#!/usr/bin/env python
"""
Daemon-Python (0.2)
Lightweight and no-nonsense POSIX daemon library
https://github.com/stackd/daemon-py

DOCUMENTATION
----------------------------------------
see README.md

LICENSE
----------------------------------------
MIT/X11, see LICENSE

DEPENDENCIES
----------------------------------------
Python 2.x.x

"""
import sys
import os
import time
import atexit
from signal import SIGTERM, SIGKILL
from argparse import ArgumentParser
sys.path.append(os.path.normpath(os.path.abspath(os.path.curdir)) )
from vispa.server import Server

VERSION = '1.0'

class Daemon(object):
    """ A generic daemon class for Python 2.x.x
    
    Usage: subclass the Daemon class and override the run() method
    """
    def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
        self.stdin = stdin
        self.stdout = stdout
        self.stderr = stderr
        self.pidfile = pidfile
    
    def daemonize(self):
        """UNIX double fork mechanism. 
        
        See Stevens' "Advanced Programming in the UNIX Environment" for details (ISBN 0201563177).
        """
        
        try: 
            pid = os.fork() 
            if pid > 0:
                # exit first parent
                sys.exit(0) 
        except OSError, e: 
            sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)
    
        # decouple from parent environment
        #os.chdir("/") 
        os.setsid() 
        os.umask(0) 
    
        # do second fork
        try: 
            pid = os.fork() 
            if pid > 0:
                # exit from second parent
                sys.exit(0) 
        except OSError, e: 
            sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1) 
    
        # redirect standard file descriptors
        sys.stdout.flush()
        sys.stderr.flush()
        si = file(self.stdin, 'r')
        so = file(self.stdout, 'a+')
        se = file(self.stderr, 'a+', 0)
        os.dup2(si.fileno(), sys.stdin.fileno())
        os.dup2(so.fileno(), sys.stdout.fileno())
        os.dup2(se.fileno(), sys.stderr.fileno())
    
        # write pidfile
        atexit.register(self.delpid)
        pid = str(os.getpid())
        file(self.pidfile,'w+').write("%s\n" % pid)
    
    def delpid(self):
        os.remove(self.pidfile)

    def start(self):
        """Start the daemon."""
        
        #Check for a pidfile to see if the daemon is already running.
        try:
            pf = file(self.pidfile,'r')
            pid = int(pf.read().strip())
            pf.close()
        except IOError:
            pid = None
    
        if pid:
            message = "pidfile %s already exists. %s running?\n"
            sys.stderr.write(message % (self.pidfile, self.__class__.__name__))
            sys.exit(1)
        
        # Start the daemon
        self.daemonize()
        self.run()

    def stop(self):
        """Stop the daemon."""
        
        #Get the pid from the pidfile.
        try:
            pf = file(self.pidfile,'r')
            pid = int(pf.read().strip())
            pf.close()
        except IOError:
            pid = None
    
        if not pid:
            message = "pidfile %s does not exist. %s not running?\n"
            sys.stderr.write(message % (self.pidfile, self.__class__.__name__))
            return # not an error in a restart

        # Try killing the daemon process    
        try:
            for i in range(50):
                os.kill(pid, SIGTERM)
                time.sleep(0.1)
            print "Try killing..."
            while 1:
                os.kill(pid, SIGKILL)
                time.sleep(0.1)
        except OSError, err:
            err = str(err)
            if err.find("No such process") > 0:
                if os.path.exists(self.pidfile):
                    os.remove(self.pidfile)
            else:
                print str(err)
                sys.exit(1)

    def restart(self):
        """Restart the daemon."""
        
        self.stop()
        self.start()
        
    def status(self):
        """Return the daemon state."""
        
        # Check for a pidfile to see if the daemon is already running
        try:
            pf = file(self.pidfile,'r')
            pid = int(pf.read().strip())
            pf.close()
        except IOError:
            pid = None
    
        if pid:
            message = "%s (%s) is running.\n"
            sys.stdout.write(message % (self.__class__.__name__, self.pidfile))
        elif not pid:
            message = "pidfile %s does not exist. %s not running.\n"
            sys.stdout.write(message % (self.pidfile, self.__class__.__name__))

    def run(self):
        """Override this method when you subclass Daemon.
        
        It will be called after the process has been daemonized by 
        start() or restart().
        """
        
class VispaDaemon(Daemon):
    def __init__(self, args):
        Daemon.__init__(self, os.path.join(args.vardir, 'vispad.pid'), stdout=os.path.join(args.vardir, 'vispad.out.txt'), stderr=os.path.join(args.vardir, 'vispad.err.txt'))
        self.args = args
        
    def run(self):
        Server(args).run()

def parse_commandline():
    parser = ArgumentParser()
    parser.add_argument('-c', '--config-dir', dest='configdir', default=os.path.expanduser('~/.vispa-%s' % VERSION),
                      help='Directory containing configuration files '\
                      '(default: ~/.vispa-%s)' % VERSION)
    parser.add_argument('-d', '--data-dir', dest='vardir', default=os.path.expanduser('~/.vispa-%s' % VERSION),
                      help='Directory containing server '\
                      'data and cache files (default: ~/.vispa-%s)' % VERSION)
    parser.add_argument('-l', '--loglevel', dest='loglevel', default=None,
                      help='enable debug messages')
    parser.add_argument('action', help='action: start, stop, restart')

    return parser.parse_args()

    
if __name__ == "__main__":
    curdir = os.path.normpath(os.path.abspath(os.path.curdir))
    args = parse_commandline()
    daemon = VispaDaemon(args)
    if 'start' == args.action:
        daemon.start()
    elif 'stop' == args.action:
        daemon.stop()
    elif 'restart' == args.action:
        daemon.restart()
    else:
        print "Unknown action!"
        sys.exit(2)
    sys.exit(0)
                   