#!/usr/bin/env python
#
# Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#

"""
This file contains the replication slave administration utility. It is used to
perform replication operations on one or more slaves.
"""

import logging
import optparse
import os.path
import signal
import sys

from mysql.utilities.exception import UtilError, UtilRplError
from mysql.utilities.common.options import add_verbosity
from mysql.utilities.common.options import add_failover_options, add_rpl_user
from mysql.utilities.common.options import check_server_lists
from mysql.utilities.common.server import check_hostname_alias
from mysql.utilities.common.topology import parse_failover_connections
from mysql.utilities.command.rpl_admin import RplCommands, purge_log
from mysql.utilities import VERSION_FRM

# Constants
NAME = "MySQL Utilities - mysqlfailover "
DESCRIPTION = "mysqlfailover - automatic replication health monitoring and failover"
USAGE = "%prog --master=root@localhost --discover-slaves-login=root " + \
        "--candidates=root@host123:3306,root@host456:3306 " 
_DATE_FORMAT = '%Y-%m-%d %H:%M:%S %p'
_DATE_LEN = 22

# Setup a terminal signal handler for SIGNIT
# Must use SetConsoleCtrlHandler function on Windows!
# If posix, save old terminal settings so we can restore them on exit.
try:
    # Only valid for *nix systems.
    import tty, termios
    old_terminal_settings = termios.tcgetattr(sys.stdin)
except:
    # Ok to fail for Windows
    pass

def set_signal_handler(func):
    # If posix, restore old terminal settings.
    if os.name == "nt":
        from ctypes import windll
        windll.kernel32.SetConsoleCtrlHandler(func, True)
    # Install SIGTERM signal handler
    else:
        signal.signal(signal.SIGTERM, func)

# If ctypes present, we have Windows so define the exit with decorators
try:
    import ctypes
    @ctypes.WINFUNCTYPE(ctypes.c_int, ctypes.c_uint)
    def on_exit(signal, func=None):
        logging.info("Failover console stopped with SIGTERM.")
        sys.exit(0)
except:
    def on_exit(signal, func=None):
        if os.name == "posix":
            termios.tcsetattr(sys.stdin, termios.TCSADRAIN,
                              old_terminal_settings)
        logging.info("Failover console stopped with SIGTERM.")
        sys.exit(0)

set_signal_handler(on_exit)

# Setup the command parser
parser = optparse.OptionParser(
    version=VERSION_FRM.format(program=os.path.basename(sys.argv[0])),
    description=DESCRIPTION,
    usage=USAGE,
    add_help_option=False)
parser.add_option("--help", action="help")

# Setup utility-specific options:
add_failover_options(parser)

# Interval for continuous mode
parser.add_option("--interval", "-i", action="store", dest="interval",
                  type="int", default="15", help="interval in seconds for "
                  "polling the master for failure and reporting health. "
                  "Default = 15 seconds. Lowest value is 5 seconds.")

# Add failover modes
parser.add_option("--failover-mode", "-f", action="store", dest="failover_mode",
                  type="choice", default="auto", choices=["auto", "elect",
                  "fail"], help="action to take when the master "
                  "fails. 'auto' = automatically fail to best slave, "
                  "'elect' = fail to candidate list or if no candidate meets "
                  "criteria fail, 'fail' = take no action and stop when master "
                  "fails. Default = 'auto'.")

# Add failover detection extension point
parser.add_option("--exec-fail-check", action="store", dest="exec_fail",
                  type="string", default=None, help="name of script to "
                      "execute on each interval to invoke failover")

# Add force to override registry entry
parser.add_option("--force", action="store_true", dest="force",
                  help="override the registration check on master for "
                  "multiple instances of the console monitoring the same "
                  "master.")

# Add refresh script external point
parser.add_option("--exec-post-failover", action="store", dest="exec_post_fail",
                  type="string", default=None, help="name of script to "
                  "execute after failover is complete and the utility has "
                  "refreshed the health report.")


# Add rediscover on interval
parser.add_option("--rediscover", action="store_true", dest="rediscover",
                  help="Rediscover slaves on interval. Allows console to "
                  "detect when slaves have been removed or added.")

# Add verbosity mode
add_verbosity(parser, False)

# Replication user and password
add_rpl_user(parser, None)

# Now we process the rest of the arguments.
opt, args = parser.parse_args()

# Check slaves list
check_server_lists(parser, opt.master, opt.slaves)

# Check for errors
if int(opt.interval) < 5:
    parser.error("The --interval option requires a value greater than or "
                 "equal to 5.")

# The value for --timeout needs to be an integer > 0.
try:
    if int(opt.timeout) <= 0:
        parser.error("The --timeout option requires a value greater than 0.")
except ValueError:
    parser.error("The --timeout option requires an integer value.")

if opt.master is None:
    parser.error("You must specify a master to monitor.")
    
if opt.slaves is None and opt.discover is None:
    parser.error("You must supply a list of slaves or the "
                 "--discover-slaves-login option.")
    
if opt.failover_mode == 'elect' and opt.candidates is None:
    parser.error("Failover mode = 'elect' reqiures at least one candidate.")
    
# Parse the master, slaves, and candidates connection parameters
try: 
    master_val, slaves_val, candidates_val = parse_failover_connections(opt)
except UtilRplError, e:
    print "ERROR:", e.errmsg
    exit(1)

# Check hostname alias
for slave_val in slaves_val:
    if check_hostname_alias(master_val, slave_val):
        parser.error("The master and one of the slaves are the same host and port.")
for cand_val in candidates_val:
    if check_hostname_alias(master_val, cand_val):
        parser.error("The master and one of the candidates are the same host and port.")

# Create dictionary of options
options = {
    'candidates'    : candidates_val,
    'ping'          : 3 if opt.ping is None else opt.ping,
    'verbosity'     : 0 if opt.verbosity is None else opt.verbosity,
    'before'        : opt.exec_before,
    'after'         : opt.exec_after,
    'fail_check'    : opt.exec_fail,
    'max_position'  : opt.max_position,
    'max_delay'     : opt.max_delay,
    'discover'      : opt.discover,
    'timeout'       : int(opt.timeout),
    'interval'      : opt.interval,
    'failover_mode' : opt.failover_mode,
    'logging'       : opt.log_file is not None,
    'log_file'      : opt.log_file,
    'force'         : opt.force,
    'post_fail'     : opt.exec_post_fail,
    'rpl_user'      : opt.rpl_user,
    'rediscover'    : opt.rediscover,
}

# Purge log file of old data
if opt.log_file is not None and not purge_log(opt.log_file, opt.log_age):
    parser.error("Error purging log file.")

# Setup log file
logging.basicConfig(filename=opt.log_file, level=logging.INFO,
                    format='%(asctime)s %(levelname)s %(message)s',
                    datefmt=_DATE_FORMAT)

try:
    rpl_cmds = RplCommands(master_val, slaves_val, options)
    rpl_cmds.auto_failover(opt.interval)
except UtilError, e:
    # log the error in case it was an usual exception
    logging.log(logging.CRITICAL, e.errmsg.strip(' '))  
    print "ERROR:", e.errmsg
    exit(1)
    
exit(0)

