#!/usr/bin/python

#    The MIT License (MIT)

#    Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>

#    Permission is hereby granted, free of charge, to any person obtaining a copy
#    of this software and associated documentation files (the "Software"), to deal
#    in the Software without restriction, including without limitation the rights
#    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#    copies of the Software, and to permit persons to whom the Software is
#    furnished to do so, subject to the following conditions:

#    The above copyright notice and this permission notice shall be included in
#    all copies or substantial portions of the Software.

#    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#    THE SOFTWARE.

import argparse
import os
import xattr
import errno


def main():
    parser = argparse.ArgumentParser(description='audit a mergerfs mount for inconsistencies')
    parser.add_argument('device',type=str,help='device')
    parser.add_argument('-v','--verbose',action='store_true',help='print details of audit item')
    parser.add_argument('-f','--fix',choices=['manual','newest'],help='fix policy')

    args = parser.parse_args()

    if args.fix:
        args.verbose = True

    if args.fix == 'manual':
        fix = manual_fix
    elif args.fix == 'newest':
        fix = newest_fix
    else:
        fix = noop_fix

    try:
        controlfile = os.path.join(args.device,".mergerfs")
        version = xattr.getxattr(controlfile,"user.mergerfs.version")

        for (dirname,dirnames,filenames) in os.walk(args.device):
            fulldirpath = os.path.join(args.device,dirname)
            check_consistancy(fulldirpath,args.verbose,fix)
            for filename in filenames:
                fullpath = os.path.join(fulldirpath,filename)
                check_consistancy(fullpath,args.verbose,fix)

    except IOError as e:
        if e.errno == errno.ENOENT:
            print("%s is not a mergerfs device" % args.device)
        else:
            print("IOError: %s" % e.strerror)


def check_consistancy(fullpath,verbose,fix):
    paths = xattr.getxattr(fullpath,"user.mergerfs.allpaths").split('\0')
    if len(paths) > 1:
        stats = [os.stat(path) for path in paths]
        if stats_different(stats):
            print("mismatch: %s" % fullpath)
            if verbose:
                print_stats(paths,stats)
            fix(paths,stats)


def noop_fix(paths,stats):
    pass


def manual_fix(paths,stats):
    done = False
    while not done:
        try:
            value = input('Which is correct?: ')
            setstat(stats[value % len(paths)],paths)
            done = True
        except NameError:
            print("Input error: enter a value between 0 and %d" % (len(paths)-1))
        except Exception as e:
            print("%s" % e)
            done = True


def newest_fix(paths,stats):
    stats.sort(key=lambda stat: stat.st_mtime)
    try:
        setstat(stats[-1],paths)
    except Exception as e:
        print("%s" % e)


def setstat(stat,paths):
    for path in paths:
        try:
            os.chmod(path,stat.st_mode)
            os.chown(path,stat.st_uid,stat.st_gid);
            print("setting %s > uid: %d gid: %d mode: %o" %
                  (path,stat.st_uid,stat.st_gid,stat.st_mode))
        except Exception as e:
            print("%s" % e)


def stats_different(stats):
    base = stats[0]
    for stat in stats:
        if ((stat.st_mode == base.st_mode) and
            (stat.st_uid  == base.st_uid)  and
            (stat.st_gid  == base.st_gid)):
            continue
        return True
    return False


def print_stats(Files,Stats):
    for i in xrange(0,len(Files)):
        print("- %i: %s > uid: %s; gid: %s; mode: %o" %
              (i,Files[i],Stats[i].st_uid,Stats[i].st_gid,Stats[i].st_mode))


if __name__ == "__main__":
    main()