import re
import string
from conda_build import exceptions
from conda_build.utils import comma_join

allowed_license_families = """
AGPL
LGPL
GPL3
GPL2
GPL
BSD
MIT
APACHE
PSF
CC
MOZILLA
PUBLIC-DOMAIN
PROPRIETARY
OTHER
NONE
""".split()

# regular expressions
gpl2_regex = re.compile('GPL[^3]*2')  # match GPL2
gpl3_regex = re.compile('GPL[^2]*3')  # match GPL3
gpl23_regex = re.compile('GPL[^2]*>= *2')  # match GPL >= 2
cc_regex = re.compile(r'CC\w+')  # match CC
punk_regex = re.compile('[%s]' % re.escape(string.punctuation))  # removes punks


def match_gpl3(family):
    """True if family matches GPL3 or GPL >= 2, else False"""
    return (gpl23_regex.search(family) or
            gpl3_regex.search(family))


def normalize(s):
    """Set to ALL CAPS, replace common GPL patterns, and strip"""
    s = s.upper()
    s = re.sub('GENERAL PUBLIC LICENSE', 'GPL', s)
    s = re.sub('LESSER *', 'L', s)
    s = re.sub('AFFERO *', 'A', s)
    return s.strip()


def remove_special_characters(s):
    """Remove punctuation, spaces, tabs, and line feeds"""
    s = punk_regex.sub(' ', s)
    s = re.sub(r'\s+', '', s)
    return s


def guess_license_family_from_index(index=None,
                                    recognized=allowed_license_families):
    """Return best guess of license_family from the conda package index.

    Note: Logic here is simple, and focuses on existing set of allowed families
    """

    if isinstance(index, dict):
        license_name = index.get('license_family', index.get('license'))
    else:  # index argument is actually a string
        license_name = index

    return guess_license_family(license_name, recognized)


def guess_license_family(license_name=None,
                         recognized=allowed_license_families):
    """Return best guess of license_family from the conda package index.

    Note: Logic here is simple, and focuses on existing set of allowed families
    """

    if license_name is None:
        return 'NONE'

    license_name = normalize(license_name)

    # Handle GPL families as special cases
    # Remove AGPL and LGPL before looking for GPL2 and GPL3
    sans_lgpl = re.sub('[A,L]GPL', '', license_name)
    if match_gpl3(sans_lgpl):
        return 'GPL3'
    elif gpl2_regex.search(sans_lgpl):
        return 'GPL2'
    elif cc_regex.search(license_name):
        return 'CC'

    license_name = remove_special_characters(license_name)
    for family in recognized:
        if remove_special_characters(family) in license_name:
            return family
    for family in recognized:
        if license_name in remove_special_characters(family):
            return family
    return 'OTHER'


def ensure_valid_license_family(meta):
    try:
        license_family = meta['about']['license_family']
    except KeyError:
        return
    allowed_families = [remove_special_characters(normalize(fam))
                                for fam in allowed_license_families]
    if remove_special_characters(normalize(license_family)) not in allowed_families:
        raise RuntimeError(exceptions.indent(
            "about/license_family '%s' not allowed. Allowed families are %s." %
            (license_family, comma_join(sorted(allowed_license_families)))))