using System;

using System.Collections.Generic;

using System.Linq;

class Program

{

    public class Product

    {

        public string Group { get; set; }

        public List<ValueAndUid> ValeursAndUids { get; set; } = new List<ValueAndUid>();

    }

​

    public class ValueAndUid

    {

        public string Item1 { get; set; }

        public string Item2 { get; set; }

    }

​

    static void Main(string[] args)

    {

        List<Product> listProducts = new List<Product>

        {

            new()

            {

                Group = "coloris",

                ValeursAndUids = new List<ValueAndUid>()

                {

                    new() {Item1 = "Beige", Item2 = "QB32-20220325-486274"},

                    new() {Item1 = "Beige", Item2 = "QB32-20220325-106045"},

                    new() {Item1 = "Venezia", Item2 = "QB32-20220325-205994"},

                    new() {Item1 = "Venezia", Item2 = "QB32-20220325-270903"},

                }

            },

            new()

            {

                Group = "ref_commercial",

                ValeursAndUids = new List<ValueAndUid>()

                {

                    new() {Item1 = "29245", Item2 = "QB32-20220325-486274"},

                    new() {Item1 = "29245", Item2 = "QB32-20220325-106045"},

                    new() {Item1 = "29245", Item2 = "QB32-20220325-205994"},

                    new() {Item1 = "29245", Item2 = "QB32-20220325-270903"},

                }

            },

            new()

            {

                Group = "Address",

                ValeursAndUids = new List<ValueAndUid>()

                {

                    new() {Item1 = "172 B", Item2 = "QB32-20220325-486274"},

                    new() {Item1 = "172 B", Item2 = "QB32-20220325-106045"},

                    new() {Item1 = "1725 A", Item2 = "QB32-20220325-205994"},

                    new() {Item1 = "1725 A", Item2 = "QB32-20220325-270903"},

                }

            }

        };

​

        // just collect all groups in a single list

        // it will produce the list: ["coloris", "ref_commercial", "Address", ""]

        List<string> groups = listProducts.Select(p => p.Group).ToList();

        groups.Add(""); // group for uids

​

        // build flat list of products

        // each product will be represented as a list of group values:

        // [ ["Beige", "29245", "172 B", "QB32-20220325-486274"], ["Beige", "29245", "172 B", "QB32-20220325-106045"],... ]

        IEnumerable<List<string>> products = listProducts

            .SelectMany(product => product.ValeursAndUids, (product, valueAndUid) => new { product.Group, valueAndUid })

            .GroupBy(item => item.valueAndUid.Item2)

            .Select(g =>

                    {

                        List<string> path = g.Select(item => item.valueAndUid.Item1).ToList();

                        path.Add(g.Key);

                        return path;

                    });

​

        TreeNode root = new TreeNode("root", "");

        TreeNode parent = root;

        foreach (List<string> path in products)

        {

            TreeNode current = parent;

​

            for (int i = 0; i < path.Count; i++)

            {

                string part = path[i];

                parent = parent.GetChild(groups[i], part);

            }

​

            parent = current;

        }

​

        root.Accept(new DepthTreeVisitor());

    }

​

    public interface Visitor

    {

        public void VisitTree(TreeNode tree);

    }

​

    public class DepthTreeVisitor : Visitor

    {

        private int level = 0;

​

        public void VisitTree(TreeNode tree)

        {

            string indentString = new string(' ', 2 * level);

            Console.WriteLine($"{indentString}{tree.GroupName} {tree.Value}");

            level++;

​

            foreach (TreeNode child in tree.Children)

            {

                child.Accept(this);

            }

​

            level--;

        }

    }

    public class TreeNode {

​

        public TreeNode(string groupName, string value)

        {

            GroupName = groupName;

            Value = value;

            Children = new HashSet<TreeNode>();

        }

​

        public string Value { get; }

        public string GroupName { get; }

        public ISet<TreeNode> Children { get; }

​

        public void Accept(Visitor visitor)

        {

            visitor.VisitTree(this);

        }

​

        public TreeNode GetChild(string group, string value)

        {

            foreach (TreeNode child in Children)

            {

                if (child.Value.Equals(value))

                {

                    return child;

                }

            }

​

            return GetChild(new TreeNode(group, value));

        }

​

        private TreeNode GetChild(TreeNode child)

        {

            Children.Add(child);

            return child;

        }

    }

}