# ##### BEGIN GPL LICENSE BLOCK #####
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
# ##### END GPL LICENSE BLOCK #####

# <pep8 compliant>

# Script copyright (C) Campbell Barton, Bastien Montagne


import math
import time

from collections import namedtuple, OrderedDict
from collections.abc import Iterable
from itertools import zip_longest, chain

import bpy
import bpy_extras
from bpy.types import Object, Bone, PoseBone, DupliObject
from mathutils import Vector, Matrix

from . import encode_bin, data_types


# "Constants"
FBX_VERSION = 7400
FBX_HEADER_VERSION = 1003
FBX_SCENEINFO_VERSION = 100
FBX_TEMPLATES_VERSION = 100

FBX_MODELS_VERSION = 232

FBX_GEOMETRY_VERSION = 124
# Revert back normals to 101 (simple 3D values) for now, 102 (4D + weights) seems not well supported by most apps
# currently, apart from some AD products.
FBX_GEOMETRY_NORMAL_VERSION = 101
FBX_GEOMETRY_BINORMAL_VERSION = 101
FBX_GEOMETRY_TANGENT_VERSION = 101
FBX_GEOMETRY_SMOOTHING_VERSION = 102
FBX_GEOMETRY_VCOLOR_VERSION = 101
FBX_GEOMETRY_UV_VERSION = 101
FBX_GEOMETRY_MATERIAL_VERSION = 101
FBX_GEOMETRY_LAYER_VERSION = 100
FBX_GEOMETRY_SHAPE_VERSION = 100
FBX_DEFORMER_SHAPE_VERSION = 100
FBX_DEFORMER_SHAPECHANNEL_VERSION = 100
FBX_POSE_BIND_VERSION = 100
FBX_DEFORMER_SKIN_VERSION = 101
FBX_DEFORMER_CLUSTER_VERSION = 100
FBX_MATERIAL_VERSION = 102
FBX_TEXTURE_VERSION = 202
FBX_ANIM_KEY_VERSION = 4008

FBX_NAME_CLASS_SEP = b"\x00\x01"
FBX_ANIM_PROPSGROUP_NAME = "d"

FBX_KTIME = 46186158000  # This is the number of "ktimes" in one second (yep, precision over the nanosecond...)


MAT_CONVERT_LAMP = Matrix.Rotation(math.pi / 2.0, 4, 'X')  # Blender is -Z, FBX is -Y.
MAT_CONVERT_CAMERA = Matrix.Rotation(math.pi / 2.0, 4, 'Y')  # Blender is -Z, FBX is +X.
# XXX I can't get this working :(
# MAT_CONVERT_BONE = Matrix.Rotation(math.pi / 2.0, 4, 'Z')  # Blender is +Y, FBX is -X.
MAT_CONVERT_BONE = Matrix()


BLENDER_OTHER_OBJECT_TYPES = {'CURVE', 'SURFACE', 'FONT', 'META'}
BLENDER_OBJECT_TYPES_MESHLIKE = {'MESH'} | BLENDER_OTHER_OBJECT_TYPES


# Lamps.
FBX_LIGHT_TYPES = {
    'POINT': 0,  # Point.
    'SUN': 1,    # Directional.
    'SPOT': 2,   # Spot.
    'HEMI': 1,   # Directional.
    'AREA': 3,   # Area.
}
FBX_LIGHT_DECAY_TYPES = {
    'CONSTANT': 0,                   # None.
    'INVERSE_LINEAR': 1,             # Linear.
    'INVERSE_SQUARE': 2,             # Quadratic.
    'CUSTOM_CURVE': 2,               # Quadratic.
    'LINEAR_QUADRATIC_WEIGHTED': 2,  # Quadratic.
}


RIGHT_HAND_AXES = {
    # Up, Forward -> FBX values (tuples of (axis, sign), Up, Front, Coord).
    ( 'X', '-Y'): ((0,  1), (1,  1), (2,  1)),
    ( 'X',  'Y'): ((0,  1), (1, -1), (2, -1)),
    ( 'X', '-Z'): ((0,  1), (2,  1), (1, -1)),
    ( 'X',  'Z'): ((0,  1), (2, -1), (1,  1)),
    ('-X', '-Y'): ((0, -1), (1,  1), (2, -1)),
    ('-X',  'Y'): ((0, -1), (1, -1), (2,  1)),
    ('-X', '-Z'): ((0, -1), (2,  1), (1,  1)),
    ('-X',  'Z'): ((0, -1), (2, -1), (1, -1)),
    ( 'Y', '-X'): ((1,  1), (0,  1), (2, -1)),
    ( 'Y',  'X'): ((1,  1), (0, -1), (2,  1)),
    ( 'Y', '-Z'): ((1,  1), (2,  1), (0,  1)),
    ( 'Y',  'Z'): ((1,  1), (2, -1), (0, -1)),
    ('-Y', '-X'): ((1, -1), (0,  1), (2,  1)),
    ('-Y',  'X'): ((1, -1), (0, -1), (2, -1)),
    ('-Y', '-Z'): ((1, -1), (2,  1), (0, -1)),
    ('-Y',  'Z'): ((1, -1), (2, -1), (0,  1)),
    ( 'Z', '-X'): ((2,  1), (0,  1), (1,  1)),
    ( 'Z',  'X'): ((2,  1), (0, -1), (1, -1)),
    ( 'Z', '-Y'): ((2,  1), (1,  1), (0, -1)),
    ( 'Z',  'Y'): ((2,  1), (1, -1), (0,  1)),  # Blender system!
    ('-Z', '-X'): ((2, -1), (0,  1), (1, -1)),
    ('-Z',  'X'): ((2, -1), (0, -1), (1,  1)),
    ('-Z', '-Y'): ((2, -1), (1,  1), (0,  1)),
    ('-Z',  'Y'): ((2, -1), (1, -1), (0, -1)),
}


FBX_FRAMERATES = (
    (-1.0, 14),  # Custom framerate.
    (120.0, 1),
    (100.0, 2),
    (60.0, 3),
    (50.0, 4),
    (48.0, 5),
    (30.0, 6),  # BW NTSC.
    (30.0 / 1.001, 9),  # Color NTSC.
    (25.0, 10),
    (24.0, 11),
    (24.0 / 1.001, 13),
    (96.0, 15),
    (72.0, 16),
    (60.0 / 1.001, 17),
)


