// ==UserScript==
// @name        Search Hobune for unavailable video IDs
// @namespace   hobune.stream
// @match       https://www.youtube.com/*
// @grant       GM_xmlhttpRequest
// @connect     hobune.stream
// @version     2.1
// @author      Somepony
// @description 2021-08-28T03:33:00Z
// ==/UserScript==

const matchURLs = ["https://www.youtube.com/watch", "https://www.youtube.com/shorts/"];
const hobuneEndpoints = ["https://hobune.stream/tpa-h/videos/","https://hobune.stream/videos/"];

// End all other async instances when one returns value in earlyArr
// Instance returns undefined when ended early
function endEarly(generator,earlyArr) {
  let isDone = false;
  return async function(...args) {
    const iter = generator(...args);
    let resumeValue;
    for (;;) {
      const n = iter.next(resumeValue);
      if (n.done) { // check if process is done
        if (earlyArr.indexOf(n.value) >= 0) {
          isDone = true; // value in earlyArr returned; end other processes
        }
        return n.value;  // final return value of passed generator
      } else if (isDone) {
        return;  // one process already returned value in earlyArr
      }

      // whatever the generator yielded, _now_ run await on it
      resumeValue = await n.value;
      // next loop, we give resumeValue back to the generator
    }
  };
}

// Check Hobune and returns on 200 or 404 (or if ended early by endEarly())
function* checkHobune(videoId,hobuneEndpoint) {
  while (true) {
    let status = yield new Promise((resolve, reject) => {
      GM_xmlhttpRequest ({
        method:     'GET',
        url:        hobuneEndpoint + videoId,
        onload:     function (response) {
                      resolve(response.status);
                    }
      });
    });
    if ([200,404].indexOf(status) >= 0) {
        return status;
    }
    yield new Promise(r => setTimeout(r, 1000));
  }
}

// Get videoId
function getVideoId() {
  let url = location.href;
  if (url.startsWith("https://www.youtube.com/shorts/")) {
    url = url.replace("https://www.youtube.com/shorts/", "https://www.youtube.com/watch?v=");
  }
  url = new URL(url)
  
  urlParams = new URLSearchParams(url.search);
  videoId = urlParams.get('v').replace(/[^a-zA-Z0-9_-]/g, "");
  
  return videoId;
}

async function main() {

  // Get videoId
  let videoId = getVideoId();
  
  // Recursively tries to find element
  // Returns undefined if element still cannot be found after load (i.e. not a player error)
  let element = (async function() {
    while (document.readyState != 'complete') {
      let x = await document.getElementsByClassName("yt-player-error-message-renderer").info;
      if (x != null) {
        return x;
      }
      await new Promise(r => setTimeout(r, 500));
    }
    let x = await document.getElementsByClassName("yt-player-error-message-renderer").info; // check one more time on load
    return x;
  }());
  
  // End early if not player error
  element = await element;
  if (element == null) {
    return;
  }
  
  // Recursively tries to check Hobune for video
  let foo = endEarly(checkHobune,[200]);
  let archivedURL = null;
  let p = Promise.all(hobuneEndpoints.map(endpoint => {
    return foo(videoId,endpoint).then(
      function(status) {
        if (status == 200) {
          archivedURL = endpoint + videoId;
        }
      }
    );
  }));

  // Append new tag
  let tag = document.createElement("yt-formatted-string");
  tag.classList.add("style-scope","yt-player-error-message-renderer","hobunecheck");
  tag.id = "subreason";
  element.appendChild(tag);
  tag.innerText = "Checking Hobune for this video...";

  // Modify tag
  await p; // wait for archivedURL
  if (archivedURL != null) {
    tag.innerHTML = `<a href="${archivedURL}">Watch on Hobune</a>`;
  } else {
    tag.innerText = "Couldn't find this video on Hobune.";
  }
  
}

if (window.top == window.self) {
  
  // Recursively check for href change and match URL
  var lastHref = null;
  (function pageURLCheckTimer() {
    if (lastHref != location.href && matchURLs.some(x => location.href.startsWith(x))) {
      lastHref = location.href;
      try {
        main();
      } catch(e) {
        console.log(e);
      }
    }
    setTimeout(pageURLCheckTimer, 100);
  }());
  
}