erp5_core: add a html viewer gadget

This gadget take an HTML string as parameter.

It first cleans it up (with hardcoded behaviour currently) by dropping unknown tag elements, unknown/unsafe tag attributes.
It is another protection layer on top of asStrippedHTML inside ERP5.

Then, it displays the output HTML and style it with an hardcoded set of rules.

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.css.css

+div[data-gadget-url$="gadget_html_viewer.html"] {
+  max-width: 50em;
+  display: block;
+  word-wrap: break-word;
+  font-family: Cambria, "Hoefler Text", Utopia, "Liberation Serif", "Nimbus Roman No9 L Regular", Times, "Times New Roman", serif;
+  text-align: justify;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] canvas,
+div[data-gadget-url$="gadget_html_viewer.html"] img,
+div[data-gadget-url$="gadget_html_viewer.html"] iframe,
+div[data-gadget-url$="gadget_html_viewer.html"] svg {
+  max-width: 100%;
+  max-height: 100vh;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] video {
+  max-width: 100%;
+  height: auto;
+  max-height: 100vh;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] h1 {
+  font-family: Cambria, "Hoefler Text", Utopia, "Liberation Serif", "Nimbus Roman No9 L Regular", Times, "Times New Roman", serif;
+  font-size: 1.5em;
+  text-transform: capitalize;
+  text-align: center;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] h2 {
+  font-family: 'Open Sans', Helvetica, Arial, sans-serif;
+  font-size: 1.3em;
+  text-transform: capitalize;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] h3 {
+  font-family: 'Open Sans', Helvetica, Arial, sans-serif;
+  font-size: 1.1em;
+  text-transform: uppercase;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] h4 {
+  font-family: 'Open Sans', Helvetica, Arial, sans-serif;
+  font-size: 1.1em;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] blockquote {
+  margin: 6pt 6pt 6pt 0;
+  padding-left: 6pt;
+  border-left: 2px solid #0E81C2;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] i,
+div[data-gadget-url$="gadget_html_viewer.html"] cite,
+div[data-gadget-url$="gadget_html_viewer.html"] em,
+div[data-gadget-url$="gadget_html_viewer.html"] var,
+div[data-gadget-url$="gadget_html_viewer.html"] address,
+div[data-gadget-url$="gadget_html_viewer.html"] dfn {
+  font-style: italic;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] strong,
+div[data-gadget-url$="gadget_html_viewer.html"] b,
+div[data-gadget-url$="gadget_html_viewer.html"] figcaption {
+  font-weight: 600;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] u,
+div[data-gadget-url$="gadget_html_viewer.html"] ins {
+  text-decoration: underline;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] s,
+div[data-gadget-url$="gadget_html_viewer.html"] strike,
+div[data-gadget-url$="gadget_html_viewer.html"] del {
+  text-decoration: line-through;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] tt,
+div[data-gadget-url$="gadget_html_viewer.html"] code,
+div[data-gadget-url$="gadget_html_viewer.html"] kbd,
+div[data-gadget-url$="gadget_html_viewer.html"] samp {
+  font-family: "Courier New", Courier, monospace;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] code,
+div[data-gadget-url$="gadget_html_viewer.html"] kbd {
+  color: #2CC32C;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] q {
+  display: inline;
+  quotes: initial;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] q:before {
+  content: open-quote;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] q:after {
+  content: close-quote;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] pre,
+div[data-gadget-url$="gadget_html_viewer.html"] xmp,
+div[data-gadget-url$="gadget_html_viewer.html"] plaintext,
+div[data-gadget-url$="gadget_html_viewer.html"] listing {
+  display: block;
+  white-space: pre-wrap;
+  font-family: "Courier New", Courier, monospace;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] table {
+  border: 1px solid #1F1F1F;
+  width: 100%;
+  margin: 0;
+  padding: 0;
+  border-collapse: collapse;
+  border-spacing: 0;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] table tr {
+  border: 1px solid #1F1F1F;
+  padding-top: 6pt;
+  padding-bottom: 6pt;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] table th,
+div[data-gadget-url$="gadget_html_viewer.html"] table td {
+  text-align: center;
+  padding-top: 6pt;
+  padding-bottom: 6pt;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] table th {
+  text-transform: uppercase;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] ul {
+  list-style: disc;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] ul li {
+  margin-left: 2em;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] ol {
+  list-style: decimal;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] ol li {
+  margin-left: 2em;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] dl {
+  display: grid;
+  grid-template-columns: max-content auto;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] dl dt {
+  grid-column-start: 1;
+}
+div[data-gadget-url$="gadget_html_viewer.html"] dl dd,
+div[data-gadget-url$="gadget_html_viewer.html"] dl dl {
+  grid-column-start: 2;
+}

