Greasemonkey-Script to display all CC albums of all pages for the currently displayed tag

Bandcamp_CC_Tag-Overview.user.js

// ==UserScript==
// @name        Bandcamp CC Tag-Overview
// @namespace   faldrian
// @description Loads all pages inline and hides albums licensed as "all rights reserved"
// @include     http://bandcamp.com/tag/*
// @include     https://bandcamp.com/tag/*
// @require     http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js
// @grant       GM_xmlhttpRequest
// @version     1.1
// ==/UserScript==


// holds all pending requests
var stack = [];

// push pages to load on the stack...
function addPageRequest(urlParam) {
  var url = urlParam;

  stack.push(function() {
    return new Promise(function(resolve, reject) {
      GM_xmlhttpRequest({
        method: "GET",
        url: url,
        onload: function (data) {
          try {
            // get all items and insert them to the page
            var content = data.responseText.match(/<ul class="item_list">(.|[\r\n])*?<\/ul>/mgi)[0];
            var itemList = $(content);
            $('div.results').append(itemList);

            // add licenses to all children
            $(itemList).find('li.item').each(function(index, newElement) {
              addItemRequest(newElement);
            });

            resolve();
          } catch (e) {
            resolve();
          }
        },
        onerror: function() {
          console.error("Error!");
          resolve();
        },
        ontimeout: function() {
          console.error("Timeout, adding again!");
          addPageRequest(url);
          resolve();
        }
      });
    });
  });
}

// push items to load on the stack...
function addItemRequest(elementParam) {
  var element = elementParam;
  stack.push(function() {
    return new Promise(function(resolve, reject) {
      // beautifix: remove "end"-CSS-Class, it destroys our layout.
      // also: Add loading-state for visual indication
      $(element).removeClass('end').addClass('state_loading');

      GM_xmlhttpRequest({
        method: "GET",
        url: $(element).find('a').attr('href'),
        onload: function(data) {
          // Get the license from the loaded album page
          try {
            // check if page was "offline"
            if (data.responseText.indexOf("We're offline briefly for maintenance") !== -1) {
              // just try again, they can't be offline, they are just badly managed.
              addItemRequest(element);
              resolve();
              return;
            }

            var licenseStr = data.responseText.match(/<div id="license"(.|[\r\n])*?<\/div>/mgi)[0];
            if (licenseStr.indexOf('all rights reserved') !== -1) {
              // remove the item, it is not CC!
              $(element).remove();
            } else {
              // add license
              licenseStr = licenseStr.replace('id="license"', "");
              $(element).find('a').append(licenseStr);

              // sanatize background-image
              var artContainer = $(element).find('.tralbum-art-container');
              var onclickaction = artContainer.attr('onclick');
              artContainer.css('background-image', onclickaction.substring(8, onclickaction.length - 1));

              // remove loading info
              $(element).removeClass('state_loading');
            }
            resolve();
          } catch (e) {
            console.error("Error fetching license: ", e, data.responseText);
            resolve();
          }
        },
        onerror: function() {
          console.error("Error!");
          resolve();
        },
        ontimeout: function() {
          console.error("Timeout, adding again!");
          addItemRequest(element);
          resolve();
        }
      });
    });
  });
}

function processQueueItem() {
  var item = stack.pop();
  if (item) {
    item().then(function(data) {
      // update status
      $('.status_floater').html("Remaining: " + stack.length);

      // and process the next
      processQueueItem();
    });
  } else {
    $('.status_floater').remove();
  }
}


function crawlPages() {
  // Add status item
  $('body').append('<div class="status_floater">Loading...</div>');

  // crawl all pages
  $('.pagelist a').each(function(index, element) {
    addPageRequest($(element).attr('href'));
  });

  // hide initial items if not CC
  $('li.item').each(function(index, element) {
    addItemRequest(element);
  });

  // Start Execution (5 Worker)
  for(var i = 0; i<5; i++) {
    processQueueItem();
  }
}


// Start this!
$(function() {
  // Insert Style-Mods
  var style = 'a:visited {color: #aaa !important;}' +
    ' .results .item:nth-child(5n) {margin-right: 0px !important;}' +
    ' .tags.one_tag .results_area .item {height: auto !important;}' +
    ' .state_loading {background-color: #FEE1AD;}' +
    ' .state_loading.state_retry {background-color: #FEBEAD}' +
    ' .status_floater {position: fixed; top: 0px; left: 0px; z-index: 1000; background-color: white; padding: 0.5em 1em;}';
  var styleElement = document.createElement('style');
  styleElement.appendChild(document.createTextNode(style));
  (document.body || document.head || document.documentElement).appendChild(styleElement);

  if(window.confirm("Bandcamp detected! Start crawling?")) {
    crawlPages();
  }
});