# Copyright (c) 2010-2012 OpenStack Foundation
#
# 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.

from __future__ import print_function
import logging

from errno import EEXIST
from itertools import islice
from operator import itemgetter
from os import mkdir
from os.path import basename, abspath, dirname, exists, join as pathjoin
from sys import argv as sys_argv, exit, stderr, stdout
from textwrap import wrap
from time import time
from datetime import timedelta
import optparse
import math

from six.moves import zip as izip
from six.moves import input

from swift.common import exceptions
from swift.common.ring import RingBuilder, Ring, RingData
from swift.common.ring.builder import MAX_BALANCE
from swift.common.ring.utils import validate_args, \
    validate_and_normalize_ip, build_dev_from_opts, \
    parse_builder_ring_filename_args, parse_search_value, \
    parse_search_values_from_opts, parse_change_values_from_opts, \
    dispersion_report, parse_add_value
from swift.common.utils import lock_parent_directory

MAJOR_VERSION = 1
MINOR_VERSION = 3
EXIT_SUCCESS = 0
EXIT_WARNING = 1
EXIT_ERROR = 2

global argv, backup_dir, builder, builder_file, ring_file
argv = backup_dir = builder = builder_file = ring_file = None


def format_device(dev):
    """
    Format a device for display.
    """
    copy_dev = dev.copy()
    for key in ('ip', 'replication_ip'):
        if ':' in copy_dev[key]:
            copy_dev[key] = '[' + copy_dev[key] + ']'
    return ('d%(id)sr%(region)sz%(zone)s-%(ip)s:%(port)sR'
            '%(replication_ip)s:%(replication_port)s/%(device)s_'
            '"%(meta)s"' % copy_dev)


def _parse_search_values(argvish):

    new_cmd_format, opts, args = validate_args(argvish)

    # We'll either parse the all-in-one-string format or the
    # --options format,
    # but not both. If both are specified, raise an error.
    try:
        search_values = {}
        if len(args) > 0:
            if new_cmd_format or len(args) != 1:
                print(Commands.search.__doc__.strip())
                exit(EXIT_ERROR)
            search_values = parse_search_value(args[0])
        else:
            search_values = parse_search_values_from_opts(opts)
        return search_values
    except ValueError as e:
        print(e)
        exit(EXIT_ERROR)


def _find_parts(devs):
    devs = [d['id'] for d in devs]
    if not devs or not builder._replica2part2dev:
        return None

    partition_count = {}
    for replica in builder._replica2part2dev:
        for partition, device in enumerate(replica):
            if device in devs:
                if partition not in partition_count:
                    partition_count[partition] = 0
                partition_count[partition] += 1

    # Sort by number of found replicas to keep the output format
    sorted_partition_count = sorted(
        partition_count.items(), key=itemgetter(1), reverse=True)

    return sorted_partition_count


def _parse_list_parts_values(argvish):

    new_cmd_format, opts, args = validate_args(argvish)

    # We'll either parse the all-in-one-string format or the
    # --options format,
    # but not both. If both are specified, raise an error.
    try:
        devs = []
        if len(args) > 0:
            if new_cmd_format:
                print(Commands.list_parts.__doc__.strip())
                exit(EXIT_ERROR)

            for arg in args:
                devs.extend(
                    builder.search_devs(parse_search_value(arg)) or [])
        else:
            devs.extend(builder.search_devs(
                parse_search_values_from_opts(opts)) or [])

        return devs
    except ValueError as e:
        print(e)
        exit(EXIT_ERROR)


def _parse_add_values(argvish):
    """
    Parse devices to add as specified on the command line.

    Will exit on error and spew warnings.

    :returns: array of device dicts
    """
    new_cmd_format, opts, args = validate_args(argvish)

    # We'll either parse the all-in-one-string format or the
    # --options format,
    # but not both. If both are specified, raise an error.
    parsed_devs = []
    if len(args) > 0:
        if new_cmd_format or len(args) % 2 != 0:
            print(Commands.add.__doc__.strip())
            exit(EXIT_ERROR)

        devs_and_weights = izip(islice(args, 0, len(args), 2),
                                islice(args, 1, len(args), 2))

        for devstr, weightstr in devs_and_weights:
            dev_dict = parse_add_value(devstr)

            if dev_dict['region'] is None:
                stderr.write('WARNING: No region specified for %s. '
                             'Defaulting to region 1.\n' % devstr)
                dev_dict['region'] = 1

            if dev_dict['replication_ip'] is None:
                dev_dict['replication_ip'] = dev_dict['ip']

            if dev_dict['replication_port'] is None:
                dev_dict['replication_port'] = dev_dict['port']

            weight = float(weightstr)
            if weight < 0:
                raise ValueError('Invalid weight value: %s' % devstr)
            dev_dict['weight'] = weight

            parsed_devs.append(dev_dict)
    else:
        parsed_devs.append(build_dev_from_opts(opts))

    return parsed_devs


def _set_weight_values(devs, weight):
    if not devs:
        print('Search value matched 0 devices.\n'
              'The on-disk ring builder is unchanged.')
        exit(EXIT_ERROR)

    if len(devs) > 1:
        print('Matched more than one device:')
        for dev in devs:
            print('    %s' % format_device(dev))
        if input('Are you sure you want to update the weight for '
                 'these %s devices? (y/N) ' % len(devs)) != 'y':
            print('Aborting device modifications')
            exit(EXIT_ERROR)

    for dev in devs:
        builder.set_dev_weight(dev['id'], weight)
        print('%s weight set to %s' % (format_device(dev),
                                       dev['weight']))


def _parse_set_weight_values(argvish):

    new_cmd_format, opts, args = validate_args(argvish)

