Add snowflake timestamp converter functions

discord/utils.js

@@ -2,6 +2,8 @@
 
 const DiscordTypes = require("discord-api-types/v10")
 
+const EPOCH = 1420070400000
+
 /**
  * @param {string[]} userRoles
  * @param {DiscordTypes.APIGuild["roles"]} guildRoles
@@ -56,5 +58,17 @@ function isWebhookMessage(message) {
 	return message.webhook_id && !isInteractionResponse
 }
 
+/** @param {string} snowflake */
+function snowflakeToTimestampExact(snowflake) {
+	return Number(BigInt(snowflake) >> 22n) + EPOCH
+}
+
+/** @param {number} timestamp */
+function timestampToSnowflakeInexact(timestamp) {
+	return String((timestamp - EPOCH) * 2**22)
+}
+
 module.exports.getPermissions = getPermissions
 module.exports.isWebhookMessage = isWebhookMessage
+module.exports.snowflakeToTimestampExact = snowflakeToTimestampExact
+module.exports.timestampToSnowflakeInexact = timestampToSnowflakeInexact

discord/utils.test.js

@@ -0,0 +1,23 @@
+const {test} = require("supertape")
+const data = require("../test/data")
+const utils = require("./utils")
+
+test("is webhook message: identifies bot interaction response as not a message", t => {
+	t.equal(utils.isWebhookMessage(data.interaction_message.thinking_interaction), false)
+})
+
+test("is webhook message: identifies webhook interaction response as not a message", t => {
+	t.equal(utils.isWebhookMessage(data.interaction_message.thinking_interaction_without_bot_user), false)
+})
+
+test("is webhook message: identifies webhook message as a message", t => {
+	t.equal(utils.isWebhookMessage(data.special_message.bridge_echo_webhook), true)
+})
+
+test("discord utils: converts snowflake to timestamp", t => {
+	t.equal(utils.snowflakeToTimestampExact("86913608335773696"), 1440792219004)
+})
+
+test("discerd utils: converts timestamp to snowflake", t => {
+	t.match(utils.timestampToSnowflakeInexact(1440792219004), /^869136083357.....$/)
+})