"""
Walk a real STEP assembly
=========================

The ``cad`` accessor on ``MultiBlock`` provides three traversal
helpers: ``walk`` yields ``(path, block)`` pairs, ``find`` filters by
glob or metadata predicates, and ``flatten`` collapses the tree to a
single-level container with path-named entries.

This walks a real multi-part STEP assembly: the NIST AM Bench 2022
build-plate layout (public domain, https://doi.org/10.18434/mds2-2607)
-- a tapped substrate plate with four bridge specimens and two
recoater guides, each a named product, exactly the structure that
lands on a developer's desk.
"""

# %%

import pandas as pd
import pyvista as pv

import pyvista_cad
from pyvista_cad.examples import downloads

# %%
# Load the real STEP assembly.

root = pyvista_cad.read_step(downloads.step_assembly_path())
root

# %%
# Walk the tree: each leaf is a named product.

rows = []
for path, block in root.cad.walk():
    rows.append(
        {
            'path': str(path),
            'kind': type(block).__name__,
            'label': block.field_data.get('cad.label', [b''])[0],
            'cells': block.n_cells if isinstance(block, pv.DataSet) else 0,
        }
    )

pd.DataFrame(rows)

# %%
# Filter by label glob ("give me every bridge specimen"), the same
# pattern as globbing a BOM for ``'M5_*'``.

bridges = root.cad.find('*PartCAD*')
pd.DataFrame({'path': [str(p) for p, _ in bridges]})

# %%
# Flatten to a single level.

list(root.cad.flatten().keys())

# %%
# Render the source assembly CAD-friendly: shaded faces with the
# topological edges overlaid, one colour per part.

pl = pv.Plotter()
pl.cad.add(root, multi_colors=True)
pl.show()