using System;

using System.Xml;

using System.IO;

​

​

namespace ApplicationTest

{

​

    public interface ICodeTest

    {

        void FunctionOne(int n);

        void FunctionTwo(int n, int p, int q);

        void FunctionThree(int start, int length);

        int FunctionFour(string xmlInput);

    }

​

​

    public class Functions : ICodeTest

    {

        /// <summary>

        /// Takes an integer n and writes the values 1 through n to the console 

        /// on separate lines. If the current number in the iteration is divisible by

        /// 5, then "Hello" will also be output for that line. If the current number

        /// is divisibly by 7, "World" will also be output for that line.

        /// </summary>

        public void FunctionOne(int n)

        {

            // create the string that will be printed out 

            string output = "";

​

            for (int i = 1; i <= n; i++)

            {

                // add the current number to the output string

                output = Convert.ToString(i);

​

                // check if number is divisible by 5

                if (i % 5 == 0)

                {

                    output += "Hello";

                }

​

                if (i % 7 == 0)

                {

                    output += "World";

                }

​

                Console.WriteLine(output);

            }

        }

​

​

        /// <summary>

        /// Takes an integer n and writes the values 1 through n to the console 

        /// on separate lines. If the current number in the iteration is divisible by

        /// p, then "Hello" will also be output for that line. If the current number

        /// is divisibly by q, "World" will also be output for that line.

        /// </summary>

        public void FunctionTwo(int n, int p, int q)

        {

            // create the string that will be printed out 

            string output = "";

​

            for (int i = 1; i <= n; i++)

            {

                // add the current number to the output string

                output = Convert.ToString(i);

​

                // check if either number is 0

                if (p != 0 && i % p == 0)

                {

                    output += "Hello";

                }

​

                if (q != 0 && i % q == 0)

                {

                    output += "World";

                }

​

                Console.WriteLine(output);

            }

        }

​

​

        /// <summary>

        /// Takes an integer start and outputs a fibonacci sequence starting

        /// with that number. The amount of values output are determined by

        /// the length parameter.

        /// </summary>

        public void FunctionThree(int start, int length)

        {

            // create variables to contain the values in the sequence

            int curr = 0;

            int prev = 0;

            int temp = 0;

​

            for (int i = 0; i < length; i++)

            {

                // check if we're on the first number

                if (i == 0)

                {

                    Console.WriteLine(start);

                    curr = start;

                    continue;

                }

​

                // print out the current number

                Console.WriteLine(curr + prev);

​

                // update variables

                temp = curr;

                curr = curr + prev;

                prev = temp;

            }

        }

​

​

        /// <summary>

        /// This functions takes a string xmlInput and returns 1 if the string is valid xml.

        /// -1 is returned if there are one or more errors. -2 is returned if the passed string

        /// is null.

        /// Resources used:

        /// https://www.w3schools.com/xml/xml_syntax.asp

        /// https://stackoverflow.com/questions/729001/how-to-determine-if-xml-is-well-formed

        /// https://docs.microsoft.com/en-us/dotnet/api/system.io.stringreader?view=net-6.0

        /// </summary>

        public int FunctionFour(string xmlInput)

        {

            // check edge case

            if (xmlInput == null || xmlInput.Length == 0)

            {

                return -2;

            }

​

            using (XmlReader reader = XmlReader.Create(new StringReader(xmlInput)))

            {

                try

                {

                    while (reader.Read())

                    {

                        // keep reading from the xml file

                    }

                }

                catch (Exception ex)

                {

                    return -1;

                }

            }

​

            // if we've made it to the end of the file, that means there were no errors

            return 1;

        }

​

​

        /// <summary>

        /// Takes a string as an input and tries to convert it to an integer. Will

        /// continue to prompt user until an integer is entered. The integer is then

        /// returned.

        /// </summary>

        public int intValidationCheck(string choiceString)

        {

            bool numEntered = false;

            int choiceInt = 0;

​

            // keep prompting the user to enter a number if they enter something other than a number

            while (!numEntered)

            {

                numEntered = int.TryParse(choiceString, out choiceInt);

​

                if (!numEntered)

                {

                    Console.WriteLine("Incorrect value entered. Please enter a correct value.");

                    choiceString = Console.ReadLine();

                    numEntered = int.TryParse(choiceString, out choiceInt);

                }

            }

​

            // if we've exited the while loop, an int was entered

            return choiceInt;

        }

​

        /// <summary>

        /// This shows the prompt for the main menu, allowing user to select which

        /// function they would like to execute.

        /// </summary>

        public int ShowPrompt()

        {

            // prompt the user to see which function they would like to execute

            Console.WriteLine("Which function would you like to test?");

            Console.WriteLine("1: 1 to n Hello World, with 5 and 7 divisibility checks");

            Console.WriteLine("2: 1 to n Hello World, with p and q divisibility checks");

            Console.WriteLine("3: Fibonacci sequence, starting at passed integer");

            Console.WriteLine("4: XML file form check");

            Console.WriteLine("5: Exit application");

            Console.WriteLine("Please enter a value: ");

            var choiceString = Console.ReadLine();

​

            // perform input validation

            return intValidationCheck(choiceString);

        }

​

​

        /// <summary>

        /// This continuously runs the application until the user decides to exit.

        /// </summary>

        public void RunApplication()

        {

            bool running = true;

​

            while (running)

            {

                // show prompt to user

                int answer = ShowPrompt();

​

                // perform input validation

                while (answer < 1 || answer > 5)

                {

                    Console.WriteLine("Incorrect value entered. Please enter a correct value.");

                    answer = ShowPrompt();

                }

​

                // check which answer was given

                switch(answer)

                {

                    case 1:

                        Console.WriteLine("Enter value for n: ");

                        var choiceString = Console.ReadLine();

                        FunctionOne(intValidationCheck(choiceString));

                        break;

                    case 2:

                        // get n 

                        Console.WriteLine("Enter value for n: ");

                        var nString = Console.ReadLine();

                        int nInt = intValidationCheck(nString);

​

                        // get p

                        Console.WriteLine("Enter value for p: ");

                        var pString = Console.ReadLine();

                        int pInt = intValidationCheck(pString);

​

                        // get q

                        Console.WriteLine("Enter value for q: ");

                        var qString = Console.ReadLine();

                        int qInt = intValidationCheck(qString);

​

                        // run function

                        FunctionTwo(nInt, pInt, qInt);

                        break;

                    case 3:

                        // get start

                        Console.WriteLine("Enter value for start: ");

                        var startString = Console.ReadLine();

                        int startInt = intValidationCheck(startString);

​

                        // get length

                        Console.WriteLine("Enter value for length: ");

                        var lengthString = Console.ReadLine();

                        int lengthInt = intValidationCheck(lengthString);

​

                        // run function

                        FunctionThree(startInt, lengthInt);

                        break;

                    case 4:

                        // get xml file

                        Console.WriteLine("Enter XML: ");

                        var xmlString = Console.ReadLine();

​

                        // run function

                        int statusCode = FunctionFour(xmlString);

                        Console.WriteLine("XML Status Code: " + statusCode);

                        break;

                    case 5:

                        running = false;

                        Console.WriteLine("Goodbye!");

                        break;

                }

            }

        }

    }

​

​

​

    public class Program

    {

        public static void Main()

        {

            // set up

            Functions functions = new Functions();

​

            // test

            functions.RunApplication();

        }

    }

}