    # We'll either parse the all-in-one-string format or the
    # --options format,
    # but not both. If both are specified, raise an error.
    try:
        devs = []
        if not new_cmd_format:
            if len(args) % 2 != 0:
                print(Commands.set_weight.__doc__.strip())
                exit(EXIT_ERROR)

            devs_and_weights = izip(islice(argvish, 0, len(argvish), 2),
                                    islice(argvish, 1, len(argvish), 2))
            for devstr, weightstr in devs_and_weights:
                devs.extend(builder.search_devs(
                    parse_search_value(devstr)) or [])
                weight = float(weightstr)
                _set_weight_values(devs, weight)
        else:
            if len(args) != 1:
                print(Commands.set_weight.__doc__.strip())
                exit(EXIT_ERROR)

            devs.extend(builder.search_devs(
                parse_search_values_from_opts(opts)) or [])
            weight = float(args[0])
            _set_weight_values(devs, weight)
    except ValueError as e:
        print(e)
        exit(EXIT_ERROR)


def _set_info_values(devs, change):

    if not devs:
        print("Search value matched 0 devices.\n"
              "The on-disk ring builder is unchanged.")
        exit(EXIT_ERROR)

    if len(devs) > 1:
        print('Matched more than one device:')
        for dev in devs:
            print('    %s' % format_device(dev))
        if input('Are you sure you want to update the info for '
                 'these %s devices? (y/N) ' % len(devs)) != 'y':
            print('Aborting device modifications')
            exit(EXIT_ERROR)

    for dev in devs:
        orig_dev_string = format_device(dev)
        test_dev = dict(dev)
        for key in change:
            test_dev[key] = change[key]
        for check_dev in builder.devs:
            if not check_dev or check_dev['id'] == test_dev['id']:
                continue
            if check_dev['ip'] == test_dev['ip'] and \
                    check_dev['port'] == test_dev['port'] and \
                    check_dev['device'] == test_dev['device']:
                print('Device %d already uses %s:%d/%s.' %
                      (check_dev['id'], check_dev['ip'],
                       check_dev['port'], check_dev['device']))
                exit(EXIT_ERROR)
        for key in change:
            dev[key] = change[key]
        print('Device %s is now %s' % (orig_dev_string,
                                       format_device(dev)))


def _parse_set_info_values(argvish):

    new_cmd_format, opts, args = validate_args(argvish)

    # We'll either parse the all-in-one-string format or the
    # --options format,
    # but not both. If both are specified, raise an error.
    if not new_cmd_format:
        if len(args) % 2 != 0:
            print(Commands.search.__doc__.strip())
            exit(EXIT_ERROR)

        searches_and_changes = izip(islice(argvish, 0, len(argvish), 2),
                                    islice(argvish, 1, len(argvish), 2))

        for search_value, change_value in searches_and_changes:
            devs = builder.search_devs(parse_search_value(search_value))
            change = {}
            ip = ''
            if change_value and change_value[0].isdigit():
                i = 1
                while (i < len(change_value) and
                       change_value[i] in '0123456789.'):
                    i += 1
                ip = change_value[:i]
                change_value = change_value[i:]
            elif change_value and change_value.startswith('['):
                i = 1
                while i < len(change_value) and change_value[i] != ']':
                    i += 1
                i += 1
                ip = change_value[:i].lstrip('[').rstrip(']')
                change_value = change_value[i:]
            if ip:
                change['ip'] = validate_and_normalize_ip(ip)
            if change_value.startswith(':'):
                i = 1
                while i < len(change_value) and change_value[i].isdigit():
                    i += 1
                change['port'] = int(change_value[1:i])
                change_value = change_value[i:]
            if change_value.startswith('R'):
                change_value = change_value[1:]
                replication_ip = ''
                if change_value and change_value[0].isdigit():
                    i = 1
                    while (i < len(change_value) and
                           change_value[i] in '0123456789.'):
                        i += 1
                    replication_ip = change_value[:i]
                    change_value = change_value[i:]
                elif change_value and change_value.startswith('['):
                    i = 1
                    while i < len(change_value) and change_value[i] != ']':
                        i += 1
                    i += 1
                    replication_ip = \
                        change_value[:i].lstrip('[').rstrip(']')
                    change_value = change_value[i:]
                if replication_ip:
                    change['replication_ip'] = \
                        validate_and_normalize_ip(replication_ip)
                if change_value.startswith(':'):
                    i = 1
                    while i < len(change_value) and change_value[i].isdigit():
                        i += 1
                    change['replication_port'] = int(change_value[1:i])
                    change_value = change_value[i:]
            if change_value.startswith('/'):
                i = 1
                while i < len(change_value) and change_value[i] != '_':
                    i += 1
                change['device'] = change_value[1:i]
                change_value = change_value[i:]
            if change_value.startswith('_'):
                change['meta'] = change_value[1:]
                change_value = ''
            if change_value or not change:
                raise ValueError('Invalid set info change value: %s' %
                                 repr(argvish[1]))
            _set_info_values(devs, change)
    else:
        devs = builder.search_devs(parse_search_values_from_opts(opts))
        change = parse_change_values_from_opts(opts)
        _set_info_values(devs, change)


def _parse_remove_values(argvish):

    new_cmd_format, opts, args = validate_args(argvish)

