Exercise: Workout manager

In this exercise, you will be creating a console-based push-up workout manager in Kotlin. The goal of this manager is to guide users through a series of push-up sets, recording their performance, and adjusting future workout suggestions based on their results. The program will also store the suggested repetitions for the user's next workout in a file.

This is how you should start the code:

val interactor = WorkoutInteractor(
    manager = WorkoutManager(),
    nextRepetitionsRepository = FileNextRepetitionsRepository(),
)
interactor.start()

Expected Components:

• Repetitions data class, that stores the number of push-ups to be done in the first and second rounds. It has two properties: firstRound and secondRound, both of type Int.
• NextRepetitionsRepository interface, defining the contract for reading and writing the next set of repetitions. It has two methods: read(), that returns the Repetitions from storage (or null if not found), and write(repetitions: Repetitions), that writes the given Repetitions to storage.
• FileNextRepetitionsRepository class, that should implement the interface NextRepetitionsRepository. It reads and writes the Repetitions object to a file named next_repetitions.txt. If the file does not exist, it should create it.
• WorkoutManager class that handles the logic for determining the next set of repetitions based on the user's performance. It has a method nextRepetitions(firstRoundDone: Int, secondRoundDone: Int, thirdRoundDone: Int, repetitions: Repetitions): Repetitions, which returns a new Repetitions object with adjusted values for the next workout based on the user's performance.
• WorkoutInteractor class that serves as the main orchestrator of the application. It interacts with the user, guides them through the workout, gets their input, and provides feedback. It has a method start() that starts the workout routine, guides the user through the push-up sets, records their performance, and provides feedback for the next workout. It also has a helper method getValidIntInput(prompt: String) to get valid integer input from the user. The constructor of this class takes a WorkoutManager and a NextRepetitionsRepository.

To read and write file, use File class. To check that a file exists, use exist method. To read the content of a file, use readText method. To write to a file, use writeText method. To create a new file, use createNewFile method.

To read user input, use readlnOrNull function. It returns null if the input is not a valid integer. To convert a string to an integer, use toIntOrNull method. To write to the console, use println function.

The algorithm for updating repetitions should be as follows:

• If the user could not do enough push-ups in the first round, decrease the repetitions for both rounds by 1.
• If the user could not do enough push-ups in the second round, decrease the repetitions for the second round by 1.
• If the user could do more push-ups in the third round than in the first round, increase the repetitions for both rounds by 1.
• If the user could do more push-ups in the third round than in the second round, increase the repetitions for the second round by 1.
• Otherwise, keep the repetitions the same.

Here is what an example conversations with the user might look like:

Hello, I am your push-ups workout assistant!
Now do 5 push-ups
How many push-ups did you do?
5
Now rest for 1 minute
Now do 5 push-ups
How many push-ups did you do?
4
Now rest for 1 minute
Now do as many push-ups as you can!
How many push-ups did you do?
3
Your next repetitions will be: 5 and 4

Hello, I am your push-ups workout assistant!
Now do 5 push-ups
How many push-ups did you do?
5
Now rest for 1 minute
Now do 4 push-ups
How many push-ups did you do?
5
Now rest for 1 minute
Now do as many push-ups as you can!
How many push-ups did you do?
6
Your next repetitions will be: 6 and 5

Hello, I am your push-ups workout assistant!
Now do 6 push-ups
How many push-ups did you do?
-1
Please enter a valid number.
How many push-ups did you do?
0
Now rest for 1 minute
Now do 5 push-ups
How many push-ups did you do?
10
Now rest for 1 minute
Now do as many push-ups as you can!
How many push-ups did you do?
0
Your next repetitions will be: 5 and 4

Instructions:

1. Start by defining the Repetitions data class with its properties.
2. Define the NextRepetitionsRepository interface with the expected methods.
3. Implement the FileNextRepetitionsRepository class. Ensure you handle potential file-related exceptions.
4. Implement the WorkoutManager class. Here, you'll decide how to adjust the repetitions for the next workout based on the user's performance.
5. Finally, implement the WorkoutInteractor class. This class will interact with the user, guide them through the workout, get their input, and provide feedback based on the logic in the WorkoutManager.
6. Once all components are implemented, run the starting code to test your application. Adjust your workout recommendations, perform the push-ups, and see how the program suggests adjustments for your next session!

Once you are done with the exercise, you can check your solution here.