# ==================================================================================================================== #
#             _____           _ _               ____             __ _                       _   _                      #
#  _ __  _   |_   _|__   ___ | (_)_ __   __ _  / ___|___  _ __  / _(_) __ _ _   _ _ __ __ _| |_(_) ___  _ __           #
# | '_ \| | | || |/ _ \ / _ \| | | '_ \ / _` || |   / _ \| '_ \| |_| |/ _` | | | | '__/ _` | __| |/ _ \| '_ \          #
# | |_) | |_| || | (_) | (_) | | | | | | (_| || |__| (_) | | | |  _| | (_| | |_| | | | (_| | |_| | (_) | | | |         #
# | .__/ \__, ||_|\___/ \___/|_|_|_| |_|\__, (_)____\___/|_| |_|_| |_|\__, |\__,_|_|  \__,_|\__|_|\___/|_| |_|         #
# |_|    |___/                          |___/                         |___/                                            #
# ==================================================================================================================== #
# Authors:                                                                                                             #
#   Patrick Lehmann                                                                                                    #
#                                                                                                                      #
# License:                                                                                                             #
# ==================================================================================================================== #
# Copyright 2021-2026 Patrick Lehmann - Bötzingen, Germany                                                             #
#                                                                                                                      #
# Licensed under the Apache License, Version 2.0 (the "License");                                                      #
# you may not use this file except in compliance with the License.                                                     #
# You may obtain a copy of the License at                                                                              #
#                                                                                                                      #
#   http://www.apache.org/licenses/LICENSE-2.0                                                                         #
#                                                                                                                      #
# Unless required by applicable law or agreed to in writing, software                                                  #
# distributed under the License is distributed on an "AS IS" BASIS,                                                    #
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.                                             #
# See the License for the specific language governing permissions and                                                  #
# limitations under the License.                                                                                       #
#                                                                                                                      #
# SPDX-License-Identifier: Apache-2.0                                                                                  #
# ==================================================================================================================== #
#
"""
Abstract configuration reader.

.. hint::

   See :ref:`high-level help <CONFIG>` for explanations and usage examples.
"""
from pathlib       import Path
from typing        import Union, ClassVar, Iterator, Type, Optional as Nullable

from pyTooling.Decorators  import export, readonly
from pyTooling.MetaClasses import ExtendedType, mixin
from pyTooling.Exceptions  import ToolingException


__all__ = ["KeyT", "NodeT", "ValueT"]


KeyT =   Union[str, int]                  #: Type variable for keys.
NodeT =  Union["Dictionary", "Sequence"]  #: Type variable for nodes.
ValueT = Union[NodeT, str, int, float]    #: Type variable for values.


@export
class ConfigurationException(ToolingException):
	"""Base-exception of all exceptions raised by :mod:`pyTooling.Configuration`."""


@export
class Node(metaclass=ExtendedType, slots=True):
	"""Abstract node in a configuration data structure."""

	DICT_TYPE: ClassVar[Type["Dictionary"]]  #: Type reference used when instantiating new dictionaries
	SEQ_TYPE:  ClassVar[Type["Sequence"]]    #: Type reference used when instantiating new sequences
	_root:     "Configuration"               #: Reference to the root node.
	_parent:   "Dictionary"                  #: Reference to a parent node.

	def __init__(self, root: "Configuration" = None, parent: Nullable[NodeT] = None) -> None:
		"""
		Initializes a node.

		:param root:   Reference to the root node.
		:param parent: Reference to the parent node.
		"""
		self._root = root
		self._parent = parent

	def __len__(self) -> int:  # type: ignore[empty-body]
		"""
		Returns the number of sub-elements.

		:returns: Number of sub-elements.
		"""

	def __getitem__(self, key: KeyT) -> ValueT:  # type: ignore[empty-body]
		"""
		Access an element in the node by index or key.

		:param key: Index or key of the element.
		:returns:   A node (sequence or dictionary) or scalar value (int, float, str).
		"""
		raise NotImplementedError()

	def __setitem__(self, key: KeyT, value: ValueT) -> None:  # type: ignore[empty-body]
		"""
		Set an element in the node by index or key.

		:param key:   Index or key of the element.
		:param value: Value to set
		"""
		raise NotImplementedError()

	def __iter__(self) -> Iterator[ValueT]:  # type: ignore[empty-body]
		"""
		Returns an iterator to iterate a node.

		:returns: Node iterator.
		"""
		raise NotImplementedError()

	@property
	def Key(self) -> KeyT:
		raise NotImplementedError()

	@Key.setter
	def Key(self, value: KeyT) -> None:
		raise NotImplementedError()

	def QueryPath(self, query: str) -> ValueT:  # type: ignore[empty-body]
		"""
		Return a node or value based on a path description to that node or value.

		:param query: String describing the path to the node or value.
		:returns:     A node (sequence or dictionary) or scalar value (int, float, str).
		"""
		raise NotImplementedError()


@export
@mixin
class Dictionary(Node):
	"""Abstract dictionary node in a configuration."""

	def __init__(self, root: "Configuration" = None, parent: Nullable[NodeT] = None) -> None:
		"""
		Initializes a dictionary.

		:param root:   Reference to the root node.
		:param parent: Reference to the parent node.
		"""
		Node.__init__(self, root, parent)

	def __contains__(self, key: KeyT) -> bool:  # type: ignore[empty-body]
		raise NotImplementedError()


@export
@mixin
class Sequence(Node):
	"""Abstract sequence node in a configuration."""

	def __init__(self, root: "Configuration" = None, parent: Nullable[NodeT] = None) -> None:
		"""
		Initializes a sequence.

		:param root:   Reference to the root node.
		:param parent: Reference to the parent node.
		"""
		Node.__init__(self, root, parent)

	def __getitem__(self, index: int) -> ValueT:  # type: ignore[empty-body]
		raise NotImplementedError()

	def __setitem__(self, index: int, value: ValueT) -> None:  # type: ignore[empty-body]
		raise NotImplementedError()


setattr(Node, "DICT_TYPE", Dictionary)
setattr(Node, "SEQ_TYPE", Sequence)


@export
@mixin
class Configuration(Node):
	"""Abstract root node in a configuration."""

	_configFile: Path  #: Path to the configuration file.

	def __init__(self, configFile: Path, root: "Configuration" = None, parent: Nullable[NodeT] = None) -> None:
		"""
		Initializes a configuration.

		:param configFile: Configuration file.
		:param root:       Reference to the root node.
		:param parent:     Reference to the parent node.
		"""
		Node.__init__(self, root, parent)
		self._configFile = configFile

	@readonly
	def ConfigFile(self) -> Path:
		"""
		Read-only property to access the configuration file's path.

		:returns: Path to the configuration file.
		"""
		return self._configFile
