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/8.0.1',
      '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="[^"]+">/, "");
  
  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 data = await fetchData(message.content.split(" ")[0]);
  if(!data) {
    return;
  }

  message.channel.send({
    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)
  });
});

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