# vi: ts=4 expandtab
#
#    Copyright (C) 2011 Canonical Ltd.
#    Copyright (C) 2013 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 os
import os.path
import re
import stat

from cloudinit import log as logging
from cloudinit.settings import PER_ALWAYS
from cloudinit import util

frequency = PER_ALWAYS

DEFAULT_CONFIG = {
    'mode': 'auto',
    'devices': ['/'],
    'ignore_growroot_disabled': False,
}


def enum(**enums):
    return type('Enum', (), enums)


RESIZE = enum(SKIPPED="SKIPPED", CHANGED="CHANGED", NOCHANGE="NOCHANGE",
              FAILED="FAILED")

LOG = logging.getLogger(__name__)


def resizer_factory(mode):
    resize_class = None
    if mode == "auto":
        for (_name, resizer) in RESIZERS:
            cur = resizer()
            if cur.available():
                resize_class = cur
                break

        if not resize_class:
            raise ValueError("No resizers available")

    else:
        mmap = {}
        for (k, v) in RESIZERS:
            mmap[k] = v

        if mode not in mmap:
            raise TypeError("unknown resize mode %s" % mode)

        mclass = mmap[mode]()
        if mclass.available():
            resize_class = mclass

        if not resize_class:
            raise ValueError("mode %s not available" % mode)

    return resize_class


class ResizeFailedException(Exception):
    pass


class ResizeGrowPart(object):
    def available(self):
        myenv = os.environ.copy()
        myenv['LANG'] = 'C'

        try:
            (out, _err) = util.subp(["growpart", "--help"], env=myenv)
            if re.search(r"--update\s+", out, re.DOTALL):
                return True

        except util.ProcessExecutionError:
            pass
        return False

    def resize(self, diskdev, partnum, partdev):
        before = get_size(partdev)
        try:
            util.subp(["growpart", '--dry-run', diskdev, partnum])
        except util.ProcessExecutionError as e:
            if e.exit_code != 1:
                util.logexc(LOG, "Failed growpart --dry-run for (%s, %s)",
                            diskdev, partnum)
                raise ResizeFailedException(e)
            return (before, before)

        try:
            util.subp(["growpart", diskdev, partnum])
        except util.ProcessExecutionError as e:
            util.logexc(LOG, "Failed: growpart %s %s", diskdev, partnum)
            raise ResizeFailedException(e)

        return (before, get_size(partdev))


class ResizeGpart(object):
    def available(self):
        if not util.which('gpart'):
            return False
        return True

    def resize(self, diskdev, partnum, partdev):
        """
        GPT disks store metadata at the beginning (primary) and at the
        end (secondary) of the disk. When launching an image with a
        larger disk compared to the original image, the secondary copy
        is lost. Thus, the metadata will be marked CORRUPT, and need to
        be recovered.
        """
        try:
            util.subp(["gpart", "recover", diskdev])
        except util.ProcessExecutionError as e:
            if e.exit_code != 0:
                util.logexc(LOG, "Failed: gpart recover %s", diskdev)
                raise ResizeFailedException(e)

        before = get_size(partdev)
        try:
            util.subp(["gpart", "resize", "-i", partnum, diskdev])
        except util.ProcessExecutionError as e:
            util.logexc(LOG, "Failed: gpart resize -i %s %s", partnum, diskdev)
            raise ResizeFailedException(e)

        # Since growing the FS requires a reboot, make sure we reboot
        # first when this module has finished.
        open('/var/run/reboot-required', 'a').close()

        return (before, get_size(partdev))


def get_size(filename):
    fd = os.open(filename, os.O_RDONLY)
    try:
        return os.lseek(fd, 0, os.SEEK_END)
    finally:
        os.close(fd)


def device_part_info(devpath):
    # convert an entry in /dev/ to parent disk and partition number

    # input of /dev/vdb or /dev/disk/by-label/foo
    # rpath is hopefully a real-ish path in /dev (vda, sdb..)
    rpath = os.path.realpath(devpath)

    bname = os.path.basename(rpath)
    syspath = "/sys/class/block/%s" % bname

    # FreeBSD doesn't know of sysfs so just get everything we need from
    # the device, like /dev/vtbd0p2.
    if util.system_info()["platform"].startswith('FreeBSD'):
        m = re.search('^(/dev/.+)p([0-9])$', devpath)
        return (m.group(1), m.group(2))

    if not os.path.exists(syspath):
        raise ValueError("%s had no syspath (%s)" % (devpath, syspath))

    ptpath = os.path.join(syspath, "partition")
    if not os.path.exists(ptpath):
        raise TypeError("%s not a partition" % devpath)

    ptnum = util.load_file(ptpath).rstrip()

