import base64
import json
import re
import sys

from maya import cmds

from .compatibility import ensure_retro_compatibility
from .namespace import maya_namespace, node_full_namespace
from .optionvar import USE_BASE64_DATA_ENCODING


PICKER_HOLDER_NODE = '_dwpicker_data'
PICKER_HOLDER_ATTRIBUTE = '_dwpicker_data'
LS_EXP = ["*." + PICKER_HOLDER_ATTRIBUTE, "*:*." + PICKER_HOLDER_ATTRIBUTE]


def get_picker_holder_node():
    if cmds.objExists(PICKER_HOLDER_NODE):
        return PICKER_HOLDER_NODE
    return create_picker_holder_node()


def create_picker_holder_node():
    with maya_namespace(":"):
        selection = cmds.ls(selection=True)
        node = cmds.createNode('script', name=PICKER_HOLDER_NODE)
        cmds.select(selection)
    cmds.setAttr(node + '.nodeState', 1)
    cmds.addAttr(node, longName=PICKER_HOLDER_ATTRIBUTE, dataType='string')
    return node


def store_local_picker_data(pickers):
    data = encode_data(pickers)
    node = get_picker_holder_node()
    cmds.setAttr(node + '.' + PICKER_HOLDER_ATTRIBUTE, data, type='string')
    clean_stray_picker_holder_nodes()


def load_local_picker_data():
    nodes = list_picker_holder_nodes()
    pickers = []
    for node in nodes:
        data = cmds.getAttr(node + '.' + PICKER_HOLDER_ATTRIBUTE)
        if not data:
            continue
        data = [ensure_retro_compatibility(p) for p in decode_data(data)]
        namespace = node_full_namespace(node)
        if namespace:
            # holder node would have namespace when it is referenced
            # and we should add it's namespace for items to be selectable
            for p in data:
                for s in p['shapes']:
                    s['action.targets'] = [
                        re.sub(r'([^|]+)', r'{}:\1'.format(namespace), n)
                        for n in s['action.targets']]
        pickers.extend(data)
    return pickers


def encode_data(pickers):
    data = json.dumps(pickers)
    if not cmds.optionVar(query=USE_BASE64_DATA_ENCODING):
        return data
    # Ensure backward compatibility.
    if sys.version_info[0] == 2:
        return base64.b64encode(bytes(data))
    return base64.b64encode(bytes(data, "utf-8"))


def decode_data(data):
    try:
        return json.loads(data)
    except ValueError:  # Happe if data encoded is encoded as base 64 string.
        return json.loads(base64.b64decode(data))


def list_picker_holder_nodes():
    """
    Look up in the scene all the nodes holding an attribute named
    "_dwpicker_holder" which are not set on the "_dwpicker_holder" node.
    This mignt happed if a node node is imported (creating a namespace or a
    incrementation).
    """
    return [node.split(".")[0] for node in cmds.ls(LS_EXP)]


def clean_stray_picker_holder_nodes():
    """
    If the scene contains multiple picker holder nodes, we remove them
    automatically to avoid repeated pickers.
    """
    for node in list_picker_holder_nodes():
        if node == PICKER_HOLDER_NODE:
            continue
        cmds.delete(node)
        if cmds.objExists(node):
            # Node is locked or in reference and cannot be removed.
            # As we cant remove it, we reset his data to avoid double pickers.
            cmds.setAttr(
                node + "." + PICKER_HOLDER_ATTRIBUTE, "", type="string")