Started work on giveaways, not completed

src/Nadeko.Bot.Modules.Utility/Giveaway/GiveawayService.cs

@@ -0,0 +1,209 @@
+using LinqToDB;
+using LinqToDB.EntityFrameworkCore;
+using NadekoBot.Common.ModuleBehaviors;
+using NadekoBot.Db.Models;
+
+namespace NadekoBot.Modules.Utility;
+
+public sealed class GiveawayService : INService, IReadyExecutor
+{
+    public static string GiveawayEmoji = "🎉";
+
+    private readonly DbService _db;
+    private readonly IBotCredentials _creds;
+    private readonly DiscordSocketClient _client;
+    private GiveawayModel[] _shardGiveaways;
+    private readonly NadekoRandom _rng;
+
+    public GiveawayService(DbService db, IBotCredentials creds, DiscordSocketClient client)
+    {
+        _db = db;
+        _creds = creds;
+        _client = client;
+        _rng = new NadekoRandom();
+
+
+        _client.ReactionAdded += OnReactionAdded;
+        _client.ReactionRemoved += OnReactionRemoved;
+    }
+
+    private async Task OnReactionRemoved(Cacheable<IUserMessage, ulong> msg,
+        Cacheable<IMessageChannel, ulong> arg2,
+        SocketReaction r)
+    {
+        if (!r.User.IsSpecified)
+            return;
+        
+        var user = r.User.Value;
+        
+        if (user.IsBot || user.IsWebhook)
+            return;
+        
+        if (r.Emote is Emoji e && e.Name == GiveawayEmoji)
+        {
+            await LeaveGivawayAsync(msg.Id, user.Id);
+        }
+    }
+
+    private async Task OnReactionAdded(Cacheable<IUserMessage, ulong> msg, Cacheable<IMessageChannel, ulong> ch,
+        SocketReaction r)
+    {
+        if (!r.User.IsSpecified)
+            return;
+
+        var user = r.User.Value;
+
+        if (user.IsBot || user.IsWebhook)
+            return;
+
+        var textChannel = ch.Value as ITextChannel;
+
+        if (textChannel is null)
+            return;
+
+
+        if (r.Emote is Emoji e && e.Name == GiveawayEmoji)
+        {
+            await JoinGivawayAsync(msg.Id, user.Id, user.Username);
+        }
+    }
+
+    public async Task OnReadyAsync()
+    {
+        // load giveaways for this shard from the database
+        await using var ctx = _db.GetDbContext();
+
+        _shardGiveaways = await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => Linq2DbExpressions.GuildOnShard(x.GuildId, _creds.TotalShards, _client.ShardId))
+            .ToArrayAsync();
+    }
+
+    public async Task<int?> StartGiveawayAsync(ulong guildId, ulong channelId, ulong messageId, TimeSpan duration,
+        string message)
+    {
+        await using var ctx = _db.GetDbContext();
+
+        // first check if there are more than 5 giveaways
+        var count = await ctx
+            .GetTable<GiveawayModel>()
+            .CountAsync(x => x.GuildId == guildId);
+
+        if (count >= 5)
+            return null;
+
+        var endsAt = DateTime.UtcNow + duration;
+        var output = await ctx.GetTable<GiveawayModel>()
+            .InsertWithOutputAsync(() => new GiveawayModel
+            {
+                GuildId = guildId,
+                MessageId = messageId,
+                Message = message,
+                EndsAt = endsAt,
+            });
+
+        return output.Id;
+    }
+
+
+    public async Task<(GiveawayModel? giveaway, GiveawayUser? winner)> EndGiveawayAsync(ulong guildId, int id)
+    {
+        await using var ctx = _db.GetDbContext();
+
+        var giveaway = await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => x.GuildId == guildId && x.Id == id)
+            .LoadWith(x => x.Participants)
+            .FirstOrDefaultAsyncLinqToDB();
+
+        if (giveaway is null)
+            return default;
+
+        await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => x.Id == id)
+            .DeleteAsync();
+
+        if (giveaway.Participants.Count == 0)
+            return default;
+        
+        if (giveaway.Participants.Count == 1)
+            return (giveaway, giveaway.Participants[0]);
+
+        return (giveaway, giveaway.Participants[_rng.Next(0, giveaway.Participants.Count - 1)]);
+    }
+
+    public async Task RerollGiveawayAsync(ulong guildId, int id)
+    {
+    }
+
+    public async Task<bool> CancelGiveawayAsync(ulong guildId, int id)
+    {
+        await using var ctx = _db.GetDbContext();
+
+        var count = await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => x.GuildId == guildId && x.Id == id)
+            .DeleteAsync();
+
+        // todo clear cache
+
+        return count > 0;
+    }
+
+    public async Task<IReadOnlyCollection<GiveawayModel>> GetGiveawaysAsync(ulong guildId)
+    {
+        await using var ctx = _db.GetDbContext();
+
+        return await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => x.GuildId == guildId)
+            .ToListAsync();
+    }
+
+    public async Task<bool> JoinGivawayAsync(ulong messageId, ulong userId, string userName)
+    {
+        await using var ctx = _db.GetDbContext();
+
+        var giveaway = await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => x.MessageId == messageId)
+            .FirstOrDefaultAsyncLinqToDB();
+
+        if (giveaway is null)
+            return false;
+
+        // add the user to the database
+        await ctx.GetTable<GiveawayUser>()
+            .InsertAsync(
+                () => new GiveawayUser()
+                {
+                    UserId = userId,
+                    GiveawayId = giveaway.Id,
+                    Name = userName,
+                }
+            );
+
+        return true;
+    }
+
+    public async Task<bool> LeaveGivawayAsync(ulong messageId, ulong userId)
+    {
+        await using var ctx = _db.GetDbContext();
+        
+        var giveaway = await ctx
+            .GetTable<GiveawayModel>()
+            .Where(x => x.MessageId == messageId)
+            .FirstOrDefaultAsyncLinqToDB();
+        
+        if (giveaway is null)
+            return false;
+        
+        await ctx
+            .GetTable<GiveawayUser>()
+            .Where(x => x.UserId == userId && x.GiveawayId == giveaway.Id)
+            .DeleteAsync();
+        
+        return true;
+    }
+}