# SPDX-License-Identifier: Apache-2.0
# Copyright 2018-2022 The glTF-Blender-IO authors.

import bpy
import mathutils
from ......io.com import gltf2_io
from ......io.com import gltf2_io_constants
from ......io.exp import gltf2_io_binary_data
from ......io.exp.gltf2_io_user_extensions import export_user_extensions
from .....com.gltf2_blender_data_path import get_target_object_path
from .....com import gltf2_blender_math
from ....gltf2_blender_gather_tree import VExportNode
from ....gltf2_blender_gather_cache import cached
from ....gltf2_blender_gather_accessors import gather_accessor
from .gltf2_blender_gather_object_keyframes import gather_object_sampled_keyframes

@cached
def gather_object_sampled_animation_sampler(
        obj_uuid: str,
        channel: str,
        action_name: str,
        node_channel_is_animated: bool,
        node_channel_interpolation: str,
        export_settings
        ):

    keyframes = __gather_keyframes(
        obj_uuid,
        channel,
        action_name,
        node_channel_is_animated,
        export_settings)

    if keyframes is None:
        # After check, no need to animate this node for this channel
        return None

    # Now we are raw input/output, we need to convert to glTF data
    input, output = __convert_keyframes(obj_uuid, channel, keyframes, action_name, export_settings)

    sampler = gltf2_io.AnimationSampler(
        extensions=None,
        extras=None,
        input=input,
        interpolation=__gather_interpolation(node_channel_is_animated, node_channel_interpolation, keyframes, export_settings),
        output=output
    )

    blender_object = export_settings['vtree'].nodes[obj_uuid].blender_object
    export_user_extensions('animation_gather_object_sampler', export_settings, blender_object, action_name)

    return sampler

def __gather_keyframes(
        obj_uuid: str,
        channel: str,
        action_name: str,
        node_channel_is_animated: bool,
        export_settings
        ):

    keyframes = gather_object_sampled_keyframes(
        obj_uuid,
        channel,
        action_name,
        node_channel_is_animated,
        export_settings
    )

    return keyframes

def __convert_keyframes(obj_uuid: str, channel: str, keyframes, action_name: str, export_settings):

    # Sliding can come from:
    # - option SLIDE for negative frames
    # - option to start animation at frame 0 for looping
    if obj_uuid in export_settings['slide'].keys() and action_name in export_settings['slide'][obj_uuid].keys():
        for k in keyframes:
            k.frame += -export_settings['slide'][obj_uuid][action_name]
            k.seconds = k.frame / bpy.context.scene.render.fps

    times = [k.seconds for k in keyframes]
    input = gather_accessor(
        gltf2_io_binary_data.BinaryData.from_list(times, gltf2_io_constants.ComponentType.Float),
        gltf2_io_constants.ComponentType.Float,
        len(times),
        tuple([max(times)]),
        tuple([min(times)]),
        gltf2_io_constants.DataType.Scalar,
        export_settings)

    is_yup = export_settings['gltf_yup']

    object_path = get_target_object_path(channel)
    transform = mathutils.Matrix.Identity(4)

    need_rotation_correction = (export_settings['gltf_cameras'] and export_settings['vtree'].nodes[obj_uuid].blender_type == VExportNode.CAMERA) or \
        (export_settings['gltf_lights'] and export_settings['vtree'].nodes[obj_uuid].blender_type == VExportNode.LIGHT)


    values = []
    fps = bpy.context.scene.render.fps
    for keyframe in keyframes:

        # Transform the data and build gltf control points
        value = gltf2_blender_math.transform(keyframe.value, channel, transform, need_rotation_correction)
        if is_yup:
            value = gltf2_blender_math.swizzle_yup(value, channel)
        keyframe_value = gltf2_blender_math.mathutils_to_gltf(value)

        # No tangents when baking, we are using LINEAR interpolation

        values += keyframe_value

    # store the keyframe data in a binary buffer
    component_type = gltf2_io_constants.ComponentType.Float
    data_type = gltf2_io_constants.DataType.vec_type_from_num(len(keyframes[0].value))

    output = gltf2_io.Accessor(
        buffer_view=gltf2_io_binary_data.BinaryData.from_list(values, component_type),
        byte_offset=None,
        component_type=component_type,
        count=len(values) // gltf2_io_constants.DataType.num_elements(data_type),
        extensions=None,
        extras=None,
        max=None,
        min=None,
        name=None,
        normalized=None,
        sparse=None,
        type=data_type
    )

    return input, output

def __gather_interpolation(
        node_channel_is_animated: bool,
        node_channel_interpolation: str,
        keyframes,
        export_settings):

    if len(keyframes) > 2:
        # keep STEP as STEP, other become LINEAR
        return {
            "STEP": "STEP"
        }.get(node_channel_interpolation, "LINEAR")
    elif len(keyframes) == 1:
        if node_channel_is_animated is False:
            return "STEP"
        else:
            return node_channel_interpolation
    else:
        # If we only have 2 keyframes, set interpolation to STEP if baked
        if node_channel_is_animated is False:
            # baked => We have first and last keyframe
            return "STEP"
        else:
            if keyframes[0].value == keyframes[1].value:
                return "STEP"
            else:
                return "LINEAR"
