import gzip
from logging.handlers import RotatingFileHandler
import shutil
import os


class GunZipRotatingFileHandler(RotatingFileHandler):
    def doRollover(self):
        if self.stream:
            self.stream.close()
            self.stream = None

        if self.backupCount > 0:
            # Rotate existing backup files
            for i in range(self.backupCount - 1, 0, -1):
                sfn = self.rotation_filename("%s.%d.gz" % (self.baseFilename, i))
                dfn = self.rotation_filename("%s.%d.gz" % (self.baseFilename, i + 1))
                if os.path.exists(sfn):
                    if os.path.exists(dfn):
                        os.remove(dfn)
                    os.rename(sfn, dfn)

            # Compress current log file to .1.gz
            dfn = self.rotation_filename(self.baseFilename + ".1.gz")
            if os.path.exists(dfn):
                os.remove(dfn)

            if os.path.exists(self.baseFilename):
                with open(self.baseFilename, "rb") as f_in:
                    with gzip.open(dfn, "wb") as f_out:
                        shutil.copyfileobj(f_in, f_out)
                os.remove(self.baseFilename)

        if not self.delay:
            self.stream = self._open()