#!/usr/bin/env python

#   Destripe 0.1
#   Copyright 2009 Vasili Revelas - vasili (at the domain) techcollective (dot) com

#   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 3 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/>.


import sys
import signal

class Destriper(object):
    def __init__(self, chunk_size, device1, device2, outfile):
        self.bytes_copied = 0L
        self.chunk_size = chunk_size
        self.device1 = device1
        self.device2 = device2
        self.outfile = outfile

    def destripe(self):
        file1 = open(self.device1, 'rb')
        file2 = open(self.device2, 'rb')
        output_file = open(self.outfile, 'wb')
        amount_written = self.chunk_size * 2
        while True:
            chunk1 = file1.read(chunk_size)
            if not chunk1:
                break
            chunk2 = file2.read(chunk_size)
            output_file.write(chunk1)
            output_file.write(chunk2)
            self.bytes_copied += amount_written
        file1.close()
        file2.close()
        output_file.close()

    def print_progress(self, *args):
        print str(self.bytes_copied / (1024*1024)) + "MB copied to " + self.outfile

def usage():
    print "Usage: %s chunk_size disk1 disk2 output_file" % sys.argv[0]
    print "Use -h or --help for help."

def help():
    print "chunk_size  : The RAID 0 stripe size in bytes. Can be used with a k suffix for kilobytes (1024 bytes)"
    print "disk1       : The first disk in the array."
    print "disk2       : The second disk in the array."
    print "output_file : The file to write the reassembled image to. Can also be a block device."
    print ""
    print "A progress message is printed when the program receives a USR1 signal."

if __name__ == '__main__':
    if ("-h" in sys.argv) or ("--help" in sys.argv):
        usage()
        help()
        sys.exit(0)
    if len(sys.argv) > 5:
        print "Error: Too many arguments."
        usage()
        sys.exit(1)
    try:
        chunk_size = sys.argv[1]
        device1 = sys.argv[2]
        device2 = sys.argv[3]
        outfile = sys.argv[4]
    except IndexError:
        print "Error: Not enough arguments."
        usage()
        sys.exit(1)
    multiplier = 1
    if chunk_size[-1].lower() == "k":
        multiplier = 1024
        chunk_size = chunk_size[:-1]
    try:
        chunk_size = int(chunk_size) * multiplier
    except ValueError:
        print "Error: chunk_size must be an integer with an optional 'k' suffix. Use -h or --help for help."
        usage()
        sys.exit(1)
    destriper = Destriper(chunk_size, device1, device2, outfile)
    signal.signal(signal.SIGUSR1, destriper.print_progress)
    try:
        destriper.destripe()
    except KeyboardInterrupt:
        print "\rGoodbye."
        sys.exit(1)