bot.js

require("dotenv").config();
const { Bot, GrammyError, HttpError } = require("grammy");
const grabLink = require("youtube-thumbnail-grabber");
const youtubeRegex = new RegExp(
  /^(http(s)?:\/\/)?((w){3}.)?youtu(be|.be)?(\.com)?\/.+|^(www\.)?youtu\.be\/.+/
);

// Bot

const bot = new Bot(process.env.BOT_TOKEN);

// Response

async function responseTime(ctx, next) {
  const before = Date.now();
  await next();
  const after = Date.now();
  console.log(`Response time: ${after - before} ms`);
}

bot.use(responseTime);

// Commands

bot.command("start", async (ctx) => {
  if (!ctx.chat.type == "private") {
    await bot.api.sendMessage(
      ctx.chat.id,
      "*Channels and groups are not supported presently.*",
      { parse_mode: "Markdown" }
    );
    return;
  }

  await ctx
    .reply("*Welcome!* ✨\n_Send a YouTube link to get the thumbnail._", {
      parse_mode: "Markdown",
    })
    .then(console.log("New user added:\n", ctx.from));
});

bot.command("help", async (ctx) => {
  await ctx
    .reply(
      "*@anzubo Project.*\n\n_This bot gets thumbnails for YouTube videos.\nSend a link to try it out!_",
      { parse_mode: "Markdown" }
    )
    .then(console.log("Help command sent to", ctx.chat.id));
});

// Messages

bot.on("message", async (ctx) => {
  // Logging

  const from = ctx.from;
  const name =
    from.last_name === undefined
      ? from.first_name
      : `${from.first_name} ${from.last_name}`;
  console.log(
    `From: ${name} (@${from.username}) ID: ${from.id}\nMessage: ${ctx.message.text}`
  );

  // Logic

  if (!youtubeRegex.test(ctx.message.text)) {
    await ctx.reply("*Send a valid YouTube link.*", {
      parse_mode: "Markdown",
      reply_to_message_id: ctx.message.message_id,
    });
    return;
  }

  try {
    async function getLink(ytUrl) {
      const thumbnailLink = grabLink(ytUrl, "max");
      await ctx.replyWithPhoto(thumbnailLink, {
        reply_to_message_id: ctx.message.message_id,
      });
    }
    await getLink(ctx.message.text);
  } catch (error) {
    if (error instanceof GrammyError) {
      if (error.message.includes("Forbidden: bot was blocked by the user")) {
        console.log("Bot was blocked by the user");
      } else if (error.message.includes("Call to 'sendPhoto' failed!")) {
        console.log("Error sending message: ", error);
        await ctx.reply(`*Error contacting Telegram.*`, {
          parse_mode: "Markdown",
          reply_to_message_id: ctx.message.message_id,
        });
      } else {
        await ctx.reply(`*An error occurred: ${error.message}*`, {
          parse_mode: "Markdown",
          reply_to_message_id: ctx.message.message_id,
        });
      }
      console.log(`Error sending message: ${error.message}`);
      return;
    } else {
      console.log(`An error occured:`, error);
      await ctx.reply(`*An error occurred.*\n_Error: ${error.message}_`, {
        parse_mode: "Markdown",
        reply_to_message_id: ctx.message.message_id,
      });
      return;
    }
  }
});

// Error

bot.catch((err) => {
  const ctx = err.ctx;
  console.error(
    "Error while handling update",
    ctx.update.update_id,
    "\nQuery:",
    ctx.msg.text
  );
  const e = err.error;
  if (e instanceof GrammyError) {
    console.error("Error in request:", e);
    if (e.description === "Forbidden: bot was blocked by the user") {
      console.log("Bot was blocked by the user");
    } else {
      ctx.reply("An error occurred");
    }
  } else if (e instanceof HttpError) {
    console.error("Could not contact Telegram:", e);
  } else {
    console.error("Unknown error:", e);
  }
});

// Run

bot.start();