    # We'll either parse the all-in-one-string format or the
    # --options format,
    # but not both. If both are specified, raise an error.
    try:
        devs = []
        if len(args) > 0:
            if new_cmd_format:
                print(Commands.remove.__doc__.strip())
                exit(EXIT_ERROR)

            for arg in args:
                devs.extend(builder.search_devs(
                    parse_search_value(arg)) or [])
        else:
            devs.extend(builder.search_devs(
                parse_search_values_from_opts(opts)))

        return devs
    except ValueError as e:
        print(e)
        exit(EXIT_ERROR)


class Commands(object):
    @staticmethod
    def unknown():
        print('Unknown command: %s' % argv[2])
        exit(EXIT_ERROR)

    @staticmethod
    def create():
        """
swift-ring-builder <builder_file> create <part_power> <replicas>
                                         <min_part_hours>
    Creates <builder_file> with 2^<part_power> partitions and <replicas>.
    <min_part_hours> is number of hours to restrict moving a partition more
    than once.
        """
        if len(argv) < 6:
            print(Commands.create.__doc__.strip())
            exit(EXIT_ERROR)
        builder = RingBuilder(int(argv[3]), float(argv[4]), int(argv[5]))
        backup_dir = pathjoin(dirname(builder_file), 'backups')
        try:
            mkdir(backup_dir)
        except OSError as err:
            if err.errno != EEXIST:
                raise
        builder.save(pathjoin(backup_dir,
                              '%d.' % time() + basename(builder_file)))
        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def default():
        """
swift-ring-builder <builder_file>
    Shows information about the ring and the devices within.
    Flags:
        DEL - marked for removal and will be removed next rebalance.
        """
        print('%s, build version %d' % (builder_file, builder.version))
        regions = 0
        zones = 0
        balance = 0
        dev_count = 0
        if builder.devs:
            regions = len(set(d['region'] for d in builder.devs
                              if d is not None))
            zones = len(set((d['region'], d['zone']) for d in builder.devs
                            if d is not None))
            dev_count = len([dev for dev in builder.devs
                             if dev is not None])
            balance = builder.get_balance()
        dispersion_trailer = '' if builder.dispersion is None else (
            ', %.02f dispersion' % (builder.dispersion))
        print('%d partitions, %.6f replicas, %d regions, %d zones, '
              '%d devices, %.02f balance%s' % (
                  builder.parts, builder.replicas, regions, zones, dev_count,
                  balance, dispersion_trailer))
        print('The minimum number of hours before a partition can be '
              'reassigned is %s (%s remaining)' % (
                  builder.min_part_hours,
                  timedelta(seconds=builder.min_part_seconds_left)))
        print('The overload factor is %0.2f%% (%.6f)' % (
            builder.overload * 100, builder.overload))

        # compare ring file against builder file
        if not exists(ring_file):
            print('Ring file %s not found, '
                  'probably it hasn\'t been written yet' % ring_file)
        else:
            builder_dict = builder.get_ring().to_dict()
            try:
                ring_dict = RingData.load(ring_file).to_dict()
            except Exception as exc:
                print('Ring file %s is invalid: %r' % (ring_file, exc))
            else:
                if builder_dict == ring_dict:
                    print('Ring file %s is up-to-date' % ring_file)
                else:
                    print('Ring file %s is obsolete' % ring_file)

        if builder.devs:
            balance_per_dev = builder._build_balance_per_dev()
            print('Devices:    id  region  zone      ip address  port  '
                  'replication ip  replication port      name '
                  'weight partitions balance flags meta')
            for dev in builder._iter_devs():
                flags = 'DEL' if dev in builder._remove_devs else ''
                print('         %5d %7d %5d %15s %5d %15s %17d %9s %6.02f '
                      '%10s %7.02f %5s %s' %
                      (dev['id'], dev['region'], dev['zone'], dev['ip'],
                       dev['port'], dev['replication_ip'],
                       dev['replication_port'], dev['device'], dev['weight'],
                       dev['parts'], balance_per_dev[dev['id']], flags,
                       dev['meta']))
        exit(EXIT_SUCCESS)

    @staticmethod
    def search():
        """
swift-ring-builder <builder_file> search <search-value>

or

swift-ring-builder <builder_file> search
    --region <region> --zone <zone> --ip <ip or hostname> --port <port>
    --replication-ip <r_ip or r_hostname> --replication-port <r_port>
    --device <device_name> --meta <meta> --weight <weight>

    Where <r_ip>, <r_hostname> and <r_port> are replication ip, hostname
    and port.
    Any of the options are optional in both cases.

