#!/usr/bin/python -W ignore::DeprecationWarning
#
# Script to manage S3-stored backups
#
# Copyright (c) 2009-2011 Ryan S. Tucker
#
# 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 optparse
import os
import pwd
import secrets
import sys
import time

from boto.s3.connection import S3Connection
from boto.s3.key import Key
import boto.exception

from collections import defaultdict
from math import log10
from subprocess import *

def open_s3(accesskey, sharedkey):
    return S3Connection(accesskey, sharedkey)

def iter_backup_buckets(conn, name=None):
    """Yields an iterator of buckets that probably have backups in them."""

    bucket_prefix = secrets.accesskey.lower() + '-bkup-'
    if name:
        bucket_prefix += name

    buckets = conn.get_all_buckets()

    for bucket in buckets:
        if bucket.name.startswith(bucket_prefix):
            yield bucket

def list_backups(bucket):
    """Returns a dict of backups in a bucket, with dicts of:
    {hostname (str):
        {Backup number (int):
            {'date': Timestamp of backup (int),
             'keys': A list of keys comprising the backup,
             'hostname': Hostname (str),
             'backupnum': Backup number (int),
             'finalized': 0, or the timestamp the backup was finalized
            }
        }
    }
    """

    backups = {}

    for key in bucket.list():
        keyparts = key.key.split('.')
        encrypted = split = tarred = final = False

        if keyparts[-1] == 'COMPLETE':
            final = True
            keyparts.pop() # back to tar
            keyparts.pop() # back to backup number
        else:
            if keyparts[-1] == 'gpg':
                encrypted = True
                keyparts.pop()

            if keyparts[-1] != 'tar' and len(keyparts[-1]) is 2:
                split = True
                keyparts.pop()

            if keyparts[-1] == 'tar':
                tarred = True
                keyparts.pop()

        nextpart = keyparts.pop()
        if nextpart == 'COMPLETE':
            print("Stray file: %s" % key.key)
            continue
        backupnum = int(nextpart)
        hostname = '.'.join(keyparts)

        lastmod = time.strptime(key.last_modified, '%Y-%m-%dT%H:%M:%S.000Z')

        if hostname in backups.keys():
            if not backupnum in backups[hostname].keys():
                backups[hostname][backupnum] = {'date': lastmod, 'hostname': hostname, 'backupnum': backupnum, 'finalized': 0, 'keys': [], 'finalkey': None, 'finalized_age': -1}
        else:
            backups[hostname] = {backupnum: {'date': lastmod, 'hostname': hostname, 'backupnum': backupnum, 'finalized': 0, 'keys': [], 'finalkey': None, 'finalized_age': -1}}
        if final:
            backups[hostname][backupnum]['finalized'] = lastmod
            backups[hostname][backupnum]['finalkey'] = key
            timestamp = time.mktime(lastmod)
            delta = int(time.time() - timestamp + time.timezone)
            backups[hostname][backupnum]['finalized_age'] = delta 
        else:
            if lastmod < backups[hostname][backupnum]['date']:
                backups[hostname][backupnum]['date'] = lastmod
            backups[hostname][backupnum]['keys'].append(key)
    return backups

def backups_by_age(conn, name=None):
    "Returns a dict of {hostname: [(backupnum, age), ...]}"
    results = defaultdict(list)
    for bucket in iter_backup_buckets(conn, name=name):
        for hostname, backups in list_backups(bucket).items():
            for backupnum, statusdict in backups.items():
                results[hostname].append((backupnum, statusdict['finalized_age']))
    return results

def choose_host_to_backup(agedict, target_count=2):
    "Takes a dict from backups_by_age, returns a hostname to back up."

    host_scores = defaultdict(int)

    for hostname, backuplist in agedict.items():
        bl = sorted(backuplist, key=lambda x: x[1])
        if len(bl) > 0 and bl[0][1] == -1:
            # unfinalized backup alert
            host_scores[hostname] += 200
            bl.pop(0)
        if len(bl) >= target_count:
            host_scores[hostname] -= 100
        host_scores[hostname] -= len(bl)
        if len(bl) > 0:
            # age of oldest backup helps score
            oldest = bl[0]
            host_scores[hostname] += log10(oldest[1])
            # recency of newest backup hurts score
            newest = bl[-1]
            host_scores[hostname] -= log10(max(1, (oldest[1] - newest[1])))

    for candidate, score in sorted(host_scores.items(), key=lambda x: x[1], reverse=True):
        yield (candidate, score)

def iter_urls(keyset, expire=86400):
    """Given a list of keys and an optional expiration time (in seconds),
       returns an iterator of URLs to fetch to reassemble the backup."""

