#!/usr/bin/python -W ignore::DeprecationWarning
# A BackupPC script to archive a host's files to Amazon S3.
#
# Point $Conf{ArchiveClientCmd} at me.
# Requires python-boto
#
# Usage: BackupPC_archiveHost tarCreatePath splitPath parPath host bkupNum \
#             compPath fileExt splitSize outLoc parFile share
#
# Create secrets.py such that it has:
# accesskey = 'amazon aws access key'
# sharedkey = 'amazon aws shared key'
# gpgsymmetrickey = 'gpg symmetric key -- make it good, but do not lose it'
# speedfile = '/path/to/a/speed-limit-file'

import base64
import glob
import md5
import os
import secrets
import socket
import sys
import time

from subprocess import *

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

import logging
import logging.handlers

logger = logging.getLogger('')
loghandler = logging.handlers.SysLogHandler('/dev/log',
                facility=logging.handlers.SysLogHandler.LOG_DAEMON)
logformatter = logging.Formatter('%(filename)s: %(levelname)s: %(message)s')
loghandler.setFormatter(logformatter)
logger.addHandler(loghandler)
logger.setLevel(logging.DEBUG)

# classes
class MyKey(Key):
    def _compute_md5(self, fp):
        """
        @type fp: file
        @param fp: File pointer to the file to MD5 hash
        
        @rtype: string
        @return: MD5 Hash of the file in fp
        """
        m = md5.new()
        try:
            s = fp.fastread(self.BufferSize)
        except AttributeError:
            s = fp.read(self.BufferSize)
        while s:
            m.update(s)
            try:
                s = fp.fastread(self.BufferSize)
            except AttributeError:
                s = fp.read(self.BufferSize)
        self.md5 = m.hexdigest()
        self.base64md5 = base64.encodestring(m.digest())
        if self.base64md5[-1] == '\n':
            self.base64md5 = self.base64md5[0:-1]
        self.size = fp.tell()
        fp.seek(0)

class SlowFile:
    def __init__(self, name, mode='rb', speed=19200):
        """Open a rate-limited filehandle.  Supports read for now.
        name, mode as normal; speed in bytes per second"""

        self.name = name
        self.mode = mode
        self.speed = speed

        self.fd = open(self.name, self.mode)

        self.closed = False
        self.encoding = None

        self.delayfactor = 1
        self.lastblocktargettime = 0

        self.lastdebug = 0

    def close(self):
        self.closed = True
        return self.fd.close()

    def fastread(self, len=1024):
        return self.fd.read(len)

    def flush(self):
        return self.fd.flush()

    def fileno(self):
        return self.fd.fileno()

    def isatty(self):
        return self.fd.isatty()

    def tell(self):
        return self.fd.tell()

    def read(self, len=1024):
        if not self.fd:
            raise IOError

        starttime = time.time()

        if self.lastblocktargettime == 0:
            # first time through
            pass
        elif starttime < self.lastblocktargettime:
            # we're early
            sleepfor = self.lastblocktargettime - starttime
            time.sleep(sleepfor)
        else:
            # we're late; something got slow.
            lateness = starttime - self.lastblocktargettime
            if lateness > 0.2:
                self.delayfactor += min(0.5, lateness)
                logger.debug('%.2f seconds late (congestion?); setting delayfactor to %.2f' % (lateness, self.delayfactor))

        targetspeed = self.speed/float(self.delayfactor)
        self.lastblocktargettime = time.time() + len/float(targetspeed)

        if time.time() > self.lastdebug+60:
            if self.delayfactor > 1:
                # reduce the penalty a bit
                self.delayfactor -= 0.2
                targetspeed = self.speed/float(self.delayfactor)
                self.lastblocktargettime = time.time() + len/float(targetspeed)

            if self.delayfactor < 1:
                self.delayfactor = 1
            if self.delayfactor > 20:
                self.delayfactor = 20

            logger.debug('Target %i bytes/second (%i kilobits/second), delay factor %.2f, block len %i' % (targetspeed, targetspeed*8/1024, self.delayfactor, len))

            if hasattr(secrets, 'speedfile'):
                try:
                    newkbits = int(open(secrets.speedfile, 'r').readline())
                    newspeed = int((newkbits/float(8))*1024)
                    if newspeed != self.speed:
                        self.delayfactor = 1
                        self.speed = newspeed
                        logger.debug('Setting new speed! %i bytes/second' % newspeed)
                        self.lastblocktargettime = 0
                except IOError:
                    logger.debug('IO Error opening semaphore file')
                except ValueError:
                    logger.debug('Semaphore file invalid')