    Shows information about matching devices.
        """
        if len(argv) < 4:
            print(Commands.search.__doc__.strip())
            print()
            print(parse_search_value.__doc__.strip())
            exit(EXIT_ERROR)

        devs = builder.search_devs(_parse_search_values(argv[3:]))

        if not devs:
            print('No matching devices found')
            exit(EXIT_ERROR)
        print('Devices:    id  region  zone      ip address  port  '
              'replication ip  replication port      name weight partitions '
              'balance meta')
        weighted_parts = builder.parts * builder.replicas / \
            sum(d['weight'] for d in builder.devs if d is not None)
        for dev in devs:
            if not dev['weight']:
                if dev['parts']:
                    balance = MAX_BALANCE
                else:
                    balance = 0
            else:
                balance = 100.0 * dev['parts'] / \
                    (dev['weight'] * weighted_parts) - 100.0
            print('         %5d %7d %5d %15s %5d %15s %17d %9s %6.02f %10s '
                  '%7.02f %s' %
                  (dev['id'], dev['region'], dev['zone'], dev['ip'],
                   dev['port'], dev['replication_ip'], dev['replication_port'],
                   dev['device'], dev['weight'], dev['parts'], balance,
                   dev['meta']))
        exit(EXIT_SUCCESS)

    @staticmethod
    def list_parts():
        """
swift-ring-builder <builder_file> list_parts <search-value> [<search-value>] ..

or

swift-ring-builder <builder_file> list_parts
    --region <region> --zone <zone> --ip <ip or hostname> --port <port>
    --replication-ip <r_ip or r_hostname> --replication-port <r_port>
    --device <device_name> --meta <meta> --weight <weight>

    Where <r_ip>, <r_hostname> and <r_port> are replication ip, hostname
    and port.
    Any of the options are optional in both cases.

    Returns a 2 column list of all the partitions that are assigned to any of
    the devices matching the search values given. The first column is the
    assigned partition number and the second column is the number of device
    matches for that partition. The list is ordered from most number of matches
    to least. If there are a lot of devices to match against, this command
    could take a while to run.
        """
        if len(argv) < 4:
            print(Commands.list_parts.__doc__.strip())
            print()
            print(parse_search_value.__doc__.strip())
            exit(EXIT_ERROR)

        if not builder._replica2part2dev:
            print('Specified builder file \"%s\" is not rebalanced yet. '
                  'Please rebalance first.' % builder_file)
            exit(EXIT_ERROR)

        devs = _parse_list_parts_values(argv[3:])
        if not devs:
            print('No matching devices found')
            exit(EXIT_ERROR)

        sorted_partition_count = _find_parts(devs)

        if not sorted_partition_count:
            print('No matching devices found')
            exit(EXIT_ERROR)

        print('Partition   Matches')
        for partition, count in sorted_partition_count:
            print('%9d   %7d' % (partition, count))
        exit(EXIT_SUCCESS)

    @staticmethod
    def add():
        """
swift-ring-builder <builder_file> add
    [r<region>]z<zone>-<ip>:<port>[R<r_ip>:<r_port>]/<device_name>_<meta>
     <weight>
    [[r<region>]z<zone>-<ip>:<port>[R<r_ip>:<r_port>]/<device_name>_<meta>
     <weight>] ...

    Where <r_ip> and <r_port> are replication ip and port.

or

swift-ring-builder <builder_file> add
    --region <region> --zone <zone> --ip <ip or hostname> --port <port>
    [--replication-ip <r_ip or r_hostname>] [--replication-port <r_port>]
    --device <device_name> --weight <weight>
    [--meta <meta>]

    Adds devices to the ring with the given information. No partitions will be
    assigned to the new device until after running 'rebalance'. This is so you
    can make multiple device changes and rebalance them all just once.
        """
        if len(argv) < 5:
            print(Commands.add.__doc__.strip())
            exit(EXIT_ERROR)

        try:
            for new_dev in _parse_add_values(argv[3:]):
                for dev in builder.devs:
                    if dev is None:
                        continue
                    if dev['ip'] == new_dev['ip'] and \
                            dev['port'] == new_dev['port'] and \
                            dev['device'] == new_dev['device']:
                        print('Device %d already uses %s:%d/%s.' %
                              (dev['id'], dev['ip'],
                               dev['port'], dev['device']))
                        print("The on-disk ring builder is unchanged.\n")
                        exit(EXIT_ERROR)
                dev_id = builder.add_dev(new_dev)
                print('Device %s with %s weight got id %s' %
                      (format_device(new_dev), new_dev['weight'], dev_id))
        except ValueError as err:
            print(err)
            print('The on-disk ring builder is unchanged.')
            exit(EXIT_ERROR)

        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def set_weight():
        """
swift-ring-builder <builder_file> set_weight <search-value> <weight>
    [<search-value> <weight] ...

or

swift-ring-builder <builder_file> set_weight
    --region <region> --zone <zone> --ip <ip or hostname> --port <port>
    --replication-ip <r_ip or r_hostname> --replication-port <r_port>
    --device <device_name> --meta <meta> --weight <weight>

    Where <r_ip>, <r_hostname> and <r_port> are replication ip, hostname
    and port.
    Any of the options are optional in both cases.

