#!/usr/bin/python
import cgi, os, os.path, time, re, xml.sax.saxutils

lockFileName = "files/todolock"
fileName = "files/todos.xml"

while(os.path.exists(lockFileName)):
    time.sleep(.25)

lockFileHandle = open(lockFileName, "w")
lockFileHandle.write("locked")
lockFileHandle.close()

form = cgi.FieldStorage()
idToUpdate = int(form.getfirst("todoID"))
nextAction = form.getfirst("nextAction")


oldFile = open(fileName, 'r')
oldFileLines = oldFile.readlines()
oldFile.close()

usedIDs = []

lineIndex = 0
todoIDre = re.compile(r'^<todo todoID="%d"' % idToUpdate)
for line in oldFileLines:
    todoIDmatch = todoIDre.match(line)
    if (todoIDmatch):
        nextActionMatch = re.match(r'^(<todo.*?todoID="%d".*?nextAction=)("|\').*?\2(.*)$' % idToUpdate, line, re.IGNORECASE)
        if (nextActionMatch):
            oldFileLines[lineIndex] = "%s%s%s\n" % (nextActionMatch.group(1), xml.sax.saxutils.quoteattr(nextAction), nextActionMatch.group(3))
        break
    lineIndex = lineIndex + 1

newFile = open(fileName, 'w')
for line in oldFileLines:
    newFile.write(line)
newFile.close()

os.remove(lockFileName)

print "Content-type: text/plain\n\n"
print "done."