source: frontend/node_modules/svgo/plugins/removeUnusedNS.js

'use strict';

exports.type = 'full';

exports.active = true;

exports.description = 'removes unused namespaces declaration';

/**
 * Remove unused namespaces declaration.
 *
 * @param {Object} item current iteration item
 * @return {Boolean} if false, item will be filtered out
 *
 * @author Kir Belevich
 */
exports.fn = function(data) {

    var svgElem,
        xmlnsCollection = [];

    /**
     * Remove namespace from collection.
     *
     * @param {String} ns namescape name
     */
    function removeNSfromCollection(ns) {

        var pos = xmlnsCollection.indexOf(ns);

        // if found - remove ns from the namespaces collection
        if (pos > -1) {
            xmlnsCollection.splice(pos, 1);
        }

    }

    /**
     * Bananas!
     *
     * @param {Array} items input items
     *
     * @return {Array} output items
     */
    function monkeys(items) {

        var i = 0,
            length = items.content.length;

        while(i < length) {

            var item = items.content[i];

            if (item.isElem('svg')) {

                item.eachAttr(function(attr) {
                    // collect namespaces
                    if (attr.prefix === 'xmlns' && attr.local) {
                        xmlnsCollection.push(attr.local);
                    }
                });

                // if svg element has ns-attr
                if (xmlnsCollection.length) {
                    // save svg element
                    svgElem = item;
                }

            }

            if (xmlnsCollection.length) {

                // check item for the ns-attrs
                if (item.prefix) {
                    removeNSfromCollection(item.prefix);
                }

                // check each attr for the ns-attrs
                item.eachAttr(function(attr) {
                    removeNSfromCollection(attr.prefix);
                });

            }

            // if nothing is found - go deeper
            if (xmlnsCollection.length && item.content) {
                monkeys(item);
            }

            i++;

        }

        return items;

    }

    data = monkeys(data);

    // remove svg element ns-attributes if they are not used even once
    if (xmlnsCollection.length) {
        xmlnsCollection.forEach(function(name) {
            svgElem.removeAttr('xmlns:' + name);
        });
    }

    return data;

};