# Copyright (c) 2018, 2019, 2021  Peter Pentchev <roam@ringlet.net>
# All rights reserved.
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# are met:
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"""Version string parsing for the feature-check Python library."""

import re

from typing import Any, Callable, List, Optional, Tuple  # noqa: H301


REX = {
    "var": r"[A-Za-z0-9_-]+",
    "value": r"[A-Za-z0-9.]+",
    "op": r"(?: < | <= | = | >= | > | lt | le | eq | ge | gt )",
    "num_alpha": r"(?P<num> [0-9]* ) (?P<alpha> .*)",
}

REX_COMP = {name: re.compile(expr + "$", re.X) for name, expr in REX.items()}


def _version_split_num_alpha(ver: str) -> Tuple[str, str]:
    """Split a version component into a numeric and an alphanumeric part.

    "2a" is split into ('2', 'a').
    """
    match = REX_COMP["num_alpha"].match(ver)
    assert match is not None
    data = match.groupdict()
    return data["num"], data["alpha"]


def _version_compare_split_empty(spl_a: List[str], spl_b: List[str]) -> Optional[int]:
    """Check if any of the split version numbers is empty."""
    if not spl_a:
        if not spl_b:
            return 0
        if _version_split_num_alpha(spl_b[0])[0] == "":
            return 1
        return -1
    if not spl_b:
        if _version_split_num_alpha(spl_a[0])[0] == "":
            return -1
        return 1

    return None


def _version_compare_split_comp(
    comp_a: str, comp_b: str, conv: Callable[[str], Any]
) -> Optional[int]:
    """Compare a single component of split version numbers."""
    if comp_a != "":
        if comp_b != "":
            if conv(comp_a) < conv(comp_b):
                return -1
            if conv(comp_a) > conv(comp_b):
                return 1
        else:
            return 1
    elif comp_b != "":
        return -1

    return None


def _version_compare_split(spl_a: List[str], spl_b: List[str]) -> int:
    """Compare two version numbers already split into component lists.

    Returns -1, 0, or 1 for the first version being less than, equal to,
    or greater than the second one.
    """
    res = _version_compare_split_empty(spl_a, spl_b)
    if res is not None:
        return res

    (first_a, first_b) = (spl_a.pop(0), spl_b.pop(0))
    (num_a, rem_a) = _version_split_num_alpha(first_a)
    assert num_a != "" or rem_a != "", "could not split " + first_a
    (num_b, rem_b) = _version_split_num_alpha(first_b)
    assert num_b != "" or rem_b != "", "could not split " + first_b

    res = _version_compare_split_comp(num_a, num_b, int)
    if res is not None:
        return res

    res = _version_compare_split_comp(rem_a, rem_b, lambda s: s)
    if res is not None:
        return res

    return _version_compare_split(spl_a, spl_b)


def version_compare(ver_a: str, ver_b: str) -> int:
    """Compare two version numbers as strings.

    Returns -1, 0, or 1 for the first version being less than, equal to,
    or greater than the second one.
    """
    return _version_compare_split(ver_a.split("."), ver_b.split("."))