    for key in keyset:
        yield key.generate_url(expires_in=expire)

def make_restore_script(backup, expire=86400):
    """Returns a quick and easy restoration script to restore the given system,
       requires a backup, and perhaps expire"""

    myhostname = backup['hostname']
    mybackupnum = backup['backupnum']
    myfilecount = len(backup['keys'])
    myfriendlytime = time.strftime('%Y-%m-%d at %H:%M GMT', backup['date'])
    myexpiretime = time.strftime('%Y-%m-%d at %H:%M GMT', time.gmtime(time.time()+expire))
    myexpiretimestamp = time.time()+expire

    output = []

    output.append('#!/bin/sh\n')
    output.append('# Restoration script for %s backup %s,\n' % (myhostname, mybackupnum))
    output.append('# a backup created on %s.\n' % (myfriendlytime))
    output.append('# To use: bash scriptname /path/to/put/the/files\n\n')
    output.append('# WARNING: THIS FILE EXPIRES AFTER %s\n' % (myexpiretime))
    output.append('if [ "`date +%%s`" -gt "%i" ];\n' % (myexpiretimestamp))
    output.append('    then echo "Sorry, but this restore script is too old.";\n')
    output.append('         exit 1;\n')
    output.append('fi\n\n')
    output.append('if [ -z "$1" ];\n')
    output.append('   then echo "Usage: ./scriptname /path/to/restore/to";\n')
    output.append('        exit 1;\n')
    output.append('fi\n\n')
    output.append('# Check the destination\n')
    output.append('if [ ! -d $1 ];\n')
    output.append('    then echo "Target $1 does not exist!";\n')
    output.append('         exit 1;\n')
    output.append('fi\n\n')
    output.append('if [ -n "`ls --almost-all $1`" ];\n')
    output.append('    then echo "Target $1 is not empty!";\n')
    output.append('         exit 1;\n')
    output.append('fi\n\n')
    output.append('# cd to the destination, create a temporary workspace\n')
    output.append('cd $1\n')
    output.append('mkdir .restorescript-scratch\n\n')
    output.append('# retrieve files\n')

    mysortedfilelist = []
    for key in backup['keys']:
        output.append('wget -O $1/.restorescript-scratch/%s "%s"\n' % (key.name, key.generate_url(expires_in=expire)))
        mysortedfilelist.append('.restorescript-scratch/' + key.name)
    mysortedfilelist.sort()

    output.append('\n# decrypt files\n')
    output.append('gpg --decrypt-files << EOF\n')
    output.append('\n'.join(mysortedfilelist))
    output.append('\nEOF\n')

    output.append('\n# join and untar files\n')
    output.append('cat .restorescript-scratch/*.tar.?? | tar -xf -\n\n')

    output.append('echo "DONE!  Have a nice day."\n##\n')

    return output

def start_archive(hosts):
    "Starts an archive operation for a list of hosts."
    if 'LOGNAME' in os.environ:
        username = os.environ['LOGNAME']
    else:
        try:
            username = pwd.getpwuid(os.getuid()).pw_name
        except KeyError:
            username = 'nobody'

    scriptdir = os.path.dirname(sys.argv[0])

    cmd = [os.path.join(scriptdir, 'BackupPC_archiveStart'), 'archives3',
           username]
    cmd.extend(hosts)

    proc = Popen(cmd)
    proc.communicate()

def main():
    # check command line options
    parser = optparse.OptionParser(
        usage="usage: %prog [options] [list|delete|script]",
        description="" +
            "Companion maintenance script for BackupPC_archiveHost_s3. " +
            "By default, it assumes the 'list' command, which displays all " +
            "of the backups currently archived on S3.  The 'delete' command " +
            "is used to delete backups.  The 'script' command produces a " +
            "script that can be used to download and restore a backup."
        )
    parser.add_option("-H", "--host", dest="host",
                      help="Name of backed-up host")
    parser.add_option("-b", "--backup-number", dest="backupnum",
                      help="Backup number")
    parser.add_option("-a", "--age", dest="age",
                      help="Delete backups older than AGE days")
    parser.add_option("-k", "--keep", dest="keep",
                      help="When used with --age, keep this many recent backups (default=1)", default=1)
    parser.add_option("-f", "--filename", dest="filename",
                      help="Output filename for script")
    parser.add_option("-x", "--expire", dest="expire",
                      help="Maximum age of script, default 86400 seconds")
    parser.add_option("-t", "--test", dest="test", action="store_true",
                      help="Test mode; don't actually delete")
    parser.add_option("-u", "--unfinalized", dest="unfinalized",
                      action="store_true", help="Consider unfinalized backups")
    parser.add_option("-s", "--start-backups", dest="start",
                      action="store_true", help="When used with --age, start backups for hosts with fewer than keep+1 backups")

