import MySQLdb

class Database():

    def __init__(self, hostname, dbname):
        self.hostname = hostname
        self.schema = dbname
        self.conn = None
        self.cur = None
        self.dcur = None
        self.error = None

    def connect(self, dbuser, dbpass):
        if self.conn:
            return True
        MySQLdb.paramstyle = 'pyformat'
        try:
            self.conn = MySQLdb.connect(host=self.hostname, db=self.schema,
                user=dbuser, passwd=dbpass, charset='utf8')
        except MySQLdb.Error as e:
            self.error = e
            return False
        self.conn.autocommit(False)
        self.cur = self.conn.cursor()
        self.dcur = self.conn.cursor(MySQLdb.cursors.DictCursor)
        return True

    def connect_local(self):
        # connection via local unix socket
        if self.conn:
            return True
        MySQLdb.paramstyle = 'pyformat'
        try:
            self.conn = MySQLdb.connect(host='localhost', db=self.schema,
                unix_socket='/run/mysqld/mysqld.sock', charset='utf8')
        except MySQLdb.Error as e:
            self.error = e
            return False
        self.cur = self.conn.cursor()
        self.dcur = self.conn.cursor(MySQLdb.cursors.DictCursor)
        return True
        
    def disconnect(self):
        self.cur.close()
        self.dcur.close()
        self.conn.close()

    def is_connected(self):
        return self.conn.open

    def last_error(self):
        if not self.error:
            return(0, '')
        code = self.error.args[0]
        text = self.error.args[1]
        self.error = None
        return(code, text)

    def execute_write(self, sql, values=(), expected_rows=None):
        """
        Execute an INSERT, UPDATE, or DELETE statement.
        expected_rows:
            None = do not check the number of affected rows
            1    = expect exactly one affected row
            0    = expect no affected rows
        """
        try:
            self.cur.execute(sql, values)
        except MySQLdb.Error as e:
            self.rollback()
            self.error = e
            return False
        if (expected_rows is not None and self.cur.rowcount != expected_rows):
            self.rollback()
            self.error = RuntimeError(
                "Expected {} affected rows, got {}".format(
                    expected_rows,
                    self.cur.rowcount
                )
            )
            return False
        self.error = None
        return True