# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function

import collections
import itertools
import re

from ._structures import Infinity


__all__ = [
    "parse", "Version", "LegacyVersion", "InvalidVersion", "VERSION_PATTERN"
]


_Version = collections.namedtuple(
    "_Version",
    ["epoch", "release", "dev", "pre", "post", "local"],
)


def parse(version):
    """
    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.
    """
    try:
        return Version(version)
    except InvalidVersion:
        return LegacyVersion(version)


class InvalidVersion(ValueError):
    """
    An invalid version was found, users should refer to PEP 440.
    """


class _BaseVersion(object):

    def __hash__(self):
        return hash(self._key)

    def __lt__(self, other):
        return self._compare(other, lambda s, o: s < o)

    def __le__(self, other):
        return self._compare(other, lambda s, o: s <= o)

    def __eq__(self, other):
        return self._compare(other, lambda s, o: s == o)

    def __ge__(self, other):
        return self._compare(other, lambda s, o: s >= o)

    def __gt__(self, other):
        return self._compare(other, lambda s, o: s > o)

    def __ne__(self, other):
        return self._compare(other, lambda s, o: s != o)

    def _compare(self, other, method):
        if not isinstance(other, _BaseVersion):
            return NotImplemented

        return method(self._key, other._key)


class LegacyVersion(_BaseVersion):

    def __init__(self, version):
        self._version = str(version)
        self._key = _legacy_cmpkey(self._version)

    def __str__(self):
        return self._version

    def __repr__(self):
        return "<LegacyVersion({0})>".format(repr(str(self)))

    @property
    def public(self):
        return self._version

    @property
    def base_version(self):
        return self._version

    @property
    def epoch(self):
        return -1

    @property
    def release(self):
        return None

    @property
    def pre(self):
        return None

    @property
    def post(self):
        return None

    @property
    def dev(self):
        return None

    @property
    def local(self):
        return None

    @property
    def is_prerelease(self):
        return False

    @property
    def is_postrelease(self):
        return False

    @property
    def is_devrelease(self):
        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):
    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):
    # 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 = []
    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)
    parts = tuple(parts)

    return epoch, parts


# Deliberately not anchored to the start and end of the string, to make it
# easier for 3rd party code to reuse
VERSION_PATTERN = r"""
    v?
    (?:
        (?:(?P<epoch>[0-9]+)!)?                           # epoch
        (?P<release>[0-9]+(?:\.[0-9]+)*)                  # release segment
        (?P<pre>                                          # pre-release
            [-_\.]?
            (?P<pre_l>(a|b|c|rc|alpha|beta|pre|preview))
            [-_\.]?
            (?P<pre_n>[0-9]+)?
        )?
        (?P<post>                                         # post release
            (?:-(?P<post_n1>[0-9]+))
            |
            (?:
                [-_\.]?
                (?P<post_l>post|rev|r)
                [-_\.]?
                (?P<post_n2>[0-9]+)?
            )
        )?
        (?P<dev>                                          # dev release
            [-_\.]?
            (?P<dev_l>dev)
            [-_\.]?
            (?P<dev_n>[0-9]+)?
        )?
    )
    (?:\+(?P<local>[a-z0-9]+(?:[-_\.][a-z0-9]+)*))?       # local version
"""


class Version(_BaseVersion):

    _regex = re.compile(
        r"^\s*" + VERSION_PATTERN + r"\s*$",
        re.VERBOSE | re.IGNORECASE,
    )

    def __init__(self, version):
        # Validate the version and parse it into pieces
        match = self._regex.search(version)
        if not match:
            raise InvalidVersion("Invalid version: '{0}'".format(version))

        # Store the parsed out pieces of the version
        self._version = _Version(
            epoch=int(match.group("epoch")) if match.group("epoch") else 0,
            release=tuple(int(i) for i in match.group("release").split(".")),
            pre=_parse_letter_version(
                match.group("pre_l"),
                match.group("pre_n"),
            ),
            post=_parse_letter_version(
                match.group("post_l"),
                match.group("post_n1") or match.group("post_n2"),
            ),
            dev=_parse_letter_version(
                match.group("dev_l"),
                match.group("dev_n"),
            ),
            local=_parse_local_version(match.group("local")),
        )

        # Generate a key which will be used for sorting
        self._key = _cmpkey(
            self._version.epoch,
            self._version.release,
            self._version.pre,
            self._version.post,
            self._version.dev,
            self._version.local,
        )

    def __repr__(self):
        return "<Version({0})>".format(repr(str(self)))

    def __str__(self):
        parts = []

        # Epoch
        if self.epoch != 0:
            parts.append("{0}!".format(self.epoch))

        # Release segment
        parts.append(".".join(str(x) for x in self.release))

        # Pre-release
        if self.pre is not None:
            parts.append("".join(str(x) for x in self.pre))

        # Post-release
        if self.post is not None:
            parts.append(".post{0}".format(self.post))

        # Development release
        if self.dev is not None:
            parts.append(".dev{0}".format(self.dev))

        # Local version segment
        if self.local is not None:
            parts.append("+{0}".format(self.local))

        return "".join(parts)

    @property
    def epoch(self):
        return self._version.epoch

    @property
    def release(self):
        return self._version.release

    @property
    def pre(self):
        return self._version.pre

    @property
    def post(self):
        return self._version.post[1] if self._version.post else None

    @property
    def dev(self):
        return self._version.dev[1] if self._version.dev else None

    @property
    def local(self):
        if self._version.local:
            return ".".join(str(x) for x in self._version.local)
        else:
            return None

    @property
    def public(self):
        return str(self).split("+", 1)[0]

    @property
    def base_version(self):
        parts = []

        # Epoch
        if self.epoch != 0:
            parts.append("{0}!".format(self.epoch))

        # Release segment
        parts.append(".".join(str(x) for x in self.release))

        return "".join(parts)

    @property
    def is_prerelease(self):
        return self.dev is not None or self.pre is not None

    @property
    def is_postrelease(self):
        return self.post is not None

    @property
    def is_devrelease(self):
        return self.dev is not None