# vi: ts=4 expandtab
#
#    Copyright (C) 2011 Canonical Ltd.
#    Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
#
#    Author: Scott Moser <scott.moser@canonical.com>
#    Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License version 3, as
#    published by the Free Software Foundation.
#
#    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

import errno
import os
import stat

from cloudinit.settings import PER_ALWAYS
from cloudinit import util

frequency = PER_ALWAYS


def _resize_btrfs(mount_point, devpth):  # pylint: disable=W0613
    return ('btrfs', 'filesystem', 'resize', 'max', mount_point)


def _resize_ext(mount_point, devpth):  # pylint: disable=W0613
    return ('resize2fs', devpth)


def _resize_xfs(mount_point, devpth):  # pylint: disable=W0613
    return ('xfs_growfs', devpth)

# Do not use a dictionary as these commands should be able to be used
# for multiple filesystem types if possible, e.g. one command for
# ext2, ext3 and ext4.
RESIZE_FS_PREFIXES_CMDS = [
    ('btrfs', _resize_btrfs),
    ('ext', _resize_ext),
    ('xfs', _resize_xfs),
]

NOBLOCK = "noblock"


def rootdev_from_cmdline(cmdline):
    found = None
    for tok in cmdline.split():
        if tok.startswith("root="):
            found = tok[5:]
            break
    if found is None:
        return None

    if found.startswith("/dev/"):
        return found
    if found.startswith("LABEL="):
        return "/dev/disk/by-label/" + found[len("LABEL="):]
    if found.startswith("UUID="):
        return "/dev/disk/by-uuid/" + found[len("UUID="):]

    return "/dev/" + found


def handle(name, cfg, _cloud, log, args):
    if len(args) != 0:
        resize_root = args[0]
    else:
        resize_root = util.get_cfg_option_str(cfg, "resize_rootfs", True)

    if not util.translate_bool(resize_root, addons=[NOBLOCK]):
        log.debug("Skipping module named %s, resizing disabled", name)
        return

    # TODO(harlowja) is the directory ok to be used??
    resize_root_d = util.get_cfg_option_str(cfg, "resize_rootfs_tmp", "/run")
    util.ensure_dir(resize_root_d)

    # TODO(harlowja): allow what is to be resized to be configurable??
    resize_what = "/"
    result = util.get_mount_info(resize_what, log)
    if not result:
        log.warn("Could not determine filesystem type of %s", resize_what)
        return

    (devpth, fs_type, mount_point) = result

    # Ensure the path is a block device.
    info = "dev=%s mnt_point=%s path=%s" % (devpth, mount_point, resize_what)
    log.debug("resize_info: %s" % info)

    container = util.is_container()

    if (devpth == "/dev/root" and not os.path.exists(devpth) and
        not container):
        devpth = rootdev_from_cmdline(util.get_cmdline())
        if devpth is None:
            log.warn("Unable to find device '/dev/root'")
            return
        log.debug("Converted /dev/root to '%s' per kernel cmdline", devpth)

    try:
        statret = os.stat(devpth)
    except OSError as exc:
        if container and exc.errno == errno.ENOENT:
            log.debug("Device '%s' did not exist in container. "
                      "cannot resize: %s" % (devpth, info))
        elif exc.errno == errno.ENOENT:
            log.warn("Device '%s' did not exist. cannot resize: %s" %
                     (devpth, info))
        else:
            raise exc
        return

    if not stat.S_ISBLK(statret.st_mode):
        if container:
            log.debug("device '%s' not a block device in container."
                      " cannot resize: %s" % (devpth, info))
        else:
            log.warn("device '%s' not a block device. cannot resize: %s" %
                     (devpth, info))
        return

    resizer = None
    fstype_lc = fs_type.lower()
    for (pfix, root_cmd) in RESIZE_FS_PREFIXES_CMDS:
        if fstype_lc.startswith(pfix):
            resizer = root_cmd
            break

    if not resizer:
        log.warn("Not resizing unknown filesystem type %s for %s",
                 fs_type, resize_what)
        return

    resize_cmd = resizer(resize_what, devpth)
    log.debug("Resizing %s (%s) using %s", resize_what, fs_type,
              ' '.join(resize_cmd))

    if resize_root == NOBLOCK:
        # Fork to a child that will run
        # the resize command
        util.fork_cb(
            util.log_time(logfunc=log.debug, msg="backgrounded Resizing",
                func=do_resize, args=(resize_cmd, log)))
    else:
        util.log_time(logfunc=log.debug, msg="Resizing",
            func=do_resize, args=(resize_cmd, log))

    action = 'Resized'
    if resize_root == NOBLOCK:
        action = 'Resizing (via forking)'
    log.debug("%s root filesystem (type=%s, val=%s)", action, fs_type,
              resize_root)


def do_resize(resize_cmd, log):
    try:
        util.subp(resize_cmd)
    except util.ProcessExecutionError:
        util.logexc(log, "Failed to resize filesystem (cmd=%s)", resize_cmd)
        raise
    # TODO(harlowja): Should we add a fsck check after this to make
    # sure we didn't corrupt anything?