#
# mdraid.py
# mdraid functions
#
# Copyright (C) 2009  Red Hat, Inc.  All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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/>.
#
# Author(s): Dave Lehman <dlehman@redhat.com>
#

import os

from pyanaconda import iutil
from ..errors import *

import gettext
_ = lambda x: gettext.ldgettext("anaconda", x)

import logging
log = logging.getLogger("storage")

# these defaults were determined empirically
MD_SUPERBLOCK_SIZE = 2.0    # MB
MD_CHUNK_SIZE = 0.5         # MB

# raidlevels constants
RAID10 = 10
RAID6 = 6
RAID5 = 5
RAID4 = 4
RAID1 = 1
RAID0 = 0

def getRaidLevels():
    mdstat_descriptors = {
        RAID10: ("[RAID10]", "[raid10]"),
        RAID6: ("[RAID6]", "[raid6]"),
        RAID5: ("[RAID5]", "[raid5]"),
        RAID4: ("[RAID4]", "[raid4]"),
        RAID1: ("[RAID1]", "[raid1]"),
        RAID0: ("[RAID0]", "[raid0]"),
    }
    avail = []
    try:
        f = open("/proc/mdstat", "r")
    except IOError:
        pass
    else:
        for l in f.readlines():
            if not l.startswith("Personalities"):
                continue

            lst = l.split()

            for level in mdstat_descriptors:
                for d in mdstat_descriptors[level]:
                    if d in lst:
                        avail.append(level)
                        break

        f.close()

    avail.sort()
    return avail

raid_levels = getRaidLevels()

raid_descriptors = {RAID10: ("raid10", "RAID10", "10", 10),
                    RAID6: ("raid6", "RAID6", "6", 6),
                    RAID5: ("raid5", "RAID5", "5", 5),
                    RAID4: ("raid4", "RAID4", "4", 4),
                    RAID1: ("raid1", "mirror", "RAID1", "1", 1),
                    RAID0: ("raid0", "stripe", "RAID0", "0", 0)}

def raidLevel(descriptor):
    for level in raid_levels:
        if isRaid(level, descriptor):
            return level
    else:
        raise MDRaidError("invalid raid level descriptor %s" % descriptor)

def raidLevelString(level):
    if level in raid_descriptors.keys():
        return raid_descriptors[level][0]
    else:
        raise MDRaidError("invalid raid level constant %s" % level)

def isRaid(raid, raidlevel):
    """Return whether raidlevel is a valid descriptor of raid"""
    if raid in raid_descriptors:
        return raidlevel in raid_descriptors[raid]
    else:
        raise MDRaidError("invalid raid level %d" % raid)

def get_raid_min_members(raidlevel):
    """Return the minimum number of raid members required for raid level"""
    raid_min_members = {RAID10: 2,
                        RAID6: 4,
                        RAID5: 3,
                        RAID4: 3,
                        RAID1: 2,
                        RAID0: 2}

    for raid, min_members in raid_min_members.items():
        if isRaid(raid, raidlevel):
            return min_members

    raise MDRaidError("invalid raid level %d" % raidlevel)

def get_raid_max_spares(raidlevel, nummembers):
    """Return the maximum number of raid spares for raidlevel."""
    raid_max_spares = {RAID10: lambda: max(0, nummembers - get_raid_min_members(RAID10)),
                       RAID6: lambda: max(0, nummembers - get_raid_min_members(RAID6)),
                       RAID5: lambda: max(0, nummembers - get_raid_min_members(RAID5)),
                       RAID4: lambda: max(0, nummembers - get_raid_min_members(RAID4)),
                       RAID1: lambda: max(0, nummembers - get_raid_min_members(RAID1)),
                       RAID0: lambda: 0}

    for raid, max_spares_func in raid_max_spares.items():
        if isRaid(raid, raidlevel):
            return max_spares_func()

    raise MDRaidError("invalid raid level %d" % raidlevel)

def get_member_space(size, disks, level=None):
    space = 0   # size of *each* member device

    if isinstance(level, str):
        level = raidLevel(level)