# ##### Misc utilities #####

DO_PERFMON = True

if DO_PERFMON:
    class PerfMon():
        def __init__(self):
            self.level = -1
            self.ref_time = []

        def level_up(self, message=""):
            self.level += 1
            self.ref_time.append(None)
            if message:
                print("\t" * self.level, message, sep="")

        def level_down(self, message=""):
            if not self.ref_time:
                if message:
                    print(message)
                return
            ref_time = self.ref_time[self.level]
            print("\t" * self.level,
                  "\tDone (%f sec)\n" % ((time.process_time() - ref_time) if ref_time is not None else 0.0),
                  sep="")
            if message:
                print("\t" * self.level, message, sep="")
            del self.ref_time[self.level]
            self.level -= 1

        def step(self, message=""):
            ref_time = self.ref_time[self.level]
            curr_time = time.process_time()
            if ref_time is not None:
                print("\t" * self.level, "\tDone (%f sec)\n" % (curr_time - ref_time), sep="")
            self.ref_time[self.level] = curr_time
            print("\t" * self.level, message, sep="")
else:
    class PerfMon():
        def __init__(self):
            pass

        def level_up(self, message=""):
            pass

        def level_down(self, message=""):
            pass

        def step(self, message=""):
            pass


# Scale/unit mess. FBX can store the 'reference' unit of a file in its UnitScaleFactor property
# (1.0 meaning centimeter, afaik). We use that to reflect user's default unit as set in Blender with scale_length.
# However, we always get values in BU (i.e. meters), so we have to reverse-apply that scale in global matrix...
# Note that when no default unit is available, we assume 'meters' (and hence scale by 100).
def units_blender_to_fbx_factor(scene):
    return 100.0 if (scene.unit_settings.system == 'NONE') else (100.0 * scene.unit_settings.scale_length)


# Note: this could be in a utility (math.units e.g.)...

UNITS = {
    "meter": 1.0,  # Ref unit!
    "kilometer": 0.001,
    "millimeter": 1000.0,
    "foot": 1.0 / 0.3048,
    "inch": 1.0 / 0.0254,
    "turn": 1.0,  # Ref unit!
    "degree": 360.0,
    "radian": math.pi * 2.0,
    "second": 1.0,  # Ref unit!
    "ktime": FBX_KTIME,
}


def units_convertor(u_from, u_to):
    """Return a convertor between specified units."""
    conv = UNITS[u_to] / UNITS[u_from]
    return lambda v: v * conv


def units_convertor_iter(u_from, u_to):
    """Return an iterable convertor between specified units."""
    conv = units_convertor(u_from, u_to)

    def convertor(it):
        for v in it:
            yield(conv(v))

    return convertor


def matrix4_to_array(mat):
    """Concatenate matrix's columns into a single, flat tuple"""
    # blender matrix is row major, fbx is col major so transpose on write
    return tuple(f for v in mat.transposed() for f in v)


def array_to_matrix4(arr):
    """Convert a single 16-len tuple into a valid 4D Blender matrix"""
    # Blender matrix is row major, fbx is col major so transpose on read
    return Matrix(tuple(zip(*[iter(arr)]*4))).transposed()


def similar_values(v1, v2, e=1e-6):
    """Return True if v1 and v2 are nearly the same."""
    if v1 == v2:
        return True
    return ((abs(v1 - v2) / max(abs(v1), abs(v2))) <= e)


def similar_values_iter(v1, v2, e=1e-6):
    """Return True if iterables v1 and v2 are nearly the same."""
    if v1 == v2:
        return True
    for v1, v2 in zip(v1, v2):
        if (v1 != v2) and ((abs(v1 - v2) / max(abs(v1), abs(v2))) > e):
            return False
    return True

def vcos_transformed_gen(raw_cos, m=None):
    # Note: we could most likely get much better performances with numpy, but will leave this as TODO for now.
    gen = zip(*(iter(raw_cos),) * 3)
    return gen if m is None else (m * Vector(v) for v in gen)

def nors_transformed_gen(raw_nors, m=None):
    # Great, now normals are also expected 4D!
    # XXX Back to 3D normals for now!
    # gen = zip(*(iter(raw_nors),) * 3 + (_infinite_gen(1.0),))
    gen = zip(*(iter(raw_nors),) * 3)
    return gen if m is None else (m * Vector(v) for v in gen)


# ##### UIDs code. #####

# ID class (mere int).
class UUID(int):
    pass


# UIDs storage.
_keys_to_uuids = {}
_uuids_to_keys = {}


def _key_to_uuid(uuids, key):
    # TODO: Check this is robust enough for our needs!
    # Note: We assume we have already checked the related key wasn't yet in _keys_to_uids!
    #       As int64 is signed in FBX, we keep uids below 2**63...
    if isinstance(key, int) and 0 <= key < 2**63:
        # We can use value directly as id!
        uuid = key
    else:
        uuid = hash(key)
        if uuid < 0:
            uuid = -uuid
        if uuid >= 2**63:
            uuid //= 2
    # Try to make our uid shorter!
    if uuid > int(1e9):
        t_uuid = uuid % int(1e9)
        if t_uuid not in uuids:
            uuid = t_uuid
    # Make sure our uuid *is* unique.
    if uuid in uuids:
        inc = 1 if uuid < 2**62 else -1
        while uuid in uuids:
            uuid += inc
            if 0 > uuid >= 2**63:
                # Note that this is more that unlikely, but does not harm anyway...
                raise ValueError("Unable to generate an UUID for key {}".format(key))
    return UUID(uuid)


def get_fbx_uuid_from_key(key):
    """
    Return an UUID for given key, which is assumed hasable.
    """
    uuid = _keys_to_uuids.get(key, None)
    if uuid is None:
        uuid = _key_to_uuid(_uuids_to_keys, key)
        _keys_to_uuids[key] = uuid
        _uuids_to_keys[uuid] = key
    return uuid


