nadekobot/src/NadekoBot/Modules/Games/Common/PollRunner.cs

using NadekoBot.Services.Database.Models;

namespace NadekoBot.Modules.Games.Common;

public class PollRunner
{
    public Poll Poll { get; }
    private readonly DbService _db;

    public event Func<IUserMessage, IGuildUser, Task> OnVoted;

    private readonly SemaphoreSlim _locker = new(1, 1);

    public PollRunner(DbService db, Poll poll)
    {
        _db = db;
        Poll = poll;
    }

    public async Task<bool> TryVote(IUserMessage msg)
    {
        PollVote voteObj;
        await _locker.WaitAsync().ConfigureAwait(false);
        try
        {
            // has to be a user message
            // channel must be the same the poll started in
            if (msg is null || msg.Author.IsBot || msg.Channel.Id != Poll.ChannelId)
                return false;

            // has to be an integer
            if (!int.TryParse(msg.Content, out var vote))
                return false;
            --vote;
            if (vote < 0 || vote >= Poll.Answers.Count)
                return false;

            var usr = msg.Author as IGuildUser;
            if (usr is null)
                return false;

            voteObj = new()
            {
                UserId = msg.Author.Id,
                VoteIndex = vote,
            };
            if (!Poll.Votes.Add(voteObj))
                return false;

            var _ = OnVoted?.Invoke(msg, usr);
        }
        finally { _locker.Release(); }

        await using (var uow = _db.GetDbContext())
        {
            var trackedPoll = uow.Poll.FirstOrDefault(x => x.Id == Poll.Id);
            trackedPoll.Votes.Add(voteObj);
            uow.SaveChanges();
        }
        return true;
    }

    public void End()
    {
        OnVoted = null;
    }
}