    Resets the devices' weights. No partitions will be reassigned to or from
    the device until after running 'rebalance'. This is so you can make
    multiple device changes and rebalance them all just once.
        """
        # if len(argv) < 5 or len(argv) % 2 != 1:
        if len(argv) < 5:
            print(Commands.set_weight.__doc__.strip())
            print()
            print(parse_search_value.__doc__.strip())
            exit(EXIT_ERROR)

        _parse_set_weight_values(argv[3:])

        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def set_info():
        """
swift-ring-builder <builder_file> set_info
    <search-value> <ip>:<port>[R<r_ip>:<r_port>]/<device_name>_<meta>
    [<search-value> <ip>:<port>[R<r_ip>:<r_port>]/<device_name>_<meta>] ...

or

swift-ring-builder <builder_file> set_info
    --ip <ip or hostname> --port <port>
    --replication-ip <r_ip or r_hostname> --replication-port <r_port>
    --device <device_name> --meta <meta>
    --change-ip <ip or hostname> --change-port <port>
    --change-replication-ip <r_ip or r_hostname>
    --change-replication-port <r_port>
    --change-device <device_name>
    --change-meta <meta>

    Where <r_ip>, <r_hostname> and <r_port> are replication ip, hostname
    and port.
    Any of the options are optional in both cases.

    For each search-value, resets the matched device's information.
    This information isn't used to assign partitions, so you can use
    'write_ring' afterward to rewrite the current ring with the newer
    device information. Any of the parts are optional in the final
    <ip>:<port>/<device_name>_<meta> parameter; just give what you
    want to change. For instance set_info d74 _"snet: 5.6.7.8" would
    just update the meta data for device id 74.
        """
        if len(argv) < 5:
            print(Commands.set_info.__doc__.strip())
            print()
            print(parse_search_value.__doc__.strip())
            exit(EXIT_ERROR)

        try:
            _parse_set_info_values(argv[3:])
        except ValueError as err:
            print(err)
            exit(EXIT_ERROR)

        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def remove():
        """
swift-ring-builder <builder_file> remove <search-value> [search-value ...]

or

swift-ring-builder <builder_file> search
    --region <region> --zone <zone> --ip <ip or hostname> --port <port>
    --replication-ip <r_ip or r_hostname> --replication-port <r_port>
    --device <device_name> --meta <meta> --weight <weight>

    Where <r_ip>, <r_hostname> and <r_port> are replication ip, hostname
    and port.
    Any of the options are optional in both cases.

    Removes the device(s) from the ring. This should normally just be used for
    a device that has failed. For a device you wish to decommission, it's best
    to set its weight to 0, wait for it to drain all its data, then use this
    remove command. This will not take effect until after running 'rebalance'.
    This is so you can make multiple device changes and rebalance them all just
    once.
        """
        if len(argv) < 4:
            print(Commands.remove.__doc__.strip())
            print()
            print(parse_search_value.__doc__.strip())
            exit(EXIT_ERROR)

        devs = _parse_remove_values(argv[3:])

        if not devs:
            print('Search value matched 0 devices.\n'
                  'The on-disk ring builder is unchanged.')
            exit(EXIT_ERROR)

        if len(devs) > 1:
            print('Matched more than one device:')
            for dev in devs:
                print('    %s' % format_device(dev))
            if input('Are you sure you want to remove these %s '
                     'devices? (y/N) ' % len(devs)) != 'y':
                print('Aborting device removals')
                exit(EXIT_ERROR)

        for dev in devs:
            try:
                builder.remove_dev(dev['id'])
            except exceptions.RingBuilderError as e:
                print('-' * 79)
                print(
                    'An error occurred while removing device with id %d\n'
                    'This usually means that you attempted to remove\n'
                    'the last device in a ring. If this is the case,\n'
                    'consider creating a new ring instead.\n'
                    'The on-disk ring builder is unchanged.\n'
                    'Original exception message: %s' %
                    (dev['id'], e))
                print('-' * 79)
                exit(EXIT_ERROR)

            print('%s marked for removal and will '
                  'be removed next rebalance.' % format_device(dev))
        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def rebalance():
        """
swift-ring-builder <builder_file> rebalance [options]
    Attempts to rebalance the ring by reassigning partitions that haven't been
    recently reassigned.
        """
        usage = Commands.rebalance.__doc__.strip()
        parser = optparse.OptionParser(usage)
        parser.add_option('-f', '--force', action='store_true',
                          help='Force a rebalanced ring to save even '
                          'if < 1% of parts changed')
        parser.add_option('-s', '--seed', help="seed to use for rebalance")
        parser.add_option('-d', '--debug', action='store_true',
                          help="print debug information")
        options, args = parser.parse_args(argv)

