part.lower())
+        if name is None:
+            return None
+        base = base / name
+    return base if (base.is_dir() if want_dir else base.is_file()) else None
+
+
+class Library:
+    def __init__(self, roots):
+        self.roots = [Path(r) for r in roots]
+        self._docs = {}
+
+    def _locate(self, rel, want_dir):
+        for root in self.roots:
+            p = root / rel
+            if p.is_dir() if want_dir else p.is_file():
+                yield root, p
+                continue
+            p = _find_nocase(root, rel.split("/"), want_dir)
+            if p:
+                yield root, p
+
+    def find(self, path):
+        """File for a library path like "/data/x.dsf", first root wins, or None."""
+        return next((p for _, p in self._locate(path.strip("/"), False)), None)
+
+    def load(self, path):
+        """Parsed DSON document for a library path. Error if missing or broken."""
+        key = path.lower()
+        if key not in self._docs:
+            f = self.find(path)
+            if f is None:
+                raise Error(f"not found in library roots: {path}")
+            self._docs[key] = read_dson(f)
+        return self._docs[key]
+
+    def walk(self, path):
+        """Library paths of every .dsf under a library directory, across all roots."""
+        seen = {}
+        for root, base in self._locate(path.strip("/"), True):
+            for f in sorted(base.rglob("*")):
+                if f.is_file() and f.suffix.lower() == ".dsf":
+                    lp = "/" + f.relative_to(root).as_posix()
+                    seen.setdefault(lp.lower(), lp)
+        return list(seen.values())