"""Export the district kit to the runtime GLB (positions + indices only).

  blender -b assets/blender/districts/nightdrive-districts.blend --python assets/blender/districts/export-districts.py [-- --preview out.png]

Normals are derived per fragment at runtime (flat shading from screen-space
derivatives), so the GLB carries no normals, UVs or materials and shared box
corners stay welded. Writes provenance next to this script.
"""
import bpy, json, hashlib, sys, math
from pathlib import Path

here = Path(__file__).resolve().parent
root = here.parents[2]
scene = bpy.data.scenes['Roadside Districts']
output = root / 'src/assets/nightdrive-districts.glb'

for obj in scene.objects:
    obj.select_set(True)
bpy.ops.export_scene.gltf(
    filepath=str(output), export_format='GLB', use_selection=True, use_active_scene=True,
    export_apply=True, export_normals=False, export_texcoords=False, export_materials='NONE',
    export_animations=False, export_cameras=False, export_lights=False, export_yup=True,
)
triangles = 0
for obj in scene.objects:
    obj.data.calc_loop_triangles()
    triangles += len(obj.data.loop_triangles)
provenance = {
    'asset': 'Nightdrive roadside districts',
    'source': 'nightdrive-districts.blend',
    'authorship': 'Original procedural modelling in Blender for this portfolio (author-districts.py); no external assets.',
    'editable_scene': 'Roadside Districts',
    'pieces': sorted({o.name.rsplit('_', 1)[0] for o in scene.objects}),
    'triangles': triangles,
    'attributes': 'POSITION + indices; flat normals derived at runtime',
    'export': '../../../src/assets/nightdrive-districts.glb',
    'sha256': hashlib.sha256(output.read_bytes()).hexdigest(),
}
(here / 'nightdrive-districts.asset.json').write_text(json.dumps(provenance, indent=2) + '\n')
print(json.dumps(provenance))

if '--preview' in sys.argv:
    target = sys.argv[sys.argv.index('--preview') + 1]
    names = provenance['pieces']
    for i, name in enumerate(names):
        for suffix in ('body', 'light'):
            obj = scene.objects[f'{name}_{suffix}']
            obj.location = ((i % 4) * 34 - 50, (i // 4) * 40, 0)
            mat = bpy.data.materials.new(f'preview-{suffix}')
            mat.diffuse_color = (0.05, 0.05, 0.08, 1) if suffix == 'body' else (0.1, 0.9, 1.0, 1)
            obj.data.materials.append(mat)
    cam = bpy.data.objects.new('preview-cam', bpy.data.cameras.new('preview-cam'))
    scene.collection.objects.link(cam)
    cam.location = (95, -95, 70)
    cam.rotation_euler = (math.radians(58), 0, math.radians(45))
    cam.data.lens = 30
    scene.camera = cam
    try:
        scene.render.engine = 'BLENDER_WORKBENCH'
    except TypeError as e:
        print(e)
    scene.display.shading.color_type = 'MATERIAL'
    scene.display.shading.light = 'STUDIO'
    scene.display.shading.show_cavity = True
    scene.render.resolution_x, scene.render.resolution_y = 1600, 1000
    scene.render.filepath = target
    bpy.ops.render.render(write_still=True)