#!/usr/bin/env python
"""
	diffback : a diff merger

	diffback is a diff merger script aimed to glue any version controls system
	with any merger application.

	(c) 2005 Brian Ray (bray@sent.com) free to use,modify,change, at your
	own risk. Leave this disclaimer.

"""

#...................................................................... 
# Source control type
SCMTYPE = 'svn'        #  'svn' or 'cvs'

#...................................................................... 
# Macintosh opendiff command
DIFFCOMMAND = 'opendiff'
DIFFARGS = ''

#...................................................................... 
# vim command (example)
# DIFFCOMMAND = 'vim'
# DIFFARGS = '-d'


#...................................................................... 
# degub settings
DEBUG = 1
DEBUGLEVEL = 0 # and above 
DEBUGTYPES = (  'Note', 'Warning', 'Cation' )


import sys,os,tempfile,traceback,re
from time import sleep


def dprint(str,level = 0 ):
	"""Wrapper to print debug messages."""
	if DEBUG == 1:

		if level <= DEBUGLEVEL:

			print "%s: %s" % (DEBUGTYPES[level] ,str)


def runit(cmd):
	"""Executes any command"""
	dprint(cmd)

	rtrncode = os.system(cmd)

	if rtrncode != 0:
		
		traceback.print_stack()

		raise Exception, "could not run command:\n\t'%s' : %s" % (cmd,rtrncode)


def checkfileisthere(filename):
	"""Checks to see if the file specified exists."""
	if not os.path.isfile(filename):
		
		traceback.print_stack()

		raise Exceptions, "could not find file:\n\t'%s'" % filename


def getsufx(filename):
	"""Trys and gets the dot suffix"""
	reo = re.compile(r'\.[^\.]*$')

  	res = reo.search(filename)

	if res != None:
	
		return res.group()
	
	else:

		return '.txt'


def maketmpcopy(filename):
	"""
	creates a temp file of BASE

	@returns str filepath
	"""
	checkfileisthere(filename)

	sufx = getsufx(filename)	

	tempfilepath = tempfile.mktemp(suffix=sufx,prefix='BASE_')

	if SCMTYPE == 'svn':

		cmd = "svn cat -r BASE %s > %s" % (filename,tempfilepath)

	elif SCMTYPE == 'cvs':

		cmd = "cvs update -p %s > %s" % (filename,tempfilepath)
	
	runit(cmd)

	return runopendiff, ( tempfilepath , filename ), False


def removefile(inf):
	"""Removes a file, as last step"""
	os.unlink(inf)

	return None, None, True


def waitonhitkey(inf):
	"""Waits for user input EOL"""
	print "Diff done. hit <Enter>"	

	raw_input();
		
	return removefile, inf, False


def runopendiff(inf):
	"""Run open diff command"""
	cmd = "%s %s %s %s" % (DIFFCOMMAND,DIFFARGS,inf[0], inf[1])

	runit(cmd)
	# wait a could seconds
	sleep(3)

	return waitonhitkey, inf[0], False


def checkargs():
	"""
	Parses commandline arguments and takes 
	the appropriate action.
	"""
	print sys.argv
	print "-"*72	
	len = sys.argv.__len__()

	if len > 1:

		return maketmpcopy,(sys.argv[len-1]) # len -1 should give last argument

	else:

		traceback.print_stack()
		raise Exception, "\tUsage :\n\t  ./svnfm <filetodiff>" 


if __name__ == "__main__":

	try:

		func,impargs = checkargs()

		done = False

		while done != True:

			func,impargs,isdone = func(impargs)

			done = isdone
		
		print "Done."	
	
	except Exception,e:

		print '_'*72
		print '-'*72

		print str(e)