content.js

function getElementByClassNameStart(classNameStart, node = document) {
  return node.querySelector(
    `[class^="${classNameStart}"],[class*=" ${classNameStart}"]`
  );
}

function getElementsByClassNameStart(classNameStart, node = document) {
  return node.querySelectorAll(
    `[class^="${classNameStart}"],[class*=" ${classNameStart}"]`
  );
}

function getElementByXpath(path) {
  return document.evaluate(
    path,
    document,
    null,
    XPathResult.FIRST_ORDERED_NODE_TYPE,
    null
  ).singleNodeValue;
}

function getBackgroundImage(node) {
  const value = node.style.backgroundImage;
  const urlRegex = /url\("(.*)"\)/;
  return value.match(urlRegex)[1];
}

// Get first image in node
function getImage(node) {
  return node.getElementsByTagName("img")[0];
}

// get first video in node
function getVideo(node) {
  return node.getElementsByTagName("video")[0];
}

// Return values:
// - undefined - nothing to download
// - "" - no manual downloading needed
const getters = {
  "vk.com": () => {
    const storyVideo = document.getElementsByClassName("stories_video")[0];
    if (storyVideo) {
      return storyVideo.src;
    }
    const gifVideo = document.getElementsByClassName("pages_gif_img")[0];
    if (gifVideo) {
      return gifVideo.src;
    }
    const imageDiv = document.getElementById("pv_photo");
    if (imageDiv) {
      return getImage(imageDiv).src;
    }
  },
  "discord.com": () => {
    function maxSizeAsset(url) {
      return url.split("?")[0] + "?size=4096";
    }

    function maxSizeImage(url) {
      const widthRegex = new RegExp("[?&]width=[0-9]+");
      const heightRegex = new RegExp("[?&]height=[0-9]+");
      return url.replace(widthRegex, "").replace(heightRegex, "");
    }

    // Close sticker dialog bound to Ctrl+S immediately
    getElementByClassNameStart(
      "stickerIcon"
    ).parentNode.parentNode.parentNode.click();

    const backdrop = getElementByClassNameStart("backdrop");
    if (backdrop) {
      const currentContainer = backdrop.parentNode;
      const video = getVideo(currentContainer);
      if (video) {
        return video.src;
      }
      const image = getImage(currentContainer);
      if (image) {
        return maxSizeImage(image.src);
      }
      return undefined;
    }

    const avatarContainer =
      getElementByClassNameStart("userPopout") ||
      getElementByClassNameStart("topSection");
    if (avatarContainer) {
      const avatarDiv = getElementByClassNameStart(
        "avatarStack",
        avatarContainer
      );
      if (avatarDiv) {
        const avatarUrl = getImage(avatarDiv).src;
        return maxSizeAsset(avatarUrl);
      }
    }

    const emojiContainer =
      getElementByClassNameStart("emojiSection") ||
      getElementByClassNameStart("reactionTooltipInner");
    if (emojiContainer) {
      const emojiUrl = getImage(emojiContainer).src;
      return maxSizeAsset(emojiUrl);
    }
  },
  "app.element.io": () => {
    document.getElementsByClassName("mx_ImageView_button_download")[0].click();
    return "";
  },
  "2ch.hk": () => {
    const videoDiv = document.getElementById("js-mv-player");
    if (videoDiv) {
      return videoDiv.getElementsByTagName("source")[0].src;
    }
    const imageDiv = document.getElementById("js-mv-main");
    if (imageDiv) {
      return getImage(imageDiv).src;
    }
  },
  "teddit.net": () => {
    const post = document.getElementById("post");
    const imageDiv = post.getElementsByClassName("image")[0];
    if (imageDiv) {
      const image = getImage(imageDiv);
      if (image) {
        return image.src;
      }
    }
  },
  "web.skype.com": () => {
    // const imageDiv = getElementByXpath(
    //   "/html/body/div[1]/div/div/div[2]/div/div/div[1]/div[2]/div[1]/div/div/div/div/div/div/div/div/div[2]/div/div"
    // );
    const imageDiv = document.querySelector(
      `[style^='position: absolute; overflow: visible; background-color: transparent; flex-grow: 0; flex-shrink: 0; inset: 0px; align-items: stretch; background-position: center center; background-repeat: no-repeat; background-image: url("https://api.asm.skype.com/v1/objects/'][style$='/views/imgpsh_mobile_save_anim"); background-size: contain; border-style: none; display: flex;']`
    );
    return getBackgroundImage(imageDiv).replace(
      "mobile_save",
      "fullsize"
    );
  },
};

const yandex = () => {
  const otherSizesButton = document.getElementsByClassName(
    "MMViewerButtons-ImageSizes"
  )[0];
  if (otherSizesButton) {
    otherSizesButton.click(); // open list
    const sizeSelector = document.getElementsByClassName(
      "MMViewerButtons-ImageSizesPopup"
    )[0];
    const resolutions = sizeSelector.getElementsByClassName(
      "MMViewerButtons-ImageSizesListItem"
    );
    otherSizesButton.click(); // close list
    return resolutions[0].href;
  } else {
    const downloadButton = document.getElementsByClassName("MMViewerButtons-OpenImage")[0];
    return downloadButton.href
  }
};

function getDownloadUrl(hostname) {
  if (getters.hasOwnProperty(hostname)) {
    return getters[hostname]();
  } else {
    if (hostname.split(".", 1)[0] === "yandex") {
      return yandex();
    }
  }
}

// Sites, where videos are undownloadable or not downloaded by regular means
const videoDownloadBlacklist = ["vk.com", "2ch.hk"];

function isVideoPlaying(video) {
  return (
    video.currentTime > 0 &&
    !video.paused &&
    !video.ended &&
    video.readyState > 2
  );
}

function getCurrentlyPlayingVideo() {
  const videos = document.getElementsByTagName("video");
  for (let i = 0; i < videos.length; ++i) {
    const video = videos.item(i);
    if (isVideoPlaying(video)) {
      if (video.src) {
        return video.src;
      } else {
        const sources = video.getElementsByTagName("source");
        for (source of sources) {
          if (source.src) {
            return source.src;
          }
        }
      }
    }
  }
}

document.addEventListener(
  "keydown",
  function (e) {
    if (
      (window.navigator.platform.match("Mac") ? e.metaKey : e.ctrlKey) &&
      e.keyCode === 83
    ) {
      let downloadUrl = getDownloadUrl(window.location.hostname);
      if (
        downloadUrl === undefined &&
        videoDownloadBlacklist.indexOf(window.location.hostname) === -1
      ) {
        downloadUrl = getCurrentlyPlayingVideo();
      }

      if (downloadUrl !== undefined) {
        e.preventDefault();
        if (downloadUrl !== "") {
          chrome.extension.sendMessage({ url: downloadUrl }, function () {});
        }
      }
    }
  },
  false
);