[V3 Core] add support for setting a color for embeds (#1707)

* [V3 Core] add support for setting a color for embeds

* Add a guild toggle for whether to use the bot color

* Add a function for getting embed color in Context

* Coroutines need to be awaited lol

redbot/core/core_commands.py

@@ -556,6 +556,42 @@ class Core:
         await ctx.bot.db.guild(ctx.guild).mod_role.set(role.id)
         await ctx.send(_("The mod role for this guild has been set."))
 
+    @_set.command(aliases=["usebotcolor"])
+    @checks.guildowner()
+    @commands.guild_only()
+    async def usebotcolour(self, ctx):
+        """
+        Toggle whether to use the bot owner-configured colour for embeds.
+
+        Default is to not use the bot's configured colour, in which case the 
+        colour used will be the colour of the bot's top role.
+        """
+        current_setting = await ctx.bot.db.guild(ctx.guild).use_bot_color()
+        await ctx.bot.db.guild(ctx.guild).use_bot_color.set(not current_setting)
+        await ctx.send(
+            _("The bot {} use its configured color for embeds.").format(
+                _("will not") if current_setting else _("will")
+            )
+        )
+
+    @_set.command(aliases=["color"])
+    @checks.is_owner()
+    async def colour(self, ctx, *, colour: discord.Colour = None):
+        """
+        Sets a default colour to be used for the bot's embeds.
+
+        Acceptable values cor the colour parameter can be found at:
+
+        http://discordpy.readthedocs.io/en/rewrite/ext/commands/api.html#discord.ext.commands.ColourConverter
+        """
+        if colour is None:
+            ctx.bot.color = discord.Color.red()
+            await ctx.bot.db.color.set(discord.Color.red().value)
+            return await ctx.send(_("The color has been reset."))
+        ctx.bot.color = colour
+        await ctx.bot.db.color.set(colour.value)
+        await ctx.send(_("The color has been set."))
+
     @_set.command()
     @checks.is_owner()
     async def avatar(self, ctx, url: str):