Can you please help me to solve the below problem in PHP?

Problem Using object-oriented concepts, create a CLI tool that accepts a string and does the following to it: converts the string to uppercase and outputs it to stdout. converts the string to alternate upper and lower case and outputs it to stdout. creates a CSV file from the string by making each character a column in the CSV and then output "CSV created!" to stdout. Make sure the code unit-testable and extendable. We would like to see a piece of code as you would do on your daily task. Sample Input hello world Sample Output HELLO WORLD hello world CSV created! Note: a CSV file is created on the root directory which containing the following: h,e,1,1,0, ,,o,r,1,d What do you need to do? Write a program or application to solve the given problem with the unit test. Prepare setup guide on how to execute the solution and unit test in the ReadMe file. Problem solving skills - Logical & critical thinking, the ability to apply the object-oriented concept or design pattern if needed. Testable code - the application of unit test and different test cases Maintainable code-easy to understand, extendable code, clean code with best practise implementation. Ability to handle unforeseen circumstance - exception handling, defensive programming