300 lines
13 KiB
C#
300 lines
13 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Text.RegularExpressions;
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using System.Threading.Tasks;
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using App.Metrics;
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using Myriad.Cache;
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using Myriad.Extensions;
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using Myriad.Gateway;
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using Myriad.Rest;
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using Myriad.Rest.Exceptions;
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using Myriad.Rest.Types.Requests;
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using Myriad.Types;
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using PluralKit.Core;
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using Serilog;
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namespace PluralKit.Bot
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{
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public class ProxyService
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{
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private static readonly TimeSpan MessageDeletionDelay = TimeSpan.FromMilliseconds(1000);
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private readonly LogChannelService _logChannel;
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private readonly IDatabase _db;
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private readonly ModelRepository _repo;
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private readonly ILogger _logger;
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private readonly WebhookExecutorService _webhookExecutor;
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private readonly ProxyMatcher _matcher;
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private readonly IMetrics _metrics;
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private readonly IDiscordCache _cache;
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private readonly DiscordApiClient _rest;
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public ProxyService(LogChannelService logChannel, ILogger logger,
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WebhookExecutorService webhookExecutor, IDatabase db, ProxyMatcher matcher, IMetrics metrics, ModelRepository repo, IDiscordCache cache, DiscordApiClient rest)
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{
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_logChannel = logChannel;
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_webhookExecutor = webhookExecutor;
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_db = db;
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_matcher = matcher;
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_metrics = metrics;
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_repo = repo;
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_cache = cache;
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_rest = rest;
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_logger = logger.ForContext<ProxyService>();
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}
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public async Task<bool> HandleIncomingMessage(Shard shard, MessageCreateEvent message, MessageContext ctx, Guild guild, Channel channel, bool allowAutoproxy, PermissionSet botPermissions)
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{
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if (!ShouldProxy(channel, message, ctx))
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return false;
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// this is hopefully temporary, so not putting it into a separate method
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if (message.Content != null && message.Content.Length > 2000) throw new PKError("PluralKit cannot proxy messages over 2000 characters in length.");
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// Fetch members and try to match to a specific member
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await using var conn = await _db.Obtain();
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List<ProxyMember> members;
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using (_metrics.Measure.Timer.Time(BotMetrics.ProxyMembersQueryTime))
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members = (await _repo.GetProxyMembers(conn, message.Author.Id, message.GuildId!.Value)).ToList();
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if (!_matcher.TryMatch(ctx, members, out var match, message.Content, message.Attachments.Length > 0,
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allowAutoproxy)) return false;
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// Permission check after proxy match so we don't get spammed when not actually proxying
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if (!await CheckBotPermissionsOrError(botPermissions, message.ChannelId))
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return false;
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// this method throws, so no need to wrap it in an if statement
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CheckProxyNameBoundsOrError(match.Member.ProxyName(ctx));
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// Check if the sender account can mention everyone/here + embed links
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// we need to "mirror" these permissions when proxying to prevent exploits
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var senderPermissions = PermissionExtensions.PermissionsFor(guild, channel, message);
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var allowEveryone = senderPermissions.HasFlag(PermissionSet.MentionEveryone);
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var allowEmbeds = senderPermissions.HasFlag(PermissionSet.EmbedLinks);
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// Everything's in order, we can execute the proxy!
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await ExecuteProxy(shard, conn, message, ctx, match, allowEveryone, allowEmbeds);
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return true;
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}
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private bool ShouldProxy(Channel channel, Message msg, MessageContext ctx)
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{
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// Make sure author has a system
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if (ctx.SystemId == null) return false;
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// Make sure channel is a guild text channel and this is a normal message
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if (channel.Type != Channel.ChannelType.GuildText && channel.Type != Channel.ChannelType.GuildNews) return false;
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if (msg.Type != Message.MessageType.Default && msg.Type != Message.MessageType.Reply) return false;
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// Make sure author is a normal user
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if (msg.Author.System == true || msg.Author.Bot || msg.WebhookId != null) return false;
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// Make sure proxying is enabled here
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if (!ctx.ProxyEnabled || ctx.InBlacklist) return false;
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// Make sure we have either an attachment or message content
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var isMessageBlank = msg.Content == null || msg.Content.Trim().Length == 0;
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if (isMessageBlank && msg.Attachments.Length == 0) return false;
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// All good!
