Add //invite command

discord/utils.js

@@ -0,0 +1,50 @@
+// @ts-check
+
+const DiscordTypes = require("discord-api-types/v10")
+
+/**
+ * @param {string[]} userRoles
+ * @param {DiscordTypes.APIGuild["roles"]} guildRoles
+ * @param {string} [userID]
+ * @param {DiscordTypes.APIGuildChannel["permission_overwrites"]} [channelOverwrites]
+ */
+function getPermissions(userRoles, guildRoles, userID, channelOverwrites) {
+	let allowed = BigInt(0)
+	let everyoneID
+	// Guild allows
+	for (const role of guildRoles) {
+		if (role.name === "@everyone") {
+			allowed |= BigInt(role.permissions)
+			everyoneID = role.id
+		}
+		if (userRoles.includes(role.id)) {
+			allowed |= BigInt(role.permissions)
+		}
+	}
+
+	if (channelOverwrites) {
+		/** @type {((overwrite: Required<DiscordTypes.APIGuildChannel>["permission_overwrites"][0]) => any)[]} */
+		const actions = [
+			// Channel @everyone deny
+			overwrite => overwrite.id === everyoneID && (allowed &= ~BigInt(overwrite.deny)),
+			// Channel @everyone allow
+			overwrite => overwrite.id === everyoneID && (allowed |= BigInt(overwrite.allow)),
+			// Role deny
+			overwrite => userRoles.includes(overwrite.id) && (allowed &= ~BigInt(overwrite.deny)),
+			// Role allow
+			overwrite => userRoles.includes(overwrite.id) && (allowed |= ~BigInt(overwrite.allow)),
+			// User deny
+			overwrite => overwrite.id === userID && (allowed &= ~BigInt(overwrite.deny)),
+			// User allow
+			overwrite => overwrite.id === userID && (allowed |= BigInt(overwrite.allow))
+		]
+		for (let i = 0; i < actions.length; i++) {
+			for (const overwrite of channelOverwrites) {
+				actions[i](overwrite)
+			}
+		}
+	}
+	return allowed
+}
+
+module.exports.getPermissions = getPermissions