import re
from typing import Iterator, List, Tuple

from pip_api._vendor.packaging.version import InvalidVersion, _BaseVersion, parse as _parse

LegacyCmpKey = Tuple[int, Tuple[str, ...]]


def parse(version: str) -> "_BaseVersion":
    """
    Parse the given version string and return either a :class:`Version` object
    or a :class:`LegacyVersion` object depending on if the given version is
    a valid PEP 440 version or a legacy version.
    Parse the given version string.
    Returns a :class:`Version` object, if the given version is a valid PEP 440 version.
    Raises :class:`InvalidVersion` otherwise.
    """
    try:
        return _parse(version)
    except InvalidVersion:
        return LegacyVersion(version)


class LegacyVersion(_BaseVersion):

    _key: LegacyCmpKey

    def __init__(self, version: str) -> None:
        self._version = str(version)
        self._key: LegacyCmpKey = _legacy_cmpkey(self._version)

    def __str__(self) -> str:
        return self._version

    def __repr__(self) -> str:
        return f"<LegacyVersion('{self}')>"

    @property
    def public(self) -> str:
        return self._version

    @property
    def base_version(self) -> str:
        return self._version

    @property
    def epoch(self) -> int:
        return -1

    @property
    def release(self) -> None:
        return None

    @property
    def pre(self) -> None:
        return None

    @property
    def post(self) -> None:
        return None

    @property
    def dev(self) -> None:
        return None

    @property
    def local(self) -> None:
        return None

    @property
    def is_prerelease(self) -> bool:
        return False

    @property
    def is_postrelease(self) -> bool:
        return False

    @property
    def is_devrelease(self) -> bool:
        return False


_legacy_version_component_re = re.compile(r"(\d+ | [a-z]+ | \.| -)", re.VERBOSE)

_legacy_version_replacement_map = {
    "pre": "c",
    "preview": "c",
    "-": "final-",
    "rc": "c",
    "dev": "@",
}


def _parse_version_parts(s: str) -> Iterator[str]:
    for part in _legacy_version_component_re.split(s):
        part = _legacy_version_replacement_map.get(part, part)

        if not part or part == ".":
            continue

        if part[:1] in "0123456789":
            # pad for numeric comparison
            yield part.zfill(8)
        else:
            yield "*" + part

    # ensure that alpha/beta/candidate are before final
    yield "*final"


def _legacy_cmpkey(version: str) -> LegacyCmpKey:

    # We hardcode an epoch of -1 here. A PEP 440 version can only have a epoch
    # greater than or equal to 0. This will effectively put the LegacyVersion,
    # which uses the defacto standard originally implemented by setuptools,
    # as before all PEP 440 versions.
    epoch = -1

    # This scheme is taken from pkg_resources.parse_version setuptools prior to
    # it's adoption of the packaging library.
    parts: List[str] = []
    for part in _parse_version_parts(version.lower()):
        if part.startswith("*"):
            # remove "-" before a prerelease tag
            if part < "*final":
                while parts and parts[-1] == "*final-":
                    parts.pop()

            # remove trailing zeros from each series of numeric parts
            while parts and parts[-1] == "00000000":
                parts.pop()

        parts.append(part)

    return epoch, tuple(parts)