"""Module for parsing and testing package version predicate strings.

"""

import re

import distutils.version

import operator

re_validPackage = re.compile(r"(?i)^\s*([a-z_]\w*(?:\.[a-z_]\w*)*)(.*)")

# (package) (rest)

re_paren = re.compile(r"^\s*\((.*)\)\s*$") # (list) inside of parentheses

re_splitComparison = re.compile(r"^\s*(<=|>=|<|>|!=|==)\s*([^\s,]+)\s*$")

# (comp) (version)

def splitUp(pred):

    """Parse a single version comparison.

    Return (comparison string, StrictVersion)

    """

    res = re_splitComparison.match(pred)

    if not res:

        raise ValueError("bad package restriction syntax: %r" % pred)

    comp, verStr = res.groups()

    return (comp, distutils.version.StrictVersion(verStr))

compmap = {"<": operator.lt, "<=": operator.le, "==": operator.eq,

           ">": operator.gt, ">=": operator.ge, "!=": operator.ne}

class VersionPredicate:

    """Parse and test package version predicates.

    >>> v = VersionPredicate('pyepat.abc (>1.0, <3333.3a1, !=1555.1b3)')

    The `name` attribute provides the full dotted name that is given::

    >>> v.name

    'pyepat.abc'

    The str() of a `VersionPredicate` provides a normalized

    human-readable version of the expression::

    >>> print v

    pyepat.abc (> 1.0, < 3333.3a1, != 1555.1b3)

    The `satisfied_by()` method can be used to determine with a given

    version number is included in the set described by the version

    restrictions::

    >>> v.satisfied_by('1.1')

    True

    >>> v.satisfied_by('1.4')

    True

    >>> v.satisfied_by('1.0')

    False

    >>> v.satisfied_by('4444.4')

    False

    >>> v.satisfied_by('1555.1b3')

    False

    `VersionPredicate` is flexible in accepting extra whitespace::

    >>> v = VersionPredicate(' pat( ==  0.1  )  ')

    >>> v.name

    'pat'

    >>> v.satisfied_by('0.1')

    True

    >>> v.satisfied_by('0.2')

    False

    If any version numbers passed in do not conform to the

    restrictions of `StrictVersion`, a `ValueError` is raised::

    >>> v = VersionPredicate('p1.p2.p3.p4(>=1.0, <=1.3a1, !=1.2zb3)')

    Traceback (most recent call last):

      ...

    ValueError: invalid version number '1.2zb3'

    It the module or package name given does not conform to what's

    allowed as a legal module or package name, `ValueError` is

    raised::

    >>> v = VersionPredicate('foo-bar')

    Traceback (most recent call last):

      ...

    ValueError: expected parenthesized list: '-bar'

    >>> v = VersionPredicate('foo bar (12.21)')

    Traceback (most recent call last):

      ...

    ValueError: expected parenthesized list: 'bar (12.21)'

    """

    def __init__(self, versionPredicateStr):

        """Parse a version predicate string.

        """

        # Fields:

        #    name:  package name

        #    pred:  list of (comparison string, StrictVersion)

        versionPredicateStr = versionPredicateStr.strip()

        if not versionPredicateStr:

            raise ValueError("empty package restriction")

        match = re_validPackage.match(versionPredicateStr)

        if not match:

            raise ValueError("bad package name in %r" % versionPredicateStr)

        self.name, paren = match.groups()

        paren = paren.strip()

        if paren:

            match = re_paren.match(paren)

            if not match:

                raise ValueError("expected parenthesized list: %r" % paren)

            str = match.groups()[0]

            self.pred = [splitUp(aPred) for aPred in str.split(",")]

            if not self.pred:

                raise ValueError("empty parenthesized list in %r"

                                 % versionPredicateStr)

        else:

            self.pred = []

    def __str__(self):

        if self.pred:

            seq = [cond + " " + str(ver) for cond, ver in self.pred]

            return self.name + " (" + ", ".join(seq) + ")"

        else:

            return self.name

    def satisfied_by(self, version):

        """True if version is compatible with all the predicates in self.

        The parameter version must be acceptable to the StrictVersion

        constructor.  It may be either a string or StrictVersion.

        """

        for cond, ver in self.pred:

            if not compmap[cond](version, ver):

                return False

        return True

_provision_rx = None

def split_provision(value):

    """Return the name and optional version number of a provision.

    The version number, if given, will be returned as a `StrictVersion`

    instance, otherwise it will be `None`.

    >>> split_provision('mypkg')

    ('mypkg', None)

    >>> split_provision(' mypkg( 1.2 ) ')

    ('mypkg', StrictVersion ('1.2'))

    """

    global _provision_rx

    if _provision_rx is None:

        _provision_rx = re.compile(

            "([a-zA-Z_]\w*(?:\.[a-zA-Z_]\w*)*)(?:\s*\(\s*([^)\s]+)\s*\))?$")

    value = value.strip()

    m = _provision_rx.match(value)

    if not m:

        raise ValueError("illegal provides specification: %r" % value)

    ver = m.group(2) or None

    if ver:

        ver = distutils.version.StrictVersion(ver)

    return m.group(1), ver