(function () {

var output, Converter;
if (typeof exports === "object" && typeof require === "function") { // we're in a CommonJS (e.g. Node.js) module
    output = exports;
    Converter = require("./Markdown.Converter").Converter;
} else {
    output = window.Markdown;
    Converter = output.Converter;
}

output.getSanitizingConverter = function () {
    var converter = new Converter();
    converter.hooks.chain("postConversion", sanitizeHtml);
    converter.hooks.chain("postConversion", balanceTags);
    return converter;
}

function sanitizeHtml(html) {
    return html.replace(/<[^>]*>?/gi, sanitizeTag);
}

// (tags that can be opened/closed) | (tags that stand alone)
var basic_tag_whitelist = /^(<\/?(b|blockquote|code|del|dd|dl|dt|em|h1|h2|h3|i|kbd|li|ol|p|pre|s|sup|sub|strong|strike|ul)>|<(br|hr)\s?\/?>)$/i;
// <a href="url..." optional title>|</a>
var a_white = /^(<a\shref="((https?|ftp):\/\/|\/)[-A-Za-z0-9+&@#\/%?=~_|!:,.;\(\)]+"(\stitle="[^"<>]+")?\s?>|<\/a>)$/i;

// <img src="url..." optional width  optional height  optional alt  optional title
var img_white = /^(<img\ssrc="(https?:\/\/|\/)[-A-Za-z0-9+&@#\/%?=~_|!:,.;\(\)]+"(\swidth="\d{1,3}")?(\sheight="\d{1,3}")?(\salt="[^"<>]*")?(\stitle="[^"<>]*")?\s?\/?>)$/i;

function sanitizeTag(tag) {
    if (tag.match(basic_tag_whitelist) || tag.match(a_white) || tag.match(img_white))
        return tag;
    else
        return "";
}

/// <summary>
/// attempt to balance HTML tags in the html string
/// by removing any unmatched opening or closing tags
/// IMPORTANT: we *assume* HTML has *already* been 
/// sanitized and is safe/sane before balancing!
/// 
/// adapted from CODESNIPPET: A8591DBA-D1D3-11DE-947C-BA5556D89593
/// </summary>
function balanceTags(html) {

    if (html == "")
        return "";

    var re = /<\/?\w+[^>]*(\s|$|>)/g;
    // convert everything to lower case; this makes
    // our case insensitive comparisons easier
    var tags = html.toLowerCase().match(re);

    // no HTML tags present? nothing to do; exit now
    var tagcount = (tags || []).length;
    if (tagcount == 0)
        return html;

    var tagname, tag;
    var ignoredtags = "<p><img><br><li><hr>";
    var match;
    var tagpaired = [];
    var tagremove = [];
    var needsRemoval = false;

    // loop through matched tags in forward order
    for (var ctag = 0; ctag < tagcount; ctag++) {
        tagname = tags[ctag].replace(/<\/?(\w+).*/, "$1");
        // skip any already paired tags
        // and skip tags in our ignore list; assume they're self-closed
        if (tagpaired[ctag] || ignoredtags.search("<" + tagname + ">") > -1)
            continue;

        tag = tags[ctag];
        match = -1;

        if (!/^<\//.test(tag)) {
            // this is an opening tag
            // search forwards (next tags), look for closing tags
            for (var ntag = ctag + 1; ntag < tagcount; ntag++) {
                if (!tagpaired[ntag] && tags[ntag] == "</" + tagname + ">") {
                    match = ntag;
                    break;
                }
            }
        }

        if (match == -1)
            needsRemoval = tagremove[ctag] = true; // mark for removal
        else
            tagpaired[match] = true; // mark paired
    }

    if (!needsRemoval)
        return html;

    // delete all orphaned tags from the string

    var ctag = 0;
    html = html.replace(re, function (match) {
        var res = tagremove[ctag] ? "" : match;
        ctag++;
        return res;
    });
    return html;
}

})();