download_part: Add utility for getting unofficial parts.

download_part.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+
+import os
+import requests
+import sys
+
+
+ldraw_path = os.path.abspath(os.path.dirname(__file__))
+
+
+def download_one_part(part):
+    """Downloads one part or subpart."""
+
+    # Try to read the parts file
+    parts_url = "https://www.ldraw.org/library/unofficial/parts/" + part
+    req = requests.get(parts_url, allow_redirects=True)
+    is_part = req.content[0] == ord("0")
+
+    # Part not found, try p file
+    if not is_part:
+        p_url = "https://www.ldraw.org/library/unofficial/p/" + part
+        req = requests.get(p_url, allow_redirects=True)
+        if req.content[0] != ord("0"):
+            sys.exit("Could not find part: " + part)
+
+    # Save the file
+    local_path = os.path.join(ldraw_path, "parts" if is_part else "p", part)
+    print(local_path)
+    with open(local_path, "wb") as local_file:
+        local_file.write(req.content)
+
+    # Display first line, which is a description of the part
+    print("Downloaded:", req.content.decode().splitlines()[0])
+
+
+def get_dependencies(part):
+    """Gets list of dependencies of a previously downloaded part."""
+    # Try to find the part in /parts or /p
+    try:
+        part_contents = open(os.path.join(ldraw_path, "parts", part)).read()
+    except FileNotFoundError:
+        part_contents = open(os.path.join(ldraw_path, "p", part)).read()
+
+    # Go through each line, and yield the part names, which are dependencies
+    for line in part_contents.splitlines():
+        *_, part_name = line.split(' ')
+
+        # Only return part names, and reverse backslash to forward slash
+        if '.dat' in part_name:
+            part_name = part_name.replace("\\", "/")
+            yield part_name
+
+
+def download_full_part(part):
+    """Downloads a part and its dependencies recursively"""
+
+    # top level part for this iteration
+    download_one_part(part)
+
+    # Find out what it depends on, then download those too
+    for dep in get_dependencies(part):
+
+        parts_path = os.path.join(ldraw_path, "parts", dep)
+        p_path = os.path.join(ldraw_path, "p", dep)
+
+        # Only download it if it doesn't already exist
+        if not os.path.isfile(parts_path) and not os.path.isfile(p_path):
+            download_full_part(dep)
+
+
+# Command line interface
+if __name__ == "__main__":
+
+    # Check arguments
+    if len(sys.argv) != 2:
+        print("Example usage:\n\n    ./download_part.py 69730c01.dat")
+
+    # Download main part
+    download_full_part(sys.argv[1])