# 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 abc
import functools
import itertools
import re

from ._compat import string_types, with_metaclass
from .version import Version, LegacyVersion, parse


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


class BaseSpecifier(with_metaclass(abc.ABCMeta, object)):

    @abc.abstractmethod
    def __str__(self):
        """
        Returns the str representation of this Specifier like object. This
        should be representative of the Specifier itself.
        """

    @abc.abstractmethod
    def __hash__(self):
        """
        Returns a hash value for this Specifier like object.
        """

    @abc.abstractmethod
    def __eq__(self, other):
        """
        Returns a boolean representing whether or not the two Specifier like
        objects are equal.
        """

    @abc.abstractmethod
    def __ne__(self, other):
        """
        Returns a boolean representing whether or not the two Specifier like
        objects are not equal.
        """

    @abc.abstractproperty
    def prereleases(self):
        """
        Returns whether or not pre-releases as a whole are allowed by this
        specifier.
        """

    @prereleases.setter
    def prereleases(self, value):
        """
        Sets whether or not pre-releases as a whole are allowed by this
        specifier.
        """

    @abc.abstractmethod
    def contains(self, item, prereleases=None):
        """
        Determines if the given item is contained within this specifier.
        """

    @abc.abstractmethod
    def filter(self, iterable, prereleases=None):
        """
        Takes an iterable of items and filters them so that only items which
        are contained within this specifier are allowed in it.
        """


class _IndividualSpecifier(BaseSpecifier):

    _operators = {}

    def __init__(self, spec="", prereleases=None):
        match = self._regex.search(spec)
        if not match:
            raise InvalidSpecifier("Invalid specifier: '{0}'".format(spec))

        self._spec = (
            match.group("operator").strip(),
            match.group("version").strip(),
        )

        # Store whether or not this Specifier should accept prereleases
        self._prereleases = prereleases

    def __repr__(self):
        pre = (
            ", prereleases={0!r}".format(self.prereleases)
            if self._prereleases is not None
            else ""
        )

        return "<{0}({1!r}{2})>".format(
            self.__class__.__name__,
            str(self),
            pre,
        )

    def __str__(self):
        return "{0}{1}".format(*self._spec)

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

    def __eq__(self, other):
        if isinstance(other, string_types):
            try:
                other = self.__class__(other)
            except InvalidSpecifier:
                return NotImplemented
        elif not isinstance(other, self.__class__):
            return NotImplemented

        return self._spec == other._spec

    def __ne__(self, other):
        if isinstance(other, string_types):
            try:
                other = self.__class__(other)
            except InvalidSpecifier:
                return NotImplemented
        elif not isinstance(other, self.__class__):
            return NotImplemented

        return self._spec != other._spec

    def _get_operator(self, op):
        return getattr(self, "_compare_{0}".format(self._operators[op]))

    def _coerce_version(self, version):
        if not isinstance(version, (LegacyVersion, Version)):
            version = parse(version)
        return version

    @property
    def operator(self):
        return self._spec[0]

    @property
    def version(self):
        return self._spec[1]

    @property
    def prereleases(self):
        return self._prereleases

    @prereleases.setter
    def prereleases(self, value):
        self._prereleases = value

    def __contains__(self, item):
        return self.contains(item)

    def contains(self, item, prereleases=None):
        # Determine if prereleases are to be allowed or not.
        if prereleases is None:
            prereleases = self.prereleases

        # Normalize item to a Version or LegacyVersion, this allows us to have
        # a shortcut for ``"2.0" in Specifier(">=2")
        item = self._coerce_version(item)

        # Determine if we should be supporting prereleases in this specifier
        # or not, if we do not support prereleases than we can short circuit
        # logic if this version is a prereleases.
        if item.is_prerelease and not prereleases:
            return False

        # Actually do the comparison to determine if this item is contained
        # within this Specifier or not.
        return self._get_operator(self.operator)(item, self.version)

    def filter(self, iterable, prereleases=None):
        yielded = False
        found_prereleases = []

        kw = {"prereleases": prereleases if prereleases is not None else True}

        # Attempt to iterate over all the values in the iterable and if any of
        # them match, yield them.
        for version in iterable:
            parsed_version = self._coerce_version(version)

            if self.contains(parsed_version, **kw):
                # If our version is a prerelease, and we were not set to allow
                # prereleases, then we'll store it for later incase nothing
                # else matches this specifier.
                if (parsed_version.is_prerelease and not
                        (prereleases or self.prereleases)):
                    found_prereleases.append(version)
                # Either this is not a prerelease, or we should have been
                # accepting prereleases from the begining.
                else:
                    yielded = True
                    yield version

