# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this library.  If not, see <http://www.gnu.org/licenses/>.

from typing import Union, Any
from vyos.configdict import dict_merge

class Xml:
    def __init__(self):
        self.ref = {}

    def define(self, ref: dict):
        self.ref = ref

    def _get_ref_node_data(self, node: dict, data: str) -> Union[bool, str]:
        res = node.get('node_data', {})
        if not res:
            raise ValueError("non-existent node data")
        if data not in res:
            raise ValueError("non-existent data field")

        return res.get(data)

    def _get_ref_path(self, path: list) -> dict:
        ref_path = path.copy()
        d = self.ref
        while ref_path and d:
            d = d.get(ref_path[0], {})
            ref_path.pop(0)
            if self._is_tag_node(d) and ref_path:
                ref_path.pop(0)

        return d

    def _is_tag_node(self, node: dict) -> bool:
        res = self._get_ref_node_data(node, 'node_type')
        return res == 'tag'

    def is_tag(self, path: list) -> bool:
        ref_path = path.copy()
        d = self.ref
        while ref_path and d:
            d = d.get(ref_path[0], {})
            ref_path.pop(0)
            if self._is_tag_node(d) and ref_path:
                if len(ref_path) == 1:
                    return False
                ref_path.pop(0)

        return self._is_tag_node(d)

    def is_tag_value(self, path: list) -> bool:
        if len(path) < 2:
            return False

        return self.is_tag(path[:-1])

    def _is_multi_node(self, node: dict) -> bool:
        b = self._get_ref_node_data(node, 'multi')
        assert isinstance(b, bool)
        return b

    def is_multi(self, path: list) -> bool:
        d = self._get_ref_path(path)
        return  self._is_multi_node(d)

    def _is_valueless_node(self, node: dict) -> bool:
        b = self._get_ref_node_data(node, 'valueless')
        assert isinstance(b, bool)
        return b

    def is_valueless(self, path: list) -> bool:
        d = self._get_ref_path(path)
        return  self._is_valueless_node(d)

    def _is_leaf_node(self, node: dict) -> bool:
        res = self._get_ref_node_data(node, 'node_type')
        return res == 'leaf'

    def is_leaf(self, path: list) -> bool:
        d = self._get_ref_path(path)
        return self._is_leaf_node(d)

    def component_version(self) -> dict:
        d = {}
        for k, v in self.ref['component_version']:
            d[k] = int(v)
        return d

    def multi_to_list(self, rpath: list, conf: dict) -> dict:
        if rpath and rpath[-1] in list(conf):
            raise ValueError('rpath should be disjoint from conf keys')

        res: Any = {}

        for k in list(conf):
            d = self._get_ref_path(rpath + [k])
            if self._is_leaf_node(d):
                if self._is_multi_node(d) and not isinstance(conf[k], list):
                    res[k] = [conf[k]]
                else:
                    res[k] = conf[k]
            else:
                res[k] = self.multi_to_list(rpath + [k], conf[k])

        return res

    def _get_default_value(self, node: dict):
        return self._get_ref_node_data(node, "default_value")

    def get_defaults(self, path: list, get_first_key=False, recursive=False) -> dict:
        """Return dict containing default values below path

        Note that descent below path will not proceed beyond an encountered
        tag node, as no tag node value is known. For a default dict relative
        to an existing config dict containing tag node values, see function:
        'relative_defaults'
        """
        res: dict = {}
        d = self._get_ref_path(path)
        for k in list(d):
            if k in ('node_data', 'component_version') :
                continue
            d_k = d[k]
            if self._is_leaf_node(d_k):
                default_value = self._get_default_value(d_k)
                if default_value is not None:
                    pos = default_value
                    if self._is_multi_node(d_k) and not isinstance(pos, list):
                        pos = [pos]
                    res |= {k: pos}
            elif self.is_tag(path + [k]):
                # tag node defaults are used as suggestion, not default value;
                # should this change, append to path and continue if recursive
                pass
            else:
                if recursive:
                    pos = self.get_defaults(path + [k], recursive=True)
                    res |= pos
        if res:
            if get_first_key or not path:
                if not isinstance(res, dict):
                    raise TypeError("Cannot get_first_key as data under node is not of type dict")
                return res
            return {path[-1]: res}

        return {}

    def _well_defined(self, path: list, conf: dict) -> bool:
        # test disjoint path + conf for sensible config paths
        def step(c):
            return [next(iter(c.keys()))] if c else []
        try:
            tmp = step(conf)
            if self.is_tag_value(path + tmp):
                c = conf[tmp[0]]
                if not isinstance(c, dict):
                    raise ValueError
                tmp = tmp + step(c)
                self._get_ref_path(path + tmp)
            else:
                self._get_ref_path(path + tmp)
        except ValueError:
            return False
        return True

    def relative_defaults(self, rpath: list, conf: dict, get_first_key=False,
                          recursive=False) -> dict:
        """Return dict containing defaults along paths of a config dict
        """
        if not conf:
            return self.get_defaults(rpath, get_first_key=get_first_key,
                                     recursive=recursive)
        if rpath and rpath[-1] in list(conf):
            conf = conf[rpath[-1]]
            if not isinstance(conf, dict):
                raise TypeError('conf at path is not of type dict')

        if not self._well_defined(rpath, conf):
            print('path to config dict does not define full config paths')
            return {}

        res: dict = {}
        for k in list(conf):
            pos = self.get_defaults(rpath + [k], recursive=recursive)
            res |= pos

            if isinstance(conf[k], dict):
                step = self.relative_defaults(rpath + [k], conf=conf[k],
                                              recursive=recursive)
                res |= step

        if res:
            if get_first_key:
                return res
            return {rpath[-1]: res} if rpath else res

        return {}

    def merge_defaults(self, path: list, conf: dict) -> dict:
        """Return config dict with defaults non-destructively merged

        This merges non-recursive defaults relative to the config dict.
        """
        if path[-1] in list(conf):
            config = conf[path[-1]]
            if not isinstance(config, dict):
                raise TypeError('conf at path is not of type dict')
            shift = False
        else:
            config = conf
            shift = True

        if not self._well_defined(path, config):
            print('path to config dict does not define config paths; conf returned unchanged')
            return conf

        d = self.relative_defaults(path, conf=config, get_first_key=shift)
        d = dict_merge(d, conf)
        return d