# myApplication.py
# Python Standard Imports
import csv

# PIP installed Imports

# Custom Imports
import Cart # import ModuleName
import Customer as Cust  # import ModuleName as Namespace/Alias
from Order import orderInfo, orderDetails # from ModuleName import ObjectName 


# As functional as possible
# __main__ statement page 35

'''  Validation on Friday chapter 7
# test when the data comes into the application
subTotal = float(input('Enter subtotal: '))  # data validation
'''

def writeToLogFile(str_lambda_FullName, orderDate,  str_subTotal, str_taxAmount, str_cartTotal):
    # File I/O page 46
    logFileName = "logfile.txt"

    with open(logFileName, 'a') as file:
        # scope of the open() we are going to use file
        '''
        'r' -> read (default) file MUST exists -> error
        'w' -> write (overwrite) it will create a file if !exist
        'a' -> append (writes to the end of the file) it will create a file if !exist
        '''
        '''
        Best practice for naming the data writing to the file
        writing structural data (csv,excel,db,...) -> data
        writing !structural data (txt, pdf) -> content    
        '''

        # strings / datetime / floats
        content = f"Customer Name: {str_lambda_FullName} Order Date: {orderDate} {str_subTotal} {str_taxAmount} {str_cartTotal}"

        file.write(content + "\n") # Python Core

        # if you use the with keyword it will automatically close the stream when done. If you just call open() (ex. page 46), you need to MANUALLY close the stream with the close().
        # file.close()

def writeToCSV(str_lambda_FullName, orderDate,  str_subTotal, str_taxAmount, str_cartTotal):

    csvFile = "orders.csv"
    with open(csvFile, 'a+', newline='') as io_csv:
        # csv writer Python Standard import csv
        writer = csv.writer(io_csv) 

        # header / table schema / fieldname
        fieldNames = ['CustomerName', 'OrderDate','SubTotal','Tax','Total']

        # data row
        data = [str_lambda_FullName, orderDate,  str_subTotal, str_taxAmount, str_cartTotal]

        # write the header
        ## if the header exists, skip the header
        ## Move to the beginning row of the buffer
        io_csv.seek(0)  # row[0] -> memory seek(0) -> stream
        reader = csv.reader(io_csv)
        existing_headers = next(reader, None)

        if existing_headers != fieldNames:
            io_csv.seek(0)
            io_csv.truncate() # Clear the current headers
            writer.writerow(fieldNames)

        # write the data row
        writer.writerow(data)



# Main Applications Function/RunTime/ProcessCode
def main():

    orderDate = orderInfo()

    # Call the nameInputs from the Customer Class
    firstName, lastName = Cust.nameInputs()

    # Lambda Functions page 43
    ## Use a lambda function to create a fullname variable from firstName and lastName

    # A single expression anonymous function that returns a value
    # The main difference between an anonyous function and a lambda function is that an anonymous function can have MULTIPLE expressions or operations BUT a lambda can only have a SINGLE expression or operation
    # lambda keyword to define the SINGLE expression ANONYMOUS function
    # syntax
    ## var_name = lambda params: expression or operation
    lambda_fullName = lambda firstName, lastName: f"{firstName} {lastName}"

    # Lambda example as a regular returned function
    def func_fullName(firstName, lastName):
        return f"{firstName} {lastName}"
    # calling the function
    rtn_fullName = func_fullName(firstName, lastName)

    # Get the subtotal from the cart and assign a local variale in the application to the value
    subtotal = Cart.cartSubTotal()  # local var in myApplication = return of the object being called  __name__ = cartSubTotal
    taxAmount = Cart.taxRate(subtotal,7)
    cartTotal = subtotal + taxAmount
    # Create a footer for the customers receipt
    # Show the customer all the values in the receipt
    print("=== Cart Totals ===")
    # lambda return
    str_lambda_FullName = lambda_fullName(firstName, lastName)
    print(f"Lambda FullName: {str_lambda_FullName}")
    # function return
    print(f"Function Full Name: {rtn_fullName}")
    # subtotal cart
    str_subTotal = f"SubTotal: ${subtotal:.2f}"  # Structural
    print(str_subTotal) #functional (value passed)
    # tax amount
    str_taxAmount = f"Tax Amount: ${taxAmount:.2f}"
    print(str_taxAmount)
    # cart total
    str_cartTotal = f"Cart Total: ${cartTotal:.2f}"
    print(str_cartTotal)
    print("====================")

    # write to log file
    writeToLogFile(str_lambda_FullName, orderDate, str_subTotal, str_taxAmount, str_cartTotal)

    # write to the order csv
    writeToCSV(str_lambda_FullName, orderDate,  str_subTotal, str_taxAmount, str_cartTotal)

# Process Runtime
# page 35
# function is defined as def main() the __name__ attr is __main__
if __name__ == "__main__":
    print("Run my cart application")
    main()
    print("Thank You for using my shopping cart")

# EOF