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.css.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="File" module="OFS.Image"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_Cacheable__manager_id</string> </key>
+            <value> <string>must_revalidate_http_cache</string> </value>
+        </item>
+        <item>
+            <key> <string>__name__</string> </key>
+            <value> <string>gadget_html_viewer.css</string> </value>
+        </item>
+        <item>
+            <key> <string>content_type</string> </key>
+            <value> <string>text/css</string> </value>
+        </item>
+        <item>
+            <key> <string>precondition</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string>gadget_html_viewer.css</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.html.html

+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>HTML viewer gadget</title>
+    <link rel="http://www.renderjs.org/rel/interface" href="interface_editor.html">
+    <link rel="stylesheet" href="gadget_html_viewer.css">
+    <script src="rsvp.js"></script>
+    <script src="renderjs.js"></script>
+    <script src="domsugar.js"></script>
+    <script src="gadget_html_viewer.js"></script>
+  </head>
+  <body>
+  </body>
+</html>

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.html.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="File" module="OFS.Image"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_Cacheable__manager_id</string> </key>
+            <value> <string>must_revalidate_http_cache</string> </value>
+        </item>
+        <item>
+            <key> <string>__name__</string> </key>
+            <value> <string>gadget_html_viewer.html</string> </value>
+        </item>
+        <item>
+            <key> <string>content_type</string> </key>
+            <value> <string>text/html</string> </value>
+        </item>
+        <item>
+            <key> <string>precondition</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string></string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.js.js

