Add system fronter command

PluralKit.Bot/Commands/SystemCommands.cs

@@ -20,7 +20,10 @@ namespace PluralKit.Bot.Commands
 
         public SystemStore Systems {get; set;}
         public MemberStore Members {get; set;}
+        
+        public SwitchStore Switches {get; set;}
         public EmbedService EmbedService {get; set;}
+        
 
         [Command]
         public async Task Query(PKSystem system = null) {
@@ -145,8 +148,22 @@ namespace PluralKit.Bot.Commands
             }
         }
 
+        [Command("fronter")]
+        public async Task SystemFronter()
+        {
+            var system = ContextEntity ?? Context.SenderSystem;
+            if (system == null) throw Errors.NoSystemError;
+            
+            var sw = await Switches.GetLatestSwitch(system);
+            if (sw == null) throw Errors.NoRegisteredSwitches;
+            
+            var members = await Switches.GetSwitchMembers(sw);
+            await Context.Channel.SendMessageAsync(embed: EmbedService.CreateFronterEmbed(sw, members.ToList()));
+        }
+
         [Command("timezone")]
         [Remarks("system timezone [timezone]")]
+        [MustHaveSystem]
         public async Task SystemTimezone([Remainder] string zoneStr = null)
         {
             if (zoneStr == null)

PluralKit.Bot/Services/EmbedService.cs

@@ -1,7 +1,9 @@
+using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
 using System.Threading.Tasks;
 using Discord;
+using NodaTime;
 
 namespace PluralKit.Bot {
     public class EmbedService {
@@ -50,8 +52,7 @@ namespace PluralKit.Bot {
             var name = member.Name;
             if (system.Name != null) name = $"{member.Name} ({system.Name})";
             
-            var color = Color.Default;
-            if (member.Color != null) color = new Color(uint.Parse(member.Color, NumberStyles.HexNumber));
+            var color = member.Color?.ToDiscordColor() ?? Color.Default;
 
             var messageCount = await _members.MessageCount(member);
 
@@ -69,5 +70,15 @@ namespace PluralKit.Bot {
 
             return eb.Build();
         }
+
+        public Embed CreateFronterEmbed(PKSwitch sw, ICollection<PKMember> members)
+        {
+            var timeSinceSwitch = SystemClock.Instance.GetCurrentInstant() - sw.Timestamp;
+            return new EmbedBuilder()
+                .WithColor(members.FirstOrDefault()?.Color?.ToDiscordColor() ?? Color.Blue)
+                .AddField("Current fronter", members.Count > 0 ? string.Join(", ", members.Select(m => m.Name)) : "*(no fronter)*", true)
+                .AddField("Since", $"{sw.Timestamp.ToString(Formats.DateTimeFormat, null)} ({timeSinceSwitch.ToString(Formats.DurationFormat, null)} ago)", true)
+                .Build();
+        }
     }
 }

PluralKit.Bot/Utils.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Data;
+using System.Globalization;
 using System.Linq;
 using System.Net.Http;
 using System.Threading.Tasks;
@@ -20,6 +21,13 @@ namespace PluralKit.Bot
             return $"{user.Username}#{user.Discriminator} ({user.Mention})";
         }
 
+        public static Color? ToDiscordColor(this string color)
+        {
+            if (uint.TryParse(color, NumberStyles.HexNumber, null, out var colorInt))
+                return new Color(colorInt);
+            throw new ArgumentException($"Invalid color string '{color}'.");
+        }
+
         public static async Task VerifyAvatarOrThrow(string url)
         {
             // List of MIME types we consider acceptable