path: root/content/sbox/box-fix.js

/**
 * Copyright 2022 Jacob K
 * Copyright 2022 Wojtek Kosior <koszko@koszko.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute forms of that code without the copy of the GNU
 * GPL normally required by section 4, provided you include this
 * license notice and, in case of non-source distribution, a URL
 * through which recipients can access the Corresponding Source.
 * If you modify file(s) with this exception, you may extend this
 * exception to your version of the file(s), but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * As a special exception to the GPL, any HTML file which merely
 * makes function calls to this code, and for that purpose
 * includes it by reference shall be deemed a separate work for
 * copyright law purposes. If you modify this code, you may extend
 * this exception to your version of the code, but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
 * license. Although I request that you do not make use of this code in a
 * proprietary program, I am not going to enforce this in court.
 */

// meta: match should be https://***.app.box.com/s/* (*** instead of * for the first section because otherwise plain app.box.com URLs won't work)
// meta: some test cases (mostly found at https://old.reddit.com/search?q="box.com"&include_over_18=on&sort=new)
	// https://uwmadison.app.box.com/s/ydht2incbdmw1lhpjg5t40adguc0fm14
		// umadison's enrollment report
		// pdf
	// https://app.box.com/s/gc4ygloi4qtimeh98dq9mmydyuydawcn
		// password-protected 7z file (nsfw)
	// https://app.box.com/shared/static/su6xx6zx50cd68zdtbm3wfxhh9kwke8x.zip
		// a soundtrack in a zip file
		// This is a static download, so it works without this script.
	// https://app.box.com/s/vysdh2u78yih3c8leetgq82il954a3g3
		// some gambling ad
		// pptx
	// https://app.box.com/s/nnlplkmjhimau404qohh9my10pwmo8es
		// a list of books(?)
		// txt
	// https://ucla.app.box.com/s/mv32q624ojihohzh8d0mhhj0b3xluzbz
		// "COVID-19 Pivot Plan Decision Matrix"
		// If you load the proprietary scripts on this page, you'll see that there is no download button
	// TODO: find a public folder link (the private links I have seem to work)
	// TODO: find a (preferably public) link with a folder inside a folder, as these may need to be handled differently

/* Extract data from a script that sets multiple variables. */ // from here: https://api-demo.hachette-hydrilla.org/content/sgoogle_sheets_download/google_sheets_download.js

let prefetchedData = null; // This variable isn't actually used.
for (const script of document.scripts) {
    const match = /Box.prefetchedData = ({([^;]|[^}];)+})/.exec(script.textContent); // looks for "Box.prefetchedData = " in the script files and then grabs the json text after that.
    if (!match)
	continue;
    prefetchedData = JSON.parse(match[1]);
}

let config = null;
for (const script of document.scripts) {
    const match = /Box.config = ({([^;]|[^}];)+})/.exec(script.textContent); // looks for "Box.config = " in the script files and then grabs the json text after that.
    if (!match)
	continue;
    config = JSON.parse(match[1]);
}

let postStreamData = null;
for (const script of document.scripts) {
    const match = /Box.postStreamData = ({([^;]|[^}];)+})/.exec(script.textContent); // looks for "Box.postStreamData = " in the script files and then grabs the json text after that.
    if (!match)
	continue;
    postStreamData = JSON.parse(match[1]);
}

// get domain from URL
const domain = document.location.href.split("/")[2];

/* Replace current page contents. */
const replacement_html = `\
<!DOCTYPE html>
<html>
  <head>
    <style>
      button, .button {
          border-radius: 10px;
          padding: 20px;
          color: #333;
          background-color:
          lightgreen;
          text-decoration: none;
          display: inline-block;
      }
      button:hover, .button:hover {
          box-shadow: -4px 8px 8px #888;
      }

      .hide {
          display: none;
      }

      #download_button .unofficial, #download_button .red_note {
          display: none;
      }
      #download_button.unofficial .unofficial {
          display: inline;
      }
      #download_button.unofficial .red_note {
          display: block;
      }
      .red_note {
          font-size: 75%;
          color: #c55;
          font-style: italic;
          text-align: center;
      }
    </style>
  </head>
  <body>
    <h1 id="loading" class="hide">loading...</h1>
    <h1 id="error" class="hide">error occured :(</h1>
    <h1 id="title" class="hide"></h1>
    <div id="single_file_section" class="hide">
      <a id="download_button" class="button">
        <span class="unofficial">unofficial</span> download
        <aside class="red_note">(officially disallowed)</aside>
      </a>
      <aside></aside>
      <h2>File info</h2>
      <div id="file_info"></div>
    </div>
  </body>
</html>
`;

/*
 * We could instead use document.write(), but browser's debugging tools would
 * not see the new page contents.
 */
const parser = new DOMParser();
const alt_doc = parser.parseFromString(replacement_html, "text/html");
document.documentElement.replaceWith(alt_doc.documentElement);

const nodes = {};
document.querySelectorAll('[id]').forEach(node => nodes[node.id] = node);

function show_error() {
    nodes.loading.classList.add("hide");
    nodes.error.classList.remove("hide");
}

function show_title(text) {
    nodes.title.innerText = text;
    nodes.loading.classList.add("hide");
    nodes.title.classList.remove("hide");
}

async function hack_file() {
    nodes.loading.classList.remove("hide");

    const tokens_url = "/app-api/enduserapp/elements/tokens";
    const file_nr = postStreamData["/app-api/enduserapp/shared-item"].itemID;
    const file_id = `file_${file_nr}`;
    const shared_name = postStreamData["/app-api/enduserapp/shared-item"].sharedName;