        def get_seed(index):
            if options.seed:
                return options.seed
            try:
                return args[index]
            except IndexError:
                pass

        if options.debug:
            logger = logging.getLogger("swift.ring.builder")
            logger.disabled = False
            logger.setLevel(logging.DEBUG)
            handler = logging.StreamHandler(stdout)
            formatter = logging.Formatter("%(levelname)s: %(message)s")
            handler.setFormatter(formatter)
            logger.addHandler(handler)

        if builder.min_part_seconds_left > 0 and not options.force:
            print('No partitions could be reassigned.')
            print('The time between rebalances must be at least '
                  'min_part_hours: %s hours (%s remaining)' % (
                      builder.min_part_hours,
                      timedelta(seconds=builder.min_part_seconds_left)))
            exit(EXIT_WARNING)

        devs_changed = builder.devs_changed
        try:
            last_balance = builder.get_balance()
            parts, balance, removed_devs = builder.rebalance(seed=get_seed(3))
        except exceptions.RingBuilderError as e:
            print('-' * 79)
            print("An error has occurred during ring validation. Common\n"
                  "causes of failure are rings that are empty or do not\n"
                  "have enough devices to accommodate the replica count.\n"
                  "Original exception message:\n %s" %
                  (e,))
            print('-' * 79)
            exit(EXIT_ERROR)
        if not (parts or options.force or removed_devs):
            print('No partitions could be reassigned.')
            print('There is no need to do so at this time')
            exit(EXIT_WARNING)
        # If we set device's weight to zero, currently balance will be set
        # special value(MAX_BALANCE) until zero weighted device return all
        # its partitions. So we cannot check balance has changed.
        # Thus we need to check balance or last_balance is special value.
        if not options.force and \
                not devs_changed and abs(last_balance - balance) < 1 and \
                not (last_balance == MAX_BALANCE and balance == MAX_BALANCE):
            print('Cowardly refusing to save rebalance as it did not change '
                  'at least 1%.')
            exit(EXIT_WARNING)
        try:
            builder.validate()
        except exceptions.RingValidationError as e:
            print('-' * 79)
            print("An error has occurred during ring validation. Common\n"
                  "causes of failure are rings that are empty or do not\n"
                  "have enough devices to accommodate the replica count.\n"
                  "Original exception message:\n %s" %
                  (e,))
            print('-' * 79)
            exit(EXIT_ERROR)
        print('Reassigned %d (%.02f%%) partitions. '
              'Balance is now %.02f.  '
              'Dispersion is now %.02f' % (
                  parts, 100.0 * parts / builder.parts,
                  balance,
                  builder.dispersion))
        status = EXIT_SUCCESS
        if builder.dispersion > 0:
            print('-' * 79)
            print(
                'NOTE: Dispersion of %.06f indicates some parts are not\n'
                '      optimally dispersed.\n\n'
                '      You may want to adjust some device weights, increase\n'
                '      the overload or review the dispersion report.' %
                builder.dispersion)
            status = EXIT_WARNING
            print('-' * 79)
        elif balance > 5 and balance / 100.0 > builder.overload:
            print('-' * 79)
            print('NOTE: Balance of %.02f indicates you should push this ' %
                  balance)
            print('      ring, wait at least %d hours, and rebalance/repush.'
                  % builder.min_part_hours)
            print('-' * 79)
            status = EXIT_WARNING
        ts = time()
        builder.get_ring().save(
            pathjoin(backup_dir, '%d.' % ts + basename(ring_file)))
        builder.save(pathjoin(backup_dir, '%d.' % ts + basename(builder_file)))
        builder.get_ring().save(ring_file)
        builder.save(builder_file)
        exit(status)

    @staticmethod
    def dispersion():
        """
swift-ring-builder <builder_file> dispersion <search_filter> [options]

    Output report on dispersion.

    --verbose option will display dispersion graph broken down by tier

    You can filter which tiers are evaluated to drill down using a regex
    in the optional search_filter arguemnt.  i.e.

        swift-ring-builder <builder_file> dispersion "r\d+z\d+$" -v

    ... would only display rows for the zone tiers

        swift-ring-builder <builder_file> dispersion ".*\-[^/]*$" -v

    ... would only display rows for the server tiers

    The reports columns are:

    Tier  : the name of the tier
    parts : the total number of partitions with assignment in the tier
    %     : the percentage of parts in the tier with replicas over assigned
    max   : maximum replicas a part should have assigned at the tier
    0 - N : the number of parts with that many replicas assigned

    e.g.
        Tier:  parts      %   max   0    1    2   3
        r1z1    1022  79.45     1   2  210  784  28

