import {isUndef} from './types';
import {trim} from './string';

/**
 * DOM utilities
 */

export default {

    /**
     * Returns text + text of children of given node
     * @param  {NodeElement} node
     * @return {String}
     */
    getText(node) {
        if (isUndef(node.textContent)) {
            return trim(node.innerText);
        }
        return trim(node.textContent);
    },

    /**
     * Returns the first text node contained in the supplied node
     * @param  {NodeElement} node node
     * @return {String}
     */
    getFirstTextNode(node) {
        for (let i = 0; i < node.childNodes.length; i++) {
            let n = node.childNodes[i];
            if (n.nodeType === 3) {
                return n.data;
            }
        }
    },

    /**
     * Creates an html element with given collection of attributes
     * @param  {String} tag a string of the html tag to create
     * @param  {Array} an undetermined number of arrays containing the with 2
     *                    items, the attribute name and its value ['id','myId']
     * @return {Object}     created element
     */
    create(tag) {
        if (!tag || tag === '') {
            return;
        }

        let el = document.createElement(tag),
            args = arguments;

        if (args.length > 1) {
            for (let i = 0; i < args.length; i++) {
                let argtype = typeof args[i];
                if (argtype === 'object' && args[i].length === 2) {
                    el.setAttribute(args[i][0], args[i][1]);
                }
            }
        }
        return el;
    },

    /**
     * Removes passed node from DOM
     * @param  {DOMElement} node
     * @return {DOMElement} old node reference
     */
    remove(node) {
        return node.parentNode.removeChild(node);
    },

    /**
     * Returns a text node with given text
     * @param  {String} txt
     * @return {Object}
     */
    text(txt) {
        return document.createTextNode(txt);
    },

    hasClass(ele, cls) {
        if (!ele) { return false; }

        if (supportsClassList()) {
            return ele.classList.contains(cls);
        }
        return ele.className.match(new RegExp('(\\s|^)' + cls + '(\\s|$)'));
    },

    addClass(ele, cls) {
        if (!ele) { return; }

        if (supportsClassList()) {
            ele.classList.add(cls);
            return;
        }

        if (ele.className === '') {
            ele.className = cls;
        }
        else if (!this.hasClass(ele, cls)) {
            ele.className += ' ' + cls;
        }
    },

    removeClass(ele, cls) {
        if (!ele) { return; }

        if (supportsClassList()) {
            ele.classList.remove(cls);
            return;
        }
        let reg = new RegExp('(\\s|^)' + cls + '(\\s|$)', 'g');
        ele.className = ele.className.replace(reg, '');
    },

    /**
     * Creates and returns an option element
     * @param  {String}  text  option text
     * @param  {String}  value option value
     * @param  {Boolean} isSel whether option is selected
     * @return {Object}        option element
     */
    createOpt(text, value, isSel) {
        let isSelected = isSel ? true : false,
            opt = isSelected ?
                this.create('option', ['value', value], ['selected', 'true']) :
                this.create('option', ['value', value]);
        opt.appendChild(this.text(text));
        return opt;
    },

    /**
     * Creates and returns a checklist item
     * @param  {Number} chkIndex  index of check item
     * @param  {String} chkValue  check item value
     * @param  {String} labelText check item label text
     * @return {Object}           li DOM element
     */
    createCheckItem(chkIndex, chkValue, labelText) {
        let li = this.create('li'),
            label = this.create('label', ['for', chkIndex]),
            check = this.create('input',
                ['id', chkIndex],
                ['name', chkIndex],
                ['type', 'checkbox'],
                ['value', chkValue]
            );
        label.appendChild(check);
        label.appendChild(this.text(labelText));
        li.appendChild(label);
        li.label = label;
        li.check = check;
        return li;
    },

    id(key) {
        return document.getElementById(key);
    },

    tag(o, tagname) {
        return o.getElementsByTagName(tagname);
    }
};

// HTML5 classList API
function supportsClassList() {
    return document.documentElement.classList;
}