# FBX export and re-import check.  blender -b ../CaptainsQuarters.blend --python export_fbx.py      (saves nothing)
# One file per mesh with its UCX hulls, each at identity in its own space, plus one assembled file.
# Same convention as models/docking-arm: data turned -90 degrees about Z, forward -Y, up Z, so that the project's
# Unreal import settings ("convert scene" + "force front X axis") give ue = (bx, -by, bz) in centimetres.
import bpy, os, json, math
from mathutils import Matrix, Vector

HERE = os.path.dirname(os.path.abspath(__file__))
FBX = os.path.join(os.path.dirname(HERE), 'fbx')
os.makedirs(FBX, exist_ok=True)
sc = bpy.context.scene
PRE = Matrix.Rotation(-math.pi / 2, 4, 'Z')

col = bpy.data.collections['CQ | Collision (UCX)']
col.hide_viewport = False
bpy.context.view_layer.update()
PARTS = [o for o in sc.objects if o.type == 'MESH' and o.name.startswith('SM_CQ_')]
HULLS = [o for o in sc.objects if o.name.startswith('UCX_')]


def tris(o):
    return sum(len(p.vertices) - 2 for p in o.data.polygons)


def dims(o):
    cs = [v.co for v in o.data.vertices]
    return sorted(round(max(c[k] for c in cs) - min(c[k] for c in cs), 4) for k in range(3))


SRC = {o.name: {'tris': tris(o), 'verts': len(o.data.vertices), 'dims': dims(o), 'mats': len(o.data.materials)} for o in PARTS}


def fbx(path, objs, types):
    for o in bpy.context.view_layer.objects:
        o.select_set(False)
    for o in objs:
        o.select_set(True)
    bpy.context.view_layer.objects.active = objs[0]
    bpy.ops.export_scene.fbx(filepath=path, use_selection=True, object_types=types, use_mesh_modifiers=False, mesh_smooth_type='OFF',
                             add_leaf_bones=False, bake_anim=False, axis_forward='-Y', axis_up='Z', global_scale=1.0,
                             apply_unit_scale=True, apply_scale_options='FBX_SCALE_NONE', use_space_transform=True,
                             bake_space_transform=False, path_mode='STRIP', use_metadata=False)


# ---- assembled: everything where it stands, under one root
root = bpy.data.objects.new('CaptainsQuarters_Root', None)
sc.collection.objects.link(root)
tops = [o for o in PARTS if o.parent is None]
for o in tops:
    o.parent = root
root.rotation_euler = (0, 0, -math.pi / 2)
bpy.context.view_layer.update()
fbx(os.path.join(FBX, 'CaptainsQuarters_Assembled.fbx'), [root] + PARTS, {'MESH', 'EMPTY'})
root.rotation_euler = (0, 0, 0)
for o in tops:
    o.parent = None
bpy.data.objects.remove(root)

# ---- parts: mesh at identity with its hulls
bpy.context.view_layer.update()
placement = {}
for p in PARTS:                                   # read every placement before anything is moved
    hulls = [h for h in HULLS if h.name.startswith('UCX_' + p.name + '_')]
    placement[p.name] = {'location_m': [round(v, 4) for v in p.matrix_world.translation],
                         'rotation_z_deg': round(math.degrees(p.matrix_world.to_euler().z), 2),
                         'parent': p.parent.name if p.parent else None, 'motion': p.get('motion', 'static'), 'hulls': len(hulls)}
    if p.parent:
        placement[p.name]['local_to_parent_m'] = [round(v, 4) for v in p.matrix_local.translation]
for p in PARTS:
    hulls = [h for h in HULLS if h.name.startswith('UCX_' + p.name + '_')]
    p.parent = None
    p.matrix_world = Matrix.Identity(4)
    for h in hulls:
        h.parent = None
        h.matrix_world = Matrix.Identity(4)
    for o in [p] + hulls:
        o.data.transform(PRE)
    bpy.context.view_layer.update()
    fbx(os.path.join(FBX, p.name + '.fbx'), [p] + hulls, {'MESH'})

# ---- read every part file back and compare with the source
report = {'parts': {}, 'placement': placement}
ok = True
for p in PARTS:
    before = set(bpy.data.objects)
    bpy.ops.import_scene.fbx(filepath=os.path.join(FBX, p.name + '.fbx'))
    new = [o for o in bpy.data.objects if o not in before]
    m = [o for o in new if o.type == 'MESH' and not o.name.startswith('UCX_')]
    h = [o for o in new if o.name.startswith('UCX_')]
    r = {'meshes': len(m), 'hulls': len(h)}
    if len(m) == 1:
        o = m[0]
        r.update({'tris': tris(o), 'dims': dims(o), 'mats': len(o.data.materials), 'uv': len(o.data.uv_layers),
                  'scale': [round(s, 4) for s in o.scale]})
        s = SRC[p.name]
        r['match'] = (r['tris'] == s['tris'] and r['mats'] == s['mats'] and r['hulls'] == placement[p.name]['hulls']
                      and all(abs(a - b) < 1e-3 for a, b in zip(r['dims'], s['dims'])))
    else:
        r['match'] = False
    ok = ok and r['match']
    report['parts'][p.name] = r
    for o in new:
        bpy.data.objects.remove(o)
report['all_match'] = ok
report['files'] = sorted(f for f in os.listdir(FBX) if f.endswith('.fbx'))
json.dump(report, open(os.path.join(HERE, 'fbx_report.json'), 'w'), indent=1)
json.dump(placement, open(os.path.join(os.path.dirname(HERE), 'quarters_layout.json'), 'w'), indent=1)
print('FBX', len(report['files']), 'files, all match:', ok)
for n, r in report['parts'].items():
    if not r['match']:
        print('FBX MISMATCH', n, json.dumps(r), json.dumps(SRC[n]))