"""WordOps MySQL core classes."""
import os
from os.path import expanduser

import pymysql
from pymysql import DatabaseError, Error, connections

from wo.core.logging import Log
from wo.core.variables import WOVar


class MySQLConnectionError(Exception):
    """Custom Exception when MySQL server Not Connected"""
    pass


class StatementExcecutionError(Exception):
    """Custom Exception when any Query Fails to execute"""
    pass


class DatabaseNotExistsError(Exception):
    """Custom Exception when Database not Exist"""
    pass


class WOMysql():
    """Method for MySQL connection"""

    def connect(self):
        # Makes connection with MySQL server
        try:
            if os.path.exists('/etc/mysql/conf.d/my.cnf'):
                connection = pymysql.connect(
                    read_default_file='/etc/mysql/conf.d/my.cnf')
            else:
                connection = pymysql.connect(read_default_file='~/.my.cnf')
            return connection
        except ValueError as e:
            Log.debug(self, str(e))
            raise MySQLConnectionError
        except pymysql.err.InternalError as e:
            Log.debug(self, str(e))
            raise MySQLConnectionError

    def dbConnection(self, db_name):
        try:
            if os.path.exists('/etc/mysql/conf.d/my.cnf'):
                connection = pymysql.connect(
                    db=db_name, read_default_file='/etc/mysql/conf.d/my.cnf')
            else:
                connection = pymysql.connect(
                    db=db_name, read_default_file='~/.my.cnf')

            return connection
        except pymysql.err.InternalError as e:
            Log.debug(self, str(e))
            raise MySQLConnectionError
        except DatabaseError as e:
            if e.args[1] == '#42000Unknown database \'{0}\''.format(db_name):
                raise DatabaseNotExistsError
            else:
                raise MySQLConnectionError
        except Exception as e:
            Log.debug(self, "[Error]Setting up database: \'" + str(e) + "\'")
            raise MySQLConnectionError

    def execute(self, statement, errormsg='', log=True):
        # Get login details from /etc/mysql/conf.d/my.cnf
        # & Execute MySQL query
        connection = WOMysql.connect(self)
        log and Log.debug(self, "Executing MySQL Statement : {0}"
                          .format(statement))
        try:
            cursor = connection.cursor()
            sql = statement
            cursor.execute(sql)

            # connection is not autocommit by default.
            # So you must commit to save your changes.
            connection.commit()
        except AttributeError as e:
            Log.debug(self, str(e))
            raise StatementExcecutionError
        except Error as e:
            Log.debug(self, str(e))
            raise StatementExcecutionError
        finally:
            connection.close()

    def backupAll(self, fulldump=False):
        import subprocess
        try:
            Log.info(self, "Backing up database at location: "
                     "/var/lib/wo-backup/mysql")
            # Setup Nginx common directory
            if not os.path.exists('/var/lib/wo-backup/mysql'):
                Log.debug(self, 'Creating directory'
                          '/var/lib/wo-backup/mysql')
                os.makedirs('/var/lib/wo-backup/mysql')
            if not fulldump:
                db = subprocess.check_output(
                    ["/usr/bin/mysql "
                     "-Bse \'show databases\'"],
                    universal_newlines=True,
                    shell=True).split('\n')
                for dbs in db:
                    if dbs == "":
                        continue
                    Log.info(self, "Backing up {0} database".format(dbs))
                    p1 = subprocess.Popen(
                        "/usr/bin/mysqldump {0} --max_allowed_packet=1024M "
                        "--single-transaction ".format(dbs),
                        stdout=subprocess.PIPE,
                        stderr=subprocess.PIPE, shell=True)
                    p2 = subprocess.Popen(
                        "/usr/bin/zstd -T0 -c > "
                        "/var/lib/wo-backup/mysql/{0}{1}.sql.zst"
                        .format(dbs, WOVar.wo_date),
                        stdin=p1.stdout, shell=True)
                    # Allow p1 to receive a SIGPIPE if p2 exits
                    p1.stdout.close()
                    output = p1.stderr.read()
                    p1.wait()
                    if p1.returncode == 0:
                        Log.debug(self, "done")
                    else:
                        Log.error(self, output.decode("utf-8"))
            else:
                Log.info(self, "Backing up all databases")
                p1 = subprocess.Popen(
                    "/usr/bin/mysqldump --all-databases "
                    "--max_allowed_packet=1024M "
                    "--single-transaction --events",
                    stdout=subprocess.PIPE,
                    stderr=subprocess.PIPE, shell=True)
                p2 = subprocess.Popen(
                    "/usr/bin/zstd -T0 -c > "
                    "/var/lib/wo-backup/mysql/fulldump-{0}.sql.zst"
                    .format(WOVar.wo_date),
                    stdin=p1.stdout, shell=True)
                p1.stdout.close()
                output = p1.stderr.read()
                p1.wait()
                if p1.returncode == 0:
                    Log.debug(self, "done")
                else:
                    Log.error(self, output.decode("utf-8"))

        except Exception as e:
            Log.error(self, "Error: process exited with status %s"
                            % e)

    def check_db_exists(self, db_name):
        try:
            if WOMysql.dbConnection(self, db_name):
                return True
        except DatabaseNotExistsError as e:
            Log.debug(self, str(e))
            return False
        except MySQLConnectionError as e:
            Log.debug(self, str(e))
            return False