import psycopg2

from settings import DB_CONNECTION

# Functions for reading scripts
class ScriptReader(object):

    @staticmethod
    def get_script(path, *args):
        script_file = open(path, 'rb')
        text = script_file.read().format(*args)
        script_file.close()
        return text

# Utils for messages
class Messages(object):

    @staticmethod
    def print_message(msg):
        print '---> {}'.format(msg)

# Redshift functions to send and retrieve data
class RedshiftDataManager(object):

    @staticmethod
    def execute_update(con, cur, script):
        try:
            cur.execute(script)
            con.commit()
            result = True
        except:
            con.rollback()
            result = False
        finally:
            con.close()
        return result

    @staticmethod
    def execute_query(con, cur, script):
        try:
            cur.execute(script)
            con.commit()
            result = cur.fetchall()
        except:
            con.rollback()
            result = None
        finally:
            con.close()
        return result

    @staticmethod
    def get_conn_string(db_conn):
        return "dbname='{}' port='5439' user='{}' password='{}' host='{}'".format(
            db_conn['db_name'], db_conn['db_username'], db_conn['db_password'], db_conn['db_host'])

    @staticmethod
    def create_conn(conn_string):
        return psycopg2.connect(conn_string)

    @staticmethod
    def get_conn():
        return RedshiftDataManager.create_conn(
            RedshiftDataManager.get_conn_string(DB_CONNECTION))

    @staticmethod
    def run_update(script):
        return RedshiftDataManager.execute_update(
            RedshiftDataManager.get_conn(),
            RedshiftDataManager.get_conn().cursor(),
            script)

    @staticmethod
    def run_query(script):
        return RedshiftDataManager.execute_query(
            RedshiftDataManager.get_conn(),
            RedshiftDataManager.get_conn().cursor(),
            script)