        r1z1 has 1022 total parts assigned, 79% of them have more than the
        recommend max replica count of 1 assigned.  Only 2 parts in the ring
        are *not* assigned in this tier (0 replica count), 210 parts have
        the recommend replica count of 1, 784 have 2 replicas, and 28 sadly
        have all three replicas in this tier.
        """
        status = EXIT_SUCCESS
        if not builder._replica2part2dev:
            print('Specified builder file \"%s\" is not rebalanced yet. '
                  'Please rebalance first.' % builder_file)
            exit(EXIT_ERROR)
        usage = Commands.dispersion.__doc__.strip()
        parser = optparse.OptionParser(usage)
        parser.add_option('-v', '--verbose', action='store_true',
                          help='Display dispersion report for tiers')
        options, args = parser.parse_args(argv)
        if args[3:]:
            search_filter = args[3]
        else:
            search_filter = None
        report = dispersion_report(builder, search_filter=search_filter,
                                   verbose=options.verbose)
        print('Dispersion is %.06f, Balance is %.06f, Overload is %0.2f%%' % (
            builder.dispersion, builder.get_balance(), builder.overload * 100))
        print('Required overload is %.6f%%' % (
            builder.get_required_overload() * 100))
        if report['worst_tier']:
            status = EXIT_WARNING
            print('Worst tier is %.06f (%s)' % (report['max_dispersion'],
                                                report['worst_tier']))
        if report['graph']:
            replica_range = range(int(math.ceil(builder.replicas + 1)))
            part_count_width = '%%%ds' % max(len(str(builder.parts)), 5)
            replica_counts_tmpl = ' '.join(part_count_width for i in
                                           replica_range)
            tiers = (tier for tier, _junk in report['graph'])
            tier_width = max(max(map(len, tiers)), 30)
            header_line = ('%-' + str(tier_width) +
                           's ' + part_count_width +
                           ' %6s %6s ' + replica_counts_tmpl) % tuple(
                               ['Tier', 'Parts', '%', 'Max'] + replica_range)
            underline = '-' * len(header_line)
            print(underline)
            print(header_line)
            print(underline)
            for tier_name, dispersion in report['graph']:
                replica_counts_repr = replica_counts_tmpl % tuple(
                    dispersion['replicas'])
                template = ''.join([
                    '%-', str(tier_width), 's ',
                    part_count_width,
                    ' %6.02f %6d %s',
                ])
                args = (
                    tier_name,
                    dispersion['placed_parts'],
                    dispersion['dispersion'],
                    dispersion['max_replicas'],
                    replica_counts_repr,
                )
                print(template % args)
        exit(status)

    @staticmethod
    def validate():
        """
swift-ring-builder <builder_file> validate
    Just runs the validation routines on the ring.
        """
        builder.validate()
        exit(EXIT_SUCCESS)

    @staticmethod
    def write_ring():
        """
swift-ring-builder <builder_file> write_ring
    Just rewrites the distributable ring file. This is done automatically after
    a successful rebalance, so really this is only useful after one or more
    'set_info' calls when no rebalance is needed but you want to send out the
    new device information.
        """
        ring_data = builder.get_ring()
        if not ring_data._replica2part2dev_id:
            if ring_data.devs:
                print('Warning: Writing a ring with no partition '
                      'assignments but with devices; did you forget to run '
                      '"rebalance"?')
            else:
                print('Warning: Writing an empty ring')
        ring_data.save(
            pathjoin(backup_dir, '%d.' % time() + basename(ring_file)))
        ring_data.save(ring_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def write_builder():
        """
swift-ring-builder <ring_file> write_builder [min_part_hours]
    Recreate a builder from a ring file (lossy) if you lost your builder
    backups.  (Protip: don't lose your builder backups).
    [min_part_hours] is one of those numbers lost to the builder,
    you can change it with set_min_part_hours.
        """
        if exists(builder_file):
            print('Cowardly refusing to overwrite existing '
                  'Ring Builder file: %s' % builder_file)
            exit(EXIT_ERROR)
        if len(argv) > 3:
            min_part_hours = int(argv[3])
        else:
            stderr.write("WARNING: default min_part_hours may not match "
                         "the value in the lost builder.\n")
            min_part_hours = 24
        ring = Ring(ring_file)
        for dev in ring.devs:
            if dev is None:
                continue
            dev.update({
                'parts': 0,
                'parts_wanted': 0,
            })
        builder_dict = {
            'part_power': 32 - ring._part_shift,
            'replicas': float(ring.replica_count),
            'min_part_hours': min_part_hours,
            'parts': ring.partition_count,
            'devs': ring.devs,
            'devs_changed': False,
            'version': 0,
            '_replica2part2dev': ring._replica2part2dev_id,
            '_last_part_moves_epoch': None,
            '_last_part_moves': None,
            '_last_part_gather_start': 0,
            '_remove_devs': [],
        }
        builder = RingBuilder.from_dict(builder_dict)
        for parts in builder._replica2part2dev:
            for dev_id in parts:
                builder.devs[dev_id]['parts'] += 1
        builder.save(builder_file)

    @staticmethod
    def pretend_min_part_hours_passed():
        """
swift-ring-builder <builder_file> pretend_min_part_hours_passed
    Resets the clock on the last time a rebalance happened, thus
    circumventing the min_part_hours check.