+/*jslint nomen: true, indent: 2 */
+/*global window, rJS, domsugar, document, DOMParser, NodeFilter*/
+(function (window, rJS, domsugar, document, DOMParser, NodeFilter) {
+  "use strict";
+
+  function startsWithOneOf(str, prefix_list) {
+    var i;
+    for (i = prefix_list.length - 1; i >= 0; i -= 1) {
+      if (str.substr(0, prefix_list[i].length) === prefix_list[i]) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  var whitelist = {
+    node_list: {
+      BODY: true,
+      P: true,
+      H1: true,
+      H2: true,
+      H3: true,
+      H4: true,
+      H5: true,
+      H6: true,
+      UL: true,
+      OL: true,
+      LI: true,
+      DL: true,
+      DT: true,
+      DD: true,
+      BLOCKQUOTE: true,
+      Q: true,
+      I: true,
+      B: true,
+      CITE: true,
+      EM: true,
+      VAR: true,
+      ADDRESS: true,
+      DFN: true,
+      U: true,
+      INS: true,
+      S: true,
+      STRIKE: true,
+      DEL: true,
+      SUP: true,
+      SUB: true,
+      MARK: true,
+      TT: true,
+      PRE: true,
+      CODE: true,
+      KBD: true,
+      SAMP: true,
+      STRONG: true,
+      SMALL: true,
+      A: true,
+      HR: true,
+      TABLE: true,
+      THEAD: true,
+      TFOOT: true,
+      TR: true,
+      TH: true,
+      TD: true,
+      BR: true,
+      IMG: true,
+      FIGURE: true,
+      FIGCAPTION: true,
+      PICTURE: true,
+      SOURCE: true,
+      TIME: true,
+      ARTICLE: true,
+      ASIDE: true,
+      NAV: true,
+      FOOTER: true
+    },
+    attribute_list: {
+      alt: true,
+      rel: true,
+      href: true,
+      src: true,
+      srcset: true,
+      media: true,
+      datetime: true,
+      class: true
+    },
+    link_node_list: {
+      A: true,
+      IMG: true,
+      FIGURE: true,
+      PICTURE: true
+    },
+    link_list: {
+      href: true,
+      src: true,
+      srcset: true
+    }
+  },
+    emptylist = {
+      BR: true,
+      HR: true
+    },
+    blacklist = {
+      SCRIPT: true,
+      STYLE: true,
+      NOSCRIPT: true,
+      FORM: true,
+      FIELDSET: true,
+      INPUT: true,
+      SELECT: true,
+      TEXTAREA: true,
+      BUTTON: true,
+      IFRAME: true,
+      SVG: true
+    };
+
+  function keepOnlyChildren(current_node) {
+    var fragment = document.createDocumentFragment();
+
+    while (current_node.firstChild) {
+      fragment.appendChild(current_node.firstChild);
+    }
+    current_node.parentNode.replaceChild(
+      fragment,
+      current_node
+    );
+  }
+
+  function cleanup(html) {
+    var html_doc = (new DOMParser()).parseFromString(html,
+                                                     'text/html'),
+      iterator,
+      current_node,
+      attribute,
+      attribute_list,
+      len,
+      link_len,
+      already_dropped,
+      finished = false;
+
+    iterator = document.createNodeIterator(
+      html_doc.body,
+      NodeFilter.SHOW_ELEMENT,
+      function () {
+        return NodeFilter.FILTER_ACCEPT;
+      }
+    );
+
+    while (!finished) {
+      current_node = iterator.nextNode();
+      finished = (current_node === null);
+      if (!finished) {
+
+        if (blacklist[current_node.nodeName]) {
+          // Drop element
+          current_node.parentNode.removeChild(current_node);
+
+        } else if (!whitelist.node_list[current_node.nodeName]) {
+          // Only keep children
+          keepOnlyChildren(current_node);
+
+        } else {
+          // Cleanup attributes
+          attribute_list = current_node.attributes;
+          len = attribute_list.length;
+          while (len !== 0) {
+            len = len - 1;
+            attribute = attribute_list[len].name;
+            if (!whitelist.attribute_list[attribute]) {
+              current_node.removeAttribute(attribute);
+            }
+          }
+
+          // Cleanup links
+          attribute_list = current_node.attributes;
+          len = attribute_list.length;
+          link_len = 0;
+          already_dropped = false;
+          while (len !== 0) {
+            len = len - 1;
+            attribute = attribute_list[len].name;
+            if (whitelist.link_list[attribute]) {
+              if (startsWithOneOf(current_node.getAttribute(attribute),
+                                  ['http://', 'https://', '//', 'data:'])) {
+                link_len += 1;
+              } else {
+                keepOnlyChildren(current_node);
+                already_dropped = true;
+                break;
+              }
+            }
+          }
+
+          // Lazy img load
+          if (current_node.nodeName === 'IMG') {
+            current_node.setAttribute('loading', 'lazy');
+          }
+
+          // Drop link node without url
+          if (whitelist.link_node_list[current_node.nodeName]) {
+            if ((link_len === 0) && (!already_dropped)) {
+              already_dropped = true;
+              keepOnlyChildren(current_node);
+            }
+          }
+
+          // Drop element if no text or link
+          if ((link_len === 0) && (!already_dropped) &&
+              (!current_node.textContent) &&
+              (!emptylist[current_node.nodeName])) {
+            current_node.parentNode.removeChild(current_node);
+          }
+        }
+
+      }
+    }
+
+    return html_doc.querySelector('body') || domsugar(null);
+  }
+
+  rJS(window)
+
+    .declareMethod('render', function (options) {
+      domsugar(this.element, Array.from(cleanup(options.value || '').childNodes));
+    });
+
+}(window, rJS, domsugar, document, DOMParser, NodeFilter));
\ No newline at end of file

