# Copyright 2014-2015 Canonical Limited.
#
# This file is part of charm-helpers.
#
# charm-helpers is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3 as
# published by the Free Software Foundation.
#
# charm-helpers 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.

#
# Copyright 2012 Canonical Ltd.
#
# This file is sourced from lp:openstack-charm-helpers
#
# Authors:
#  James Page <james.page@ubuntu.com>
#  Adam Gandelman <adamg@ubuntu.com>
#

import os
import shutil
import json
import time

from subprocess import (
    check_call,
    check_output,
    CalledProcessError,
)
from charmhelpers.core.hookenv import (
    relation_get,
    relation_ids,
    related_units,
    log,
    DEBUG,
    INFO,
    WARNING,
    ERROR,
)
from charmhelpers.core.host import (
    mount,
    mounts,
    service_start,
    service_stop,
    service_running,
    umount,
)
from charmhelpers.fetch import (
    apt_install,
)

KEYRING = '/etc/ceph/ceph.client.{}.keyring'
KEYFILE = '/etc/ceph/ceph.client.{}.key'

CEPH_CONF = """[global]
auth supported = {auth}
keyring = {keyring}
mon host = {mon_hosts}
log to syslog = {use_syslog}
err to syslog = {use_syslog}
clog to syslog = {use_syslog}
"""


def install():
    """Basic Ceph client installation."""
    ceph_dir = "/etc/ceph"
    if not os.path.exists(ceph_dir):
        os.mkdir(ceph_dir)

    apt_install('ceph-common', fatal=True)


def rbd_exists(service, pool, rbd_img):
    """Check to see if a RADOS block device exists."""
    try:
        out = check_output(['rbd', 'list', '--id',
                            service, '--pool', pool]).decode('UTF-8')
    except CalledProcessError:
        return False

    return rbd_img in out


def create_rbd_image(service, pool, image, sizemb):
    """Create a new RADOS block device."""
    cmd = ['rbd', 'create', image, '--size', str(sizemb), '--id', service,
           '--pool', pool]
    check_call(cmd)


def pool_exists(service, name):
    """Check to see if a RADOS pool already exists."""
    try:
        out = check_output(['rados', '--id', service,
                            'lspools']).decode('UTF-8')
    except CalledProcessError:
        return False

    return name in out


def get_osds(service):
    """Return a list of all Ceph Object Storage Daemons currently in the
    cluster.
    """
    version = ceph_version()
    if version and version >= '0.56':
        return json.loads(check_output(['ceph', '--id', service,
                                        'osd', 'ls',
                                        '--format=json']).decode('UTF-8'))

    return None


def create_pool(service, name, replicas=3):
    """Create a new RADOS pool."""
    if pool_exists(service, name):
        log("Ceph pool {} already exists, skipping creation".format(name),
            level=WARNING)
        return

    # Calculate the number of placement groups based
    # on upstream recommended best practices.
    osds = get_osds(service)
    if osds:
        pgnum = (len(osds) * 100 // replicas)
    else:
        # NOTE(james-page): Default to 200 for older ceph versions
        # which don't support OSD query from cli
        pgnum = 200

    cmd = ['ceph', '--id', service, 'osd', 'pool', 'create', name, str(pgnum)]
    check_call(cmd)

    cmd = ['ceph', '--id', service, 'osd', 'pool', 'set', name, 'size',
           str(replicas)]
    check_call(cmd)


def delete_pool(service, name):
    """Delete a RADOS pool from ceph."""
    cmd = ['ceph', '--id', service, 'osd', 'pool', 'delete', name,
           '--yes-i-really-really-mean-it']
    check_call(cmd)


def _keyfile_path(service):
    return KEYFILE.format(service)


def _keyring_path(service):
    return KEYRING.format(service)


def create_keyring(service, key):
    """Create a new Ceph keyring containing key."""
    keyring = _keyring_path(service)
    if os.path.exists(keyring):
        log('Ceph keyring exists at %s.' % keyring, level=WARNING)
        return