# XXX Not sure we'll actually need this one?
def get_key_from_fbx_uuid(uuid):
    """
    Return the key which generated this uid.
    """
    assert(uuid.__class__ == UUID)
    return _uuids_to_keys.get(uuid, None)


# Blender-specific key generators
def get_bid_name(bid):
    library = getattr(bid, "library", None)
    if library is not None:
        return "%s_L_%s" % (bid.name, library.name)
    else:
        return bid.name


def get_blenderID_key(bid):
    if isinstance(bid, Iterable):
        return "|".join("B" + e.rna_type.name + "#" + get_bid_name(e) for e in bid)
    else:
        return "B" + bid.rna_type.name + "#" + get_bid_name(bid)


def get_blenderID_name(bid):
    if isinstance(bid, Iterable):
        return "|".join(get_bid_name(e) for e in bid)
    else:
        return get_bid_name(bid)


def get_blender_empty_key(obj):
    """Return bone's keys (Model and NodeAttribute)."""
    return "|".join((get_blenderID_key(obj), "Empty"))


def get_blender_mesh_shape_key(me):
    """Return main shape deformer's key."""
    return "|".join((get_blenderID_key(me), "Shape"))


def get_blender_mesh_shape_channel_key(me, shape):
    """Return shape channel and geometry shape keys."""
    return ("|".join((get_blenderID_key(me), "Shape", get_blenderID_key(shape))),
            "|".join((get_blenderID_key(me), "Geometry", get_blenderID_key(shape))))


def get_blender_bone_key(armature, bone):
    """Return bone's keys (Model and NodeAttribute)."""
    return "|".join((get_blenderID_key((armature, bone)), "Data"))


def get_blender_bindpose_key(obj, mesh):
    """Return object's bindpose key."""
    return "|".join((get_blenderID_key(obj), get_blenderID_key(mesh), "BindPose"))


def get_blender_armature_skin_key(armature, mesh):
    """Return armature's skin key."""
    return "|".join((get_blenderID_key(armature), get_blenderID_key(mesh), "DeformerSkin"))


def get_blender_bone_cluster_key(armature, mesh, bone):
    """Return bone's cluster key."""
    return "|".join((get_blenderID_key(armature), get_blenderID_key(mesh),
                     get_blenderID_key(bone), "SubDeformerCluster"))


def get_blender_anim_id_base(scene, ref_id):
    if ref_id is not None:
        return get_blenderID_key(scene) + "|" + get_blenderID_key(ref_id)
    else:
        return get_blenderID_key(scene)


def get_blender_anim_stack_key(scene, ref_id):
    """Return single anim stack key."""
    return get_blender_anim_id_base(scene, ref_id) + "|AnimStack"


def get_blender_anim_layer_key(scene, ref_id):
    """Return ID's anim layer key."""
    return get_blender_anim_id_base(scene, ref_id) + "|AnimLayer"


def get_blender_anim_curve_node_key(scene, ref_id, obj_key, fbx_prop_name):
    """Return (stack/layer, ID, fbxprop) curve node key."""
    return "|".join((get_blender_anim_id_base(scene, ref_id), obj_key, fbx_prop_name, "AnimCurveNode"))


def get_blender_anim_curve_key(scene, ref_id, obj_key, fbx_prop_name, fbx_prop_item_name):
    """Return (stack/layer, ID, fbxprop, item) curve key."""
    return "|".join((get_blender_anim_id_base(scene, ref_id), obj_key, fbx_prop_name,
                     fbx_prop_item_name, "AnimCurve"))


# ##### Element generators. #####

# Note: elem may be None, in this case the element is not added to any parent.
def elem_empty(elem, name):
    sub_elem = encode_bin.FBXElem(name)
    if elem is not None:
        elem.elems.append(sub_elem)
    return sub_elem


def _elem_data_single(elem, name, value, func_name):
    sub_elem = elem_empty(elem, name)
    getattr(sub_elem, func_name)(value)
    return sub_elem


def _elem_data_vec(elem, name, value, func_name):
    sub_elem = elem_empty(elem, name)
    func = getattr(sub_elem, func_name)
    for v in value:
        func(v)
    return sub_elem


def elem_data_single_bool(elem, name, value):
    return _elem_data_single(elem, name, value, "add_bool")


def elem_data_single_int16(elem, name, value):
    return _elem_data_single(elem, name, value, "add_int16")


def elem_data_single_int32(elem, name, value):
    return _elem_data_single(elem, name, value, "add_int32")


def elem_data_single_int64(elem, name, value):
    return _elem_data_single(elem, name, value, "add_int64")


def elem_data_single_float32(elem, name, value):
    return _elem_data_single(elem, name, value, "add_float32")


def elem_data_single_float64(elem, name, value):
    return _elem_data_single(elem, name, value, "add_float64")


def elem_data_single_bytes(elem, name, value):
    return _elem_data_single(elem, name, value, "add_bytes")


def elem_data_single_string(elem, name, value):
    return _elem_data_single(elem, name, value, "add_string")


def elem_data_single_string_unicode(elem, name, value):
    return _elem_data_single(elem, name, value, "add_string_unicode")


def elem_data_single_bool_array(elem, name, value):
    return _elem_data_single(elem, name, value, "add_bool_array")


def elem_data_single_int32_array(elem, name, value):
    return _elem_data_single(elem, name, value, "add_int32_array")


def elem_data_single_int64_array(elem, name, value):
    return _elem_data_single(elem, name, value, "add_int64_array")


def elem_data_single_float32_array(elem, name, value):
    return _elem_data_single(elem, name, value, "add_float32_array")


def elem_data_single_float64_array(elem, name, value):
    return _elem_data_single(elem, name, value, "add_float64_array")


def elem_data_single_byte_array(elem, name, value):
    return _elem_data_single(elem, name, value, "add_byte_array")


def elem_data_vec_float64(elem, name, value):
    return _elem_data_vec(elem, name, value, "add_float64")


# ##### Generators for standard FBXProperties70 properties. #####

def elem_properties(elem):
    return elem_empty(elem, b"Properties70")


