using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using System.Text.Json;

using System.Text.Json.Serialization;

​

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

​

//https://stackoverflow.com/questions/66492617/how-to-append-positions-when-create-polyline-with-xamarin-forms-maps-in-runtime

using Xamarin.Forms.Maps;

using Xamarin.Forms;

​

    public static class PolylineFactory

    {

        const string latitudeJsonName = "Lat";

        const string longitudeJsonName = "Lng";

        public static Polyline FromLatLngJson(string jsonString, float? strokeWidth = default, Color strokeColor = default)

        {

            using var doc = JsonDocument.Parse(jsonString); 

            var query = doc.RootElement.EnumerateArray()

                // GetProperty performs property name matching as an ordinal, case-sensitive comparison.

                .Select(e => new Position(e.GetProperty(latitudeJsonName).GetDouble(), e.GetProperty(longitudeJsonName).GetDouble()));

​

            var polyline = new Polyline();

            if (strokeColor != default)

                polyline.StrokeColor = strokeColor;

            if (strokeWidth != default)

                polyline.StrokeWidth = strokeWidth.Value;

            foreach (var position in query)

                polyline.Geopath.Add(position);

            return polyline;

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            string jsonString = " [ {\"timestamp\": 1514172600000, \"Lat\": 37.33417925, \"Lng\": -122.04153133}, " + "{\"timestamp\": 1514172610000, \"Lat\": 37.33419725, \"Lng\": -122.04151333} ]";

​

            var polyline = PolylineFactory.FromLatLngJson(jsonString, 12, Color.Blue);

            Console.WriteLine($"polyline.StrokeWidth={polyline.StrokeWidth}, polyline.StrokeColor={polyline.StrokeColor}");

            Console.WriteLine("polyline.Geopath={0}", JsonSerializer.Serialize(polyline.Geopath, new JsonSerializerOptions { WriteIndented = true }));

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

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

            Console.WriteLine("System.Text.Json version: " + typeof(JsonSerializer).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;

        }

    }

​