From 53036da6a5632fa713e8715f18daa1964ed14687 Mon Sep 17 00:00:00 2001
From: Ske <voltasalt@gmail.com>
Date: Wed, 1 Jul 2020 18:18:38 +0200
Subject: [PATCH] Move checks in Context to extension methods

---
 PluralKit.Bot/CommandSystem/Context.cs       | 44 ----------------
 PluralKit.Bot/CommandSystem/ContextChecks.cs | 54 ++++++++++++++++++++
 2 files changed, 54 insertions(+), 44 deletions(-)
 create mode 100644 PluralKit.Bot/CommandSystem/ContextChecks.cs

diff --git a/PluralKit.Bot/CommandSystem/Context.cs b/PluralKit.Bot/CommandSystem/Context.cs
index d79e5693..ef68229d 100644
--- a/PluralKit.Bot/CommandSystem/Context.cs
+++ b/PluralKit.Bot/CommandSystem/Context.cs
@@ -7,7 +7,6 @@ using App.Metrics;
 
 using Autofac;
 
-
 using DSharpPlus;
 using DSharpPlus.Entities;
 using DSharpPlus.Exceptions;
@@ -241,43 +240,6 @@ namespace PluralKit.Bot
             return $"Member not found. Note that a member ID is 5 characters long.";
         }
 
-        public Context CheckSystem()
-        {
-            if (_senderSystem == null)
-                throw Errors.NoSystemError;
-            return this;
-        }
-
-        public Context CheckNoSystem()
-        {
-            if (_senderSystem != null)
-                throw Errors.ExistingSystemError;
-            return this;
-        }
-
-        public Context CheckOwnMember(PKMember member)
-        {
-            if (member.System != _senderSystem.Id)
-                throw Errors.NotOwnMemberError;
-            return this;
-        }
-
-        public Context CheckAuthorPermission(Permissions neededPerms, string permissionName)
-        {
-            // TODO: can we always assume Author is a DiscordMember? I would think so, given they always come from a
-            // message received event...
-            var hasPerms = Channel.PermissionsInSync(Author);
-            if ((hasPerms & neededPerms) != neededPerms)
-                throw new PKError($"You must have the \"{permissionName}\" permission in this server to use this command.");
-            return this;
-        }
-
-        public Context CheckGuildContext()
-        {
-            if (Channel.Guild != null) return this;
-            throw new PKError("This command can not be run in a DM.");
-        }
-
         public LookupContext LookupContextFor(PKSystem target) => 
             System?.Id == target.Id ? LookupContext.ByOwner : LookupContext.ByNonOwner;
         
@@ -287,12 +249,6 @@ namespace PluralKit.Bot
         public LookupContext LookupContextFor(PKMember target) =>
             System?.Id == target.System ? LookupContext.ByOwner : LookupContext.ByNonOwner;
 
-        public Context CheckSystemPrivacy(PKSystem target, PrivacyLevel level)
-        {
-            if (level.CanAccess(LookupContextFor(target))) return this;
-            throw new PKError("You do not have permission to access this information.");
-        }
-
         public async Task<DiscordChannel> MatchChannel()
         {
             if (!MentionUtils.TryParseChannel(PeekArgument(), out var channel)) 
diff --git a/PluralKit.Bot/CommandSystem/ContextChecks.cs b/PluralKit.Bot/CommandSystem/ContextChecks.cs
new file mode 100644
index 00000000..54bb45a6
--- /dev/null
+++ b/PluralKit.Bot/CommandSystem/ContextChecks.cs
@@ -0,0 +1,54 @@
+using System.Threading.Channels;
+
+using DSharpPlus;
+
+using PluralKit.Core;
+
+namespace PluralKit.Bot
+{
+    public static class ContextChecks
+    {
+        public static Context CheckGuildContext(this Context ctx)
+        {
+            if (ctx.Channel.Guild != null) return ctx;
+            throw new PKError("This command can not be run in a DM.");
+        }
+        
+        public static Context CheckSystemPrivacy(this Context ctx, PKSystem target, PrivacyLevel level)
+        {
+            if (level.CanAccess(ctx.LookupContextFor(target))) return ctx;
+            throw new PKError("You do not have permission to access this information.");
+        }
+        
+        public static Context CheckOwnMember(this Context ctx, PKMember member)
+        {
+            if (member.System != ctx.System?.Id)
+                throw Errors.NotOwnMemberError;
+            return ctx;
+        }
+        
+        public static Context CheckSystem(this Context ctx)
+        {
+            if (ctx.System == null)
+                throw Errors.NoSystemError;
+            return ctx;
+        }
+
+        public static Context CheckNoSystem(this Context ctx)
+        {
+            if (ctx.System != null)
+                throw Errors.ExistingSystemError;
+            return ctx;
+        }
+        
+        public static Context CheckAuthorPermission(this Context ctx, Permissions neededPerms, string permissionName)
+        {
+            // TODO: can we always assume Author is a DiscordMember? I would think so, given they always come from a
+            // message received event...
+            var hasPerms = ctx.Channel.PermissionsInSync(ctx.Author);
+            if ((hasPerms & neededPerms) != neededPerms)
+                throw new PKError($"You must have the \"{permissionName}\" permission in this server to use this command.");
+            return ctx;
+        }
+    }
+}
\ No newline at end of file