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

namespace IdleMafiaBot
{

    sealed class Turns
    {

        const double WaitPointsPerMinute = 10;

        sealed class Waiter { public DateTime Since, Seen; public int Need; }

        readonly object gate = new object();
        readonly List<Bot> order;
        readonly Dictionary<Bot, Waiter> waiting = new Dictionary<Bot, Waiter>();
        Bot holder;

        public Turns(IEnumerable<Bot> bots) { order = bots.ToList(); }

        internal static double Score(int need, double waitedMinutes) { return Math.Max(0, need) + waitedMinutes * WaitPointsPerMinute; }

        public bool Take(Bot b, int need, Func<bool> stopped, int maxMs)
        {
            int end = Environment.TickCount + maxMs;
            lock (gate)
                while (true)
                {
                    if (stopped()) throw new StopException();
                    if (!order.Contains(b)) return true;
                    Waiter me;
                    if (!waiting.TryGetValue(b, out me)) waiting[b] = me = new Waiter { Since = DateTime.UtcNow };
                    me.Need = need;
                    me.Seen = DateTime.UtcNow;
                    if (holder == null && Next() == b) { holder = b; waiting.Remove(b); return true; }
                    int left = end - Environment.TickCount;
                    if (left <= 0) return false;
                    Monitor.Wait(gate, Math.Min(500, left));
                }
        }

        Bot Next()
        {
            var now = DateTime.UtcNow;
            return waiting.Where(w => now - w.Value.Seen < TimeSpan.FromMinutes(1))
                          .OrderByDescending(w => Score(w.Value.Need, (now - w.Value.Since).TotalMinutes)).ThenBy(w => w.Value.Since).First().Key;
        }

        public bool Wanted(Bot b) { lock (gate) return waiting.Keys.Any(o => o != b); }

        public void Pass(Bot b)
        {
            lock (gate)
            {
                if (holder == b) holder = null;
                Monitor.PulseAll(gate);
            }
        }

        public void Leave(Bot b)
        {
            lock (gate)
            {
                if (!order.Remove(b)) return;
                waiting.Remove(b);
                if (holder == b) holder = null;
                Monitor.PulseAll(gate);
            }
        }
    }
}