import os
import sys
import logging, logging.handlers

def checkpid(pid):
    try:
        os.kill(pid, 0)
        return True
    except OSError, info:
        if info.errno == 3:
            return False
        else:
            return True

class Daemon:
    name = 'basedaemon'
    loggingsubject = 'BaseDaemon logging'
    logdir = '/home/lampotila/logs'
    
    def __init__(self):
        self.formatter = logging.Formatter("---------------------\n%(asctime)s %(process)s %(pathname)s:%(lineno)d:\n%(message)s\n",
                                           "%Y-%m-%dT%H:%M:%S")
        
        self.emailhandler = logging.handlers.SMTPHandler('mail.inet.fi', 'lampotila@warri1.dyndns.org',
                                                         ['jpa@lm.mail.kapsi.fi'], self.loggingsubject)
        self.emailhandler.setLevel(logging.ERROR)
        self.emailhandler.setFormatter(self.formatter)
        
        logfile = os.path.join(self.logdir, self.name + ".log")
        self.filehandler = logging.handlers.RotatingFileHandler(logfile, 'a', 100 * 1024, backupCount = 3)
        self.filehandler.setLevel(logging.INFO)
        self.filehandler.setFormatter(self.formatter)
        
        self.logger = logging.getLogger()
        self.logger.addHandler(self.emailhandler)
        self.logger.addHandler(self.filehandler)
        self.logger.setLevel(logging.INFO)
        
        self.pidfile = os.path.join(self.logdir, self.name + ".pid")
    
    def run(self):
        pass
    
    def start(self):
        if os.path.exists(self.pidfile):
            oldpid = int(open(self.pidfile, 'r').read())
        
            if checkpid(oldpid):
                print "Already running under pid %d!" % oldpid
                return
        
        if len(sys.argv) > 1 and sys.argv[1] == '-d':
            self.screenhandler = logging.handlers.StreamHandler()
            self.screenhandler.setLevel(logging.DEBUG)
            self.screenhandler.setFormatter(self.formatter)
            self.logger.addHandler(self.screenhandler)
            self.run()
            return

        if os.fork() > 0:
            sys.exit(0)

        os.chdir('/')
        os.setsid()
        os.umask(0)

        if os.fork() > 0:
            sys.exit(0)

        self.logger.info('Started, PID: %d' % os.getpid())
        
        open(self.pidfile, "w").write("%d\n" % os.getpid())

        try:
            self.run()
        except:
            self.logger.critical("Main thread crashed", exc_info = True)
        
        self.logger.info("Server shut down")