import csv
import psycopg2
from datetime import datetime
import os
import time
HDR_DFND = False


def connect_db():
    return psycopg2.connect("dbname='test' user='%s' host='localhost'" % os.environ['USER'])


def add_to_csv(writer, time_delta_del_insert, time_delta_update=None):
    global HDR_DFND
    if not HDR_DFND:
        writer.writerow(['Time to Delete and Insert', 'Time to Update'])
        HDR_DFND = True
    writer.writerow([time_delta_del_insert, time_delta_update])


def do_the_things(conn):
    cursor = conn.cursor()
    with open('sql_test.csv', 'w') as output_file:
        writer = csv.writer(output_file, delimiter=',')
        while True:
            start_delete_insert = datetime.now()
            cursor.execute("""DELETE FROM my_tb WHERE name = 'test';""")
            cursor.execute("""INSERT INTO my_tb VALUES ('test', 1);""")
            conn.commit()
            stop_delete_insert = datetime.now()
            start_update = datetime.now()
            cursor.execute(
                """UPDATE my_tb SET name = 'test', value = 1 WHERE name = 'test';""")
            conn.commit()
            stop_update = datetime.now()
            timed_ms_del_insert = (stop_delete_insert - start_delete_insert).__str__().split('.')[1]
            timed_ms_update = (stop_update - start_update).__str__().split('.')[1]
            add_to_csv(writer, timed_ms_del_insert, timed_ms_update)
            time.sleep(1)


def main():
    conn = connect_db()
    do_the_things(conn)


if __name__ == "__main__":
    main()