# Define Product Object

class Product:

def $\_\_$init$\_\_($self$,$ name, price, quantity$)$:

self.name $=$ name

self.price $=$ price

self.quantity $=$ quantity

def $\_\_$str$\_\_($self$)$:

return f$"$Product$($name$=\{$self$.$name$\},$ price$=\{$self$.$price$\},$ quantity$=\{$self$.$quantity$\})"$

# Create productList

productList $=[]$

# Define Functions Needed to Maintain productList

def add$\_$product$($name$,$ price, quantity$)$:

productList.append$($Product$($name$,$ price, quantity$))$

def delete$\_$product$($name$)$:

global productList

productList $=[$product for product in productList if product.name $!=$ name$]$

def change$\_$price$($name$,$ new$\_$price$)$:

for product in productList:

if product.name $==$ name:

product.price $=$ new$\_$price

break

def purchase$\_$product$\_$units$($name$,$ units$)$:

for product in productList:

if product.name $==$ name:

product.quantity $+=$ units

break

def sell$\_$product$\_$units$($name$,$ units$)$:

for product in productList:

if product.name $==$ name:

if product.quantity $>=$ units:

product.quantity $-=$ units

else:

print$("$Not enough units in stock"$)$

break

def display$\_$product$($name$)$:

for product in productList:

if product.name $==$ name:

print$($product$)$

break

def display$\_$all$\_$products$()$:

for product in productList:

print$($product$)$

# Main Part of Program

# Read Data About Products from text file into productList

def read$\_$products$\_$from$\_$file$($filename$)$:

with open$($filename$,\text{'}$r$\text{'})$ as file:

for line in file:

name, price, quantity $=$ line.strip$().$split$(\text{'},\text{'})$

add$\_$product$($name$,$ float$($price$),$ int$($quantity$))$

def write$\_$products$\_$to$\_$file$($filename$)$:

with open$($filename$,\text{'}$w$\text{'})$ as file:

for product in productList:

file.write$($f$"\{$product$.$name$\},\{$product$.$price$\},\{$product$.$quantity$\}$

$")$

# Enter Transaction Loop

choice $=0$

while choice $!=8$:

print$("1.$ Add Product"$)$

print$("2.$ Delete Product"$)$

print$("3.$ Change Price"$)$

print$("4.$ Purchase Product Units"$)$

print$("5.$ Sell Product Units"$)$

print$("6.$ Display One Product"$)$

print$("7.$ Display All Products"$)$

print$("8.$ Exit"$)$

choice $=$ int$($input$("$Enter Choice: $"))$

# do if elif choice

if choice $==1$:

name $=$ input$("$Enter product name: $")$

price $=$ float$($input$("$Enter product price: $"))$

quantity $=$ int$($input$("$Enter product quantity: $"))$

add$\_$product$($name$,$ price, quantity$)$

elif choice $==2$:

name $=$ input$("$Enter product name to delete: $")$

delete$\_$product$($name$)$

elif choice $==3$:

name $=$ input$("$Enter product name to change price: $")$

new$\_$price $=$ float$($input$("$Enter new price: $"))$

change$\_$price$($name$,$ new$\_$price$)$

elif choice $==4$:

name $=$ input$("$Enter product name to purchase units: $")$

units $=$ int$($input$("$Enter number of units to purchase: $"))$

purchase$\_$product$\_$units$($name$,$ units$)$

elif choice $==5$:

name $=$ input$("$Enter product name to sell units: $")$

units $=$ int$($input$("$Enter number of units to sell: $"))$

sell$\_$product$\_$units$($name$,$ units$)$

elif choice $==6$:

name $=$ input$("$Enter product name to display: $")$

display$\_$one$\_$product$($name$)$

elif choice $==7$:

display$\_$all$\_$products$()$

elif choice $==8$:

write$\_$products$\_$to$\_$file$(\text{'}$products$.$txt$\text{'})$

print$("$leaving the program..."$)$

else:

print$("$Invalid choice, please try again$>.<")$