#!/usr/bin/env python3
#
# Copyright 2016 Canonical Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#  http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import json
import os
import re
from collections import OrderedDict
from subprocess import check_output, CalledProcessError
import sys


_path = os.path.dirname(os.path.realpath(__file__))
_root = os.path.abspath(os.path.join(_path, '..'))
_hooks = os.path.abspath(os.path.join(_path, '../hooks'))


def _add_path(path):
    if path not in sys.path:
        sys.path.insert(1, path)

_add_path(_root)
_add_path(_hooks)

from charmhelpers.core.hookenv import (
    action_fail,
    action_set,
    action_get,
    is_leader,
    leader_set,
)

from hooks.rabbit_utils import (
    ConfigRenderer,
    CONFIG_FILES,
    pause_unit_helper,
    resume_unit_helper,
    assess_status,
    list_vhosts,
    vhost_queue_info,
)


def pause(args):
    """Pause the RabbitMQ services.
    @raises Exception should the service fail to stop.
    """
    pause_unit_helper(ConfigRenderer(CONFIG_FILES))


def resume(args):
    """Resume the RabbitMQ services.
    @raises Exception should the service fail to start."""
    resume_unit_helper(ConfigRenderer(CONFIG_FILES))


def cluster_status(args):
    """Return the output of 'rabbitmqctl cluster_status'."""
    try:
        clusterstat = check_output(['rabbitmqctl', 'cluster_status'],
                                   universal_newlines=True)
        action_set({'output': clusterstat})
    except CalledProcessError as e:
        action_set({'output': e.output})
        action_fail('Failed to run rabbitmqctl cluster_status')
    except Exception:
        raise


def check_queues(args):
    """Check for queues with greater than N messages.
    Return those queues to the user."""
    queue_depth = (action_get('queue-depth'))
    vhost = (action_get('vhost'))
    result = []
    # rabbitmqctl's output contains lines we don't want, such as
    # 'Listing queues ..' and '...done.', which may vary by release.
    # Actual queue results *should* always look like 'test\t0'
    queue_pattern = re.compile('.*\t[0-9]*')
    try:
        queues = check_output(['rabbitmqctl', 'list_queues',
                               '-p', vhost]).decode('utf-8').split('\n')
        result = list({queue: size for (queue, size) in
                       [i.split('\t') for i in queues
                        if re.search(queue_pattern, i)]
                       if int(size) >= queue_depth})

        action_set({'output': result, 'outcome': 'Success'})
    except CalledProcessError as e:
        action_set({'output': e.output})
        action_fail('Failed to run rabbitmqctl list_queues')


def complete_cluster_series_upgrade(args):
    """ Complete the series upgrade process

    After all nodes have been upgraded, this action is run to inform the whole
    cluster the upgrade is done. Config files will be re-rendered with each
    peer in the wsrep_cluster_address config.
    """
    if is_leader():
        # Unset cluster_series_upgrading
        leader_set(cluster_series_upgrading="")
    assess_status(ConfigRenderer(CONFIG_FILES))


def list_unconsumed_queues(args):
    """List queues which are unconsumed in RabbitMQ"""
    count = 0
    for vhost in list_vhosts():
        try:
            queue_info_dict = vhost_queue_info(vhost)
        except CalledProcessError as e:
            # if no queues, just raises an exception
            action_set({'output': e.output,
                        'return-code': e.returncode})
            action_fail("Failed to query RabbitMQ vhost {} queues"
                        "".format(vhost))
            return False

        for queue in queue_info_dict:
            if queue['consumers'] == 0:
                vhostqueue = "unconsumed-queues.{}".format(count)
                value = OrderedDict((
                    ('vhost', vhost),
                    ('name', queue['name']),
                    ('messages', queue['messages']),
                ))
                action_set({vhostqueue: json.dumps(value)})
                count += 1

    action_set({'unconsumed-queue-count': count})


# A dictionary of all the defined actions to callables (which take
# parsed arguments).
ACTIONS = {
    "pause": pause,
    "resume": resume,
    "cluster-status": cluster_status,
    "check-queues": check_queues,
    "complete-cluster-series-upgrade": complete_cluster_series_upgrade,
    "list-unconsumed-queues": list_unconsumed_queues,
}


def main(args):
    action_name = os.path.basename(args[0])
    try:
        action = ACTIONS[action_name]
    except KeyError:
        s = "Action {} undefined".format(action_name)
        action_fail(s)
        return s
    else:
        try:
            action(args)
        except Exception as e:
            action_fail("Action {} failed: {}".format(action_name, str(e)))


if __name__ == "__main__":
    sys.exit(main(sys.argv))