feat(bot): add support for Discord message context commands (#513)

PluralKit.Bot/ApplicationCommands/Message.cs

@@ -0,0 +1,152 @@
+using Autofac;
+
+using Myriad.Cache;
+using Myriad.Extensions;
+using Myriad.Rest;
+using Myriad.Rest.Types;
+using Myriad.Types;
+
+using NodaTime;
+
+using PluralKit.Core;
+
+namespace PluralKit.Bot;
+
+public class ApplicationCommandProxiedMessage
+{
+    private readonly DiscordApiClient _rest;
+    private readonly IDiscordCache _cache;
+    private readonly EmbedService _embeds;
+    private readonly ModelRepository _repo;
+
+    public ApplicationCommandProxiedMessage(DiscordApiClient rest, IDiscordCache cache, EmbedService embeds,
+                                            ModelRepository repo)
+    {
+        _rest = rest;
+        _cache = cache;
+        _embeds = embeds;
+        _repo = repo;
+    }
+
+    public async Task QueryMessage(InteractionContext ctx)
+    {
+        var messageId = ctx.Event.Data!.TargetId!.Value;
+        var msg = await ctx.Repository.GetFullMessage(messageId);
+        if (msg == null)
+            throw Errors.MessageNotFound(messageId);
+
+        var showContent = true;
+        var channel = await _rest.GetChannelOrNull(msg.Message.Channel);
+        if (channel == null)
+            showContent = false;
+
+        var embeds = new List<Embed>();
+
+        var guild = await _cache.GetGuild(ctx.GuildId);
+        if (msg.Member != null)
+            embeds.Add(await _embeds.CreateMemberEmbed(
+                msg.System,
+                msg.Member,
+                guild,
+                LookupContext.ByNonOwner,
+                DateTimeZone.Utc
+            ));
+
+        embeds.Add(await _embeds.CreateMessageInfoEmbed(msg, showContent));
+
+        await ctx.Reply(embeds: embeds.ToArray());
+    }
+
+    public async Task DeleteMessage(InteractionContext ctx)
+    {
+        var messageId = ctx.Event.Data!.TargetId!.Value;
+
+        // check for command messages
+        var (authorId, channelId) = await ctx.Services.Resolve<CommandMessageService>().GetCommandMessage(messageId);
+        if (authorId != null)
+        {
+            if (authorId != ctx.User.Id)
+                throw new PKError("You can only delete command messages queried by this account.");
+
+            var isDM = (await _repo.GetDmChannel(ctx.User!.Id)) == channelId;
+            await DeleteMessageInner(ctx, channelId!.Value, messageId, isDM);
+            return;
+        }
+
+        // and do the same for proxied messages
+        var message = await ctx.Repository.GetFullMessage(messageId);
+        if (message != null)
+        {
+            if (message.System?.Id != ctx.System.Id && message.Message.Sender != ctx.User.Id)
+                throw new PKError("You can only delete your own messages.");
+
+            await DeleteMessageInner(ctx, message.Message.Channel, message.Message.Mid, false);
+            return;
+        }
+
+        // otherwise, we don't know about this message at all!
+        throw Errors.MessageNotFound(messageId);
+    }
+
+    internal async Task DeleteMessageInner(InteractionContext ctx, ulong channelId, ulong messageId, bool isDM = false)
+    {
+        if (!((await _cache.PermissionsIn(channelId)).HasFlag(PermissionSet.ManageMessages) || isDM))
+            throw new PKError("PluralKit does not have the *Manage Messages* permission in this channel, and thus cannot delete the message."
+                + " Please contact a server administrator to remedy this.");
+
+        await ctx.Rest.DeleteMessage(channelId, messageId);
+        await ctx.Reply($"{Emojis.Success} Message deleted.");
+    }
+
+    public async Task PingMessageAuthor(InteractionContext ctx)
+    {
+        var messageId = ctx.Event.Data!.TargetId!.Value;
+        var msg = await ctx.Repository.GetFullMessage(messageId);
+        if (msg == null)
+            throw Errors.MessageNotFound(messageId);
+
+        // Check if the "pinger" has permission to send messages in this channel
+        // (if not, PK shouldn't send messages on their behalf)
+        var member = await _rest.GetGuildMember(ctx.GuildId, ctx.User.Id);
+        var requiredPerms = PermissionSet.ViewChannel | PermissionSet.SendMessages;
+        if (member == null || !(await _cache.PermissionsFor(ctx.ChannelId, member)).HasFlag(requiredPerms))
+        {
+            throw new PKError("You do not have permission to send messages in this channel.");
+        };
+
+        var config = await _repo.GetSystemConfig(msg.System.Id);
+
+        if (config.PingsEnabled)
+        {
+            // If the system has pings enabled, go ahead
+            await ctx.Respond(InteractionResponse.ResponseType.ChannelMessageWithSource,
+                new InteractionApplicationCommandCallbackData
+                {
+                    Content = $"Psst, **{msg.Member.DisplayName()}** (<@{msg.Message.Sender}>), you have been pinged by <@{ctx.User.Id}>.",
+                    Components = new[]
+                    {
+                        new MessageComponent
+                        {
+                            Type = ComponentType.ActionRow,
+                            Components = new[]
+                            {
+                                new MessageComponent
+                                {
+                                    Style = ButtonStyle.Link,
+                                    Type = ComponentType.Button,
+                                    Label = "Jump",
+                                    Url = msg.Message.JumpLink(),
+                                }
+                            }
+                        }
+                    },
+                    AllowedMentions = new AllowedMentions { Users = new[] { msg.Message.Sender } },
+                    Flags = new() { },
+                });
+        }
+        else
+        {
+            await ctx.Reply($"{Emojis.Error} {msg.Member.DisplayName()}'s system has disabled command pings.");
+        }
+    }
+}