    # for a partition, real syspath is something like:
    # /sys/devices/pci0000:00/0000:00:04.0/virtio1/block/vda/vda1
    rsyspath = os.path.realpath(syspath)
    disksyspath = os.path.dirname(rsyspath)

    diskmajmin = util.load_file(os.path.join(disksyspath, "dev")).rstrip()
    diskdevpath = os.path.realpath("/dev/block/%s" % diskmajmin)

    # diskdevpath has something like 253:0
    # and udev has put links in /dev/block/253:0 to the device name in /dev/
    return (diskdevpath, ptnum)


def devent2dev(devent):
    if devent.startswith("/dev/"):
        return devent
    else:
        result = util.get_mount_info(devent)
        if not result:
            raise ValueError("Could not determine device of '%s' % dev_ent")
        return result[0]


def resize_devices(resizer, devices):
    # returns a tuple of tuples containing (entry-in-devices, action, message)
    info = []
    for devent in devices:
        try:
            blockdev = devent2dev(devent)
        except ValueError as e:
            info.append((devent, RESIZE.SKIPPED,
                         "unable to convert to device: %s" % e,))
            continue

        try:
            statret = os.stat(blockdev)
        except OSError as e:
            info.append((devent, RESIZE.SKIPPED,
                         "stat of '%s' failed: %s" % (blockdev, e),))
            continue

        if (not stat.S_ISBLK(statret.st_mode) and
                not stat.S_ISCHR(statret.st_mode)):
            info.append((devent, RESIZE.SKIPPED,
                         "device '%s' not a block device" % blockdev,))
            continue

        try:
            (disk, ptnum) = device_part_info(blockdev)
        except (TypeError, ValueError) as e:
            info.append((devent, RESIZE.SKIPPED,
                         "device_part_info(%s) failed: %s" % (blockdev, e),))
            continue

        try:
            (old, new) = resizer.resize(disk, ptnum, blockdev)
            if old == new:
                info.append((devent, RESIZE.NOCHANGE,
                             "no change necessary (%s, %s)" % (disk, ptnum),))
            else:
                info.append((devent, RESIZE.CHANGED,
                             "changed (%s, %s) from %s to %s" %
                             (disk, ptnum, old, new),))

        except ResizeFailedException as e:
            info.append((devent, RESIZE.FAILED,
                         "failed to resize: disk=%s, ptnum=%s: %s" %
                         (disk, ptnum, e),))

    return info


def handle(_name, cfg, _cloud, log, _args):
    if 'growpart' not in cfg:
        log.debug("No 'growpart' entry in cfg.  Using default: %s" %
                  DEFAULT_CONFIG)
        cfg['growpart'] = DEFAULT_CONFIG

    mycfg = cfg.get('growpart')
    if not isinstance(mycfg, dict):
        log.warn("'growpart' in config was not a dict")
        return

    mode = mycfg.get('mode', "auto")
    if util.is_false(mode):
        log.debug("growpart disabled: mode=%s" % mode)
        return

    if util.is_false(mycfg.get('ignore_growroot_disabled', False)):
        if os.path.isfile("/etc/growroot-disabled"):
            log.debug("growpart disabled: /etc/growroot-disabled exists")
            log.debug("use ignore_growroot_disabled to ignore")
            return

    devices = util.get_cfg_option_list(mycfg, "devices", ["/"])
    if not len(devices):
        log.debug("growpart: empty device list")
        return

    try:
        resizer = resizer_factory(mode)
    except (ValueError, TypeError) as e:
        log.debug("growpart unable to find resizer for '%s': %s" % (mode, e))
        if mode != "auto":
            raise e
        return

    resized = util.log_time(logfunc=log.debug, msg="resize_devices",
                            func=resize_devices, args=(resizer, devices))
    for (entry, action, msg) in resized:
        if action == RESIZE.CHANGED:
            log.info("'%s' resized: %s" % (entry, msg))
        else:
            log.debug("'%s' %s: %s" % (entry, action, msg))

RESIZERS = (('growpart', ResizeGrowPart), ('gpart', ResizeGpart))