# Properties definitions, format: (b"type_1", b"label(???)", "name_set_value_1", "name_set_value_2", ...)
# XXX Looks like there can be various variations of formats here... Will have to be checked ultimately!
#     Also, those "custom" types like 'FieldOfView' or 'Lcl Translation' are pure nonsense,
#     these are just Vector3D ultimately... *sigh* (again).
FBX_PROPERTIES_DEFINITIONS = {
    # Generic types.
    "p_bool": (b"bool", b"", "add_int32"),  # Yes, int32 for a bool (and they do have a core bool type)!!!
    "p_integer": (b"int", b"Integer", "add_int32"),
    "p_ulonglong": (b"ULongLong", b"", "add_int64"),
    "p_double": (b"double", b"Number", "add_float64"),  # Non-animatable?
    "p_number": (b"Number", b"", "add_float64"),  # Animatable-only?
    "p_enum": (b"enum", b"", "add_int32"),
    "p_vector_3d": (b"Vector3D", b"Vector", "add_float64", "add_float64", "add_float64"),  # Non-animatable?
    "p_vector": (b"Vector", b"", "add_float64", "add_float64", "add_float64"),  # Animatable-only?
    "p_color_rgb": (b"ColorRGB", b"Color", "add_float64", "add_float64", "add_float64"),  # Non-animatable?
    "p_color": (b"Color", b"", "add_float64", "add_float64", "add_float64"),  # Animatable-only?
    "p_string": (b"KString", b"", "add_string_unicode"),
    "p_string_url": (b"KString", b"Url", "add_string_unicode"),
    "p_timestamp": (b"KTime", b"Time", "add_int64"),
    "p_datetime": (b"DateTime", b"", "add_string_unicode"),
    # Special types.
    "p_object": (b"object", b""),  # XXX Check this! No value for this prop??? Would really like to know how it works!
    "p_compound": (b"Compound", b""),
    # Specific types (sic).
    # ## Objects (Models).
    "p_lcl_translation": (b"Lcl Translation", b"", "add_float64", "add_float64", "add_float64"),
    "p_lcl_rotation": (b"Lcl Rotation", b"", "add_float64", "add_float64", "add_float64"),
    "p_lcl_scaling": (b"Lcl Scaling", b"", "add_float64", "add_float64", "add_float64"),
    "p_visibility": (b"Visibility", b"", "add_float64"),
    "p_visibility_inheritance": (b"Visibility Inheritance", b"", "add_int32"),
    # ## Cameras!!!
    "p_roll": (b"Roll", b"", "add_float64"),
    "p_opticalcenterx": (b"OpticalCenterX", b"", "add_float64"),
    "p_opticalcentery": (b"OpticalCenterY", b"", "add_float64"),
    "p_fov": (b"FieldOfView", b"", "add_float64"),
    "p_fov_x": (b"FieldOfViewX", b"", "add_float64"),
    "p_fov_y": (b"FieldOfViewY", b"", "add_float64"),
}


def _elem_props_set(elem, ptype, name, value, flags):
    p = elem_data_single_string(elem, b"P", name)
    for t in ptype[:2]:
        p.add_string(t)
    p.add_string(flags)
    if len(ptype) == 3:
        getattr(p, ptype[2])(value)
    elif len(ptype) > 3:
        # We assume value is iterable, else it's a bug!
        for callback, val in zip(ptype[2:], value):
            getattr(p, callback)(val)


def _elem_props_flags(animatable, animated, custom):
    # XXX: There are way more flags, see
    #      http://help.autodesk.com/view/FBX/2015/ENU/?guid=__cpp_ref_class_fbx_property_flags_html
    #      Unfortunately, as usual, no doc at all about their 'translation' in actual FBX file format.
    #      Curse you-know-who.
    if animatable:
        if animated:
            if custom:
                return b"A+U"
            return b"A+"
        if custom:
            return b"AU"
        return b"A"
    if custom:
        return b"U"
    return b""


def elem_props_set(elem, ptype, name, value=None, animatable=False, animated=False, custom=False):
    ptype = FBX_PROPERTIES_DEFINITIONS[ptype]
    _elem_props_set(elem, ptype, name, value, _elem_props_flags(animatable, animated, custom))


def elem_props_compound(elem, cmpd_name, custom=False):
    def _setter(ptype, name, value, animatable=False, animated=False, custom=False):
        name = cmpd_name + b"|" + name
        elem_props_set(elem, ptype, name, value, animatable=animatable, animated=animated, custom=custom)

    elem_props_set(elem, "p_compound", cmpd_name, custom=custom)
    return _setter


def elem_props_template_init(templates, template_type):
    """
    Init a writing template of given type, for *one* element's properties.
    """
    ret = OrderedDict()
    tmpl = templates.get(template_type)
    if tmpl is not None:
        written = tmpl.written[0]
        props = tmpl.properties
        ret = OrderedDict((name, [val, ptype, anim, written]) for name, (val, ptype, anim) in props.items())
    return ret


def elem_props_template_set(template, elem, ptype_name, name, value, animatable=False, animated=False):
    """
    Only add a prop if the same value is not already defined in given template.
    Note it is important to not give iterators as value, here!
    """
    ptype = FBX_PROPERTIES_DEFINITIONS[ptype_name]
    if len(ptype) > 3:
        value = tuple(value)
    tmpl_val, tmpl_ptype, tmpl_animatable, tmpl_written = template.get(name, (None, None, False, False))
    # Note animatable flag from template takes precedence over given one, if applicable.
    # However, animated properties are always written, since they cannot match their template!
    if tmpl_ptype is not None and not animated:
        if (tmpl_written and
            ((len(ptype) == 3 and (tmpl_val, tmpl_ptype) == (value, ptype_name)) or
             (len(ptype) > 3 and (tuple(tmpl_val), tmpl_ptype) == (value, ptype_name)))):
            return  # Already in template and same value.
        _elem_props_set(elem, ptype, name, value, _elem_props_flags(tmpl_animatable, animated, False))
        template[name][3] = True
    else:
        _elem_props_set(elem, ptype, name, value, _elem_props_flags(animatable, animated, False))


def elem_props_template_finalize(template, elem):
    """
    Finalize one element's template/props.
    Issue is, some templates might be "needed" by different types (e.g. NodeAttribute is for lights, cameras, etc.),
    but values for only *one* subtype can be written as template. So we have to be sure we write those for the other
    subtypes in each and every elements, if they are not overriden by that element.
    Yes, hairy, FBX that is to say. When they could easily support several subtypes per template... :(
    """
    for name, (value, ptype_name, animatable, written) in template.items():
        if written:
            continue
        ptype = FBX_PROPERTIES_DEFINITIONS[ptype_name]
        _elem_props_set(elem, ptype, name, value, _elem_props_flags(animatable, False, False))


# ##### Templates #####
# TODO: check all those "default" values, they should match Blender's default as much as possible, I guess?

