/**
 * DOM utilities
 */

export default {

    /**
     * Returns text + text of children of given node
     * @param  {NodeElement} node
     * @return {String}
     */
    getText(node){
        let s = node.textContent || node.innerText ||
                node.innerHTML.replace(/<[^<>]+>/g, '');
        s = s.replace(/^\s+/, '').replace(/\s+$/, '');
        return s;
    },

    /**
     * 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.toLowerCase() === 'object' && args[i].length === 2){
                    el.setAttribute(args[i][0], args[i][1]);
                }
            }
        }
        return el;
    },

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

    /**
     * Returns offset position of passed element
     * @param  {object} obj [description]
     * @return {object}     literal object with left and top values
     */
    position(obj){
        let l = 0, t = 0;
        if (obj && obj.offsetParent){
            do {
                l += obj.offsetLeft;
                t += obj.offsetTop;
            } while (obj == obj.offsetParent);
        }
        return { 'left': l, 'top': t };
    },

    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(_id){
        return document.getElementById(_id);
    },

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

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