NadekoBot/NadekoBot.Core/Modules/Gambling/Common/CurrencyRaffleGame.cs

using Discord;
using NadekoBot.Common;
using NLog;
using System.Collections.Generic;
using System.Linq;

namespace NadekoBot.Core.Modules.Gambling.Common
{
    public class CurrencyRaffleGame
    {
        public enum Type {
            Mixed,
            Normal
        }

        public class User
        {
            public IUser DiscordUser { get; set; }
            public int Amount { get; set; }

            public override int GetHashCode()
            {
                return DiscordUser.GetHashCode();
            }

            public override bool Equals(object obj)
            {
                return obj is User u
                    ? u.DiscordUser == DiscordUser
                    : false;
            }
        }

        private readonly HashSet<User> _users = new HashSet<User>();
        public IEnumerable<User> Users => _users;
        public Type GameType { get; }
        private readonly Logger _log;

        public CurrencyRaffleGame(Type type)
        {
            GameType = type;
            _log = LogManager.GetCurrentClassLogger();
        }

        public bool AddUser(IUser usr, int amount)
        {
            // if game type is normal, and someone already joined the game 
            // (that's the user who created it)
            if (GameType == Type.Normal && _users.Count > 0 &&
                _users.First().Amount != amount)
                return false;

            if (!_users.Add(new User
            {
                DiscordUser = usr,
                Amount = amount,
            }))
            {
                return false;
            }
            
            return true;
        }

        public User GetWinner()
        {
            var rng = new NadekoRandom();
            if (GameType == Type.Mixed)
            {
                var num = rng.Next(0, Users.Sum(x => x.Amount));
                var sum = 0;
                foreach (var u in Users)
                {
                    sum += u.Amount;
                    if (sum > num)
                        return u;
                }
                _log.Error("Woah. Report this.\nRoll: {0}\nAmounts: {1}", num, string.Join(",", Users.Select(x => x.Amount)));
            }

            var usrs = _users.ToArray();
            return usrs[rng.Next(0, usrs.Length)];
        }
    }
}