    *****************************
    USE THIS WITH EXTREME CAUTION
    *****************************

    If you run this command and deploy rebalanced rings before a replication
    pass completes, you may introduce unavailability in your cluster. This
    has an end-user impact.
        """
        builder.pretend_min_part_hours_passed()
        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def set_min_part_hours():
        """
swift-ring-builder <builder_file> set_min_part_hours <hours>
    Changes the <min_part_hours> to the given <hours>. This should be set to
    however long a full replication/update cycle takes. We're working on a way
    to determine this more easily than scanning logs.
        """
        if len(argv) < 4:
            print(Commands.set_min_part_hours.__doc__.strip())
            exit(EXIT_ERROR)
        builder.change_min_part_hours(int(argv[3]))
        print('The minimum number of hours before a partition can be '
              'reassigned is now set to %s' % argv[3])
        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def set_replicas():
        """
swift-ring-builder <builder_file> set_replicas <replicas>
    Changes the replica count to the given <replicas>. <replicas> may
    be a floating-point value, in which case some partitions will have
    floor(<replicas>) replicas and some will have ceiling(<replicas>)
    in the correct proportions.

    A rebalance is needed to make the change take effect.
    """
        if len(argv) < 4:
            print(Commands.set_replicas.__doc__.strip())
            exit(EXIT_ERROR)

        new_replicas = argv[3]
        try:
            new_replicas = float(new_replicas)
        except ValueError:
            print(Commands.set_replicas.__doc__.strip())
            print("\"%s\" is not a valid number." % new_replicas)
            exit(EXIT_ERROR)

        if new_replicas < 1:
            print("Replica count must be at least 1.")
            exit(EXIT_ERROR)

        builder.set_replicas(new_replicas)
        print('The replica count is now %.6f.' % builder.replicas)
        print('The change will take effect after the next rebalance.')
        builder.save(builder_file)
        exit(EXIT_SUCCESS)

    @staticmethod
    def set_overload():
        """
swift-ring-builder <builder_file> set_overload <overload>[%]
    Changes the overload factor to the given <overload>.

    A rebalance is needed to make the change take effect.
    """
        if len(argv) < 4:
            print(Commands.set_overload.__doc__.strip())
            exit(EXIT_ERROR)

        new_overload = argv[3]
        if new_overload.endswith('%'):
            percent = True
            new_overload = new_overload.rstrip('%')
        else:
            percent = False
        try:
            new_overload = float(new_overload)
        except ValueError:
            print(Commands.set_overload.__doc__.strip())
            print("%r is not a valid number." % new_overload)
            exit(EXIT_ERROR)

        if percent:
            new_overload *= 0.01
        if new_overload < 0:
            print("Overload must be non-negative.")
            exit(EXIT_ERROR)

        if new_overload > 1 and not percent:
            print("!?! Warning overload is greater than 100% !?!")
            status = EXIT_WARNING
        else:
            status = EXIT_SUCCESS

        builder.set_overload(new_overload)
        print('The overload factor is now %0.2f%% (%.6f)' % (
            builder.overload * 100, builder.overload))
        print('The change will take effect after the next rebalance.')
        builder.save(builder_file)
        exit(status)


def main(arguments=None):
    global argv, backup_dir, builder, builder_file, ring_file
    if arguments is not None:
        argv = arguments
    else:
        argv = sys_argv

    if len(argv) < 2:
        print("swift-ring-builder %(MAJOR_VERSION)s.%(MINOR_VERSION)s\n" %
              globals())
        print(Commands.default.__doc__.strip())
        print()
        cmds = [c for c in dir(Commands)
                if getattr(Commands, c).__doc__ and not c.startswith('_') and
                c != 'default']
        cmds.sort()
        for cmd in cmds:
            print(getattr(Commands, cmd).__doc__.strip())
            print()
        print(parse_search_value.__doc__.strip())
        print()
        for line in wrap(' '.join(cmds), 79, initial_indent='Quick list: ',
                         subsequent_indent='            '):
            print(line)
        print('Exit codes: 0 = operation successful\n'
              '            1 = operation completed with warnings\n'
              '            2 = error')
        exit(EXIT_SUCCESS)

    builder_file, ring_file = parse_builder_ring_filename_args(argv)
    if builder_file != argv[1]:
        print('Note: using %s instead of %s as builder file' % (
              builder_file, argv[1]))

    try:
        builder = RingBuilder.load(builder_file)
    except exceptions.UnPicklingError as e:
        print(e)
        exit(EXIT_ERROR)
    except (exceptions.FileNotFoundError, exceptions.PermissionError) as e:
        if len(argv) < 3 or argv[2] not in('create', 'write_builder'):
            print(e)
            exit(EXIT_ERROR)
    except Exception as e:
        print('Problem occurred while reading builder file: %s. %s' %
              (builder_file, e))
        exit(EXIT_ERROR)

    backup_dir = pathjoin(dirname(builder_file), 'backups')
    try:
        mkdir(backup_dir)
    except OSError as err:
        if err.errno != EEXIST:
            raise

    if len(argv) == 2:
        command = "default"
    else:
        command = argv[2]
    if argv[0].endswith('-safe'):
        try:
            with lock_parent_directory(abspath(builder_file), 15):
                getattr(Commands, command, Commands.unknown)()
        except exceptions.LockTimeout:
            print("Ring/builder dir currently locked.")
            exit(2)
    else:
        getattr(Commands, command, Commands.unknown)()