    (options, args) = parser.parse_args()

    conn = open_s3(secrets.accesskey, secrets.sharedkey)

    if options.backupnum and not options.host:
        parser.error('Must specify --host when specifying --backup-number')

    if options.backupnum:
        options.backupnum = int(options.backupnum)

    # TODO: refactor this somewhere better
    backups_by_age_list = backups_by_age(conn)
    score_iter = choose_host_to_backup(backups_by_age_list, target_count=int(options.keep))
    
    if len(args) == 0:
        args.append('list')

    if len(args) > 1:
        parser.error('Too many arguments.')

    if args[0] != 'delete' and options.age:
        parser.error('--age only makes sense with delete')

    if options.start and not (args[0] == 'delete' and options.age):
        parser.error('--start-backups only makes sense with delete and --age')

    if args[0] != 'script' and (options.expire or options.filename):
        parser.error('--expire and --filename only make sense with script')

    if args[0] in ['list', 'script', 'delete']:
        if options.host:
            buckets = iter_backup_buckets(conn, name=options.host)
            if not buckets:
                parser.error('No buckets found for host "%s"' % options.host)
        else:
            buckets = iter_backup_buckets(conn)
            if not buckets:
                parser.error('No buckets found!')
    else:
        parser.error('Invalid option: %s' + args[0])

    if args[0] == 'script':
        if not options.host:
            parser.error('Must specify --host to generate a script for')

        backups = list_backups(buckets.next())

        if not options.backupnum and options.unfinalized:
            # assuming highest number
            options.backupnum = max(backups[options.host].keys())
        elif not options.backupnum:
            # assuming highest finalized number
            options.backupnum = 0
            for backup in backups[options.host].keys():
                if backups[options.host][backup]['finalized'] > 0:
                    options.backupnum = max(options.backupnum, backup)
            if options.backupnum == 0:
                parser.error('No finalized backups found!  Try --unfinalized if you dare')

        backup = backups[options.host][options.backupnum]

        if not options.expire:
            options.expire = "86400"

        if options.filename:
            fd = open(options.filename, 'w')
            fd.writelines(make_restore_script(backup, expire=int(options.expire)))
        else:
            sys.stdout.writelines(make_restore_script(backup, expire=int(options.expire)))
    elif args[0] == 'list':
        sys.stdout.write('%25s | %5s | %20s | %5s\n' % ("Hostname", "Bkup#", "Age", "Files"))
        sys.stdout.write('-'*72 + '\n')
        for bucket in buckets:
            hostnames = list_backups(bucket)
            for hostname in hostnames.keys():
                backups = hostnames[hostname]
                for backupnum in sorted(backups.keys()):
                    filecount = len(backups[backupnum]['keys'])
                    datestruct = backups[backupnum]['date']
                    if backups[backupnum]['finalized'] > 0:
                        inprogress = ''
                    else:
                        inprogress = '*'
                    timestamp = time.mktime(datestruct)
                    delta = int(time.time() - timestamp + time.timezone)
                    if delta < 3600:
                        prettydelta = '%i min ago' % (delta/60)
                    elif delta < 86400:
                        prettydelta = '%i hr ago' % (delta/3600)
                    else:
                        days = int(delta/60/60/24)
                        if days == 1:
                            s = ''
                        else:
                            s = 's'
                        prettydelta = '%i day%s ago' % (days, s)

