"""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*)*)(.*)",
 re.ASCII)
# (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(
 r"([a-zA-Z_]\w*(?:\.[a-zA-Z_]\w*)*)(?:\s*\(\s*([^)\s]+)\s*\))?$",
 re.ASCII)
 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