def checkTransaction(day, value, t_type, dscr):
    '''
        The function checks if the parameters match the description
    :param day:
    :param value:
    :param t_type:
    :param dscr:
    :return: True - parameters are ok
        False - if they don't
    '''
    if(day < 1 or day > 30):
        return False
    if(value < 1):
        return False
    if(t_type != 'in' and t_type != 'out'):
        return False
    return True

def constructTransaction(transactions, day, value, t_type, dscr):
    '''
    The function takes list and gives it the parameters of the transaction
    :param day: int
    :param value: int
    :param t_type: str
    :param dscr: str
    :return: list of 4 elements if the parameters are valid
        empty list if they are not
    '''
    if( checkTransaction(day, value, t_type, dscr) == False):
        print('The parameters are invalid')
    transactions.append( day )
    transactions.append( value )
    transactions.append( t_type )
    transactions.append( dscr )

def addTransaction(tees, transaction ):
    '''
    The function adds a transaction to the history
    :param tees: history of saves
    :param transaction: list of 4 parameters
    :return:
    '''
    last_save = getTransactions( tees )
    last_save.append( transaction )
    tees.append( last_save )

def getTransactions( tees ):
    '''
    The function returns the current list of transactions
    :param tees: history of saves
    :return:
    '''
    return tees[ len( tees ) - 1 ]

def checkPosition(transactions, pos):
    ''''''
    if(pos < len(transactions)):
        return True
    return False

def getPosition( transactions, pos ):
    if(checkPosition( transactions, pos ) == False):
        print('Out of range')
        return []
    return transactions[ pos ]

def printTransactions(tees):
    '''
    The function prints all the currnet transactions
    :param tees: history of saves
    :return:
    '''
    aux = getTransactions( tees )
    for i in aux:
        print( i )

def createTransaction(tees, day, value, t_type, dscr):
    '''
    The function creates a new transaction and adds it to the history
    :param tees: history of saves
    :param day:
    :param value:
    :param t_type:
    :param dscr:
    :return:
    '''
    aux = []
    constructTransaction(aux, day, value, t_type, dscr)
    addTransaction(tees, aux)

def loadTransactions( tees ):
    '''
    The function adds 10 transactions to the history
    :param tees: history of saves
    :return:
    '''
    createTransaction(tees, 1, 1000, 'in', 'verify')
    createTransaction(tees, 2, 20, 'out', 'verify')
    createTransaction(tees, 2, 489, 'out', 'verify')
    createTransaction(tees, 3, 200, 'in', 'verify')
    createTransaction(tees, 4, 300, 'out', 'verify')
    createTransaction(tees, 5, 29, 'out', 'verify')
    createTransaction(tees, 5, 2000, 'in', 'verify')
    createTransaction(tees, 5, 500, 'out', 'verify')
    createTransaction(tees, 6, 50, 'out', 'verify')
    createTransaction(tees, 7, 100, 'out', 'verify')

def readCommand():
    comm = input('command > ')
    pos = comm.find(' ')
    if pos == -1:
        return (comm, [])
    command = comm[:pos]
    parameters = comm[pos + 1:]
    parameters = parameters.split(" ")
    for i in range(len(parameters)):
        parameters[i] = parameters[i].strip()
    return (command, parameters)

def print_commands():
    print('The possible commands are: ')
    print('-> add')
    print('-> insert')
    print('-> remove')
    print('-> list')

def start( tees = []):
    pair = readCommand()
    cmd = pair[ 0 ]
    parameters = pair[ 1 ]
    if(cmd == 'list' and parameters == []):
        printTransactions( tees )
    start( tees )


def initialize():
    tees = [ [] ]
    print_commands()
    loadTransactions( tees )
    start( tees )

initialize()