Unit_56

using System;
using System.Collections.Generic;
using System.Linq;

namespace Ijunior
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Army army = new Army();
            army.Work();
        }
    }

    class Army
    {
        private Database _database = new Database();

        public void Work()
        {
            string letter = "Б";

            ShowPlatoons();
            Console.WriteLine($"\nПеревод солдат с фамилией на букву {letter}\n");
            _database.TransferSoldiers(letter);
            ShowPlatoons();
        }

        private void ShowPlatoons()
        {
            Console.WriteLine("Первый отряд:\n");
            _database.ShowInfo(_database.FirstPlatoon);
            Console.WriteLine("\nВторой отряд:\n");
            _database.ShowInfo(_database.SecondPlatoon);
        }
    }

    class Database
    {
        private List<Soldier> _firstPlatoon;
        private List<Soldier> _secondPlatoon;

        public Database()
        {
            _firstPlatoon = new List<Soldier>();
            _secondPlatoon = new List<Soldier>();
            AddSoldiers();
        }

        public List<Soldier> FirstPlatoon => _firstPlatoon.ToList();
        public List<Soldier> SecondPlatoon => _secondPlatoon.ToList();

        public void TransferSoldiers(string letter)
        {
            var transferredSoldiers = _firstPlatoon.Where(soldier => soldier.Name.StartsWith(letter));

            _secondPlatoon = _secondPlatoon.Union(transferredSoldiers).ToList();
            _firstPlatoon = _firstPlatoon.Except(transferredSoldiers).ToList();
        }

        public void ShowInfo(List<Soldier> platoon)
        {
            foreach (Soldier soldier in platoon)
            {
                Console.WriteLine($"{soldier.Name}");
            }
        }

        private void AddSoldiers()
        {
            _firstPlatoon.Add(new Soldier("Александров"));
            _firstPlatoon.Add(new Soldier("Борисов"));
            _firstPlatoon.Add(new Soldier("Беляев"));
            _firstPlatoon.Add(new Soldier("Гусев"));
            _firstPlatoon.Add(new Soldier("Быков"));

            _secondPlatoon.Add(new Soldier("Егоров"));
            _secondPlatoon.Add(new Soldier("Кузнецов"));
            _secondPlatoon.Add(new Soldier("Лебедев"));
            _secondPlatoon.Add(new Soldier("Павлов"));
            _secondPlatoon.Add(new Soldier("Васильев"));
        }
    }

    class Soldier
    {
        public Soldier(string name)
        {
            Name = name;
        }

        public string Name { get; }
    }
}