##############################################################################
#
# Copyright (c) 2002 Zope Foundation and Contributors.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE
#
##############################################################################
"""
Zope signal handlers for clean shutdown, restart and log rotation.
"""

import logging
import os
import sys

import Lifetime

from .threads import dump_threads


logger = logging.getLogger("Z2")

if os.name == 'nt':
    try:
        from WinSignalHandler import SignalHandler
    except ImportError:
        msg = ('Can not install signal handlers.  Please install '
               '(or upgrade) your pywin32 installation '
               '(https://sf.net/projects/pywin32)')
        logger.warning(msg)
        SignalHandler = None
else:
    from SignalHandler import SignalHandler

def shutdownFastHandler():
    """Shutdown cleanly on SIGTERM. This is registered first,
       so it should be called after all other handlers."""
    logger.info("Shutting down fast")
    Lifetime.shutdown(0,fast=1)


def shutdownHandler():
    """Shutdown cleanly on SIGINT. This is registered first,
       so it should be called after all other handlers."""
    logger.info("Shutting down")
    sys.exit(0)

def restartHandler():
    """Restart cleanly on SIGHUP. This is registered first, so it
       should be called after all other SIGHUP handlers."""
    logger.info("Restarting")
    Lifetime.shutdown(1)


def showStacks():
    """Dump a stracktrace of all threads on the console."""
    print dump_threads()
    sys.stdout.flush()


class LogfileReopenHandler:
    """Reopen log files on SIGUSR2.

    This is registered first, so it should be called after all other
    SIGUSR2 handlers.
    """
    def __init__(self, loggers):
        self.loggers = [log for log in loggers if log is not None]

    def __call__(self):
        for log in self.loggers:
            log.reopen()
        logger.info("Log files reopened successfully")

# On Windows, a 'reopen' is useless - the file can not be renamed
# while open, so we perform a trivial 'rotate'.
class LogfileRotateHandler:
    """Rotate log files on SIGUSR2. Only called on Windows. This is 
       registered first, so it should be called after all other SIGUSR2 
       handlers."""
    def __init__(self, loggers):
        self.loggers = [log for log in loggers if log is not None]

    def __call__(self):
        logger.debug("Log files rotation starting...")
        for log in self.loggers:
            for f in log.handler_factories:
                handler = f()
                if hasattr(handler, 'rotate') and callable(handler.rotate):
                    handler.rotate()
        logger.info("Log files rotation complete")

def registerZopeSignals(loggers):
    from signal import SIGTERM, SIGINT
    try:
        from signal import SIGHUP, SIGUSR1, SIGUSR2
    except ImportError:
        # Windows doesn't have these (but also doesn't care what the exact
        # numbers are)
        SIGHUP = 1
        SIGUSR1 = 10
        SIGUSR2 = 12

    if not SignalHandler:
        return
    SignalHandler.registerHandler(SIGTERM, shutdownFastHandler)
    SignalHandler.registerHandler(SIGINT, shutdownHandler)
    if os.name != 'nt':
        SignalHandler.registerHandler(SIGHUP, restartHandler)
        SignalHandler.registerHandler(SIGUSR1, showStacks)
        SignalHandler.registerHandler(SIGUSR2, LogfileReopenHandler(loggers))
    else:
        # no restart handler on windows.
        # Log files get 'rotated', not 'reopened'
        SignalHandler.registerHandler(SIGUSR2, LogfileRotateHandler(loggers))
