/* eslint-disable no-unused-vars */

/**
 * The Theme class helps manage the card themes.
 * Usually it overrides or enhances aspects of the card.js.
 *
 * @class Theme
 */
class Theme {

    /**
     * Loads a config file and parses it to JSON.
     *
     * @static
     * @param {string} [path=null] - Optional: A path where the config file is located at (including the filename and extension).
     * @returns {Promise} - Returns a promise, that returns the parsed json file when resolved.
     * @memberof Theme
     */
    static loadConfig(path = null) {
        return new Promise((resolve, reject) => {
            path = (path) ? path : './config.json'

            let xhttp = new XMLHttpRequest()
            xhttp.onreadystatechange = function () {
                if (this.readyState == 4) {

                    if (this.status == 200 || Theme._isLocal()) {
                        try {
                            const json = JSON.parse(this.responseText)
                            resolve(json)

                        } catch (e) {
                            reject(e)
                        }
                    } else reject('Invalid request : ' + this.status)
                }
            }
            xhttp.open('GET', path, true)
            xhttp.send()
        })
    }

    static _isLocal() {
        return (window.location.protocol == 'file:')
    }
}