feat: Create subcommandPermCheck plugin (#113)

* feat: Create subcommandPermCheck plugin

This plugin was requested to be uploaded for basic sub command permission handling. Only available for slash commands and will fault out for other command types.

* edit: resolve conflicts

Removed deconstructed interaction
Made errors more understandable
Corrected the example to use a parameter as the first object and input correct properties.

---------

Co-authored-by: Jacob Nguyen <76754747+jacoobes@users.noreply.github.com>

plugins/subcommandPermCheck.ts

@@ -0,0 +1,109 @@
+//@ts-nocheck
+/**
+ * @plugin
+ * Inspired by the plugin "requirePermission" created by Benzo-Fury & needhamgary, this plugin will set permissions for specific subcommands without manually writing it into the code.
+ *
+ * @author @Peter-MJ-Parker [<@371759410009341952>]
+ * @version 1.0
+ * @example
+ * ```ts
+ * import { subcommandPermCheck } from "../plugins/subcommandPerms.js";
+ * import { commandModule, CommandType } from "@sern/handler";
+ * import { PermissionFlagBits } from "discord.js";
+ * export default commandModule({
+ *  type: CommandType.Slash,
+ *  plugins: [
+ *   subcommandPermCheck({
+ *    list: [
+ *      { name: "string", perms: [PermissionFlagBits.Administrator] },
+ *      { name: "number", perms: [PermissionFlagBits.SendMessages, PermissionFlagBits.UseVAD] }
+ *    ],
+ *   needAllPerms: true, //all = Require the member to have all perms stated or at least one?
+ *   //response: "OPTIONAL - respond to user with this message or default."
+ *   })
+ *  ],
+ *  execute: ({ interaction }) => {
+ * 		//your code here
+ *  }
+ * })
+ * ```
+ * @end
+ */
+
+/** Marked TODO's will be reconfigured with release of sern v4! **/
+import type { GuildMember, PermissionResolvable, TextChannel } from 'discord.js';
+import { type CommandType, CommandControlPlugin, controller } from '@sern/handler';
+
+export const permsToString = (...perms: PermissionResolvable[]) => {
+  return new PermissionsBitField(perms)
+    .toArray()
+    .map((perm) => `\`${perm}\``)
+    .join(", ");
+};
+
+export function subcommandPermCheck(opts: Options) {
+  return CommandControlPlugin<CommandType.Slash>(async (ctx) => {
+    if (!ctx.isSlash()) {
+      throw new Error('You did not provide a slash command.', { cause: "The plugin 'subcommandPermCheck' is meant for Slash commands only!" });
+      //TODO: return state to command rather than error
+      return controller.stop();
+    }
+
+    if (ctx.guild === null) {
+      await ctx.reply({
+        content: "This sub command cannot be used in DM's!",
+        ephemeral: true
+      });
+      return controller.stop();
+    }
+    const member = ctx.member as GuildMember;
+    const subcommands = opts.list;
+    let sub = ctx.options.getSubcommand();
+
+    /** WILL BE REWRITTEN WHEN SERN V4 IS RELEASED!!! **/
+    for (const { name, perms } of subcommands) {
+      if (name !== sub) {
+        throw new Error("You provided a subcommand name which doesn't exist in given command.", {
+          cause: `subcommand: \`${name}\` not found on command: ${ctx.interaction.commandName}.`
+        });
+        //TODO: return state to command rather than error
+        return controller.stop();
+      } else {
+        const each = permsToString(perms);
+        const { needAllPerms } = opts;
+        const memberPermissions = member.permissionsIn(ctx.channel as TextChannel);
+        if (needAllPerms === true) {
+          if (!memberPermissions.has(perms)) {
+            await ctx.reply({
+              content:
+                opts.response ??
+                `You are required to have all of the following permissions to run this subcommand in this channel:\n${each}`,
+              ephemeral: true
+            });
+            //TODO: return state to command
+            return controller.stop();
+          }
+        } else {
+          if (!memberPermissions.any(perms)) {
+            await ctx.reply({
+              content:
+                opts.response ??
+                `You are required to have at least one of the following permissions to run this subcommand in this channel:\n${each}`,
+              ephemeral: true
+            });
+            //TODO: return state to command
+            return controller.stop();
+          }
+        }
+      }
+    }
+    //TODO: return state to command
+    return controller.next();
+  });
+}
+
+interface Options {
+  list: { name: string; perms: PermissionResolvable[] }[];
+  needAllPerms: boolean;
+  response?: string;
+}