"""
.. codeauthor:: Tsuyoshi Hombashi <tsuyoshi.hombashi@gmail.com>
"""

import re
from re import Pattern
from typing import Final

from ._base import VarNameSanitizer


class PythonVarNameSanitizer(VarNameSanitizer):
    __PYTHON_RESERVED_KEYWORDS: Final = [
        "and",
        "del",
        "from",
        "not",
        "while",
        "as",
        "elif",
        "global",
        "or",
        "with",
        "assert",
        "else",
        "if",
        "pass",
        "yield",
        "break",
        "except",
        "import",
        "print",
        "class",
        "exec",
        "in",
        "raise",
        "continue",
        "finally",
        "is",
        "return",
        "def",
        "for",
        "lambda",
        "try",
    ]
    __PYTHON_BUILTIN_CONSTANTS: Final = [
        "False",
        "True",
        "None",
        "NotImplemented",
        "Ellipsis",
        "__debug__",
    ]

    __RE_INVALID_VAR_NAME: Final = re.compile("[^a-zA-Z0-9_]")
    __RE_INVALID_VAR_NAME_HEAD: Final = re.compile("^[^a-zA-Z]+")

    @property
    def reserved_keywords(self) -> list[str]:
        return self.__PYTHON_RESERVED_KEYWORDS + self.__PYTHON_BUILTIN_CONSTANTS

    @property
    def _invalid_var_name_head_re(self) -> Pattern[str]:
        return self.__RE_INVALID_VAR_NAME_HEAD

    @property
    def _invalid_var_name_re(self) -> Pattern[str]:
        return self.__RE_INVALID_VAR_NAME


def validate_python_var_name(var_name: str) -> None:
    """
    :param str var_name: Name to validate.
    :raises pathvalidate.ValidationError (ErrorReason.INVALID_CHARACTER):
        If the ``var_name`` is invalid as
        `Python identifier
        <https://docs.python.org/3/reference/lexical_analysis.html#identifiers>`__.
    :raises pathvalidate.ValidationError (ErrorReason.RESERVED_NAME):
        If the ``var_name`` is equals to
        `Python reserved keywords
        <https://docs.python.org/3/reference/lexical_analysis.html#keywords>`__
        or
        `Python built-in constants
        <https://docs.python.org/3/library/constants.html>`__.

    :Example:
        :ref:`example-validate-var-name`
    """

    PythonVarNameSanitizer(var_name).validate()


def sanitize_python_var_name(var_name: str, replacement_text: str = "") -> str:
    """
    Make a valid Python variable name from ``var_name``.

    To make a valid name:

    - Replace invalid characters for a Python variable name within
      the ``var_name`` with the ``replacement_text``
    - Delete invalid chars for the beginning of the variable name
    - Append underscore (``"_"``) at the tail of the name if sanitized name
      is one of the Python reserved names

    :param str filename: Name to sanitize.
    :param str replacement_text: Replacement text.
    :return: A replacement string.
    :rtype: str
    :raises ValueError: If ``var_name`` or ``replacement_text`` is invalid.

    :Example:
        :ref:`example-sanitize-var-name`

    .. seealso::
        :py:func:`.validate_python_var_name`
    """

    return PythonVarNameSanitizer(var_name).sanitize(replacement_text)