import pyodbc
from datetime import datetime,  timedelta

SERVER = '<server name or IP>'
DATABASE = '<db name>'
USERNAME = '<db username>'
PASSWORD = '<db password>'
PORT='1433'

connection_string = f'DRIVER={{ODBC Driver 17 for SQL Server}};SERVER={SERVER};PORT={PORT};DATABASE={DATABASE};UID={USERNAME};PWD={PASSWORD};TrustServerCertificate=yes'
db_connection = pyodbc.connect(connection_string) 
cursor = db_connection.cursor()

#Set default values 
sign_in_date_time_check = datetime.fromtimestamp(0)
card_code_check = False
 
while True:
    #Get from card when inputed - card id will be a string
    card_code_input = input()

    date_time_now = datetime.now()
    time_now = date_time_now.time()

    #Find user in the database used only for checking that the user exists
    cursor.execute('SELECT SignInTime FROM EmployeeRegister WHERE CardID = ?', card_code_input)
    db_user_entry = cursor.fetchall()
    db_sign_in_time = db_user_entry[0][0]

    #if no user info is returned and thus user does not exist reset loop
    if not db_user_entry:
        print('User does not exist')
        continue

    #Prevent double tap of card
    if card_code_input == card_code_check and sign_in_date_time_check > date_time_now:
        print('Double tap prevented')
        continue

    #Save sign in/sign out card code and time + 5 seconds
    sign_in_date_time_check = date_time_now + timedelta(seconds = 50)
    card_code_check = card_code_input


    #If user is signed in sign them out
    if db_sign_in_time:
        print('Signed Out')
        cursor.execute('UPDATE EmployeeRegister SET SignInTime = ? WHERE CardID = ?', None, card_code_input)
        db_connection.commit()
        continue
    
    print('Database updated')
    #Update database with sign in time
    cursor.execute('UPDATE EmployeeRegister SET SignInTime = ? WHERE CardID = ?', time_now, card_code_input)
    db_connection.commit()