# Scale-test scene builder and FBX exporter for the Blender -> Unreal pipeline.
#
# Builds three 1 m cubes in the project geographic frame (EPSG:26911, origin
# Hollywood x Highland, X east / Y north / Z up):
#   ScaleTest_A  centred at (0, 0, 0.5)      - origin + 1 m size reference
#   ScaleTest_B  centred at (10, 0, 0.5)     - +10 m east probe
#   ScaleTest_C  centred at (0, 10, 0.5)     - +10 m north probe
# and exports them as one FBX with the named export preset "ue_metric_v1".
#
# Run headless (see Art/blender/README.md for the Flatpak invocation):
#   blender -b --factory-startup --python Tools/scale_test_export.py -- \
#     --out /tmp/gigline/scaletest.fbx --save-blend Art/blender/scaletest/scale-test-<date>.blend

import argparse
import os
import sys

import bpy


def build_scene():
    scene = bpy.context.scene
    for obj in list(bpy.data.objects):
        bpy.data.objects.remove(obj, do_unlink=True)

    mat = bpy.data.materials.new("M_ScaleTest_Red")
    mat.use_nodes = True
    bsdf = mat.node_tree.nodes.get("Principled BSDF")
    bsdf.inputs["Base Color"].default_value = (0.8, 0.05, 0.05, 1.0)

    specs = {
        "ScaleTest_A": (0.0, 0.0, 0.5),
        "ScaleTest_B": (10.0, 0.0, 0.5),
        "ScaleTest_C": (0.0, 10.0, 0.5),
    }
    for name, loc in specs.items():
        bpy.ops.mesh.primitive_cube_add(size=1.0, location=loc)
        obj = bpy.context.active_object
        obj.name = name
        obj.data.materials.append(mat)
        print(f"[scale_test] created {name} at {loc}")


def export_fbx(path):
    os.makedirs(os.path.dirname(path), exist_ok=True)
    # Named export preset "ue_metric_v1" - change only via a new preset name.
    bpy.ops.export_scene.fbx(
        filepath=path,
        use_selection=False,
        object_types={"MESH"},
        apply_unit_scale=True,
        apply_scale_options="FBX_SCALE_NONE",
        axis_forward="-Y",
        axis_up="Z",
        use_space_transform=True,
        use_mesh_modifiers=True,
        mesh_smooth_type="OFF",
        path_mode="AUTO",
        bake_space_transform=False,
    )
    print(f"[scale_test] exported FBX preset ue_metric_v1 -> {path}")


def main():
    argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
    parser = argparse.ArgumentParser()
    parser.add_argument("--out", default="/tmp/gigline/scaletest.fbx")
    parser.add_argument("--save-blend", default=None)
    args = parser.parse_args(argv)

    build_scene()

    if args.save_blend:
        os.makedirs(os.path.dirname(args.save_blend), exist_ok=True)
        bpy.ops.wm.save_as_mainfile(filepath=args.save_blend)
        print(f"[scale_test] saved {args.save_blend}")

    export_fbx(args.out)


main()