.greetmsg, .greetdmmsg, .acr and .byemsg now accept json which will cause the output to be a discord embed. You can create a proper json using http://nadekobot.xyz/embedbuilder/

src/NadekoBot/DataStructures/CREmbed.cs

@@ -0,0 +1,91 @@
+using Discord;
+using Newtonsoft.Json;
+using NLog;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace NadekoBot.DataStructures
+{
+    public class CREmbed
+    {
+        private static readonly Logger _log;
+        public string PlainText { get; set; }
+        public string Title { get; set; }
+        public string Description { get; set; }
+        public CREmbedFooter Footer { get; set; }
+        public string Thumbnail { get; set; }
+        public string Image { get; set; }
+        public CREmbedField[] Fields { get; set; }
+        public uint Color { get; set; } = 7458112;
+
+        static CREmbed()
+        {
+            _log = LogManager.GetCurrentClassLogger();
+        }
+
+        public bool IsValid =>
+            !string.IsNullOrWhiteSpace(Title) ||
+            !string.IsNullOrWhiteSpace(Description) ||
+            !string.IsNullOrWhiteSpace(Thumbnail) ||
+            !string.IsNullOrWhiteSpace(Image) ||
+            (Footer != null && (!string.IsNullOrWhiteSpace(Footer.Text) || !string.IsNullOrWhiteSpace(Footer.IconUrl))) ||
+            (Fields != null && Fields.Length > 0);
+
+        public EmbedBuilder ToEmbed()
+        {
+            var embed = new EmbedBuilder()
+                .WithTitle(Title)
+                .WithDescription(Description)
+                .WithColor(new Discord.Color(Color));
+            if (Footer != null)
+                embed.WithFooter(efb => efb.WithIconUrl(Footer.IconUrl).WithText(Footer.Text));
+            embed.WithThumbnailUrl(Thumbnail)
+                .WithImageUrl(Image);
+
+            if (Fields != null)
+                foreach (var f in Fields)
+                {
+                    embed.AddField(efb => efb.WithName(f.Name).WithValue(f.Value).WithIsInline(f.Inline));
+                }
+
+            return embed;
+        }
+
+        public static bool TryParse(string input, out CREmbed embed)
+        {
+            embed = null;
+            if (string.IsNullOrWhiteSpace(input))
+                return false;
+
+            try
+            {
+                var crembed = JsonConvert.DeserializeObject<CREmbed>(input);
+
+                if (!crembed.IsValid)
+                    return false;
+
+                embed = crembed;
+                return true;
+            }
+            catch (Exception ex)
+            {
+                return false;
+            }
+        }
+    }
+
+    public class CREmbedField
+    {
+        public string Name { get; set; }
+        public string Value { get; set; }
+        public bool Inline { get; set; }
+    }
+
+    public class CREmbedFooter {
+        public string Text { get; set; }
+        public string IconUrl { get; set; }
+    }
+}

src/NadekoBot/Modules/Administration/Commands/ServerGreetCommands.cs

@@ -2,6 +2,7 @@
 using Discord.Commands;
 using Discord.WebSocket;
 using NadekoBot.Attributes;
+using NadekoBot.DataStructures;
 using NadekoBot.Extensions;
 using NadekoBot.Services;
 using NadekoBot.Services.Database;
@@ -83,8 +84,9 @@ namespace NadekoBot.Modules.Administration
                 return settings;
             }
 
-            //todo optimize ASAP
+            private static Task UserLeft(IGuildUser user)
-            private static async Task UserLeft(IGuildUser user)
+            {
+                var _ = Task.Run(async () =>
                 {
                     try
                     {
@@ -95,7 +97,24 @@ namespace NadekoBot.Modules.Administration
 
                         if (channel == null) //maybe warn the server owner that the channel is missing
                             return;
-
+                        CREmbed embedData;
+                        if (CREmbed.TryParse(conf.ChannelByeMessageText, out embedData))
+                        {
+                            embedData.PlainText = embedData.PlainText?.Replace("%user%", user.Username).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                            embedData.Description = embedData.Description?.Replace("%user%", user.Username).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                            embedData.Title = embedData.Title?.Replace("%user%", user.Username).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                            try
+                            {
+                                var toDelete = await channel.EmbedAsync(embedData.ToEmbed(), embedData.PlainText ?? "").ConfigureAwait(false);
+                                if (conf.AutoDeleteByeMessagesTimer > 0)
+                                {
+                                    toDelete.DeleteAfter(conf.AutoDeleteByeMessagesTimer);
+                                }
+                            }
+                            catch (Exception ex) { _log.Warn(ex); }
+                        }
+                        else
+                        {
                             var msg = conf.ChannelByeMessageText.Replace("%user%", user.Username).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
                             if (string.IsNullOrWhiteSpace(msg))
                                 return;
@@ -109,10 +128,15 @@ namespace NadekoBot.Modules.Administration
                             }
                             catch (Exception ex) { _log.Warn(ex); }
                         }
+                    }
                     catch { }
+                });
+                return Task.CompletedTask;
             }
 
