# (c) 2017,  Red Hat, inc
#
# 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 hashlib
import os
import re
import string

from ansible.errors import AnsibleError, AnsibleOptionsError
from ansible.module_utils._text import to_bytes, to_native
from ansible.module_utils.parsing.convert_bool import boolean
from ansible.module_utils.six import string_types
from ansible.template import Templar

try:
    from __main__ import display
except ImportError:
    from ansible.utils.display import Display
    display = Display()

_SAFE_GROUP = re.compile("[^A-Za-z0-9\_]")


class BaseInventoryPlugin(object):
    """ Parses an Inventory Source"""

    TYPE = 'generator'

    def __init__(self, cache=None):

        self.inventory = None
        self.display = display
        self.cache = cache

    def parse(self, inventory, loader, path, cache=True):
        ''' Populates self.groups from the given data. Raises an error on any parse failure.  '''

        self.loader = loader
        self.inventory = inventory
        self.templar = Templar(loader=loader)

    def verify_file(self, path):
        ''' Verify if file is usable by this plugin, base does minimal accessability check '''

        b_path = to_bytes(path, errors='surrogate_or_strict')
        return (os.path.exists(b_path) and os.access(b_path, os.R_OK))

    def get_cache_prefix(self, path):
        ''' create predictable unique prefix for plugin/inventory '''

        m = hashlib.sha1()
        m.update(to_bytes(self.NAME, errors='surrogate_or_strict'))
        d1 = m.hexdigest()

        n = hashlib.sha1()
        n.update(to_bytes(path, errors='surrogate_or_strict'))
        d2 = n.hexdigest()

        return 's_'.join([d1[:5], d2[:5]])

    def clear_cache(self):
        pass

    def populate_host_vars(self, hosts, variables, group=None, port=None):
        for host in hosts:
            self.inventory.add_host(host, group=group, port=port)
            for k in variables:
                self.inventory.set_variable(host, k, variables[k])

    def _compose(self, template, variables):
        ''' helper method for pluigns to compose variables for Ansible based on jinja2 expression and inventory vars'''
        t = self.templar
        t.set_available_variables(variables)
        return t.do_template('%s%s%s' % (t.environment.variable_start_string, template, t.environment.variable_end_string), disable_lookups=True)

    def _set_composite_vars(self, compose, variables, host, strict=False):
        ''' loops over compose entries to create vars for hosts '''
        if compose and isinstance(compose, dict):
            for varname in compose:
                try:
                    composite = self._compose(compose[varname], variables)
                except Exception as e:
                    if strict:
                        raise AnsibleOptionsError("Could set %s: %s" % (varname, to_native(e)))
                    continue
                self.inventory.set_variable(host, varname, composite)

    def _add_host_to_composed_groups(self, groups, variables, host, strict=False):
        ''' helper to create complex groups for plugins based on jinaj2 conditionals, hosts that meet the conditional are added to group'''
        # process each 'group entry'
        if groups and isinstance(groups, dict):
            self.templar.set_available_variables(variables)
            for group_name in groups:
                conditional = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % groups[group_name]
                try:
                    result = boolean(self.templar.template(conditional))
                except Exception as e:
                    if strict:
                        raise AnsibleOptionsError("Could not add to group %s: %s" % (group_name, to_native(e)))
                    continue
                if result:
                    # ensure group exists
                    self.inventory.add_group(group_name)
                    # add host to group
                    self.inventory.add_child(group_name, host)

    def _add_host_to_keyed_groups(self, keys, variables, host, strict=False):
        ''' helper to create groups for plugins based on variable values and add the corresponding hosts to it'''
        if keys and isinstance(keys, list):
            for keyed in keys:
                if keyed and isinstance(keyed, dict):
                    prefix = keyed.get('prefix', '')
                    key = keyed.get('key')
                    if key is not None:
                        try:
                            groups = to_safe_group_name('%s_%s' % (prefix, self._compose(key, variables)))
                        except Exception as e:
                            if strict:
                                raise AnsibleOptionsError("Could not generate group on %s: %s" % (key, to_native(e)))
                            continue
                        if isinstance(groups, string_types):
                            groups = [groups]
                        for group_name in groups:
                            if group_name not in self.inventory.groups:
                                self.inventory.add_group(group_name)
                                self.inventory.add_child(group_name, host)
                    else:
                        raise AnsibleOptionsError("No key supplied, invalid entry")
                else:
                    raise AnsibleOptionsError("Invalid keyed group entry, it must be a dictionary: %s " % keyed)


class BaseFileInventoryPlugin(BaseInventoryPlugin):
    """ Parses a File based Inventory Source"""

    TYPE = 'storage'

    def __init__(self, cache=None):

        # file based inventories are always local so no need for cache
        super(BaseFileInventoryPlugin, self).__init__(cache=None)


# Helper methods
def to_safe_group_name(name):
    ''' Converts 'bad' characters in a string to underscores so they can be used as Ansible hosts or groups '''
    return _SAFE_GROUP.sub("_", name)


def detect_range(line=None):
    '''
    A helper function that checks a given host line to see if it contains
    a range pattern described in the docstring above.

    Returns True if the given line contains a pattern, else False.
    '''
    return '[' in line


def expand_hostname_range(line=None):
    '''
    A helper function that expands a given line that contains a pattern
    specified in top docstring, and returns a list that consists of the
    expanded version.

    The '[' and ']' characters are used to maintain the pseudo-code
    appearance. They are replaced in this function with '|' to ease
    string splitting.

    References: http://ansible.github.com/patterns.html#hosts-and-groups
    '''
    all_hosts = []
    if line:
        # A hostname such as db[1:6]-node is considered to consists
        # three parts:
        # head: 'db'
        # nrange: [1:6]; range() is a built-in. Can't use the name
        # tail: '-node'

        # Add support for multiple ranges in a host so:
        # db[01:10:3]node-[01:10]
        # - to do this we split off at the first [...] set, getting the list
        #   of hosts and then repeat until none left.
        # - also add an optional third parameter which contains the step. (Default: 1)
        #   so range can be [01:10:2] -> 01 03 05 07 09

        (head, nrange, tail) = line.replace('[', '|', 1).replace(']', '|', 1).split('|')
        bounds = nrange.split(":")
        if len(bounds) != 2 and len(bounds) != 3:
            raise AnsibleError("host range must be begin:end or begin:end:step")
        beg = bounds[0]
        end = bounds[1]
        if len(bounds) == 2:
            step = 1
        else:
            step = bounds[2]
        if not beg:
            beg = "0"
        if not end:
            raise AnsibleError("host range must specify end value")
        if beg[0] == '0' and len(beg) > 1:
            rlen = len(beg)  # range length formatting hint
            if rlen != len(end):
                raise AnsibleError("host range must specify equal-length begin and end formats")

            def fill(x):
                return str(x).zfill(rlen)  # range sequence

        else:
            fill = str

        try:
            i_beg = string.ascii_letters.index(beg)
            i_end = string.ascii_letters.index(end)
            if i_beg > i_end:
                raise AnsibleError("host range must have begin <= end")
            seq = list(string.ascii_letters[i_beg:i_end + 1:int(step)])
        except ValueError:  # not an alpha range
            seq = range(int(beg), int(end) + 1, int(step))

        for rseq in seq:
            hname = ''.join((head, fill(rseq), tail))

            if detect_range(hname):
                all_hosts.extend(expand_hostname_range(hname))
            else:
                all_hosts.append(hname)

        return all_hosts