    /*
     * We need to perform a POST to obtain a token that will be used later to
     * authenticate against Box's API endpoint.
     */
    const tokens_response = await fetch(tokens_url, {
	method: "POST",
	headers: {
	    "Accept":               "application/json",
	    "Content-Type":         "application/json",
	    "Request-Token":        config.requestToken,
	    "X-Box-Client-Name":    "enduserapp",
	    "X-Box-Client-Version": "20.712.2",
	    "X-Box-EndUser-API":    `sharedName=${shared_name}`,
	    "X-Request-Token":      config.requestToken
	},
	body: JSON.stringify({"fileIDs": [file_id]})
    });
    console.log("tokens_response", tokens_response);

    const access_token = (await tokens_response.json())[file_id].read;
    console.log("access_token", access_token);

    const fields = [
	"permissions", "shared_link", "sha1", "file_version", "name", "size",
	"extension", "representations", "watermark_info",
	"authenticated_download_url", "is_download_available",
	"content_created_at", "content_modified_at", "created_at", "created_by",
	"modified_at", "modified_by", "owned_by", "description",
	"metadata.global.boxSkillsCards", "expires_at", "version_limit",
	"version_number", "is_externally_owned", "restored_from",
	"uploader_display_name"
    ];

    const file_info_url =
	  `https://api.box.com/2.0/files/${file_nr}?fields=${fields.join()}`;

    /*
     * We need to perform a GET to obtain file metadata. The fields we curently
     * make use of are "authenticated_download_url" and "file_version", but in
     * the request we also include names of other fields that the original Box
     * client would include. The metadata is then dumped as JSON on the page, so
     * the user, if curious, can look at it.
     */
    const file_info_response = await fetch(file_info_url, {
	headers: {
	    "Accept":            "application/json",
	    "Authorization":     `Bearer ${access_token}`,
	    "BoxApi":            `shared_link=${document.URL}`,
	    "X-Box-Client-Name": "ContentPreview",
	    "X-Rep-Hints":       "[3d][pdf][text][mp3][json][jpg?dimensions=1024x1024&paged=false][jpg?dimensions=2048x2048,png?dimensions=2048x2048][dash,mp4][filmstrip]"
	},
    });
    console.log("file_info_response", file_info_response);

    const file_info = await file_info_response.json();
    console.log("file_info", file_info);

    const params = new URLSearchParams();
    params.set("preview",            true);
    params.set("version",            file_info.file_version.id);
    params.set("access_token",       access_token);
    params.set("shared_link",        document.URL);
    params.set("box_client_name",    "box-content-preview");
    params.set("box_client_version", "2.82.0");
    params.set("encoding",           "gzip");

    /* We use file metadata from earlier requests to construct the link. */
    const download_url =
	  `${file_info.authenticated_download_url}?${params.toString()}`;
    console.log("download_url", download_url);

    show_title(file_info.name);

    nodes.download_button.href = download_url;
    if (!file_info.permissions.can_download)
	nodes.download_button.classList.add("unofficial");
    nodes.file_info.innerText =  JSON.stringify(file_info);
    nodes.single_file_section.classList.remove("hide");
}

if (postStreamData["/app-api/enduserapp/shared-item"].itemType == "file") {
    /*
     * We call hack_file and in case it asynchronously throws an exception, we
     * make an error message appear.
     */
    hack_file().then(() => {}, show_error);
} else if (postStreamData["/app-api/enduserapp/shared-item"].itemType == "folder") {
    show_title(postStreamData["/app-api/enduserapp/shared-folder"].currentFolderName);

    // TODO: implement a download folder button (included in proprietary app)
    /*
      The original download folder button sends a GET request that gets 2 URLs
      in the response. 1 of those URLs downloads the file, and a POST request
      is sent after (or maybe while in some cases?) a file is downloaded, to
      let the server know how much is downloaded.
    */
    // for each item in the folder, show a button with a link to download it
    postStreamData["/app-api/enduserapp/shared-folder"].items.forEach(function(item) {
	console.log("item", item);

	const file_direct_url = "https://"+domain+"/index.php?rm=box_download_shared_file&shared_name="+postStreamData["/app-api/enduserapp/shared-item"].sharedName+"&file_id="+item.typedID;

	const folderButton = nodes.download_button.cloneNode(false);
	folderButton.removeAttribute("id");

	if (item.type == "file") {
	    folderButton.href = file_direct_url;
	    folderButton.innerText = item.name; // show the name of the file
	} else if (item.type == "folder") {
	    folderButton.innerText = "[folders inside folders not yet supported]";
	} else {
	    folderButton.innerText = "[this item type is not supported]";
	}

	document.body.appendChild(folderButton);
    });
} else {
	console.log('expected "folder" or "file" as the item type (postStreamData["/app-api/enduserapp/shared-item"].itemType) but got ' + postStreamData["/app-api/enduserapp/shared-item"].itemType + ' instead; this item type is not implemented');
	show_error();
}