"""
Script de clonage des bases de données mariaDb depuis le
serveur de production vers le serveur local
(requiert python 3.6+)

> Configuration: settings.yml

Usage:
  clonedb.py [-v] [-y] [<dbname>]
  clonedb.py (-h | --help)
  clonedb.py --version

Options:
  -y, --yes       Do not ask for confirmation
  -h --help       Show this screen.
  --version       Show version.

@author: olivier.massot, 05-2020
"""
import logging
import subprocess
import sys

import yaml
from docopt import docopt
from path import Path

import logging_
from locker import Lockfile, AlreadyRunning
from mysql import MySqlServer

__VERSION__ = "0.1"

HERE = Path(__file__).parent

# Start logger
logger = logging.getLogger('clonedb')
logging_.start("clonedb", replace=True)

# Load settings
with open(HERE / 'settings.yml', 'r') as f:
    SETTINGS = yaml.load(f, Loader=yaml.FullLoader)

# FIX the default ascii encoding on some linux dockers...
sys.stdout = open(sys.stdout.fileno(), mode='w', encoding='utf8', buffering=1)

# Utilities
def _format_cmd(cmd):
    if type(cmd) is list:
        return " ".join(cmd)
    return cmd


def _run_process(cmds):
    logger.debug("Run: %s", " ".join(map(str, cmds)))
    logpipe = logging_.LogPipe('clonedb')
    try:
        # noinspection PyTypeChecker
        p = subprocess.run(cmds, shell=False, stdin=sys.stdin, stdout=logpipe, stderr=logpipe)
        if p.returncode != 0:
            logger.error("Process was terminated by signal %s", p.returncode)
            raise RuntimeError()

    except (OSError, RuntimeError) as e:
        logger.error("Execution failed: %s", e)
        raise RuntimeError(f"An error happened at runtime: {e}")

    finally:
        logpipe.close()


class SshTunnel:
    def __init__(self, host, port=22, user="root", key_file="~/.ssh/id_rsa"):
        self.host = host
        self.port = port
        self.user = user
        self.key_file = key_file

    def call(self, cmd):
        ssh_call = ["ssh",
                    "-i", self.key_file,
                    "-p", str(self.port),
                    "-o", "StrictHostKeyChecking=no",
                    f"{self.user}@{self.host}",
                    ]

        ssh_cmd = ssh_call + cmd
        _run_process(ssh_cmd)


def clonedb(ssh_tunnel, remote_mysql, local_mysql, dbname, options):
    logger.info(f"*** Cloning {dbname} ***")
    logger.debug(f"From {remote_mysql}")
    logger.debug(f"To {local_mysql}")

    dump_cmd = ["mysqldump",
                "--single-transaction",
                "-u", remote_mysql.username,
                f"--password={remote_mysql.password}",
                "--add-drop-database",
                "--compress",
                dbname]

    restore_cmd = ["mysql",
                   "-h", local_mysql.host,
                   "-P", str(local_mysql.port),
                   "-u", local_mysql.username,
                   f"--password={local_mysql.password}",
                   "-D", dbname]

    cloning_cmd = dump_cmd + ['|'] + restore_cmd

    try:
        ssh_tunnel.call(cloning_cmd)
        logger.info("> the database was successfully cloned")
    except RuntimeError:
        logger.error(f"<!> An error happened while cloning the '{dbname}' database")


def ask_confirmation(msg):
    logger.debug('Ask for confirmation...')
    msg += "\nWould you like to continue? (yes/no)"
    while 1:
        answer = input(msg)
        if answer in ('oui', 'yes', 'y', 'o'):
            logger.debug(f"> user confirmed by answering '{answer}'")
            return True
        elif answer in ('non', 'no', 'n'):
            logger.debug(f"> user cancelled by answering '{answer}'")
            return False
        else:
            msg = "The answer could'nt be understood. Continue? (yes/no)"


def main(dbnames, prompt=True):
    ssh_tunnel = SshTunnel(**SETTINGS['ssh'])
    remote_mysql = MySqlServer(**SETTINGS['remote'])
    local_mysql = MySqlServer(**SETTINGS['local'])

    if prompt:
        # Ask for confirmation
        msg = f"""The followind databases will be cloned
from '{remote_mysql}' to '{local_mysql}':
> {', '.join(dbnames)}
"WARNING: the existing local databases will be replaced"""

        if not ask_confirmation(msg):
            logger.info("-- Operation cancelled by user --")
            return

    # start to clone
    for dbname in dbnames:
        options = SETTINGS['databases'].get(dbname, None) or {}
        clonedb(ssh_tunnel, remote_mysql, local_mysql, dbname, options)


if __name__ == '__main__':

    # parse CLI arguments
    arguments = docopt(__doc__, help=__doc__, version=__VERSION__)
    prompt = "--yes" in arguments
    dbname = arguments.get('dbname', None)

    print('\n')
    logger.info("Start db cloning utility...")
    logger.debug(f"Arguments: {arguments}")
    logger.debug(f"Settings: {SETTINGS}")

    # database to clone
    if arguments.get('<dbname>', None):
        dbnames = [arguments['<dbname>']]
    else:
        dbnames = list(SETTINGS['databases'])

    with Lockfile(path=HERE / '.clonedb.lock',
                  on_error=lambda: logger.critical("A cloning process is already running, please wait...")):
        main(dbnames, prompt)