import re
import typing
from typing import List, Iterable

import addon_utils
import bpy.types
from bpy.types import NlaStrip, Object, AnimData


def rgb_to_srgb(c: float):
    if c > 0.0031308:
        return 1.055 * (pow(c, (1.0 / 2.4))) - 0.055
    else:
        return 12.92 * c


def get_nla_strips_in_frame_range(animation_data: AnimData, frame_min: float, frame_max: float) -> List[NlaStrip]:
    if animation_data is None:
        return []
    strips = []
    for nla_track in animation_data.nla_tracks:
        if nla_track.mute:
            continue
        for strip in nla_track.strips:
            if (strip.frame_start < frame_min and strip.frame_end > frame_max) or \
                    (frame_min <= strip.frame_start < frame_max) or \
                    (frame_min < strip.frame_end <= frame_max):
                strips.append(strip)
    return strips


def populate_bone_collection_list(armature_object: Object, bone_collection_list: bpy.props.CollectionProperty) -> None:
    '''
    Updates the bone collections collection.

    Bone collection selections are preserved between updates unless none of the groups were previously selected;
    otherwise, all collections are selected by default.
    '''
    has_selected_collections = any([g.is_selected for g in bone_collection_list])
    unassigned_collection_is_selected, selected_assigned_collection_names = True, []

    if armature_object is None:
        return

    if has_selected_collections:
        # Preserve group selections before clearing the list.
        # We handle selections for the unassigned group separately to cover the edge case
        # where there might be an actual group with 'Unassigned' as its name.
        unassigned_collection_idx, unassigned_collection_is_selected = next(iter([
            (i, g.is_selected) for i, g in enumerate(bone_collection_list) if g.index == -1]), (-1, False))

        selected_assigned_collection_names = [
            g.name for i, g in enumerate(bone_collection_list) if i != unassigned_collection_idx and g.is_selected]

    bone_collection_list.clear()

    armature = armature_object.data

    if armature is None:
        return

    item = bone_collection_list.add()
    item.name = 'Unassigned'
    item.index = -1
    # Count the number of bones without an assigned bone collection
    item.count = sum(map(lambda bone: 1 if len(bone.collections) == 0 else 0, armature.bones))
    item.is_selected = unassigned_collection_is_selected

    for bone_collection_index, bone_collection in enumerate(armature.collections):
        item = bone_collection_list.add()
        item.name = bone_collection.name
        item.index = bone_collection_index
        item.count = len(bone_collection.bones)
        item.is_selected = bone_collection.name in selected_assigned_collection_names if has_selected_collections else True


def check_bone_names(bone_names: Iterable[str]):
    pattern = re.compile(r'^[a-zA-Z\d_\- ]+$')
    invalid_bone_names = [x for x in bone_names if pattern.match(x) is None]
    if len(invalid_bone_names) > 0:
        raise RuntimeError(f'The following bone names are invalid: {invalid_bone_names}.\n'
                           f'Bone names must only contain letters, numbers, spaces, hyphens and underscores.\n'
                           f'You can bypass this by disabling "Enforce Bone Name Restrictions" in the export settings.')


def get_export_bone_names(armature_object: Object, bone_filter_mode: str, bone_collection_indices: List[int]) -> List[str]:
    '''
    Returns a sorted list of bone indices that should be exported for the given bone filter mode and bone collections.

    Note that the ancestors of bones within the bone collections will also be present in the returned list.

    :param armature_object: Blender object with type 'ARMATURE'
    :param bone_filter_mode: One of ['ALL', 'BONE_COLLECTIONS']
    :param bone_collection_indices: List of bone collection indices to be exported.
    :return: A sorted list of bone indices that should be exported.
    '''
    if armature_object is None or armature_object.type != 'ARMATURE':
        raise ValueError('An armature object must be supplied')

    armature_data = typing.cast(bpy.types.Armature, armature_object.data)
    bones = armature_data.bones
    bone_names = [x.name for x in bones]

    # Get a list of the bone indices that we are explicitly including.
    bone_index_stack = []
    is_exporting_unassigned_bone_collections = -1 in bone_collection_indices
    bone_collections = list(armature_data.collections)

    for bone_index, bone in enumerate(bones):
        # Check if this bone is in any of the collections in the bone collection indices list.
        this_bone_collection_indices = set(bone_collections.index(x) for x in bone.collections)
        is_in_exported_bone_collections = len(set(bone_collection_indices).intersection(this_bone_collection_indices)) > 0

        if bone_filter_mode == 'ALL' or \
                (len(bone.collections) == 0 and is_exporting_unassigned_bone_collections) or \
                is_in_exported_bone_collections:
            bone_index_stack.append((bone_index, None))

    # For each bone that is explicitly being added, recursively walk up the hierarchy and ensure that all of
    # those ancestor bone indices are also in the list.
    bone_indices = dict()
    while len(bone_index_stack) > 0:
        bone_index, instigator_bone_index = bone_index_stack.pop()
        bone = bones[bone_index]
        if bone.parent is not None:
            parent_bone_index = bone_names.index(bone.parent.name)
            if parent_bone_index not in bone_indices:
                bone_index_stack.append((parent_bone_index, bone_index))
        bone_indices[bone_index] = instigator_bone_index

    # Sort the bone index list in-place.
    bone_indices = [(x[0], x[1]) for x in bone_indices.items()]
    bone_indices.sort(key=lambda x: x[0])

    # Split out the bone indices and the instigator bone names into separate lists.
    # We use the bone names for the return values because the bone name is a more universal way of referencing them.
    # For example, users of this function may modify bone lists, which would invalidate the indices and require an
    # index mapping scheme to resolve it. Using strings is more comfy and results in less code downstream.
    instigator_bone_names = [bones[x[1]].name if x[1] is not None else None for x in bone_indices]
    bone_names = [bones[x[0]].name for x in bone_indices]

    # Ensure that the hierarchy we are sending back has a single root bone.
    bone_indices = [x[0] for x in bone_indices]
    root_bones = [bones[bone_index] for bone_index in bone_indices if bones[bone_index].parent is None]
    if len(root_bones) > 1:
        # There is more than one root bone.
        # Print out why each root bone was included by linking it to one of the explicitly included bones.
        root_bone_names = [bone.name for bone in root_bones]
        for root_bone_name in root_bone_names:
            bone_name = root_bone_name
            while True:
                # Traverse the instigator chain until the end to find the true instigator bone.
                # TODO: in future, it would be preferential to have a readout of *all* instigator bones.
                instigator_bone_name = instigator_bone_names[bone_names.index(bone_name)]
                if instigator_bone_name is None:
                    print(f'Root bone "{root_bone_name}" was included because {bone_name} was marked for export')
                    break
                bone_name = instigator_bone_name

        raise RuntimeError('Exported bone hierarchy must have a single root bone.\n'
                           f'The bone hierarchy marked for export has {len(root_bones)} root bones: {root_bone_names}.\n'
                           f'Additional debugging information has been written to the console.')

    return bone_names


def is_bdk_addon_loaded():
    return addon_utils.check('bdk_addon')[1]