### TODO - load the data from csv file         ### use csv.reader to append rows of filename to data

IN PYTHON - please help with lines beginning with ###TODO

import csv
import random as rand
import sys

# define functions
        
def load_csv_data(filename):
    """
    load the data from csv file
    returns a tuple containing two lists:
    col_names: first row of csv file (list of strings)
    row_data: all other rows of csv file (list of list of strings)
    
    if error is encountered reading filename, returns -1
    """
    try:
        data = []
        ### TODO - load the data from csv file
        ### use csv.reader to append rows of filename to data
    
    except:
        print("Error loading data.")
        return -1

    # if successful, return tuple of column names and row data
    col_names = data[0]
    row_data = data[1:]
    return (col_names, row_data)

def display_menu():
    ### TODO - print the main menu
    print("Main Menu")
    print("1 - Get Clean Sample")
    print("2 - Calculate Total Profit in Sample")
    print("Q - Quit")

def get_valid_menu_option():
    ### TODO - get valid menu option from the user
    ### use prompt ">>> choose menu option: "
    ### if not valid selection, print message "invalid input" and get again
    ### repeat until valid and return that result
    user_input = (">>> choose menu option: ")
    if user_input != '1':
        print("invalid input")
    elif user_input != '2':
        print("invalid input")
    elif user_input != 'Q':
        print("invalid input")
    else:
        print(">>> choose menu option: ")
    return user_input
    
def get_clean_sample(data, n=20):
    # get n rows randomly sampled w/o replacement from the data
    sample = rand.sample(data, n)
    
    ### TODO - convert string types in all rows of sample to int / float type
    ### positions 0 and 8 should be integers
    ### positions 9 and 10 should be floats
    ### return the updated sample
    
def print_sample_summary(sample):
    """print summary data for a given sample, returns nothing"""
    print(f"\nSample size {len(sample)} rows x {len(sample[0])} cols.")
    print("First order number:\t", sample[0][0])
    print("Last order number:\t", sample[-1][0])
    tot = 0
    for row in sample:
        tot += row[8]
    avg = tot / len(sample)
    print("Average units per order:", avg)
    
# check if run as module or script
if __name__ == "__main__":
    
    # set random seed
    seed = input("*** Enter random seed (integer) or ENTER for none: ")
    if seed:
        rand.seed(int(seed))
        print("\nRandom seed set to", seed)
    else:
        print("\nNo random seed set")
        
    # load csv data file
    # this file must be in the same directory as your .py file
    file = "5000 Sales Records.csv"
    data = load_csv_data(file)
    if data == -1:
        print("Ending.")
        sys.exit()
    else:
        # unpack the data tuple into header and rows; print result
        col_names, row_data = data
        print(f"\nLoaded '{file}', {len(row_data)} rows x {len(row_data[0])} cols.")
    
    ### TODO - implement main menu loop per specification