import os
import re
import subprocess;
from .CronFile import CronFile

class Parser:
    def parse(self):
        cronFile = CronFile()
        crontab = ""
        
        with subprocess.Popen(["crontab", "-l"], stdout=subprocess.PIPE, encoding="utf-8") as proc:
            crontab = proc.communicate()[0]

        begin = re.search("^\s*#\s*BEGIN\((\w+)\).*$", crontab, flags=re.MULTILINE)
        while begin:
            section = begin.group(1)
            cronFile.add_fragment(None, crontab[:begin.span()[0]])

            crontab = crontab[begin.span()[1]:]
            end = re.search("^\s*#\s*END\({0}\).*$".format(section), crontab, flags=re.MULTILINE)
            if end:
                cronFile.add_fragment(section, crontab[:end.span()[0]])
                crontab = crontab[end.span()[1]:]

            begin = re.search("^\s*#\s*BEGIN\((\w+)\).*$", crontab, flags=re.MULTILINE)

        cronFile.add_fragment(None, crontab)

        return cronFile

    def update(self, cronFile):
        with subprocess.Popen(["crontab", "-"], stdin=subprocess.PIPE, encoding="utf-8") as proc:
            crontab = proc.communicate(self.render(cronFile))

    def render(self, cronFile):
        result = ""
        for fragment in cronFile.fragments:
            if fragment[0] is None:
                result += fragment[1]
            else:
                result += "\n# BEGIN({0})".format(fragment[0])
                result += fragment[1]
                result += "\n# END({0})\n".format(fragment[0])
        return result