# This code is part of Ansible, but is an independent component.
# This particular file snippet, and this file snippet only, is BSD licensed.
# Modules you write using this snippet, which is embedded dynamically by Ansible
# still belong to the author of the module, and may assign their own license
# to the complete work.
#
# Copyright (c), James Laska
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
#
#    * Redistributions of source code must retain the above copyright
#      notice, this list of conditions and the following disclaimer.
#    * Redistributions in binary form must reproduce the above copyright notice,
#      this list of conditions and the following disclaimer in the documentation
#      and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import os
import re
import types
import ConfigParser
import shlex


class RegistrationBase(object):
    def __init__(self, module, username=None, password=None):
        self.module = module
        self.username = username
        self.password = password

    def configure(self):
        raise NotImplementedError("Must be implemented by a sub-class")

    def enable(self):
        # Remove any existing redhat.repo
        redhat_repo = '/etc/yum.repos.d/redhat.repo'
        if os.path.isfile(redhat_repo):
            os.unlink(redhat_repo)

    def register(self):
        raise NotImplementedError("Must be implemented by a sub-class")

    def unregister(self):
        raise NotImplementedError("Must be implemented by a sub-class")

    def unsubscribe(self):
        raise NotImplementedError("Must be implemented by a sub-class")

    def update_plugin_conf(self, plugin, enabled=True):
        plugin_conf = '/etc/yum/pluginconf.d/%s.conf' % plugin
        if os.path.isfile(plugin_conf):
            cfg = ConfigParser.ConfigParser()
            cfg.read([plugin_conf])
            if enabled:
                cfg.set('main', 'enabled', 1)
            else:
                cfg.set('main', 'enabled', 0)
            fd = open(plugin_conf, 'rwa+')
            cfg.write(fd)
            fd.close()

    def subscribe(self, **kwargs):
        raise NotImplementedError("Must be implemented by a sub-class")


class Rhsm(RegistrationBase):
    def __init__(self, module, username=None, password=None):
        RegistrationBase.__init__(self, module, username, password)
        self.config = self._read_config()
        self.module = module

    def _read_config(self, rhsm_conf='/etc/rhsm/rhsm.conf'):
        '''
            Load RHSM configuration from /etc/rhsm/rhsm.conf.
            Returns:
             * ConfigParser object
        '''

        # Read RHSM defaults ...
        cp = ConfigParser.ConfigParser()
        cp.read(rhsm_conf)

        # Add support for specifying a default value w/o having to standup some configuration
        # Yeah, I know this should be subclassed ... but, oh well
        def get_option_default(self, key, default=''):
            sect, opt = key.split('.', 1)
            if self.has_section(sect) and self.has_option(sect, opt):
                return self.get(sect, opt)
            else:
                return default

        cp.get_option = types.MethodType(get_option_default, cp, ConfigParser.ConfigParser)

        return cp

    def enable(self):
        '''
            Enable the system to receive updates from subscription-manager.
            This involves updating affected yum plugins and removing any
            conflicting yum repositories.
        '''
        RegistrationBase.enable(self)
        self.update_plugin_conf('rhnplugin', False)
        self.update_plugin_conf('subscription-manager', True)

    def configure(self, **kwargs):
        '''
            Configure the system as directed for registration with RHN
            Raises:
              * Exception - if error occurs while running command
        '''
        args = ['subscription-manager', 'config']

        # Pass supplied **kwargs as parameters to subscription-manager.  Ignore
        # non-configuration parameters and replace '_' with '.'.  For example,
        # 'server_hostname' becomes '--system.hostname'.
        for k,v in kwargs.items():
            if re.search(r'^(system|rhsm)_', k):
                args.append('--%s=%s' % (k.replace('_','.'), v))
        
        self.module.run_command(args, check_rc=True)

    @property
    def is_registered(self):
        '''
            Determine whether the current system
            Returns:
              * Boolean - whether the current system is currently registered to
                          RHN.
        '''
        # Quick version...
        if False:
            return os.path.isfile('/etc/pki/consumer/cert.pem') and \
                   os.path.isfile('/etc/pki/consumer/key.pem')

        args = ['subscription-manager', 'identity']
        rc, stdout, stderr = self.module.run_command(args, check_rc=False)
        if rc == 0:
            return True
        else:
            return False

    def register(self, username, password, autosubscribe, activationkey):
        '''
            Register the current system to the provided RHN server
            Raises:
              * Exception - if error occurs while running command
        '''
        args = ['subscription-manager', 'register']

        # Generate command arguments
        if activationkey:
            args.append('--activationkey "%s"' % activationkey)
        else:
            if autosubscribe:
                args.append('--autosubscribe')
            if username:
                args.extend(['--username', username])
            if password:
                args.extend(['--password', password])

        # Do the needful...
        rc, stderr, stdout = self.module.run_command(args, check_rc=True)

    def unsubscribe(self):
        '''
            Unsubscribe a system from all subscribed channels
            Raises:
              * Exception - if error occurs while running command
        '''
        args = ['subscription-manager', 'unsubscribe', '--all']
        rc, stderr, stdout = self.module.run_command(args, check_rc=True)

    def unregister(self):
        '''
            Unregister a currently registered system
            Raises:
              * Exception - if error occurs while running command
        '''
        args = ['subscription-manager', 'unregister']
        rc, stderr, stdout = self.module.run_command(args, check_rc=True)

    def subscribe(self, regexp):
        '''
            Subscribe current system to available pools matching the specified
            regular expression
            Raises:
              * Exception - if error occurs while running command
        '''

        # Available pools ready for subscription
        available_pools = RhsmPools(self.module)

        for pool in available_pools.filter(regexp):
            pool.subscribe()


class RhsmPool(object):
    '''
        Convenience class for housing subscription information
    '''

    def __init__(self, module, **kwargs):
        self.module = module
        for k,v in kwargs.items():
            setattr(self, k, v)

    def __str__(self):
        return str(self.__getattribute__('_name'))

    def subscribe(self):
        args = "subscription-manager subscribe --pool %s" % self.PoolId
        rc, stdout, stderr = self.module.run_command(args, check_rc=True)
        if rc == 0:
            return True
        else:
            return False


class RhsmPools(object):
    """
        This class is used for manipulating pools subscriptions with RHSM
    """
    def __init__(self, module):
        self.module = module
        self.products = self._load_product_list()

    def __iter__(self):
        return self.products.__iter__()

    def _load_product_list(self):
        """
            Loads list of all available pools for system in data structure
        """
        args = "subscription-manager list --available"
        rc, stdout, stderr = self.module.run_command(args, check_rc=True)

        products = []
        for line in stdout.split('\n'):
            # Remove leading+trailing whitespace
            line = line.strip()
            # An empty line implies the end of an output group
            if len(line) == 0:
                continue
            # If a colon ':' is found, parse
            elif ':' in line:
                (key, value) = line.split(':',1)
                key = key.strip().replace(" ", "")  # To unify
                value = value.strip()
                if key in ['ProductName', 'SubscriptionName']:
                    # Remember the name for later processing
                    products.append(RhsmPool(self.module, _name=value, key=value))
                elif products:
                    # Associate value with most recently recorded product
                    products[-1].__setattr__(key, value)
                # FIXME - log some warning?
                #else:
                    # warnings.warn("Unhandled subscription key/value: %s/%s" % (key,value))
        return products

    def filter(self, regexp='^$'):
        '''
            Return a list of RhsmPools whose name matches the provided regular expression
        '''
        r = re.compile(regexp)
        for product in self.products:
            if r.search(product._name):
                yield product

