"""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(
"([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