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

namespace TopReplays.Extensions
{
    public static class IEnumerableExtensions
    {
        private class TournamentSeedPosition<T>
        {
            public int Seed
            {
                get;
                set;
            }

            public T TournamentObject
            {
                get;
                set;
            }
        }

        public static T SelectRandom<T>(this IEnumerable<T> ienumerable)
        {
            Random r = new Random();
            return ienumerable.ElementAt<T>(r.Next(ienumerable.Count()));
        }

        public static IEnumerable<T> TournamentSeedShuffle<T>(this IEnumerable<T> players)
        {
            List<TournamentSeedPosition<T>> finalPositions = new List<TournamentSeedPosition<T>>();

            finalPositions.Add(new TournamentSeedPosition<T>
            {
                Seed = 1,
                TournamentObject = players.ElementAt(0)
            });

            finalPositions.Add(new TournamentSeedPosition<T>
            {
                Seed = 2,
                TournamentObject = players.ElementAt(1)
            });

            double nr_rounds = Math.Ceiling(Math.Log(players.Count(), 2));

            for (int round = 2; round <= nr_rounds; round++)
            {
                int currentRoundMatchPairing = Convert.ToInt32(Math.Pow(2, round)) + 1;
                int currentPlayer = 0;

                while (currentPlayer < finalPositions.Count())
                {
                    int currentOpponent = currentRoundMatchPairing - finalPositions.ElementAt(currentPlayer).Seed;
                    finalPositions.Insert(currentPlayer + 1, new TournamentSeedPosition<T>
                    {
                        Seed = currentOpponent,
                        TournamentObject = players.ElementAt(currentOpponent - 1)
                    });

                    currentPlayer += 2;
                }
            }

            return finalPositions.Select(t => t.TournamentObject);
        }
    }
}