From 961f494fa2bcf6781b06fe0d3b430ddb008d8f9f Mon Sep 17 00:00:00 2001
From: Dmitriy Pleshevskiy <dmitriy@pleshevski.ru>
Date: Sat, 1 Jul 2023 14:06:47 +0300
Subject: [PATCH] use option instead of null

---
 main.mjs | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/main.mjs b/main.mjs
index 0aed906..d2a7415 100644
--- a/main.mjs
+++ b/main.mjs
@@ -1,5 +1,6 @@
 import TelegramBot from "node-telegram-bot-api";
 import {
+  option,
   readerTaskEither as rte,
   readonlyArray,
   semigroup,
@@ -17,13 +18,13 @@ console.log("The telegram bot listens for updates");
 
 bot.on("channel_post", async (msg) => {
   const link = extractMessageLink(msg);
-  if (!link) {
+  if (option.isNone(link)) {
     console.log("cannot find link in msg:", msg);
     return;
   }
 
   pipe(
-    describeArticle(link),
+    describeArticle(link.value),
     rte.map(
       flow(
         readonlyArray.foldMap({
@@ -44,21 +45,24 @@ bot.on("channel_post", async (msg) => {
   )(config)();
 });
 
-// TODO: use option instead
 function extractMessageLink(msg) {
-  return getTextLink(msg) || getMessageUrl(msg);
+  return pipe(
+    getTextLink(msg),
+    option.orElse(() => getMessageUrl(msg)),
+  );
 }
 
 const RE_URL =
   /(http|https):\/\/([\w_-]+(?:(?:\.[\w_-]+)+))([\w.,@?^=%&:\/~+#-]*[\w@?^=%&\/~+#-])/;
 
 function getMessageUrl(msg) {
-  return RE_URL.exec(msg.text)[0];
+  return option.fromNullable(RE_URL.exec(msg.text)?.[0]);
 }
 
 function getTextLink(msg) {
-  const textLink = (msg.entities ?? []).find(isTextLink);
-  return textLink ? textLink.url : null;
+  return readonlyArray.findFirstMap(
+    flow(option.fromPredicate(isTextLink), option.map((link) => link.url)),
+  )(msg.entities ?? readonnlyArray.empty);
 }
 
 function isTextLink(msgEntity) {