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return true;
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}
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private async Task ExecuteProxy(Shard shard, IPKConnection conn, Message trigger, MessageContext ctx,
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ProxyMatch match, bool allowEveryone, bool allowEmbeds)
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{
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// Create reply embed
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var embeds = new List<Embed>();
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if (trigger.Type == Message.MessageType.Reply && trigger.MessageReference?.ChannelId == trigger.ChannelId)
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{
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var repliedTo = trigger.ReferencedMessage.Value;
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if (repliedTo != null)
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{
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var nickname = await FetchReferencedMessageAuthorNickname(trigger, repliedTo);
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var embed = CreateReplyEmbed(match, trigger, repliedTo, nickname);
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if (embed != null)
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embeds.Add(embed);
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}
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// TODO: have a clean error for when message can't be fetched instead of just being silent
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}
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// Send the webhook
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var content = match.ProxyContent;
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if (!allowEmbeds) content = content.BreakLinkEmbeds();
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var proxyMessage = await _webhookExecutor.ExecuteWebhook(new ProxyRequest
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{
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GuildId = trigger.GuildId!.Value,
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ChannelId = trigger.ChannelId,
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Name = match.Member.ProxyName(ctx),
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AvatarUrl = match.Member.ProxyAvatar(ctx),
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Content = content,
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Attachments = trigger.Attachments,
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Embeds = embeds.ToArray(),
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AllowEveryone = allowEveryone,
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});
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await HandleProxyExecutedActions(shard, conn, ctx, trigger, proxyMessage, match);
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}
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private async Task<string?> FetchReferencedMessageAuthorNickname(Message trigger, Message referenced)
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{
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if (referenced.WebhookId != null)
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return null;
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try
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{
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var member = await _rest.GetGuildMember(trigger.GuildId!.Value, referenced.Author.Id);
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return member?.Nick;
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}
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catch (ForbiddenException)
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{
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_logger.Warning("Failed to fetch member {UserId} in guild {GuildId} when getting reply nickname, falling back to username",
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referenced.Author.Id, trigger.GuildId!.Value);
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return null;
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}
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}
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private Embed CreateReplyEmbed(ProxyMatch match, Message trigger, Message repliedTo, string? nickname)
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{
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// repliedTo doesn't have a GuildId field :/
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var jumpLink = $"https://discord.com/channels/{trigger.GuildId}/{repliedTo.ChannelId}/{repliedTo.Id}";
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var content = new StringBuilder();
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var hasContent = !string.IsNullOrWhiteSpace(repliedTo.Content);
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if (hasContent)
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{
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var msg = repliedTo.Content;
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if (msg.Length > 100)
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{
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msg = repliedTo.Content.Substring(0, 100);
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var spoilersInOriginalString = Regex.Matches(repliedTo.Content, @"\|\|").Count;
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var spoilersInTruncatedString = Regex.Matches(msg, @"\|\|").Count;
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if (spoilersInTruncatedString % 2 == 1 && spoilersInOriginalString % 2 == 0)
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msg += "||";
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msg += "…";
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}
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content.Append($"**[Reply to:]({jumpLink})** ");
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content.Append(msg);
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if (repliedTo.Attachments.Length > 0)
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content.Append($" {Emojis.Paperclip}");
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}
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else
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{
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content.Append($"*[(click to see attachment)]({jumpLink})*");
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}
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var username = nickname ?? repliedTo.Author.Username;
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var avatarUrl = $"https://cdn.discordapp.com/avatars/{repliedTo.Author.Id}/{repliedTo.Author.Avatar}.png";
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return new Embed
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{
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// unicodes: [three-per-em space] [left arrow emoji] [force emoji presentation]
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Author = new($"{username}\u2004\u21a9\ufe0f", IconUrl: avatarUrl),
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Description = content.ToString(),
