#! /usr/bin/env python

import commands, os, re
from optparse import OptionParser

## Read command line opts
parser = OptionParser()
parser.add_option("-l", "--maxlength", dest="maxlength", help="set max path length to MAXLENGTH", metavar="MAXLENGTH")
parser.add_option("-s", "--step", dest="step", help="try increasing MAXLENGTH in units of STEP to get an acceptable short path", metavar="STEP")
(options, args) = parser.parse_args()

## Set max length of path string
MAXLENGTH = 15
if options.maxlength != None: MAXLENGTH = int(options.maxlength)

STEP = 5
if options.step != None: STEP = int(options.step)

## Get path and handle stale file handle error
path = commands.getoutput("pwd")
if re.search("pwd:\s+error", path) != None:
    print "...",

else:
    ## Do HOME -> ~ substitution
    shortpath = re.sub(os.environ["HOME"], "~", path)
    
    ## Truncate the subst path to match the MAXLENGTH param
    ## If it won't work, increase MAXLENGTH by STEP and try again recursively
    pathlen = len(shortpath)
    if len(shortpath) > MAXLENGTH:
        subpathlen1, subpathlen2 = 0, 0
        while subpathlen2 == 0:
            while subpathlen1 < MAXLENGTH:
                subpathlen2 = subpathlen1
                subpathlen1 = pathlen - shortpath[:pathlen-subpathlen1].rfind('/')
            #print MAXLENGTH, subpathlen2
            MAXLENGTH = MAXLENGTH + STEP

        ## Obtain the shortened path (NB. subpathlen > 0)
        if shortpath[0] == "~":
            shortpath = "~/..." + shortpath[-subpathlen2:]
        else:
            shortpath = "..." + shortpath[-subpathlen2:]
    print shortpath