const discord = require("discord.js");
require("dotenv").config();

// for some reason, node.js's built-in fetch function doesn't work for this
// also node-fetch doesn't like being required
const fetch = (...args) => import("node-fetch").then(n => n.default(...args));

const client = new discord.Client({
  intents: [
    discord.GatewayIntentBits.Guilds,
    discord.GatewayIntentBits.GuildMessages,
    discord.GatewayIntentBits.MessageContent,
  ],
  sweepers: {
    messages: {
      lifetime: 3600,
      interval: 3600,
    }
  }
});

// grab data from an instagram url
async function fetchData(url) {
  const res = await fetch(url, {
    headers: {
      'User-Agent': 'curl/8.1.0',
      'Accept': '*/*'
    },
    credentials: "omit",
  });
  if(!res.ok) {
    console.log("oops. fetching instagram link returned bad status", res.statusText);
    return;
  }
  const text = await res.text();

  // here's where the wacky stuff happens
  // okay so instagram for some reason includes a full JSON-LD dump of
  // the post in the html returned, in this script tag
  // i just need to find the boundaries and parse the json
  let index = text.indexOf('<script type="application/ld+json"');
  if(index < 0) {
    console.log("couldn't find json data in html");
    return;
  }
  let json = text.substring(index);
  json = json.replace(/^<script type="application\/ld\+json"( nonce="[^"]+")?>/, "");
  console.log("Found JSON");
  
  index = json.indexOf('}</script>');
  if(index < 0) {
    console.log("couldn't find end of json data in html");
    return;
  }
  json = json.substring(0, index+1);

  let data;
  try {
    data = JSON.parse(json);
  } catch(err) {
    console.log("couldn't parse json", err);
    return;
  }

  return data;
}

client.on("messageCreate", async message => {
  if(message.author.bot) {
    return;
  }
  if(!/^https?:\/\/(www\.)?instagram\.com\/reel/.test(message.content)) {
    return;
  }
  const url = message.content.split(" ")[0];
  console.log("Fetching content for URL: " + url);
  
  let data;
  try {
    data = await fetchData(url);
  } catch(err) {
    console.log("Error fetching, retrying:", err);
    try {
      data = await fetchData(url);
    } catch(err) {
      console.log("Error fetching URL: " + url);
      console.log("Error:", err);
      message.channel.send("Failed to fetch data for link");
      return;
    }
  }

  if(!data) {
    console.log("data is empty");
    message.channel.send("Link had no data, or something went wrong");
    return;
  }

  const sendObj = {
    embeds: [{
      author: {
        name: data?.author?.alternateName,
        icon_url: data?.author?.image,
      },
      title: data?.author?.name,
      description: data?.headline,
    }],
    files: (data.video || []).map(d => d.contentUrl)
  };

  const interval = setInterval(() => message.channel.sendTyping().catch(() => {}), 3000);
  let success = true;
  try {
    console.log("posting...");
    message.channel.sendTyping().catch(() => {});
    await message.channel.send(sendObj);
  } catch(err) {
    console.log("Error posting to discord, attempting backup:", err);
    sendObj.content = sendObj.files.join(" ");
    delete sendObj.files;
    try {
      await message.channel.send(sendObj);
    } catch(err) {
      console.log("error posting backup", err);
      success = false;
    }
  }
  if(success) console.log("posted!");
  clearInterval(interval);
});

client.login(process.env.TOKEN).then(() => console.log("Logged into Discord as", client.user.username + "#" + client.user.discriminator));