    cmd = ['ceph-authtool', keyring, '--create-keyring',
           '--name=client.{}'.format(service), '--add-key={}'.format(key)]
    check_call(cmd)
    log('Created new ceph keyring at %s.' % keyring, level=DEBUG)


def delete_keyring(service):
    """Delete an existing Ceph keyring."""
    keyring = _keyring_path(service)
    if not os.path.exists(keyring):
        log('Keyring does not exist at %s' % keyring, level=WARNING)
        return

    os.remove(keyring)
    log('Deleted ring at %s.' % keyring, level=INFO)


def create_key_file(service, key):
    """Create a file containing key."""
    keyfile = _keyfile_path(service)
    if os.path.exists(keyfile):
        log('Keyfile exists at %s.' % keyfile, level=WARNING)
        return

    with open(keyfile, 'w') as fd:
        fd.write(key)

    log('Created new keyfile at %s.' % keyfile, level=INFO)


def get_ceph_nodes():
    """Query named relation 'ceph' to determine current nodes."""
    hosts = []
    for r_id in relation_ids('ceph'):
        for unit in related_units(r_id):
            hosts.append(relation_get('private-address', unit=unit, rid=r_id))

    return hosts


def configure(service, key, auth, use_syslog):
    """Perform basic configuration of Ceph."""
    create_keyring(service, key)
    create_key_file(service, key)
    hosts = get_ceph_nodes()
    with open('/etc/ceph/ceph.conf', 'w') as ceph_conf:
        ceph_conf.write(CEPH_CONF.format(auth=auth,
                                         keyring=_keyring_path(service),
                                         mon_hosts=",".join(map(str, hosts)),
                                         use_syslog=use_syslog))
    modprobe('rbd')


def image_mapped(name):
    """Determine whether a RADOS block device is mapped locally."""
    try:
        out = check_output(['rbd', 'showmapped']).decode('UTF-8')
    except CalledProcessError:
        return False

    return name in out


def map_block_storage(service, pool, image):
    """Map a RADOS block device for local use."""
    cmd = [
        'rbd',
        'map',
        '{}/{}'.format(pool, image),
        '--user',
        service,
        '--secret',
        _keyfile_path(service),
    ]
    check_call(cmd)


def filesystem_mounted(fs):
    """Determine whether a filesytems is already mounted."""
    return fs in [f for f, m in mounts()]


def make_filesystem(blk_device, fstype='ext4', timeout=10):
    """Make a new filesystem on the specified block device."""
    count = 0
    e_noent = os.errno.ENOENT
    while not os.path.exists(blk_device):
        if count >= timeout:
            log('Gave up waiting on block device %s' % blk_device,
                level=ERROR)
            raise IOError(e_noent, os.strerror(e_noent), blk_device)

        log('Waiting for block device %s to appear' % blk_device,
            level=DEBUG)
        count += 1
        time.sleep(1)
    else:
        log('Formatting block device %s as filesystem %s.' %
            (blk_device, fstype), level=INFO)
        check_call(['mkfs', '-t', fstype, blk_device])


def place_data_on_block_device(blk_device, data_src_dst):
    """Migrate data in data_src_dst to blk_device and then remount."""
    # mount block device into /mnt
    mount(blk_device, '/mnt')
    # copy data to /mnt
    copy_files(data_src_dst, '/mnt')
    # umount block device
    umount('/mnt')
    # Grab user/group ID's from original source
    _dir = os.stat(data_src_dst)
    uid = _dir.st_uid
    gid = _dir.st_gid
    # re-mount where the data should originally be
    # TODO: persist is currently a NO-OP in core.host
    mount(blk_device, data_src_dst, persist=True)
    # ensure original ownership of new mount.
    os.chown(data_src_dst, uid, gid)


# TODO: re-use
def modprobe(module):
    """Load a kernel module and configure for auto-load on reboot."""
    log('Loading kernel module', level=INFO)
    cmd = ['modprobe', module]
    check_call(cmd)
    with open('/etc/modules', 'r+') as modules:
        if module not in modules.read():
            modules.write(module)


def copy_files(src, dst, symlinks=False, ignore=None):
    """Copy files from src to dst."""
    for item in os.listdir(src):
        s = os.path.join(src, item)
        d = os.path.join(dst, item)
        if os.path.isdir(s):
            shutil.copytree(s, d, symlinks, ignore)
        else:
            shutil.copy2(s, d)


def ensure_ceph_storage(service, pool, rbd_img, sizemb, mount_point,
                        blk_device, fstype, system_services=[],
                        replicas=3):
    """NOTE: This function must only be called from a single service unit for
    the same rbd_img otherwise data loss will occur.

