# ##### 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

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 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_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_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.
#MAT_CONVERT_BONE = Matrix.Rotation(math.pi / -2.0, 4, 'X')  # Blender is +Y, FBX is +Z.
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, Front -> FBX values (tuples of (axis, sign), Up, Front, Coord).
    # Note: Since we always stay in right-handed system, third coord sign is always positive!
    ('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)),  # Blender system!
    ('Z',  '-Y'): ((2, 1),  (1, 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)),
}


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 #####

# 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_convert(val, u_from, u_to):
    """Convert value."""
    conv = UNITS[u_to] / UNITS[u_from]
    return val * conv


def units_convert_iter(it, u_from, u_to):
    """Convert value."""
    conv = UNITS[u_to] / UNITS[u_from]
    return (v * conv for v in it)


def matrix_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 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)


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


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


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


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_armature_bindpose_key(armature, mesh):
    """Return armature's bindpose key."""
    return "|".join((get_blenderID_key(armature), 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, custom):
    if animatable and custom:
        return b"AU"
    elif animatable:
        return b"A"
    elif custom:
        return b"U"
    return b""


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


def elem_props_compound(elem, cmpd_name, custom=False):
    def _setter(ptype, name, value, animatable=False, custom=False):
        name = cmpd_name + b"|" + name
        elem_props_set(elem, ptype, name, value, animatable=animatable, 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 = None
    if template_type in templates:
        tmpl = templates[template_type]
        written = tmpl.written[0]
        props = tmpl.properties
        ret = OrderedDict((name, [val, ptype, anim, written]) for name, (val, ptype, anim) in props.items())
    return ret or OrderedDict()


def elem_props_template_set(template, elem, ptype_name, name, value, animatable=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.
    if tmpl_ptype is not None:
        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, False))
        template[name][3] = True
    else:
        _elem_props_set(elem, ptype, name, value, _elem_props_flags(animatable, 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 ths 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))


##### 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():
        if type_name not in templates:
            templates[type_name] = [OrderedDict(((prop_type_name, (properties, nbr_users)),)), nbr_users]
        else:
            templates[type_name][0][prop_type_name] = (properties, nbr_users)
            templates[type_name][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():
                elem_props_set(props, ptype, name, value, animatable=animatable)


##### 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 = {}
        if key in cache:
            instance = cache[key]
            # 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', '_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((armature, bdata))
            self.bdata = bdata
            self._ref = armature

    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':
            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() * 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() 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() if par else Matrix()
            return par_mat_inv * self.bdata.matrix_local
        else:
            return self.matrix_local
    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
    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...
        #       Also, do not apply it to children objects.
        # TODO: Check whether this can work for bones too...
        return (scene_data.settings.bake_space_transform and self._tag == 'OB' and
                self.bdata.type in BLENDER_OBJECT_TYPES_MESHLIKE and not self.has_valid_parent(scene_data.objects))

    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))))

        if self._tag == 'BO':
            if rest:
                matrix = self.matrix_rest_global if is_global else self.matrix_rest_local
            else:  # Current pose.
                matrix = self.matrix_global if is_global else self.matrix_local
        else:
            # Since we have to apply corrections to some types of object, we always need local Blender space here...
            matrix = self.matrix_local
            parent = self.parent

            # Lamps and cameras need to be rotated (in local space!).
            if self.bdata.type == 'LAMP':
                matrix = matrix * MAT_CONVERT_LAMP
            elif self.bdata.type == 'CAMERA':
                matrix = matrix * MAT_CONVERT_CAMERA

            # 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_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_local * matrix
                    # ...and move it back into parent's *FBX* local space.
                    par_mat = parent.fbx_object_matrix(scene_data, local_space=True)
                    matrix = par_mat.inverted() * 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)

    #### Duplis...
    def dupli_list_create(self, scene, settings='PREVIEW'):
        if self._tag == 'OB':
            # Sigh, why raise exception here? :/
            try:
                self.bdata.dupli_list_create(scene, settings)
            except:
                pass

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

    def get_dupli_list(self):
        if self._tag == 'OB':
            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).
FBXSettingsMedia = namedtuple("FBXSettingsMedia", (
    "path_mode", "base_src", "base_dst", "subdir",
    "embed_textures", "copy_set",
))

# Helper container gathering all exporter settings.
FBXSettings = namedtuple("FBXSettings", (
    "report", "to_axes", "global_matrix", "global_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", "use_armature_deform_only",
    "bake_anim", "bake_anim_use_nla_strips", "bake_anim_use_all_actions", "bake_anim_step", "bake_anim_simplify_factor",
    "use_metadata", "media_settings", "use_custom_properties",
))

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