using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

using CsvHelper;

using CsvHelper.Configuration;

using CsvHelper.Configuration.Attributes;

using CsvHelper.Expressions;

using CsvHelper.TypeConversion;

​

using Newtonsoft.Json;

​

//https://stackoverflow.com/questions/66984134/compare-csv-header-to-map-class

​

    public class VisitExport

    {

        public int? Count { get; set; }

        public string CustomerName { get; set; }

        public string CustomerAddress { get; set; }

    }

​

    public class VisitMap : ClassMap<VisitExport>

    {

        public VisitMap()

        {

            Map(m => m.Count).Name("Count");

            Map(m => m.CustomerName).Name("Customer Name");

            Map(m => m.CustomerAddress).Name("Customer Address");

        }

    }

​

    public class VisitMapBackwards : ClassMap<VisitExport>

    {

        public VisitMapBackwards()

        {

            Map(m => m.CustomerAddress).Name("Customer Address");

            Map(m => m.CustomerName).Name("Customer Name");

            Map(m => m.Count).Name("Count");

        }

    }

    class TestClass

    {

        public static void Test()

        {

            var inputList = new List<VisitExport>

            {

                new VisitExport { Count = 101, CustomerName = "name 101", CustomerAddress = "customer address 101" },

                new VisitExport { Count = null, CustomerName = "name 1", CustomerAddress = "customer address 1" },

                new VisitExport { Count = 202, CustomerName = "name 202", CustomerAddress = "customer address 202" },

            };

​

            var json0 = JsonConvert.SerializeObject(inputList);

            var csv1 = TestOutput(inputList, new VisitMap());

            Console.WriteLine("CSV export for model:");

            Console.WriteLine(csv1);

            var csv1Lower = csv1.ToLowerInvariant();

            var csv2 = TestOutput(inputList, new VisitMapBackwards());

​

            var newList1 = TestInput(csv1, new VisitMap());

            var newList2 = TestInput(csv2, new VisitMap());

            var newList11 = TestInput(csv1Lower, new VisitMap(), (args) => args.Header.ToLowerInvariant());

​

            Console.WriteLine("Caught expected exception: {0}",

                              Assert.Throws<HeaderValidationException>(() =>

                                                                       {

                                                                           TestInput(GetMissingColumnCsv(), new VisitMap());

                                                                       })?.Message);

            Console.WriteLine("Caught expected exception: {0}",

                              Assert.Throws<HeaderValidationException>(() =>

                                                                       {

                                                                           TestInput(GetMissingColumnCsv().ToLowerInvariant(), new VisitMap(), (args) => args.Header.ToLowerInvariant());

                                                                       })?.Message);

            var json1 = JsonConvert.SerializeObject(newList1);

            var json11 = JsonConvert.SerializeObject(newList11);

            var json2 = JsonConvert.SerializeObject(newList2);

            Assert.AreEqual(json0, json1);

            Assert.AreEqual(json0, json11);

            Assert.AreEqual(json0, json2);

        }   

        public static List<VisitExport> TestInput(string csv, ClassMap<VisitExport> map, PrepareHeaderForMatch prepareHeaderForMatch = default)

        {

            var culture = CultureInfo.GetCultureInfo("en-GB");

            var config = new CsvConfiguration (culture)

            {

                HeaderValidated = (args) => 

                { 

                     // Add additional logic as required here

                    ConfigurationFunctions.HeaderValidated(args); 

                },

            };

            if (prepareHeaderForMatch != null)

                config.PrepareHeaderForMatch = prepareHeaderForMatch;

            using (var reader  = new StringReader(csv))

            using (var readCsv  = new CsvReader(reader, config))

            {

                readCsv.Context.RegisterClassMap(map);

                var fileContent = readCsv.GetRecords<VisitExport>();

                return fileContent.ToList();

            }

        }

        public static string TestOutput(List<VisitExport> inputList, ClassMap<VisitExport> map)

        {

            var culture = CultureInfo.GetCultureInfo("en-GB");

            var config = new CsvConfiguration (culture);

            var sb = new StringBuilder();

            using (var textWriter = new StringWriter(sb))

            using (var csvWriter = new CsvWriter(textWriter, config))

            {

                csvWriter.Context.RegisterClassMap(map);

                csvWriter.WriteRecords(inputList);

            }

            return sb.ToString();

        }   

        static string GetMissingColumnCsv() => @"Customer Name,Count

name 1,

name 101,101

name 202,202

";

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("CsvHelper: " + typeof(CsvConfiguration).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.Location.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​