    Ensures given pool and RBD image exists, is mapped to a block device,
    and the device is formatted and mounted at the given mount_point.

    If formatting a device for the first time, data existing at mount_point
    will be migrated to the RBD device before being re-mounted.

    All services listed in system_services will be stopped prior to data
    migration and restarted when complete.
    """
    # Ensure pool, RBD image, RBD mappings are in place.
    if not pool_exists(service, pool):
        log('Creating new pool {}.'.format(pool), level=INFO)
        create_pool(service, pool, replicas=replicas)

    if not rbd_exists(service, pool, rbd_img):
        log('Creating RBD image ({}).'.format(rbd_img), level=INFO)
        create_rbd_image(service, pool, rbd_img, sizemb)

    if not image_mapped(rbd_img):
        log('Mapping RBD Image {} as a Block Device.'.format(rbd_img),
            level=INFO)
        map_block_storage(service, pool, rbd_img)

    # make file system
    # TODO: What happens if for whatever reason this is run again and
    # the data is already in the rbd device and/or is mounted??
    # When it is mounted already, it will fail to make the fs
    # XXX: This is really sketchy!  Need to at least add an fstab entry
    #      otherwise this hook will blow away existing data if its executed
    #      after a reboot.
    if not filesystem_mounted(mount_point):
        make_filesystem(blk_device, fstype)

        for svc in system_services:
            if service_running(svc):
                log('Stopping services {} prior to migrating data.'
                    .format(svc), level=DEBUG)
                service_stop(svc)

        place_data_on_block_device(blk_device, mount_point)

        for svc in system_services:
            log('Starting service {} after migrating data.'
                .format(svc), level=DEBUG)
            service_start(svc)


def ensure_ceph_keyring(service, user=None, group=None):
    """Ensures a ceph keyring is created for a named service and optionally
    ensures user and group ownership.

    Returns False if no ceph key is available in relation state.
    """
    key = None
    for rid in relation_ids('ceph'):
        for unit in related_units(rid):
            key = relation_get('key', rid=rid, unit=unit)
            if key:
                break

    if not key:
        return False

    create_keyring(service=service, key=key)
    keyring = _keyring_path(service)
    if user and group:
        check_call(['chown', '%s.%s' % (user, group), keyring])

    return True


def ceph_version():
    """Retrieve the local version of ceph."""
    if os.path.exists('/usr/bin/ceph'):
        cmd = ['ceph', '-v']
        output = check_output(cmd).decode('US-ASCII')
        output = output.split()
        if len(output) > 3:
            return output[2]
        else:
            return None
    else:
        return None


class CephBrokerRq(object):
    """Ceph broker request.

    Multiple operations can be added to a request and sent to the Ceph broker
    to be executed.

    Request is json-encoded for sending over the wire.

    The API is versioned and defaults to version 1.
    """
    def __init__(self, api_version=1):
        self.api_version = api_version
        self.ops = []

    def add_op_create_pool(self, name, replica_count=3):
        self.ops.append({'op': 'create-pool', 'name': name,
                         'replicas': replica_count})

    @property
    def request(self):
        return json.dumps({'api-version': self.api_version, 'ops': self.ops})


class CephBrokerRsp(object):
    """Ceph broker response.

    Response is json-decoded and contents provided as methods/properties.

    The API is versioned and defaults to version 1.
    """
    def __init__(self, encoded_rsp):
        self.api_version = None
        self.rsp = json.loads(encoded_rsp)

    @property
    def exit_code(self):
        return self.rsp.get('exit-code')

    @property
    def exit_msg(self):
        return self.rsp.get('stderr')
