#!/usr/bin/python

import sys
from subprocess import check_output
import shlex

def helpAndQuit():
    print "svnbinsearch -r[low_revision]:[high_revision] [local_svn_repo]"
    print "\tlow/high_revision: The revision range to binary search. Low revision should work, high revision should not."
    print "\t                   This argument string gets passed, in its entirety, to our svn log command."
    print "\t                   ex: svnbinsearch -r167165:167344"
    print "\tlocal_svn_repo: Your local SVN working copy. If not given, it uses the current directory."
    sys.exit(1)

def askUserIfWorks(rev):
    response = ''
    while len(response) == 0 or (response[0] != 'Y' and response[0] != 'N'):
        sys.stdout.write("Try revision {0}... does it work? (input Y/N): ".format(rev))
        response = raw_input().strip().upper()

    return response[0] == 'Y'

svn_revision_range = ''
svn_repo = '.'

if len(sys.argv) < 2:
    helpAndQuit()
else:
    svn_revision_range = sys.argv[1]

if len(sys.argv) >= 3:
    svn_repo = sys.argv[2]

svn_argstr = "svn log -q {0} {1}".format(svn_revision_range, svn_repo)
print "Getting revision list with `{0}`...".format(svn_argstr)
svn_output = check_output(shlex.split(svn_argstr))

svn_output = svn_output.split("\n")

rev_list = []
for s in svn_output:
    if len(s) == 0:
        continue
    if s[0] == '-':
        continue
    spacePos = s.find(' ')
    if spacePos == -1:
        continue
    rev_list.append(s[:spacePos])

lo = 0
hi = len(rev_list)-1
while (lo <= hi):
    mid = lo + (hi - lo) / 2
    doesWork = askUserIfWorks(rev_list[mid])
    if doesWork:
        lo = mid+1
    else:
        hi = mid-1

if hi < 0:
    print "Error: the lowest revision given ({0}) does not work!".format(rev_list[0])
elif lo >= len(rev_list):
    print "Error: the highest revision given ({0}) works fine!".format(rev_list[-1])
else:
    print "Problem revision is {0}!".format(rev_list[lo])