FBXTemplate = namedtuple("FBXTemplate", ("type_name", "prop_type_name", "properties", "nbr_users", "written"))


def fbx_templates_generate(root, fbx_templates):
    # We may have to gather different templates in the same node (e.g. NodeAttribute template gathers properties
    # for Lights, Cameras, LibNodes, etc.).
    ref_templates = {(tmpl.type_name, tmpl.prop_type_name): tmpl for tmpl in fbx_templates.values()}

    templates = OrderedDict()
    for type_name, prop_type_name, properties, nbr_users, _written in fbx_templates.values():
        tmpl = templates.get(type_name)
        if tmpl is None:
            templates[type_name] = [OrderedDict(((prop_type_name, (properties, nbr_users)),)), nbr_users]
        else:
            tmpl[0][prop_type_name] = (properties, nbr_users)
            tmpl[1] += nbr_users

    for type_name, (subprops, nbr_users) in templates.items():
        template = elem_data_single_string(root, b"ObjectType", type_name)
        elem_data_single_int32(template, b"Count", nbr_users)

        if len(subprops) == 1:
            prop_type_name, (properties, _nbr_sub_type_users) = next(iter(subprops.items()))
            subprops = (prop_type_name, properties)
            ref_templates[(type_name, prop_type_name)].written[0] = True
        else:
            # Ack! Even though this could/should work, looks like it is not supported. So we have to chose one. :|
            max_users = max_props = -1
            written_prop_type_name = None
            for prop_type_name, (properties, nbr_sub_type_users) in subprops.items():
                if nbr_sub_type_users > max_users or (nbr_sub_type_users == max_users and len(properties) > max_props):
                    max_users = nbr_sub_type_users
                    max_props = len(properties)
                    written_prop_type_name = prop_type_name
            subprops = (written_prop_type_name, properties)
            ref_templates[(type_name, written_prop_type_name)].written[0] = True

        prop_type_name, properties = subprops
        if prop_type_name and properties:
            elem = elem_data_single_string(template, b"PropertyTemplate", prop_type_name)
            props = elem_properties(elem)
            for name, (value, ptype, animatable) in properties.items():
                try:
                    elem_props_set(props, ptype, name, value, animatable=animatable)
                except Exception as e:
                    print("Failed to write template prop (%r)" % e)
                    print(props, ptype, name, value, animatable)


# ##### FBX animation helpers. #####


class AnimationCurveNodeWrapper:
    """
    This class provides a same common interface for all (FBX-wise) AnimationCurveNode and AnimationCurve elements,
    and easy API to handle those.
    """
    __slots__ = (
        'elem_keys', '_keys', 'default_values', 'fbx_group', 'fbx_gname', 'fbx_props',
        'force_keying', 'force_startend_keying')

    kinds = {
        'LCL_TRANSLATION': ("Lcl Translation", "T", ("X", "Y", "Z")),
        'LCL_ROTATION': ("Lcl Rotation", "R", ("X", "Y", "Z")),
        'LCL_SCALING': ("Lcl Scaling", "S", ("X", "Y", "Z")),
        'SHAPE_KEY': ("DeformPercent", "DeformPercent", ("DeformPercent",)),
    }

    def __init__(self, elem_key, kind, force_keying, force_startend_keying, default_values=...):
        self.elem_keys = [elem_key]
        assert(kind in self.kinds)
        self.fbx_group = [self.kinds[kind][0]]
        self.fbx_gname = [self.kinds[kind][1]]
        self.fbx_props = [self.kinds[kind][2]]
        self.force_keying = force_keying
        self.force_startend_keying = force_startend_keying
        self._keys = []  # (frame, values, write_flags)
        if default_values is not ...:
            assert(len(default_values) == len(self.fbx_props[0]))
            self.default_values = default_values
        else:
            self.default_values = (0.0) * len(self.fbx_props[0])

    def __bool__(self):
        # We are 'True' if we do have some validated keyframes...
        return bool(self._keys) and (True in ((True in k[2]) for k in self._keys))

    def add_group(self, elem_key, fbx_group, fbx_gname, fbx_props):
        """
        Add another whole group stuff (curvenode, animated item/prop + curvnode/curve identifiers).
        E.g. Shapes animations is written twice, houra!
        """
        assert(len(fbx_props) == len(self.fbx_props[0]))
        self.elem_keys.append(elem_key)
        self.fbx_group.append(fbx_group)
        self.fbx_gname.append(fbx_gname)
        self.fbx_props.append(fbx_props)

    def add_keyframe(self, frame, values):
        """
        Add a new keyframe to all curves of the group.
        """
        assert(len(values) == len(self.fbx_props[0]))
        self._keys.append((frame, values, [True] * len(values)))  # write everything by default.

    def simplify(self, fac, step, force_keep=False):
        """
        Simplifies sampled curves by only enabling samples when:
            * their values relatively differ from the previous sample ones.
        """
        if not self._keys:
            return

        if fac == 0.0:
            return

        # So that, with default factor and step values (1), we get:
        min_reldiff_fac = fac * 1.0e-3  # min relative value evolution: 0.1% of current 'order of magnitude'.
        min_absdiff_fac = 0.1  # A tenth of reldiff...
        keys = self._keys