    min_members = get_raid_min_members(level)
    if disks < min_members:
        raise MDRaidError("raid%d requires at least %d disks"
                         % (level, min_members))

    if level == RAID0:
        # you need the sum of the member sizes to equal your desired capacity
        space = size / disks
    elif level == RAID1:
        # you need each member's size to equal your desired capacity
        space = size
    elif level in (RAID4, RAID5):
        # you need the sum of all but one members' sizes to equal your desired
        # capacity
        space = size / (disks - 1)
    elif level == RAID6:
        # you need the sum of all but two members' sizes to equal your desired
        # capacity
        space = size / (disks - 2)
    elif level == RAID10:
        # you need the sum of the member sizes to equal twice your desired
        # capacity
        space = size / (disks / 2.0)

    space += MD_SUPERBLOCK_SIZE

    return space * disks

def mdadm(args):
    ret = iutil.execWithRedirect("mdadm", args,
                                 stdout = "/dev/tty5",
                                 stderr = "/dev/tty5")
    if ret:
        raise MDRaidError("running mdadm " + " ".join(args) + " failed")

def mdcreate(device, level, disks, spares=0, metadataVer=None, bitmap=False):
    argv = ["--create", device, "--run", "--level=%s" % level]
    raid_devs = len(disks) - spares
    argv.append("--raid-devices=%d" % raid_devs)
    if spares:
        argv.append("--spare-devices=%d" % spares)
    if metadataVer:
        argv.append("--metadata=%s" % metadataVer)
    if bitmap:
        argv.append("--bitmap=internal")
    argv.extend(disks)
    
    try:
        mdadm(argv)
    except MDRaidError as msg:
        raise MDRaidError("mdcreate failed for %s: %s" % (device, msg))

def mddestroy(device):
    args = ["--zero-superblock", device]

    try:
        mdadm(args)
    except MDRaidError as msg:
        raise MDRaidError("mddestroy failed for %s: %s" % (device, msg))

def mdadd(device):
    args = ["--incremental", "--quiet"]
    args.append(device)

    try:
        mdadm(args)
    except MDRaidError as msg:
        raise MDRaidError("mdadd failed for %s: %s" % (device, msg))

def mdactivate(device, members=[], super_minor=None, uuid=None):
    if super_minor is None and not uuid:
        raise MDRaidError("mdactivate requires either a uuid or a super-minor")
    
    if uuid:
        identifier = "--uuid=%s" % uuid
    else:
        identifier = ""

    args = ["--assemble", device, identifier, "--run"]
    args += members

    try:
        mdadm(args)
    except MDRaidError as msg:
        raise MDRaidError("mdactivate failed for %s: %s" % (device, msg))

def mddeactivate(device):
    args = ["--stop", device]

    try:
        mdadm(args)
    except MDRaidError as msg:
        raise MDRaidError("mddeactivate failed for %s: %s" % (device, msg))

def mdexamine(device):
    vars = iutil.execWithCapture("mdadm",
                                 ["--examine", "--brief", device],
                                 stderr="/dev/tty5").split()

    info = {}
    if len(vars) > 1 and vars[1].startswith("/dev/md"):
        info["device"] = vars[1]
        vars = vars[2:]
    elif len(vars) > 1:
        vars = vars[1:]

    for var in vars:
        (name, equals, value) = var.partition("=")
        if not equals:
            continue

        info[name.lower()] = value.strip()

    return info

def md_node_from_name(name):
    named_path = "/dev/md/" + name
    try:
        node = os.path.basename(os.readlink(named_path))
    except OSError as e:
        raise MDRaidError("md_node_from_name failed: %s" % e)
    else:
        return node

def name_from_md_node(node):
    md_dir = "/dev/md"
    name = None
    # It's sad, but it's what we've got.
    for link in os.listdir(md_dir):
        full_path = "%s/%s" % (md_dir, link)
        md_name = os.path.basename(os.readlink(full_path))
        log.debug("link: %s -> %s" % (link, os.readlink(full_path)))
        if md_name == node:
            name = link
            break

    if not name:
        raise MDRaidError("name_from_md_node(%s) failed" % node)

    log.debug("returning %s" % name)
    return name