/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
*/

let config;

function Config (xhr) {
    function loadPreferences (xhr) {
        const parser = new DOMParser();
        const doc = parser.parseFromString(xhr.responseText, 'application/xml');
        const preferences = doc.getElementsByTagName('preference');

        return Array.prototype.slice.call(preferences);
    }

    this.xhr = xhr;
    this.preferences = loadPreferences(this.xhr);
}

function readConfig (success, error) {
    var xhr;

    if (typeof config !== 'undefined') {
        success(config);
    }

    function fail (msg) {
        console.error(msg);

        if (error) {
            error(msg);
        }
    }

    var xhrStatusChangeHandler = function () {
        if (xhr.readyState === 4) {
            if (xhr.status === 200 || xhr.status === 304 || xhr.status === 0 /* file:// */) {
                config = new Config(xhr);
                success(config);
            } else {
                fail('[Electron][cordova.js][xhrStatusChangeHandler] Could not XHR config.xml: ' + xhr.statusText);
            }
        }
    };

    xhr = new XMLHttpRequest();
    xhr.addEventListener('load', xhrStatusChangeHandler);

    try {
        xhr.open('get', 'config.xml', true);
        xhr.send();
    } catch (e) {
        fail('[Electron][cordova.js][readConfig] Could not XHR config.xml: ' + JSON.stringify(e));
    }
}

/**
 * Reads a preference value from config.xml.
 * Returns preference value or undefined if it does not exist.
 * @param {String} preferenceName Preference name to read */
Config.prototype.getPreferenceValue = function getPreferenceValue (preferenceName) {
    var preferenceItem = this.preferences && this.preferences.filter(function (item) {
        return item.attributes.name && item.attributes.name.value === preferenceName;
    });

    if (preferenceItem && preferenceItem[0] && preferenceItem[0].attributes && preferenceItem[0].attributes.value) {
        return preferenceItem[0].attributes.value.value;
    }
};

exports.readConfig = readConfig;