                    sys.stdout.write('%25s | %5i | %20s | %5i%s\n' % (hostname, backupnum, prettydelta, filecount, inprogress))
        sys.stdout.write('* == not yet finalized (Age == time of last activity)\n')
    elif args[0] == 'delete':
        if options.age:
            maxage = int(options.age)*86400
            needs_backup = []
            for bucket in buckets:
                hostnames = list_backups(bucket)
                for hostname in hostnames.keys():
                    backups = hostnames[hostname]
                    backuplist = sorted(backups.keys())
                    oldest_timestamp = -1
                    # remove a number of recent backups from the delete list
                    to_ignore = int(options.keep)
                    while to_ignore > 0:
                        if len(backuplist) > 0:
                            backupnum = backuplist.pop()
                            filecount = len(backups[backupnum]['keys'])
                            datestruct = backups[backupnum]['date']
                            timestamp = time.mktime(datestruct)
                            delta = int(time.time() - timestamp + time.timezone)
                            if backups[backupnum]['finalized'] == 0:
                                sys.stdout.write('Ignoring in-progress backup %s #%i\n' % (hostname, backupnum))
                            else:
                                sys.stdout.write('Keeping recent backup %s #%i (%i files, age %.2f days)\n' % (hostname, backupnum, filecount, delta/86400.0))
                                if timestamp < oldest_timestamp:
                                    oldest_timestamp = timestamp
                                to_ignore -= 1
                        else:
                            to_ignore = 0
                    deletes = 0
                    for backupnum in backuplist:
                        filecount = len(backups[backupnum]['keys'])
                        if backups[backupnum]['finalized'] > 0:
                            datestruct = backups[backupnum]['finalized']
                        else:
                            datestruct = backups[backupnum]['date']
                        timestamp = time.mktime(datestruct)
                        delta = int(time.time() - timestamp + time.timezone)
                        if delta > maxage:
                            if not options.unfinalized and backups[backupnum]['finalized'] == 0:
                                sys.stdout.write('Bypassing unfinalized backup %s #%i (%i files, age %.2f days)\n' % (hostname, backupnum, filecount, delta/86400.0))
                            else:
                                sys.stdout.write('Deleting %s #%i (%i files, age %.2f days)...' % (hostname, backupnum, filecount, delta/86400.0))
                                for key in backups[backupnum]['keys']:
                                    if options.test:
                                        sys.stdout.write('*')
                                    else:
                                        key.delete()
                                        sys.stdout.write('.')
                                if backups[backupnum]['finalkey']:
                                    if options.test:
                                        sys.stdout.write('X')
                                    else:
                                        backups[backupnum]['finalkey'].delete()
                                        sys.stdout.write('!')
                                sys.stdout.write('\n')
                                deletes += 1
                    if (len(backuplist)-deletes) < int(options.keep):
                        needs_backup.append((oldest_timestamp, hostname))
            #if options.start and len(needs_backup) > 0:
            #    sys.stdout.write('Starting archive operation for host: %s\n' % sorted(needs_backup)[0][1])
            #    start_archive([sorted(needs_backup)[0][1]])
            if options.start:
                for candidate, score in score_iter:
                    if score > 0:
                        sys.stdout.write('Starting archive operation for host: %s (score=%g)\n' % (candidate, score))
                        start_archive([candidate])
                        break

        elif options.host and options.backupnum:
            for bucket in buckets:
                hostnames = list_backups(bucket)
                if options.host in hostnames.keys():
                    if options.backupnum not in hostnames[options.host].keys():
                        parser.error('Backup number %i not found' % options.backupnum)
                    toast = hostnames[options.host][options.backupnum]
                    filecount = len(toast['keys'])
                    if toast['finalized'] > 0:
                        datestruct = toast['finalized']
                    else:
                        datestruct = toast['date']

                    datestruct = toast['date']
                    timestamp = time.mktime(datestruct)
                    delta = int(time.time() - timestamp + time.timezone)

                    if options.unfinalized and toast['finalized'] > 0:
                        sys.stdout.write('Bypassing finalized backup %s #%i (%i files, age %.2f days)\n' % (hostname, backupnum, filecount, delta/86400.0))
                    else:
                        sys.stdout.write('Deleting %s #%i (%i files, age %.2f days)...' % (options.host, options.backupnum, filecount, delta/86400.0))
                        for key in toast['keys']:
                            if options.test:
                                sys.stdout.write('*')
                            else:
                                key.delete()
                                sys.stdout.write('.')
                        if toast['finalkey']:
                            if options.test:
                                sys.stdout.write('X')
                            else:
                                toast['finalkey'].delete()
                                sys.stdout.write('!')
                        sys.stdout.write('\n')
                else:
                    parser.error('Host %s not found' % options.host)
        else:
            parser.error('Need either an age or a host AND backup number.')

if __name__ == '__main__':
    main()