#!/usr/local/bin/python

import sys
import os
import string

def usage():
	sys.stderr.write('Usage: %s -c chunkhandlerprog -n nameprefix [-t tmpdir] [-b blocksize]\n' % sys.argv[0])
	sys.stderr.write('-c specifies the chunk handling program to handle each chunk, and is required\n')
	sys.stderr.write('-n specifies the nameprefix to use on all files created, and is required\n')
	sys.stderr.write('-t specifies the temporary directory to write files to, and is optional.  Defaults to $TMPDIR or /tmp\n')
	sys.stderr.write('-b specifies the length of files to create, and is optional.  Defaults to 1 gigabyte\n')
	sys.stderr.write('-d specifies the number of digits to use in filenames.  Defaults to 5\n')
	sys.exit(1)

# set some defaults
prog=nameprefix=""
if os.environ.has_key('TMPDIR'):
	tmpdir=os.environ['TMPDIR']
else:
	tmpdir='/tmp'
blocksize=2**(3*10)
digits=5
verbose=0

# parse options
while sys.argv[1:]:
	if sys.argv[1] == '-c' and sys.argv[2:]:
		prog=sys.argv[2]
		del sys.argv[1]
		del sys.argv[1]
	elif sys.argv[1] == '-n' and sys.argv[2:]:
		nameprefix=sys.argv[2]
		del sys.argv[1]
		del sys.argv[1]
	elif sys.argv[1] == '-t' and sys.argv[2:]:
		tmpdir=sys.argv[2]
		del sys.argv[1]
		del sys.argv[1]
	elif sys.argv[1] == '-b' and sys.argv[2:]:
		blocksize=string.atoi(sys.argv[2])
		del sys.argv[1]
		del sys.argv[1]
	elif sys.argv[1] == '-b' and sys.argv[2:]:
		digits=string.atoi(sys.argv[2])
		del sys.argv[1]
		del sys.argv[1]
	elif sys.argv[1] == '-v':
		verbose = 1
		del sys.argv[1]
	else:
		usage()

# verify options
if nameprefix == '' or prog == '':
	sys.stderr.write('-n and -c are both required options\n')
	usage()

# pad a number with leading zeros, converting it from an integer to a
# string
def pad(n):
	s = str(n)
	while len(s) < digits:
		s = '0' + s
	return s

blockno=0
while 1:
	if verbose:
		sys.stderr.write('Reading block %d\n' % blockno)
	block = sys.stdin.read(blocksize)
	if not block:
		break
	if verbose:
		sys.stderr.write('Read block of length %d\n' % len(block))
	filename = "%s/%s.%s" % (tmpdir, nameprefix, pad(blockno))
	if verbose:
		sys.stderr.write('Writing file %s\n' % filename)
	file = open(filename, "w")
	file.write(block)
	file.close()
	command = "%s %s" % (prog, filename)
	if verbose:
		sys.stderr.write('Performing command %s\n' % command)
	# retval is likely the shell return value * 256, but 0 is still 0, and
	# nonzero is still nonzero
	#os.system('echo '+command+' | od -cx')
	retval = os.system(command)
	if retval == 0:
		if verbose:
			sys.stderr.write('Command executed successfully\n')	
	else:
		sys.stderr.write('Error executing %s\n' % command)
		sys.stderr.write('Return value from command was %s\n' % str(retval))
		sys.stderr.write('Abnormal termination\n')
		sys.exit(1)
	if verbose:
		sys.stderr.write('Deleting %s\n' % filename)
	os.unlink(filename)
	blockno += 1

if verbose:
	sys.stderr.write('Normal termination\n')
sys.exit(0)