            self.lastdebug = time.time()

        return self.fd.read(len)

    def seek(self, offset, mode=0):
        self.delayfactor = 1
        return self.fd.seek(offset, mode)

    def write(self, data):
        raise NotImplementedError

# functions
def is_exe(fpath):
    return os.path.exists(fpath) and os.access(fpath, os.X_OK)

def encrypt_file(filename, key, compress='/bin/cat'):
    compressmap = {'cat': 'none', 'gzip': 'ZLIB', 'bzip2': 'BZIP2'}
    if os.path.basename(compress) in compressmap.keys():
        compress_algo = compressmap[os.path.basename(compress)]
    else:
        compress_algo = 'none'

    cmd =  ['/usr/bin/gpg', '--batch', '--no-tty']
    cmd.extend(['--compress-algo', compress_algo])
    cmd.extend(['--output', '%s.gpg' % filename])
    cmd.extend(['--passphrase-fd', '0'])
    cmd.extend(['--symmetric', filename])

    if is_exe(cmd[0]):
        logger.info('Encrypting %s (compression: %s)' % (filename, compress_algo))
        logger.debug(`cmd`)
    else:
        logger.error('%s is not an executable file!' % cmd[0])

    proc = Popen(cmd, stdin=PIPE, stdout=PIPE)
    proc.communicate(key)

    if os.path.exists(filename + '.gpg'):
        oldfilesize = os.path.getsize(filename)
        newfilesize = os.path.getsize(filename + '.gpg')
        compressed = ((oldfilesize - newfilesize) / float(oldfilesize)) * 100
        logger.info('%s shrunk by %.2f%% (%i -> %i bytes)' % (filename, compressed, oldfilesize, newfilesize))
        os.unlink(filename)
        return filename + '.gpg'
    else:
        logger.error('%s.gpg does not exist' % filename)
        raise Exception

def open_s3(accesskey, sharedkey, host):
    conn = S3Connection(accesskey, sharedkey, is_secure=False)
    mybucketname = (accesskey + '-bkup-' + host).lower()
    try:
        bucket = conn.get_bucket(mybucketname)
    except boto.exception.S3ResponseError:
        logging.info('Creating bucket %s' % mybucketname)
        bucket = conn.create_bucket(mybucketname)
    bucket.set_acl('private')
    return bucket

def handle_progress(transmitted, pending):
    logging.debug('%i of %i bytes transmitted (%.2f%%)' % (transmitted, pending, (transmitted/float(pending))*100))

def send_file(bucket, filename, cmd, mesg):
    basefilename = os.path.basename(filename)
    if bucket.get_key(basefilename):
        logging.error('Duplicate filename %s! I hope that is OK.' % basefilename)
    k = MyKey(bucket)
    k.key = basefilename
    if cmd: k.set_metadata('backuppc-cmd', cmd)
    if mesg: k.set_metadata('backuppc-mesg', mesg)
    logging.info('Uploading %s...' % basefilename)

    fd = SlowFile(name=filename, mode='rb')

    putHeaders = {'x-amz-storage-class': 'REDUCED_REDUNDANCY'}

    k.set_contents_from_file(fd, headers=putHeaders, cb=handle_progress)

    return k

if __name__ == '__main__':
    # Read in arguments
    if len(sys.argv) != 12:
        sys.stderr.write("Usage: %s tarCreatePath splitPath parPath host bkupNum \
              compPath fileExt splitSize outLoc parFile share\n" % sys.argv[0])
        sys.exit(1)
    else:
        tarCreate   = sys.argv[1]
        splitPath   = sys.argv[2]
        parPath     = sys.argv[3]
        host        = sys.argv[4]
        bkupNum     = int(sys.argv[5])
        compPath    = sys.argv[6]
        fileExt     = sys.argv[7]
        splitSize   = int(sys.argv[8])
        outLoc      = sys.argv[9]
        parfile     = sys.argv[10]
        share       = sys.argv[11]

    for i in [tarCreate, compPath, splitPath, parPath]:
        if i is not '' and not is_exe(i):
            sys.stderr.write('Error: %s is not an executable program\n' % i)
            sys.exit(1)

