How to write a simple accounting program in bash scripting

I'm struggling to write a bash script for this simple program as shown below:

Prints the following text

Welcome to the Accountant Program
Please enter one option to proceed.
Type ‘Exit’ to close the program
Type ‘Sales’ to go to the sales menu
Type ‘Print’ to go to print menu.

If the user types Exit the program should terminate.

If the user types Sales, the program shall go to Sales menu. Once the sales menu launches the program should print the following text.

Please enter the amount, item code, item price or type m to go back
to the main menu.
Upon this, the user types an integer value for amount of items, an integer value for the item code, and an integer value for the item price. Once the values are entered the program should writes

| <Date and time>, <Item Code>, (item price*item amount) |
to a file named Database.txt where will be retrieved from the operating system.

After this the program should repeat the text given above, i.e.,

Please enter the amount, item code, item price or type m to go back
to the main menu.
If the user presses m then the program shall switch back to the main menu, otherwise it repeats.

If the user types Print in the main menu the program shall switch to the Print Menu and prints the followings to the screen:
Please enter one option
Type F to print results to a file
Type S to print results to the screen.
Type m to go back to the main menu.

If user presses F, then the program should ask the file name by saying
Type the name of the file

Needless to say that the user should then provide the name of the file and the program should copies the contents of the Database.txt to the new file.