        p_currframe, p_key, p_key_write = keys[0]
        p_keyed = list(p_key)
        are_keyed = [False] * len(p_key)
        for currframe, key, key_write in keys:
            for idx, (val, p_val) in enumerate(zip(key, p_key)):
                key_write[idx] = False
                p_keyedval = p_keyed[idx]
                if val == p_val:
                    # Never write keyframe when value is exactly the same as prev one!
                    continue
                # This is contracted form of relative + absolute-near-zero difference:
                #     absdiff = abs(a - b)
                #     if absdiff < min_reldiff_fac * min_absdiff_fac:
                #         return False
                #     return (absdiff / ((abs(a) + abs(b)) / 2)) > min_reldiff_fac
                # Note that we ignore the '/ 2' part here, since it's not much significant for us.
                if abs(val - p_val) > (min_reldiff_fac * max(abs(val) + abs(p_val), min_absdiff_fac)):
                    # If enough difference from previous sampled value, key this value *and* the previous one!
                    key_write[idx] = True
                    p_key_write[idx] = True
                    p_keyed[idx] = val
                    are_keyed[idx] = True
                elif abs(val - p_keyedval) > (min_reldiff_fac * max((abs(val) + abs(p_keyedval)), min_absdiff_fac)):
                    # Else, if enough difference from previous keyed value, key this value only!
                    key_write[idx] = True
                    p_keyed[idx] = val
                    are_keyed[idx] = True
            p_currframe, p_key, p_key_write = currframe, key, key_write

        # If we write nothing (action doing nothing) and are in 'force_keep' mode, we key everything! :P
        # See T41766.
        # Also, it seems some importers (e.g. UE4) do not handle correctly armatures where some bones
        # are not animated, but are children of animated ones, so added an option to systematically force writing
        # one key in this case.
        # See T41719, T41605, T41254...
        if self.force_keying or (force_keep and not self):
            are_keyed[:] = [True] * len(are_keyed)

        # If we did key something, ensure first and last sampled values are keyed as well.
        if self.force_startend_keying:
            for idx, is_keyed in enumerate(are_keyed):
                if is_keyed:
                    keys[0][2][idx] = keys[-1][2][idx] = True

    def get_final_data(self, scene, ref_id, force_keep=False):
        """
        Yield final anim data for this 'curvenode' (for all curvenodes defined).
        force_keep is to force to keep a curve even if it only has one valid keyframe.
        """
        curves = [[] for k in self._keys[0][1]]
        for currframe, key, key_write in self._keys:
            for curve, val, wrt in zip(curves, key, key_write):
                if wrt:
                    curve.append((currframe, val))

        force_keep = force_keep or self.force_keying
        for elem_key, fbx_group, fbx_gname, fbx_props in \
            zip(self.elem_keys, self.fbx_group, self.fbx_gname, self.fbx_props):
            group_key = get_blender_anim_curve_node_key(scene, ref_id, elem_key, fbx_group)
            group = OrderedDict()
            for c, def_val, fbx_item in zip(curves, self.default_values, fbx_props):
                fbx_item = FBX_ANIM_PROPSGROUP_NAME + "|" + fbx_item
                curve_key = get_blender_anim_curve_key(scene, ref_id, elem_key, fbx_group, fbx_item)
                # (curve key, default value, keyframes, write flag).
                group[fbx_item] = (curve_key, def_val, c,
                                   True if (len(c) > 1 or (len(c) > 0 and force_keep)) else False)
            yield elem_key, group_key, group, fbx_group, fbx_gname


# ##### FBX objects generators. #####

# FBX Model-like data (i.e. Blender objects, dupliobjects and bones) are wrapped in ObjectWrapper.
# This allows us to have a (nearly) same code FBX-wise for all those types.
# The wrapper tries to stay as small as possible, by mostly using callbacks (property(get...))
# to actual Blender data it contains.
# Note it caches its instances, so that you may call several times ObjectWrapper(your_object)
# with a minimal cost (just re-computing the key).

class MetaObjectWrapper(type):
    def __call__(cls, bdata, armature=None):
        if bdata is None:
            return None
        dup_mat = None
        if isinstance(bdata, Object):
            key = get_blenderID_key(bdata)
        elif isinstance(bdata, DupliObject):
            key = "|".join((get_blenderID_key((bdata.id_data, bdata.object)), cls._get_dup_num_id(bdata)))
            dup_mat = bdata.matrix.copy()
        else:  # isinstance(bdata, (Bone, PoseBone)):
            if isinstance(bdata, PoseBone):
                bdata = armature.data.bones[bdata.name]
            key = get_blenderID_key((armature, bdata))

        cache = getattr(cls, "_cache", None)
        if cache is None:
            cache = cls._cache = {}
        instance = cache.get(key)
        if instance is not None:
            # Duplis hack: since duplis are not persistent in Blender (we have to re-create them to get updated
            # info like matrix...), we *always* need to reset that matrix when calling ObjectWrapper() (all
            # other data is supposed valid during whole cache live, so we can skip resetting it).
            instance._dupli_matrix = dup_mat
            return instance

        instance = cls.__new__(cls, bdata, armature)
        instance.__init__(bdata, armature)
        instance.key = key
        instance._dupli_matrix = dup_mat
        cache[key] = instance
        return instance


class ObjectWrapper(metaclass=MetaObjectWrapper):
    """
    This class provides a same common interface for all (FBX-wise) object-like elements:
    * Blender Object
    * Blender Bone and PoseBone
    * Blender DupliObject
    Note since a same Blender object might be 'mapped' to several FBX models (esp. with duplis),
    we need to use a key to identify each.
    """
    __slots__ = (
        'name', 'key', 'bdata', 'parented_to_armature',
        '_tag', '_ref', '_dupli_matrix'
    )

    @classmethod
    def cache_clear(cls):
        if hasattr(cls, "_cache"):
            del cls._cache

    @staticmethod
    def _get_dup_num_id(bdata):
        return ".".join(str(i) for i in bdata.persistent_id if i != 2147483647)

    def __init__(self, bdata, armature=None):
        """
        bdata might be an Object, DupliObject, Bone or PoseBone.
        If Bone or PoseBone, armature Object must be provided.
        """
        if isinstance(bdata, Object):
            self._tag = 'OB'
            self.name = get_blenderID_name(bdata)
            self.bdata = bdata
            self._ref = None
        elif isinstance(bdata, DupliObject):
            self._tag = 'DP'
            self.name = "|".join((get_blenderID_name((bdata.id_data, bdata.object)),
                                  "Dupli", self._get_dup_num_id(bdata)))
            self.bdata = bdata.object
            self._ref = bdata.id_data
        else:  # isinstance(bdata, (Bone, PoseBone)):
            if isinstance(bdata, PoseBone):
                bdata = armature.data.bones[bdata.name]
            self._tag = 'BO'
            self.name = get_blenderID_name(bdata)
            self.bdata = bdata
            self._ref = armature
        self.parented_to_armature = False

    def __eq__(self, other):
        return isinstance(other, self.__class__) and self.key == other.key

    def __hash__(self):
        return hash(self.key)

