# (c) 2014, Brian Coca <bcoca@ansible.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

# Make coding more python3-ish
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type


import collections
import itertools
import math

from ansible import errors
from ansible.module_utils import basic


def unique(a):
    if isinstance(a, collections.Hashable):
        c = set(a)
    else:
        c = []
        for x in a:
            if x not in c:
                c.append(x)
    return c


def intersect(a, b):
    if isinstance(a, collections.Hashable) and isinstance(b, collections.Hashable):
        c = set(a) & set(b)
    else:
        c = unique(filter(lambda x: x in b, a))
    return c


def difference(a, b):
    if isinstance(a, collections.Hashable) and isinstance(b, collections.Hashable):
        c = set(a) - set(b)
    else:
        c = unique(filter(lambda x: x not in b, a))
    return c


def symmetric_difference(a, b):
    if isinstance(a, collections.Hashable) and isinstance(b, collections.Hashable):
        c = set(a) ^ set(b)
    else:
        c = unique(filter(lambda x: x not in intersect(a, b), union(a, b)))
    return c


def union(a, b):
    if isinstance(a, collections.Hashable) and isinstance(b, collections.Hashable):
        c = set(a) | set(b)
    else:
        c = unique(a + b)
    return c


def min(a):
    _min = __builtins__.get('min')
    return _min(a)


def max(a):
    _max = __builtins__.get('max')
    return _max(a)


def logarithm(x, base=math.e):
    try:
        if base == 10:
            return math.log10(x)
        else:
            return math.log(x, base)
    except TypeError as e:
        raise errors.AnsibleFilterError('log() can only be used on numbers: %s' % str(e))


def power(x, y):
    try:
        return math.pow(x, y)
    except TypeError as e:
        raise errors.AnsibleFilterError('pow() can only be used on numbers: %s' % str(e))


def inversepower(x, base=2):
    try:
        if base == 2:
            return math.sqrt(x)
        else:
            return math.pow(x, 1.0 / float(base))
    except TypeError as e:
        raise errors.AnsibleFilterError('root() can only be used on numbers: %s' % str(e))


def human_readable(size, isbits=False, unit=None):
    ''' Return a human readable string '''
    try:
        return basic.bytes_to_human(size, isbits, unit)
    except:
        raise errors.AnsibleFilterError("human_readable() can't interpret following string: %s" % size)


def human_to_bytes(size, default_unit=None, isbits=False):
    ''' Return bytes count from a human readable string '''
    try:
        return basic.human_to_bytes(size, default_unit, isbits)
    except:
        raise errors.AnsibleFilterError("human_to_bytes() can't interpret following string: %s" % size)


class FilterModule(object):
    ''' Ansible math jinja2 filters '''

    def filters(self):
        filters = {
            # general math
            'min': min,
            'max': max,

            # exponents and logarithms
            'log': logarithm,
            'pow': power,
            'root': inversepower,

            # set theory
            'unique': unique,
            'intersect': intersect,
            'difference': difference,
            'symmetric_difference': symmetric_difference,
            'union': union,

            # combinatorial
            'permutations': itertools.permutations,
            'combinations': itertools.combinations,

            # computer theory
            'human_readable': human_readable,
            'human_to_bytes': human_to_bytes,

        }

        # py2 vs py3, reverse when py3 is predominant version
        try:
            filters['zip'] = itertools.izip
            filters['zip_longest'] = itertools.izip_longest
        except AttributeError:
            try:
                filters['zip'] = itertools.zip
                filters['zip_longest'] = itertools.zip_longest
            except:
                pass

        return filters
