using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public class AppCategoryDataModel

    {

        public int AppCategoryId { get; set; }

        public int? ParentAppCategoryId { get; set; }

        public string AppCategoryName { get; set; }

        public int? ProtocolId { get; set; }

        public string ProtocolTitle { get; set; }

    }

    public class AppCategory

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public int ProtocolCount { get; set; }

        public List<AppCategory> SubCategories { get; set; }

        public List<ProtocolDetails> ProtocolData { get; set; }

    }

    public class ProtocolDetails

    {

        public int Id { get; set; }

        public string Title { get; set; }

    }

    public static void Main()

    {

        var appCategoryList = new List<AppCategoryDataModel>()

        {

            new() { AppCategoryId = 4844, ParentAppCategoryId = null, AppCategoryName = "ItemResearch", ProtocolId = 5164, ProtocolTitle="ABC: Evaluation" },

            new() { AppCategoryId = 4844, ParentAppCategoryId = null, AppCategoryName = "ItemResearch", ProtocolId = null, ProtocolTitle=""},

            new() { AppCategoryId = 4845, ParentAppCategoryId = null, AppCategoryName = "ItemHostpital", ProtocolId = null, ProtocolTitle="" },

            new() { AppCategoryId = 4845, ParentAppCategoryId = null, AppCategoryName = "ItemHostpital", ProtocolId =5162 , ProtocolTitle="ABC: 3/28/20" },

            new() { AppCategoryId = 4845, ParentAppCategoryId = null, AppCategoryName = "ItemHostpital", ProtocolId =5164 , ProtocolTitle="ABC: Evaluation" },

            new() { AppCategoryId = 4845, ParentAppCategoryId = null, AppCategoryName = "ItemHostpital", ProtocolId =5165 , ProtocolTitle="ABC: section", },

            new() { AppCategoryId = 4845, ParentAppCategoryId = null, AppCategoryName = "ItemHostpital", ProtocolId =5192 , ProtocolTitle="ABC: 3/31/20", },

            new() { AppCategoryId = 4846, ParentAppCategoryId = null, AppCategoryName = "Contact information", ProtocolId = null, ProtocolTitle="", },

            new() { AppCategoryId = 4846, ParentAppCategoryId = null, AppCategoryName = "Contact information", ProtocolId =5164 , ProtocolTitle="ABC: Evaluation", },

            new() { AppCategoryId = 4852, ParentAppCategoryId = null, AppCategoryName = "UP", ProtocolId =null , ProtocolTitle="", },

            new() { AppCategoryId = 4852, ParentAppCategoryId = null, AppCategoryName = "UP", ProtocolId = 5164, ProtocolTitle="ABC: Evaluation", },

            new() { AppCategoryId = 5023, ParentAppCategoryId = null, AppCategoryName = "Call survival guide", ProtocolId = null, ProtocolTitle="" },

            new() { AppCategoryId = 5023, ParentAppCategoryId = null, AppCategoryName = "Call survival guides", ProtocolId =5164 , ProtocolTitle="ABC: Evaluation" },

            new() { AppCategoryId = 5085, ParentAppCategoryId = null, AppCategoryName = "OE", ProtocolId =null, ProtocolTitle="" },

            new() { AppCategoryId = 5085, ParentAppCategoryId = null, AppCategoryName = "OE", ProtocolId =5164 , ProtocolTitle="ABC: Evaluation" },

            new() { AppCategoryId = 5099, ParentAppCategoryId = null, AppCategoryName = "OEM", ProtocolId =null , ProtocolTitle=null },

            new() { AppCategoryId = 5334, ParentAppCategoryId = 5085, AppCategoryName = "mmkk update", ProtocolId =null , ProtocolTitle= null },

            new() { AppCategoryId = 5336, ParentAppCategoryId = 5085, AppCategoryName = "xdgdrg", ProtocolId =null , ProtocolTitle=null },

            new() { AppCategoryId = 5348, ParentAppCategoryId = 5023, AppCategoryName = "test", ProtocolId =null , ProtocolTitle=null },

            new() { AppCategoryId = 5341, ParentAppCategoryId = 5023, AppCategoryName = "New Category Level-1", ProtocolId =null , ProtocolTitle= null },

            new() { AppCategoryId = 5349, ParentAppCategoryId = 5341, AppCategoryName = "New Category Level-2", ProtocolId =null , ProtocolTitle= null },

            new() { AppCategoryId = 5352, ParentAppCategoryId = 5348, AppCategoryName = "New category3", ProtocolId =null , ProtocolTitle= null },

        }

            .OrderBy(ap => ap.AppCategoryName)

            .ToList();

        Dictionary<int, AppCategory> dictCategories = new();

        var firstLevelCategories = GetSubCategories(appCategoryList, null);

        foreach (var category in firstLevelCategories)

        {

            dictCategories.Add(category.Id, category);

        }

        // PRINT HIERARCHY

        // first level

        foreach (var category in dictCategories.Values)

        {

            Console.WriteLine(category.Name);

            foreach (var protocol in category.ProtocolData)

            {

                Console.WriteLine("\t" + protocol.Title);

            }

            // second level

            foreach (var subCategory in category.SubCategories)

            {

                Console.WriteLine("\t\t" + subCategory.Name);

                // third level

                foreach (var subSubCategory in subCategory.SubCategories)

                {

                    Console.WriteLine("\t\t\t" + subSubCategory.Name);

                }

            }

        }

    }

    private static List<AppCategory> GetSubCategories(List<AppCategoryDataModel> appCategories, int? parentAppCategoryId)

    {

        if (!appCategories.Any(ac => ac.ParentAppCategoryId == parentAppCategoryId))

        {

            return new();

        }

        List<AppCategory> subCategories = appCategories

            .Where(ac => ac.ParentAppCategoryId == parentAppCategoryId)

            .GroupBy(ac => ac.AppCategoryId)

            .Select(gr => new AppCategory

                {

                    Id = gr.Key,

                    Name = gr.First().AppCategoryName,

                    ProtocolData = gr

                        .Where(ac => ac.ProtocolId != null)

                        .Select(ac => new ProtocolDetails

                            {

                                Id = ac.ProtocolId.Value,

                                Title = ac.ProtocolTitle

                            })

                        .ToList()

                })

            .ToList();

        foreach (var subCategory in subCategories)

        {

            subCategory.SubCategories = GetSubCategories(appCategories, subCategory.Id);

            subCategory.ProtocolCount = subCategory.ProtocolData.Count;

        }

        return subCategories;

    }

}