-            private static async Task UserJoined(IGuildUser user)
+            private static Task UserJoined(IGuildUser user)
+            {
+                var _ = Task.Run(async () =>
                 {
                     try
                     {
@@ -122,6 +146,25 @@ namespace NadekoBot.Modules.Administration
                         {
                             var channel = (await user.Guild.GetTextChannelsAsync()).SingleOrDefault(c => c.Id == conf.GreetMessageChannelId);
                             if (channel != null) //maybe warn the server owner that the channel is missing
+                            {
+
+                                CREmbed embedData;
+                                if (CREmbed.TryParse(conf.ChannelGreetMessageText, out embedData))
+                                {
+                                    embedData.PlainText = embedData.PlainText?.Replace("%user%", user.Mention).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                                    embedData.Description = embedData.Description?.Replace("%user%", user.Mention).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                                    embedData.Title = embedData.Title?.Replace("%user%", user.ToString()).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                                    try
+                                    {
+                                        var toDelete = await channel.EmbedAsync(embedData.ToEmbed(), embedData.PlainText ?? "").ConfigureAwait(false);
+                                        if (conf.AutoDeleteGreetMessagesTimer > 0)
+                                        {
+                                            toDelete.DeleteAfter(conf.AutoDeleteGreetMessagesTimer);
+                                        }
+                                    }
+                                    catch (Exception ex) { _log.Warn(ex); }
+                                }
+                                else
                                 {
                                     var msg = conf.ChannelGreetMessageText.Replace("%user%", user.Mention).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
                                     if (!string.IsNullOrWhiteSpace(msg))
@@ -138,6 +181,7 @@ namespace NadekoBot.Modules.Administration
                                     }
                                 }
                             }
+                        }
 
                         if (conf.SendDmGreetMessage)
                         {
@@ -145,7 +189,21 @@ namespace NadekoBot.Modules.Administration
 
                             if (channel != null)
                             {
-                            var msg = conf.DmGreetMessageText.Replace("%user%", user.Username).Replace("%server%", user.Guild.Name);
+                                CREmbed embedData;
+                                if (CREmbed.TryParse(conf.ChannelGreetMessageText, out embedData))
+                                {
+                                    embedData.PlainText = embedData.PlainText?.Replace("%user%", user.ToString()).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                                    embedData.Description = embedData.Description?.Replace("%user%", user.ToString()).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                                    embedData.Title = embedData.Title?.Replace("%user%", user.ToString()).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
+                                    try
+                                    {
+                                        await channel.EmbedAsync(embedData.ToEmbed(), embedData.PlainText ?? "").ConfigureAwait(false);
+                                    }
+                                    catch (Exception ex) { _log.Warn(ex); }
+                                }
+                                else
+                                {
+                                    var msg = conf.DmGreetMessageText.Replace("%user%", user.ToString()).Replace("%id%", user.Id.ToString()).Replace("%server%", user.Guild.Name);
                                     if (!string.IsNullOrWhiteSpace(msg))
                                     {
                                         await channel.SendConfirmAsync(msg).ConfigureAwait(false);
@@ -153,7 +211,10 @@ namespace NadekoBot.Modules.Administration
                                 }
                             }
                         }
+                    }
                     catch { }
+                });
+                return Task.CompletedTask;
             }
 
             [NadekoCommand, Usage, Description, Aliases]

src/NadekoBot/Modules/CustomReactions/CustomReactions.cs

@@ -11,6 +11,8 @@ using NLog;
 using System.Diagnostics;
 using Discord.WebSocket;
 using System;
+using Newtonsoft.Json;
+using NadekoBot.DataStructures;
 
 namespace NadekoBot.Modules.CustomReactions
 {
@@ -69,7 +71,22 @@ namespace NadekoBot.Modules.CustomReactions
                     if (reaction != null)
                     {
                         if (reaction.Response != "-")
+                        {
+                            CREmbed crembed;
+                            if (CREmbed.TryParse(reaction.Response, out crembed))
+                            {
+                                try { await channel.EmbedAsync(crembed.ToEmbed(), crembed.PlainText ?? "").ConfigureAwait(false); }
+                                catch (Exception ex)
+                                {
+                                    _log.Warn("Sending CREmbed failed");
+                                    _log.Warn(ex);
+                                }
+                            }
+                            else
+                            {
                                 try { await channel.SendMessageAsync(reaction.ResponseWithContext(umsg)).ConfigureAwait(false); } catch { }
+                            }
+                        }
 
                         ReactionStats.AddOrUpdate(reaction.Trigger, 1, (k, old) => ++old);
                         return true;
@@ -90,8 +107,21 @@ namespace NadekoBot.Modules.CustomReactions
             var greaction = grs[new NadekoRandom().Next(0, grs.Length)];
 
             if (greaction != null)
+            {
+                CREmbed crembed;
+                if (CREmbed.TryParse(greaction.Response, out crembed))
+                {
+                    try { await channel.EmbedAsync(crembed.ToEmbed(), crembed.PlainText ?? "").ConfigureAwait(false); }
+                    catch (Exception ex)
+                    {
+                        _log.Warn("Sending CREmbed failed");
+                        _log.Warn(ex);
+                    }
+                }
+                else
                 {
                     try { await channel.SendMessageAsync(greaction.ResponseWithContext(umsg)).ConfigureAwait(false); } catch { }
+                }
                 ReactionStats.AddOrUpdate(greaction.Trigger, 1, (k, old) => ++old);
                 return true;
             }