        # Now that we've iterated over everything, determine if we've yielded
        # any values, and if we have not and we have any prereleases stored up
        # then we will go ahead and yield the prereleases.
        if not yielded and found_prereleases:
            for version in found_prereleases:
                yield version


class LegacySpecifier(_IndividualSpecifier):

    _regex_str = (
        r"""
        (?P<operator>(==|!=|<=|>=|<|>))
        \s*
        (?P<version>
            [^,;\s)]* # Since this is a "legacy" specifier, and the version
                      # string can be just about anything, we match everything
                      # except for whitespace, a semi-colon for marker support,
                      # a closing paren since versions can be enclosed in
                      # them, and a comma since it's a version separator.
        )
        """
    )

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

    _operators = {
        "==": "equal",
        "!=": "not_equal",
        "<=": "less_than_equal",
        ">=": "greater_than_equal",
        "<": "less_than",
        ">": "greater_than",
    }

    def _coerce_version(self, version):
        if not isinstance(version, LegacyVersion):
            version = LegacyVersion(str(version))
        return version

    def _compare_equal(self, prospective, spec):
        return prospective == self._coerce_version(spec)

    def _compare_not_equal(self, prospective, spec):
        return prospective != self._coerce_version(spec)

    def _compare_less_than_equal(self, prospective, spec):
        return prospective <= self._coerce_version(spec)

    def _compare_greater_than_equal(self, prospective, spec):
        return prospective >= self._coerce_version(spec)

    def _compare_less_than(self, prospective, spec):
        return prospective < self._coerce_version(spec)

    def _compare_greater_than(self, prospective, spec):
        return prospective > self._coerce_version(spec)


def _require_version_compare(fn):
    @functools.wraps(fn)
    def wrapped(self, prospective, spec):
        if not isinstance(prospective, Version):
            return False
        return fn(self, prospective, spec)
    return wrapped


class Specifier(_IndividualSpecifier):

    _regex_str = (
        r"""
        (?P<operator>(~=|==|!=|<=|>=|<|>|===))
        (?P<version>
            (?:
                # The identity operators allow for an escape hatch that will
                # do an exact string match of the version you wish to install.
                # This will not be parsed by PEP 440 and we cannot determine
                # any semantic meaning from it. This operator is discouraged
                # but included entirely as an escape hatch.
                (?<====)  # Only match for the identity operator
                \s*
                [^\s]*    # We just match everything, except for whitespace
                          # since we are only testing for strict identity.
            )
            |
            (?:
                # The (non)equality operators allow for wild card and local
                # versions to be specified so we have to define these two
                # operators separately to enable that.
                (?<===|!=)            # Only match for equals and not equals

                \s*
                v?
                (?:[0-9]+!)?          # epoch
                [0-9]+(?:\.[0-9]+)*   # release
                (?:                   # pre release
                    [-_\.]?
                    (a|b|c|rc|alpha|beta|pre|preview)
                    [-_\.]?
                    [0-9]*
                )?
                (?:                   # post release
                    (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)
                )?

                # You cannot use a wild card and a dev or local version
                # together so group them with a | and make them optional.
                (?:
                    (?:[-_\.]?dev[-_\.]?[0-9]*)?         # dev release
                    (?:\+[a-z0-9]+(?:[-_\.][a-z0-9]+)*)? # local
                    |
                    \.\*  # Wild card syntax of .*
                )?
            )
            |
            (?:
                # The compatible operator requires at least two digits in the
                # release segment.
                (?<=~=)               # Only match for the compatible operator

                \s*
                v?
                (?:[0-9]+!)?          # epoch
                [0-9]+(?:\.[0-9]+)+   # release  (We have a + instead of a *)
                (?:                   # pre release
                    [-_\.]?
                    (a|b|c|rc|alpha|beta|pre|preview)
                    [-_\.]?
                    [0-9]*
                )?
                (?:                                   # post release
                    (?:-[0-9]+)|(?:[-_\.]?(post|rev|r)[-_\.]?[0-9]*)
                )?
                (?:[-_\.]?dev[-_\.]?[0-9]*)?          # dev release
            )
            |
            (?:
                # All other operators only allow a sub set of what the