    # open s3 connection
    bucket = open_s3(secrets.accesskey, secrets.sharedkey, host)

    beginning = time.time()

    mesg = "Writing archive for host %s, backup #%i" % (host, bkupNum)
    if splitSize > 0 and is_exe(splitPath):
        mesg += ', split into %i byte chunks' % splitSize
    if secrets.gpgsymmetrickey:
        mesg += ', encrypted with secret key'

    logger.info(mesg)
    sys.stdout.write(time.strftime('%d-%H:%M:%S') + ": " + mesg + '\n')
    sys.stdout.flush()

    # Prepare the pipeline
    if share == '*':
        share = '\*'

    cmd = '%s -t -h %s -n %i -s %s . ' % (tarCreate, host, bkupNum, share)

    if splitSize > 0 and is_exe(splitPath):
        filehead = '%s/%s.%i.tar.' % (outLoc, host, bkupNum)
        fileglob = filehead + '*'
        cmd += '| %s -b %i - %s' % (splitPath, splitSize, filehead)
    else:
        fileglob = '%s/%s.%i.tar' % (outLoc, host, bkupNum)
        cmd += '> %s' % fileglob
        filehead = fileglob + '.'

    # is there already evidence of this having been done before?
    if glob.glob('%s/%s.*.tar.*' % (outLoc, host)):
        logger.info('Evidence of failed execution run prior!  Finishing it.')
        somefile = os.path.basename(glob.glob('%s/%s.*.tar.*' % (outLoc, host))[0])
        keyparts = somefile.split('.')
        encrypted = split = tarred = final = False
        if keyparts[-1] == 'gpg':
            keyparts.pop()
        if keyparts[-1] != 'tar' and len(keyparts[-1]) is 2:
            keyparts.pop()
        if keyparts[-1] == 'tar':
            keyparts.pop()

        bkupNum = int(keyparts.pop())

        filehead = '%s/%s.%i.tar.' % (outLoc, host, bkupNum)
        fileglob = filehead + '*'

        mesg = "Continuing upload for host %s, backup #%i" % (host, bkupNum)
        if splitSize > 0 and is_exe(splitPath):
            mesg += ', split into %i byte chunks' % splitSize
        if secrets.gpgsymmetrickey:
            mesg += ', encrypted with secret key'

        logger.info(mesg)
        sys.stdout.write(time.strftime('%d-%H:%M:%S') + ": " + mesg + '\n')
        sys.stdout.flush()
    else:
        logger.debug('Executing %s' % cmd)

        returncode = os.system(cmd)

        if returncode != 0:
            logger.error('%s died with exit code %i' % (cmd, returncode))
            sys.exit(1)

    logging.info('Beginning post-processing of %i files from %s #%i' % (len(glob.glob(fileglob)), host, bkupNum))

    for i in sorted(glob.glob(fileglob)):
        sending_start = time.time()
        if secrets.gpgsymmetrickey and not i.endswith('.gpg'):
            sendfile = encrypt_file(i, secrets.gpgsymmetrickey, compPath)
        else:
            # either encryption is off, or the file is already encrypted
            sendfile = i
        encrypt_seconds = time.time() - sending_start

        # create some output so backuppc doesn't time out
        sys.stdout.write("%s: Sending %s to S3...\n" % (time.strftime('%d-%H:%M:%S'), sendfile))
        sys.stdout.flush()

        retry_count = 0
        max_retries = 10

        while retry_count <= max_retries:
            try:
                key = send_file(bucket, sendfile, cmd, mesg)
                key.set_acl('private')
                key.close()
                retry_count = max_retries+1
            except (boto.exception.S3ResponseError, socket.error), e:
                retry_count += 1
                sleeptime = 2**retry_count
                err = 'Encountered exception %s, retrying in %i seconds (%i/%i)' % (e, sleeptime, retry_count, max_retries)
                logger.error(err)
                sys.stdout.write(time.strftime('%d-%H:%M:%S') + ': ' + err + '\n')
                sys.stdout.flush()
                time.sleep(sleeptime)

        size = os.path.getsize(sendfile)

        os.unlink(sendfile)

        sending_seconds = time.time() - sending_start

        bytespersecond = size / (sending_seconds - encrypt_seconds)

        sys.stdout.write('%s: File sent.  Total time %i seconds, crypto time %i seconds, transfer speed %i bytes/second.\n' % (time.strftime('%d-%H:%M:%S'), sending_seconds, encrypt_seconds, bytespersecond))
        sys.stdout.flush()

    # finalize the backup
    key = MyKey(bucket)
    key.key = '%sCOMPLETE' % os.path.basename(filehead)
    key.set_contents_from_string('%s %s "%s"' % (beginning, time.time(), mesg))
    key.close()