NadekoBot/NadekoBot/Classes/Trivia/TriviaGame.cs

using Discord;
using Discord.Commands;
using NadekoBot.Extensions;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace NadekoBot.Classes.Trivia {
    internal class TriviaGame {
        private readonly object _guessLock = new object();

        private Server server { get; }
        private Channel channel { get; }

        private int QuestionDurationMiliseconds { get; } = 30000;
        private int HintTimeoutMiliseconds { get; } = 6000;
        private CancellationTokenSource triviaCancelSource { get; set; }

        public TriviaQuestion CurrentQuestion { get; private set; }
        public HashSet<TriviaQuestion> oldQuestions { get; } = new HashSet<TriviaQuestion>();

        public ConcurrentDictionary<User, int> Users { get; } = new ConcurrentDictionary<User, int>();

        public bool GameActive { get; private set; } = false;
        public bool ShouldStopGame { get; private set; }

        public int WinRequirement { get; } = 10;

        public TriviaGame(CommandEventArgs e) {
            server = e.Server;
            channel = e.Channel;
            Task.Run(StartGame);
        }

        private async Task StartGame() {
            while (!ShouldStopGame) {
                // reset the cancellation source
                triviaCancelSource = new CancellationTokenSource();
                var token = triviaCancelSource.Token;
                // load question
                CurrentQuestion = TriviaQuestionPool.Instance.GetRandomQuestion(oldQuestions);
                if (CurrentQuestion == null) {
                    await channel.SendMessage($":exclamation: Failed loading a trivia question");
                    await End();
                    return;
                }
                oldQuestions.Add(CurrentQuestion); //add it to exclusion list so it doesn't show up again
                                                   //sendquestion
                await channel.SendMessage($":question: **{CurrentQuestion.Question}**");

                //receive messages
                NadekoBot.Client.MessageReceived += PotentialGuess;

                //allow people to guess
                GameActive = true;

                try {
                    //hint
                    await Task.Delay(HintTimeoutMiliseconds, token);
                    await channel.SendMessage($":exclamation:**Hint:** {CurrentQuestion.GetHint()}");

                    //timeout
                    await Task.Delay(QuestionDurationMiliseconds - HintTimeoutMiliseconds, token);

                } catch (TaskCanceledException) {
                    Console.WriteLine("Trivia cancelled");
                }
                GameActive = false;
                if (!triviaCancelSource.IsCancellationRequested)
                    await channel.Send($":clock2: :question: **Time's up!** The correct answer was **{CurrentQuestion.Answer}**");
                NadekoBot.Client.MessageReceived -= PotentialGuess;
                // load next question if game is still running
                await Task.Delay(2000);
            }
            await End();
        }

        private async Task End() {
            ShouldStopGame = true;
            await channel.SendMessage("**Trivia game ended**\n" + GetLeaderboard());
            TriviaGame throwAwayValue;
            Commands.Trivia.RunningTrivias.TryRemove(server.Id, out throwAwayValue);
        }

        public async Task StopGame() {
            if (!ShouldStopGame)
                await channel.SendMessage(":exclamation: Trivia will stop after this question.");
            ShouldStopGame = true;
        }

        private async void PotentialGuess(object sender, MessageEventArgs e) {
            try {
                if (e.Channel.IsPrivate) return;
                if (e.Server != server) return;
                if (e.User.Id == NadekoBot.Client.CurrentUser.Id) return;

                var guess = false;
                lock (_guessLock) {
                    if (GameActive && CurrentQuestion.IsAnswerCorrect(e.Message.Text) && !triviaCancelSource.IsCancellationRequested) {
                        Users.TryAdd(e.User, 0); //add if not exists
                        Users[e.User]++; //add 1 point to the winner
                        guess = true;
                    }
                }
                if (!guess) return;
                triviaCancelSource.Cancel();
                await channel.SendMessage($"☑️ {e.User.Mention} guessed it! The answer was: **{CurrentQuestion.Answer}**");
                if (Users[e.User] != WinRequirement) return;
                ShouldStopGame = true;
                await channel.Send($":exclamation: We have a winner! Its {e.User.Mention}.");
                // add points to the winner
                await FlowersHandler.AddFlowersAsync(e.User, "Won Trivia", 2);
            } catch { }
        }

        public string GetLeaderboard() {
            if (Users.Count == 0)
                return "";

            var sb = new StringBuilder();
            sb.Append("**Leaderboard:**\n-----------\n");

            foreach (var kvp in Users.OrderBy(kvp => kvp.Value)) {
                sb.AppendLine($"**{kvp.Key.Name}** has {kvp.Value} points".ToString().SnPl(kvp.Value));
            }

            return sb.ToString();
        }
    }
}