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Color = match.Member.Color?.ToDiscordColor(),
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};
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}
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private async Task HandleProxyExecutedActions(Shard shard, IPKConnection conn, MessageContext ctx,
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Message triggerMessage, Message proxyMessage,
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ProxyMatch match)
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{
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Task SaveMessageInDatabase() => _repo.AddMessage(conn, new PKMessage
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{
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Channel = triggerMessage.ChannelId,
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Guild = triggerMessage.GuildId,
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Member = match.Member.Id,
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Mid = proxyMessage.Id,
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OriginalMid = triggerMessage.Id,
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Sender = triggerMessage.Author.Id
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});
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Task LogMessageToChannel() => _logChannel.LogMessage(ctx, match, triggerMessage, proxyMessage.Id).AsTask();
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async Task DeleteProxyTriggerMessage()
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{
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// Wait a second or so before deleting the original message
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await Task.Delay(MessageDeletionDelay);
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try
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{
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await _rest.DeleteMessage(triggerMessage.ChannelId, triggerMessage.Id);
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}
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catch (NotFoundException)
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{
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_logger.Debug("Trigger message {TriggerMessageId} was already deleted when we attempted to; deleting proxy message {ProxyMessageId} also",
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triggerMessage.Id, proxyMessage.Id);
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await HandleTriggerAlreadyDeleted(proxyMessage);
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// Swallow the exception, we don't need it
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}
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}
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// Run post-proxy actions (simultaneously; order doesn't matter)
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// Note that only AddMessage is using our passed-in connection, careful not to pass it elsewhere and run into conflicts
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await Task.WhenAll(
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DeleteProxyTriggerMessage(),
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SaveMessageInDatabase(),
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LogMessageToChannel()
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);
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}
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private async Task HandleTriggerAlreadyDeleted(Message proxyMessage)
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{
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// If a trigger message is deleted before we get to delete it, we can assume a mod bot or similar got to it
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// In this case we should also delete the now-proxied message.
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// This is going to hit the message delete event handler also, so that'll do the cleanup for us
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try
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{
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await _rest.DeleteMessage(proxyMessage.ChannelId, proxyMessage.Id);
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}
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catch (NotFoundException) { }
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catch (UnauthorizedException) { }
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}
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private async Task<bool> CheckBotPermissionsOrError(PermissionSet permissions, ulong responseChannel)
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{
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// If we can't send messages at all, just bail immediately.
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// 2020-04-22: Manage Messages does *not* override a lack of Send Messages.
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if (!permissions.HasFlag(PermissionSet.SendMessages))
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return false;
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if (!permissions.HasFlag(PermissionSet.ManageWebhooks))
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{
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// todo: PKError-ify these
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await _rest.CreateMessage(responseChannel, new MessageRequest
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{
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Content = $"{Emojis.Error} PluralKit does not have the *Manage Webhooks* permission in this channel, and thus cannot proxy messages. Please contact a server administrator to remedy this."
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});
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return false;
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}
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if (!permissions.HasFlag(PermissionSet.ManageMessages))
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{
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await _rest.CreateMessage(responseChannel, new MessageRequest
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{
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Content = $"{Emojis.Error} PluralKit does not have the *Manage Messages* permission in this channel, and thus cannot delete the original trigger message. Please contact a server administrator to remedy this."
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});
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return false;
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}
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return true;
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}
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private void CheckProxyNameBoundsOrError(string proxyName)
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{
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if (proxyName.Length > Limits.MaxProxyNameLength) throw Errors.ProxyNameTooLong(proxyName);
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}
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}
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}
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