// Idea from http://stackoverflow.com/questions/295566/sanitize-rewrite-html-on-the-client-side
// https://quip.com/aO0pAZO9m9SG

'use strict';

export var Sanitizer = {
  sanitize: (function() {
    var PERMITTED_TAGS = {
          "A":          true,
          "ABBR":       true,
          "ACRONYM":    true,
          "ADDRESS":    true,
          "AREA":       true,
          "B":          true,
          "BDO":        true,
          "BODY":       true,
          "BIG":        true,
          "BLOCKQUOTE": true,
          "BR":         true,
          "BUTTON":     true,
          "CAPTION":    true,
          "CENTER":     true,
          "CITE":       true,
          "CODE":       true,
          "COL":        true,
          "COLGROUP":   true,
          "DD":         true,
          "DEL":        true,
          "DFN":        true,
          "DIR":        true,
          "DIV":        true,
          "DL":         true,
          "DT":         true,
          "EM":         true,
          "FIELDSET":   true,
          "FONT":       true,
          "FORM":       true,
          "H1":         true,
          "H2":         true,
          "H3":         true,
          "H4":         true,
          "H5":         true,
          "H6":         true,
          "HR":         true,
          "I":          true,
          "IMG":        true,
          "INPUT":      true,
          "INS":        true,
          "KBD":        true,
          "LABEL":      true,
          "LEGEND":     true,
          "LI":         true,
          "MAP":        true,
          "MENU":       true,
          "OL":         true,
          "OPTGROUP":   true,
          "OPTION":     true,
          "P":          true,
          "PRE":        true,
          "Q":          true,
          "S":          true,
          "SAMP":       true,
          "SELECT":     true,
          "SMALL":      true,
          "SPAN":       true,
          "STYLE":      false, // explanation here
          "STRIKE":     true,
          "STRONG":     true,
          "SUB":        true,
          "SUP":        true,
          "TABLE":      true,
          "TBODY":      true,
          "TD":         true,
          "TEXTAREA":   true,
          "TFOOT":      true,
          "TH":         true,
          "THEAD":      true,
          "TR":         true,
          "TT":         true,
          "U":          true,
          "UL":         true,
          "VAR":        true
        },

        PERMITTED_STYLES = [
          "direction",
          "font",
          "font-family",
          "font-style",
          "font-variant",
          "font-size",
          "font-weight",
          "letter-spacing",
          "line-height",
          "text-align",
          "text-decoration",
          "text-indent",
          "text-overflow",
          "text-shadow",
          "text-transform",
          "white-space",
          "word-spacing",
          "word-wrap",
          "vertical-align",
          //
          "color",
          "background",
          "background-color",
          "background-image",
          "background-repeat",
          //
          "border",
          "border-color",
          "border-radius",
          "height",
          "margin",
          "padding",
          "width",
          "max-width",
          "min-width",
          //
          "clear",
          "float",
          //
          "border-collapse",
          "border-spacing",
          "caption-side",
          "empty-cells",
          "table-layout",
          //
          "list-style-type",
          "list-style-position"
        ],

        PERMITTED_ATTRIBUTES = {
          "href":  true,//sanitize
          "src":   true,//sanitize
          "style": true,
          "color": true,
          "bgcolor": true,
          "width": true,
          "height" : true,
          "colspan": true,
          "rowspan": true,
          "cellspacing": true,
          "cellpadding": true,
          "border": true,
          "align": true,
          "valign": true,
          "dir": true,

          // Migadu specific, added only after preprocessed
          "data-proxy-src": true,
          "data-proxy-style": true,
          "target": true,
        },

        PROTOCOL_SEPARATOR = /:|(&#0*58)|(&#x70)|(&#x0*3a)|(%|%)3A/i,

        PERMITTED_PROTOCOLS = {
          'ftp':    true,
          'http':   true,
          'https':  true,
          'irc':    true,
          'mailto': true,
          'news':   true,
          'gopher': true,
          'nntp':   true,
          'telnet': true,
          'webcal': true,
          'xmpp':   true,
          'callto': true,
          'feed':   true
        },

        doSanitizeHTML = function(inputHTML, callbackFunc) {
          var sandboxedIFrame,

              makeSanitizedCopy = function(node) {
                var newNode, i, l, attr, trimmedAttributeValue, subCopy;

                if (node.nodeType === Node.TEXT_NODE)
                  return node.cloneNode(true);

                if (!(node.nodeType === Node.ELEMENT_NODE &&
                     typeof PERMITTED_TAGS[node.tagName] !== "undefined"))
                  return document.createDocumentFragment();

                newNode = sandboxedIFrame.contentDocument.createElement(node.tagName);

                for (i = 0, l = node.attributes.length; i < l; i += 1) {
                  attr = node.attributes[i];

                  if (PERMITTED_ATTRIBUTES[attr.name])
                    switch (attr.name) {
                      case "style":
                        PERMITTED_STYLES.forEach(function(st) {
                          var elStyle = node.style[st];
                          if (elStyle.length)
                            newNode.style[st] = node.style[st];
                        });
                        break;
                      case "src":
                      case "href" :
                        trimmedAttributeValue = attr.value.trim();
                        if (typeof PERMITTED_PROTOCOLS[trimmedAttributeValue.split(PROTOCOL_SEPARATOR)[0]] !== "undefined")
                          newNode.setAttribute(attr.name, trimmedAttributeValue);
                        break;
                      default:
                        newNode.setAttribute(attr.name, attr.value);
                    }
                }

                for (i = 0, l = node.childNodes.length; i < l; i += 1) {
                  subCopy = makeSanitizedCopy(node.childNodes[i]);
                  newNode.appendChild(subCopy, false);
                }

                return newNode;
              };


        if (typeof callbackFunc === 'undefined')
          return;

        sandboxedIFrame = document.createElement("IFRAME");

        if (typeof sandboxedIFrame["sandbox"] === "undefined") {
          alert("Your browser does not support sandboxed iframes. Please upgrade to a modern browser.");
          return;
        }

        sandboxedIFrame.setAttribute("src", "about:blank");
        sandboxedIFrame.setAttribute("sandbox", "allow-same-origin");
        sandboxedIFrame.style.display = "none";

        sandboxedIFrame.addEventListener("load", function(ev) {
          sandboxedIFrame.contentWindow.document.write(inputHTML);
          callbackFunc(makeSanitizedCopy(sandboxedIFrame.contentDocument.body).innerHTML);
          document.body.removeChild(sandboxedIFrame);
        });

        document.body.appendChild(sandboxedIFrame);
      };


      return doSanitizeHTML;
    })()
};