    # #### Common to all _tag values.
    def get_fbx_uuid(self):
        return get_fbx_uuid_from_key(self.key)
    fbx_uuid = property(get_fbx_uuid)

    def get_hide(self):
        return self.bdata.hide
    hide = property(get_hide)

    def get_parent(self):
        if self._tag == 'OB':
            if (self.bdata.parent and self.bdata.parent.type == 'ARMATURE' and
                self.bdata.parent_type == 'BONE' and self.bdata.parent_bone):
                # Try to parent to a bone.
                bo_par = self.bdata.parent.pose.bones.get(self.bdata.parent_bone, None)
                if (bo_par):
                    return ObjectWrapper(bo_par, self.bdata.parent)
                else:  # Fallback to mere object parenting.
                    return ObjectWrapper(self.bdata.parent)
            else:
                # Mere object parenting.
                return ObjectWrapper(self.bdata.parent)
        elif self._tag == 'DP':
            return ObjectWrapper(self.bdata.parent or self._ref)
        else:  # self._tag == 'BO'
            return ObjectWrapper(self.bdata.parent, self._ref) or ObjectWrapper(self._ref)
    parent = property(get_parent)

    def get_matrix_local(self):
        if self._tag == 'OB':
            return self.bdata.matrix_local.copy()
        elif self._tag == 'DP':
            return self._ref.matrix_world.inverted_safe() * self._dupli_matrix
        else:  # 'BO', current pose
            # PoseBone.matrix is in armature space, bring in back in real local one!
            par = self.bdata.parent
            par_mat_inv = self._ref.pose.bones[par.name].matrix.inverted_safe() if par else Matrix()
            return par_mat_inv * self._ref.pose.bones[self.bdata.name].matrix
    matrix_local = property(get_matrix_local)

    def get_matrix_global(self):
        if self._tag == 'OB':
            return self.bdata.matrix_world.copy()
        elif self._tag == 'DP':
            return self._dupli_matrix
        else:  # 'BO', current pose
            return self._ref.matrix_world * self._ref.pose.bones[self.bdata.name].matrix
    matrix_global = property(get_matrix_global)

    def get_matrix_rest_local(self):
        if self._tag == 'BO':
            # Bone.matrix_local is in armature space, bring in back in real local one!
            par = self.bdata.parent
            par_mat_inv = par.matrix_local.inverted_safe() if par else Matrix()
            return par_mat_inv * self.bdata.matrix_local
        else:
            return self.matrix_local.copy()
    matrix_rest_local = property(get_matrix_rest_local)

    def get_matrix_rest_global(self):
        if self._tag == 'BO':
            return self._ref.matrix_world * self.bdata.matrix_local
        else:
            return self.matrix_global.copy()
    matrix_rest_global = property(get_matrix_rest_global)

    # #### Transform and helpers
    def has_valid_parent(self, objects):
        par = self.parent
        if par in objects:
            if self._tag == 'OB':
                par_type = self.bdata.parent_type
                if par_type in {'OBJECT', 'BONE'}:
                    return True
                else:
                    print("Sorry, “{}” parenting type is not supported".format(par_type))
                    return False
            return True
        return False

    def use_bake_space_transform(self, scene_data):
        # NOTE: Only applies to object types supporting this!!! Currently, only meshes and the like...
        # TODO: Check whether this can work for bones too...
        return (scene_data.settings.bake_space_transform and self._tag in {'OB', 'DP'} and
                self.bdata.type in BLENDER_OBJECT_TYPES_MESHLIKE | {'EMPTY'})

    def fbx_object_matrix(self, scene_data, rest=False, local_space=False, global_space=False):
        """
        Generate object transform matrix (*always* in matching *FBX* space!).
        If local_space is True, returned matrix is *always* in local space.
        Else if global_space is True, returned matrix is always in world space.
        If both local_space and global_space are False, returned matrix is in parent space if parent is valid,
        else in world space.
        Note local_space has precedence over global_space.
        If rest is True and object is a Bone, returns matching rest pose transform instead of current pose one.
        Applies specific rotation to bones, lamps and cameras (conversion Blender -> FBX).
        """
        # Objects which are not bones and do not have any parent are *always* in global space
        # (unless local_space is True!).
        is_global = (not local_space and
                     (global_space or not (self._tag in {'DP', 'BO'} or self.has_valid_parent(scene_data.objects))))

        # Objects (meshes!) parented to armature are not parented to anything in FBX, hence we need them
        # in global space, which is their 'virtual' local space...
        is_global = is_global or self.parented_to_armature

        # Since we have to apply corrections to some types of object, we always need local Blender space here...
        matrix = self.matrix_rest_local if rest else self.matrix_local
        parent = self.parent

        # Bones, lamps and cameras need to be rotated (in local space!).
        if self._tag == 'BO':
            # If we have a bone parent we need to undo the parent correction.
            if not is_global and scene_data.settings.bone_correction_matrix_inv and parent and parent.is_bone:
                matrix = scene_data.settings.bone_correction_matrix_inv * matrix
            # Apply the bone correction.
            if scene_data.settings.bone_correction_matrix:
                matrix = matrix * scene_data.settings.bone_correction_matrix
        elif self.bdata.type == 'LAMP':
            matrix = matrix * MAT_CONVERT_LAMP
        elif self.bdata.type == 'CAMERA':
            matrix = matrix * MAT_CONVERT_CAMERA

        if self._tag in {'DP', 'OB'} and parent:
            if parent._tag == 'BO':
                # In bone parent case, we get transformation in **bone tip** space (sigh).
                # Have to bring it back into bone root, which is FBX expected value.
                matrix = Matrix.Translation((0, (parent.bdata.tail - parent.bdata.head).length, 0)) * matrix

