RandomOverkillSolution.cs

using System;
using System.Linq;

namespace ConsoleApp1
{
	/// <summary>
	///     Target:
	///     1) Read in Number of students
	///     2) Create array with number of elements for age (int) & weight (double)
	///     3) Reading of age & weight
	///     4) Search for the most difficult students (mobbing!)
	///     5) Count how many students are 16 years old.
	///     X) Calculate average age
	///     XX) Determine total weight of the class
	/// </summary>
	internal class Program
	{
		private static readonly (int min, int max) RandomAgeRange = (min: 10, max: 95);
		private static readonly (double min, double max) RandomWeightRange = (min: 45f, max: 185f);
		private static readonly ConsoleColor OriginalConsoleForeground = Console.ForegroundColor;

		private delegate bool TryParseMethod<TResult>(string? str, out TResult parsedResult);

		/// <summary>
		///     Overload/Wrapper of <see cref="Console.ReadLine" />.
		///     Prints the given <paramref name="prefix" /> first on the same line.
		///     <example>"Age > "</example>
		/// </summary>
		private static string ReadLine(string prefix = "> ")
		{
			Console.Write(prefix);
			return Console.ReadLine() ?? string.Empty;
		}

		/// <summary>
		///     Read the console input until the user input is parsable to <typeparamref name="TResult" />.
		///     Use the <paramref name="fallback" /> parameter, to define fallback/default values after X tries.
		/// </summary>
		private static TResult ParseUntilValid<TResult>(TryParseMethod<TResult> tryParse, string? retryMessage = null, (TResult fallbackValue, int afterTries)? fallback = null,
			string? inputPrefix = null)
			where TResult : unmanaged
		{
			inputPrefix ??= "> ";
			TResult parsedValue;
			string userInput;

			var tries = fallback?.afterTries ?? -1;
			while (!tryParse(userInput = ReadLine(tries == decimal.Zero ? $"([ENTER] for default) {inputPrefix}" : inputPrefix), out parsedValue))
			{
				if (tries == -1 || --tries > 0)
				{
					var input = userInput;
					RunInColor(ConsoleColor.Red, () => Console.WriteLine(retryMessage ?? $"User input \"{input}\" does not match the excepted type \"{typeof(TResult)}\"!"));
				}
				else
				{
					return fallback?.fallbackValue
							?? throw new ArgumentNullException(nameof(fallback), $"{nameof(fallback)}.{nameof(fallback.Value.fallbackValue)} is not allowed to be null.");
				}
			}

			return parsedValue;
		}

		private static void PrintLine(char lineChar = '#')
			=> Console.WriteLine(string.Empty.PadRight(Console.BufferWidth, lineChar));

		private static void TryWriteCentered(string text)
			=> Console.WriteLine(text.Length > Console.BufferWidth ? text : string.Empty.PadLeft((Console.BufferWidth - text.Length) / 2) + text);

		private static void EmptyLine()
			=> Console.WriteLine();

		private static void WholeProgram()
		{
			PrintLine();
			TryWriteCentered("Simple students coding session task");
			TryWriteCentered("BUT SLIGHTLY OVER ENGINEERED!");
			PrintLine();

			EmptyLine();

			// Read amount of students.
			Console.WriteLine("Number of students in class?");
			var studentsInClass = ParseUntilValid<int>(int.TryParse);

			var students = Enumerable.Repeat<(int number, int age, double weight)>((default, default, default), studentsInClass);

			Console.WriteLine("Automatic generate random values? ['true' / 'false'] (false is default)");
			var autoFill = ParseUntilValid<bool>(bool.TryParse, fallback: (false, 0));

			if (autoFill)
			{
				var random = new Random();
				var randomAge = new Func<int>(() => random.Next(RandomAgeRange.min, RandomAgeRange.max));
				var randomWeight = new Func<double>(() => random.NextDouble() * (RandomWeightRange.max - RandomWeightRange.min) + RandomWeightRange.min);

				students = students.Select((s, i) => (number: i + 1, age: randomAge(), weight: randomWeight())).ToList();
			}
			else
			{
				const int inputPadding = 10;
				var getAge = new Func<int>(() => ParseUntilValid<int>(int.TryParse, inputPrefix: $"{"Age".PadRight(inputPadding)} > "));
				var getWeight = new Func<double>(() => ParseUntilValid<double>(double.TryParse, inputPrefix: $"{"Weight".PadRight(inputPadding)} > "));
				students = students.Select((s, i) =>
				{
					PrintLine('-');
					Console.WriteLine($"Enter properties of student no. \"{i + 1}\".");
					return (number: i + 1, age: getAge(), weight: getWeight());
				}).ToList();

				PrintLine('-');
			}

			// Print students overview.
			PrintLine();
			TryWriteCentered($"Students data {(autoFill ? "generated" : "collected")}.");

			PrintLine();

			var pad = new Func<double, string>(d => $"{d}".PadRight(5));
			foreach (var (number, age, weight) in students)
			{
				Console.WriteLine("Nr. " + pad(number) + "Age: " + pad(age) + "Weight: " + pad(weight));
			}

			PrintLine();

			EmptyLine();
			EmptyLine();


			TryWriteCentered("NO. 4) Fattiest/heaviest student:");
			TryWriteCentered($"{students.Max(s => s.weight)} KG");
			EmptyLine();

			TryWriteCentered("NO. 5) Number of students who are 16 years old:");
			TryWriteCentered($"{students.Count(s => s.age == 16)} students.");
			EmptyLine();


			TryWriteCentered("NO. 6/X) Average age of the class:");
			TryWriteCentered($"{students.Average(s => s.age)} years.");
			EmptyLine();

			TryWriteCentered("NO. 7/XX) Total weight of class:");
			TryWriteCentered($"{students.Sum(s => s.weight)} KG");
			EmptyLine();

			PrintLine();
			RunInColor(ConsoleColor.Cyan, () => TryWriteCentered("Have a nice day!"));
		}

		private static void RunInColor(ConsoleColor color, Action action)
		{
			Console.ForegroundColor = color;
			action();
			Console.ForegroundColor = OriginalConsoleForeground;
		}

		private static void Main()
		{
			do
			{
				Console.Clear();
				WholeProgram();
				PrintLine();

				RunInColor(ConsoleColor.Red, () => Console.WriteLine("Press 'e' to exit. Otherwise the program run's again."));
			} while (Console.ReadLine()?.ToLower() != "e");
		}
	}
}