add retry policy

src/common/sendDiscordMessage.ts

@@ -6,6 +6,23 @@ import { Client, MessageEmbed, TextChannel } from "discord.js";
 
 dayjs.extend(customParseFormat);
 
+/**
+ * Retry mechanism for failed date checks
+ *
+ * This implementation allows the bot to retry fetching and posting content
+ * when a date check fails. It will retry at hourly intervals for a number of attempts
+ * specified by the RETRY_ATTEMPTS environment variable (defaults to 3).
+ *
+ * This is useful when:
+ * 1. The website hasn't updated with today's post yet
+ * 2. There are temporary network issues
+ * 3. The website structure changed temporarily
+ */
+
+// Sleep function to delay between retry attempts
+const sleep = (ms: number): Promise<void> =>
+	new Promise((resolve) => setTimeout(resolve, ms));
+
 export async function sendDiscordMessage(
 	client: Client,
 	url: string,
@@ -57,8 +74,59 @@ export async function sendDiscordMessage(
 	await Promise.all(promises);
 }
 
+/**
+ * Fetches and sends the next legica-dana post to all Discord channels
+ *
+ * This function implements a retry mechanism that will:
+ * 1. Try to fetch and post the latest content
+ * 2. If it fails (especially due to date check), wait for 1 hour
+ * 3. Retry up to the number of times specified in RETRY_ATTEMPTS env var
+ *
+ * @param client The Discord client used to send messages
+ * @throws Error if all retry attempts fail
+ */
 export async function sendNextMessage(client: Client): Promise<void> {
-	const href = await getFirstHtml();
-	if (!href) throw new Error("URL cannot be empty!");
-	await sendDiscordMessage(client, href, dayjs());
+	// Get max retry attempts from config
+	const maxRetries = config.RETRY_ATTEMPTS;
+	let attempts = 0;
+	let lastError: Error | null = null;
+
+	// Keep trying until we've reached max attempts
+	while (attempts < maxRetries) {
+		try {
+			// Get the URL of the latest post
+			const href = await getFirstHtml();
+			if (!href) throw new Error("URL cannot be empty!");
+
+			// Try to send the message
+			await sendDiscordMessage(client, href, dayjs());
+
+			// If successful, return
+			return;
+		} catch (error: unknown) {
+			attempts++;
+			const typedError = error instanceof Error ? error : new Error(String(error));
+			lastError = typedError;
+
+			// Log the retry attempt
+			console.error(
+				`Attempt ${attempts}/${maxRetries} failed: ${typedError.message}`
+			);
+
+			// If we've reached max attempts, throw the last error
+			if (attempts >= maxRetries) {
+				throw new Error(
+					`Failed after ${attempts} attempts. Last error: ${
+						lastError?.message || "Unknown error"
+					}`
+				);
+			}
+
+			// Wait for 1 hour before retrying (3600000 ms)
+			console.log(
+				`Waiting 1 hour before retry attempt ${attempts + 1}/${maxRetries}...`
+			);
+			await sleep(3600000);
+		}
+	}
 }