        # Our matrix is in local space, time to bring it in its final desired space.
        if parent:
            if is_global:
                # Move matrix to global Blender space.
                matrix = (parent.matrix_rest_global if rest else parent.matrix_global) * matrix
            elif parent.use_bake_space_transform(scene_data):
                # Blender's and FBX's local space of parent may differ if we use bake_space_transform...
                # Apply parent's *Blender* local space...
                matrix = (parent.matrix_rest_local if rest else parent.matrix_local) * matrix
                # ...and move it back into parent's *FBX* local space.
                par_mat = parent.fbx_object_matrix(scene_data, rest=rest, local_space=True)
                matrix = par_mat.inverted_safe() * matrix

        if self.use_bake_space_transform(scene_data):
            # If we bake the transforms we need to post-multiply inverse global transform.
            # This means that the global transform will not apply to children of this transform.
            matrix = matrix * scene_data.settings.global_matrix_inv
        if is_global:
            # In any case, pre-multiply the global matrix to get it in FBX global space!
            matrix = scene_data.settings.global_matrix * matrix

        return matrix

    def fbx_object_tx(self, scene_data, rest=False, rot_euler_compat=None):
        """
        Generate object transform data (always in local space when possible).
        """
        matrix = self.fbx_object_matrix(scene_data, rest=rest)
        loc, rot, scale = matrix.decompose()
        matrix_rot = rot.to_matrix()
        # quat -> euler, we always use 'XYZ' order, use ref rotation if given.
        if rot_euler_compat is not None:
            rot = rot.to_euler('XYZ', rot_euler_compat)
        else:
            rot = rot.to_euler('XYZ')
        return loc, rot, scale, matrix, matrix_rot

    # #### _tag dependent...
    def get_is_object(self):
        return self._tag == 'OB'
    is_object = property(get_is_object)

    def get_is_dupli(self):
        return self._tag == 'DP'
    is_dupli = property(get_is_dupli)

    def get_is_bone(self):
        return self._tag == 'BO'
    is_bone = property(get_is_bone)

    def get_type(self):
        if self._tag in {'OB', 'DP'}:
            return self.bdata.type
        return ...
    type = property(get_type)

    def get_armature(self):
        if self._tag == 'BO':
            return ObjectWrapper(self._ref)
        return None
    armature = property(get_armature)

    def get_bones(self):
        if self._tag == 'OB' and self.bdata.type == 'ARMATURE':
            return (ObjectWrapper(bo, self.bdata) for bo in self.bdata.data.bones)
        return ()
    bones = property(get_bones)

    def get_material_slots(self):
        if self._tag in {'OB', 'DP'}:
            return self.bdata.material_slots
        return ()
    material_slots = property(get_material_slots)

    def is_deformed_by_armature(self, arm_obj):
        if not (self.is_object and self.type == 'MESH'):
            return False
        if self.parent == arm_obj and self.bdata.parent_type == 'ARMATURE':
            return True
        for mod in self.bdata.modifiers:
            if mod.type == 'ARMATURE' and mod.object in {arm_obj.bdata, arm_obj.bdata.proxy}:
                return True

    # #### Duplis...
    def dupli_list_create(self, scene, settings='PREVIEW'):
        if self._tag == 'OB' and self.bdata.is_duplicator:
            self.bdata.dupli_list_create(scene, settings)

    def dupli_list_clear(self):
        if self._tag == 'OB'and self.bdata.is_duplicator:
            self.bdata.dupli_list_clear()

    def get_dupli_list(self):
        if self._tag == 'OB'and self.bdata.is_duplicator:
            return (ObjectWrapper(dup) for dup in self.bdata.dupli_list)
        return ()
    dupli_list = property(get_dupli_list)


def fbx_name_class(name, cls):
    return FBX_NAME_CLASS_SEP.join((name, cls))


# ##### Top-level FBX data container. #####

# Helper sub-container gathering all exporter settings related to media (texture files).
FBXExportSettingsMedia = namedtuple("FBXExportSettingsMedia", (
    "path_mode", "base_src", "base_dst", "subdir",
    "embed_textures", "copy_set", "embedded_set",
))

# Helper container gathering all exporter settings.
FBXExportSettings = namedtuple("FBXExportSettings", (
    "report", "to_axes", "global_matrix", "global_scale", "apply_unit_scale",
    "bake_space_transform", "global_matrix_inv", "global_matrix_inv_transposed",
    "context_objects", "object_types", "use_mesh_modifiers",
    "mesh_smooth_type", "use_mesh_edges", "use_tspace",
    "armature_nodetype", "use_armature_deform_only", "add_leaf_bones",
    "bone_correction_matrix", "bone_correction_matrix_inv",
    "bake_anim", "bake_anim_use_all_bones", "bake_anim_use_nla_strips", "bake_anim_use_all_actions",
    "bake_anim_step", "bake_anim_simplify_factor", "bake_anim_force_startend_keying",
    "use_metadata", "media_settings", "use_custom_props",
))

# Helper container gathering some data we need multiple times:
#     * templates.
#     * settings, scene.
#     * objects.
#     * object data.
#     * skinning data (binding armature/mesh).
#     * animations.
FBXExportData = namedtuple("FBXExportData", (
    "templates", "templates_users", "connections",
    "settings", "scene", "objects", "animations", "animated", "frame_start", "frame_end",
    "data_empties", "data_lamps", "data_cameras", "data_meshes", "mesh_mat_indices",
    "data_bones", "data_leaf_bones", "data_deformers_skin", "data_deformers_shape",
    "data_world", "data_materials", "data_textures", "data_videos",
))

# Helper container gathering all importer settings.
FBXImportSettings = namedtuple("FBXImportSettings", (
    "report", "to_axes", "global_matrix", "global_scale",
    "bake_space_transform", "global_matrix_inv", "global_matrix_inv_transposed",
    "use_custom_normals", "use_cycles", "use_image_search",
    "use_alpha_decals", "decal_offset",
    "use_anim", "anim_offset",
    "use_custom_props", "use_custom_props_enum_as_string",
    "cycles_material_wrap_map", "image_cache",
    "ignore_leaf_bones", "force_connect_children", "automatic_bone_orientation", "bone_correction_matrix",
    "use_prepost_rot",
))