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.js.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="File" module="OFS.Image"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_Cacheable__manager_id</string> </key>
+            <value> <string>must_revalidate_http_cache</string> </value>
+        </item>
+        <item>
+            <key> <string>__name__</string> </key>
+            <value> <string>gadget_html_viewer.js</string> </value>
+        </item>
+        <item>
+            <key> <string>content_type</string> </key>
+            <value> <string>application/javascript</string> </value>
+        </item>
+        <item>
+            <key> <string>precondition</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string></string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.less.txt

+@sans-serif: 'Open Sans', Helvetica, Arial, sans-serif;
+@monospace: "Courier New", Courier, monospace;
+@serif: Cambria, "Hoefler Text", Utopia, "Liberation Serif", "Nimbus Roman No9 L Regular", Times, "Times New Roman", serif;
+@margin-size: 6pt;
+@border-size: 2px;
+@border-type: solid;
+@colorsubheaderbackground: #0E81C2;
+@bold-font-weight: 600;
+@black: #1F1F1F;
+@colorforeground: @black;
+
+
+div[data-gadget-url$="gadget_html_viewer.html"] {
+  max-width: 50em;
+
+  display: block;
+  word-wrap: break-word;
+  font-family: @serif;
+  text-align: justify;
+
+  canvas, img, iframe, svg {
+    max-width: 100%;
+    max-height: 100vh;
+  }
+  video {
+    max-width: 100%;
+    height: auto;
+    max-height: 100vh;
+  }
+
+
+  h1 {
+    font-family: @serif;
+    font-size: 1.5em;
+    text-transform: capitalize;
+    text-align: center;
+  }
+
+  h2 {
+    font-family: @sans-serif;
+    font-size: 1.3em;
+    text-transform: capitalize;
+  }
+
+  h3 {
+    font-family: @sans-serif;
+    font-size: 1.1em;
+    text-transform: uppercase;
+  }
+
+  h4 {
+    font-family: @sans-serif;
+    font-size: 1.1em;
+  }
+
+  blockquote {
+    margin: @margin-size @margin-size @margin-size 0;
+    padding-left: @margin-size;
+    border-left: @border-size @border-type @colorsubheaderbackground;
+  }
+
+  i, cite, em, var, address, dfn {
+    font-style: italic;
+  }
+
+  strong, b, figcaption {
+    font-weight: @bold-font-weight;
+  }
+
+  u, ins {
+    text-decoration: underline;
+  }
+
+  s, strike, del {
+    text-decoration: line-through;
+  }
+
+  tt, code, kbd, samp {
+      font-family: @monospace;
+  }
+
+  code, kbd {
+    color: #2CC32C;
+  }
+
+  q {
+    display: inline;
+    &:before {
+      content: open-quote;
+    }
+    &:after {
+      content: close-quote;
+    }
+    quotes: initial;
+  }
+
+  pre, xmp, plaintext, listing {
+    display: block;
+    white-space: pre-wrap;
+    font-family: @monospace;
+  }
+
+  table {
+    border: 1px solid @colorforeground;
+    width: 100%;
+    margin:0;
+    padding:0;
+    border-collapse: collapse;
+    border-spacing: 0;
+
+    tr {
+      border: 1px solid @colorforeground;
+      padding-top: @margin-size;
+      padding-bottom: @margin-size;
+    }
+    th, td {
+      text-align: center;
+      padding-top: @margin-size;
+      padding-bottom: @margin-size;
+    }
+
+    th {
+      text-transform: uppercase;
+    }
+  }
+
+  ul {
+    list-style: disc;
+    li {
+      margin-left: 2em;
+    }
+  }
+
+  ol {
+    list-style: decimal;
+    li {
+      margin-left: 2em;
+    }
+  }
+
+  dl {
+    display: grid;
+    grid-template-columns: max-content auto;
+    dt {
+      grid-column-start: 1;
+    }
+
+    dd, dl {
+      grid-column-start: 2;
+    }
+  }
+
+
+}

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/gadget_html_viewer.less.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="File" module="OFS.Image"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>__name__</string> </key>
+            <value> <string>gadget_html_viewer.less</string> </value>
+        </item>
+        <item>
+            <key> <string>content_type</string> </key>
+            <value> <string>text/plain</string> </value>
+        </item>
+        <item>
+            <key> <string>precondition</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string></string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>