const fetch = require("node-fetch");
const AbortController = require("abort-controller");
const fileType = require("file-type");
const { promisify } = require("util");
const { writeFile } = require("fs").promises;
const execPromise = promisify(require("child_process").exec);
const urlRegex = /(?:\w+:)?\/\/(\S+)/;

// this checks if the file is, in fact, an image
const typeCheck = async (image, image2, gifv = false) => {
  // download the file to a buffer
  const controller = new AbortController();
  const timeout = setTimeout(() => {
    controller.abort();
  }, 25000);
  try {
    const imageRequest = await fetch(image, { signal: controller.signal });
    const imageBuffer = await imageRequest.buffer();
    if (imageBuffer.size >= 25 * 1024 * 1024) return;
    // get the file type
    const imageType = await fileType.fromBuffer(imageBuffer);
    // check if the file is a jpeg, png, or webp
    const formats = ["image/jpeg", "image/png", "image/webp", "image/gif"];
    if (gifv) formats.push("video/mp4");
    if (imageType && formats.includes(imageType.mime)) {
      // if it is, then return the url with the file type
      const path = `/tmp/${Math.random().toString(36).substring(2, 15)}.${imageType.ext}`;
      await writeFile(path, imageBuffer);
      const payload = {
        type: imageType.ext !== "mp4" ? (imageType.ext === "jpg" ? "jpeg" : imageType.ext) : "gif",
        path: path,
        url: image2
      };
      if (payload.type === "gif") payload.delay = (await execPromise(`ffprobe -v 0 -of csv=p=0 -select_streams v:0 -show_entries stream=r_frame_rate ${path}`)).stdout.replace("\n", "");
      return payload;
    } else {
      // if not, then return false
      return false;
    }
  } catch (error) {
    if (error.name === "AbortError") {
      throw Error("Timed out");
    } else {
      throw error;
    }
  } finally {
    clearTimeout(timeout);
  }
};

const checkImages = async (message) => {
  let type;
  // first check the embeds
  if (message.embeds.length !== 0) {
    // embeds can have 2 possible entries with images, we check the thumbnail first
    if (message.embeds[0].type === "gifv") {
      type = await typeCheck(message.embeds[0].video.url, message.embeds[0].video.url, true);
    } else if (message.embeds[0].thumbnail) {
      type = await typeCheck(message.embeds[0].thumbnail.proxy_url, message.embeds[0].thumbnail.url);
      // if there isn't a thumbnail check the image area
    } else if (message.embeds[0].image) {
      type = await typeCheck(message.embeds[0].image.proxy_url, message.embeds[0].image.url);
    }
  // then check the attachments
  } else if (message.attachments.length !== 0) {
    // get type of file
    type = await typeCheck(message.attachments[0].proxy_url, message.attachments[0].url);
    // if there's nothing in the attachments check the urls in the message if there are any
  } else if (urlRegex.test(message.content)) {
    // get url
    const url = message.content.match(urlRegex);
    // get type of file
    type = await typeCheck(url[0], url[0]);
  }
  // if the file is an image then return it
  return type ? type : false;
};

// this checks for the latest message containing an image and returns the url of the image
module.exports = async (cmdMessage) => {
  // we start by checking the current message for images
  const result = await checkImages(cmdMessage);
  if (result !== false) return result;
  // if there aren't any then iterate over the last few messages in the channel
  const messages = await cmdMessage.channel.getMessages();
  // iterate over each message
  for (const message of messages) {
    const result = await checkImages(message);
    if (result === false) {
      continue;
    } else {
      return result;
    }
  }
};