var PRETTY_INDENTATION = "  ";


class ENode{
  constructor(tag){
    this.__tag = tag;
    this.__classes = [];
    this.__attribs = [];
    this.__children = [];
  }

  appendChild(c){
    var val = (c instanceof ENode) ? c : c.toString();
    this.__children.push(c);
    return this;
  }

  addClass(cname){
    this.__classes.push(cname);
  }

  addAttribute(aname, aval){
    this.__attribs.push([aname, aval]);
  }

  toPrettyString(depth){
    depth || (depth = 0);
    var ind = "";
    var strind = "";
    var eol = "";
    if (depth > -1){
      if (depth > 0)
        ind = PRETTY_INDENTATION + (new Array(depth)).join(PRETTY_INDENTATION);
      strind = ind + PRETTY_INDENTATION;
      eol = "\n";
    }

    var r = ind + "<" + this.__tag.toUpperCase();
    if (this.__attribs.length > 0){
      var attr = this.__attribs.reduce(function(a, at){
        a += ((a !== "") ? " " : "") + at[0].trim() + "=\"" + at[1] + "\"";
        return a;
      }, "");
      r += " " + attr;
    }

    if (this.__children.length > 0){
      r += ">" + eol;
      var lcn = true // lcn = Last Child was Node;
      r += this.__children.reduce(function(a, c){
        if (c instanceof ENode){
          a += ((lcn === false) ? "\n" : "") + ((depth >= 0) ? c.toPrettyString(depth + 1) : c.toString());
          lcn = true;
        } else {
          a += strind + c;
          lcn = false;
        }
        return a;
      }, "");
      r += ((lcn === false) ? eol : "") + ind + "</" + this.__tag.toUpperCase() + ">" + eol;
    } else {
      r += " />" + eol;
    }
    return r;
  }

  toString(){
    return this.toPrettyString(-1);
  }
}


function el(){
  if (arguments.length < 1)
    throw new Error("Invalid number of arguments.");

  var ename = arguments[0];
  var args = Array.prototype.slice.call(arguments, 1);

  var e = new ENode(ename);
  args.forEach(function(item){
    if (item === null){return;}
    // If given an array, assume it to be an array children.
    if (item instanceof Array){
      item.forEach(itm => e.appendChild((itm instanceof ENode) ? itm : itm.toString()));

    // If given an ENode, then it IS a child
    } else if (item instanceof ENode){
      e.appendChild(item);

    // All objects are assumed to be attributes.
    } else if (item instanceof Object){
      var keys = Object.keys(item);
      keys.forEach(function(key){
        if (item.hasOwnProperty(key)){
          if (typeof(item[key]) === "string"){
            e.addAttribute(key.toString(), item[key]);
          }
        }
      });

    // Everything else is assumed to be a child.
    } else {
      e.appendChild(item.toString());
    }
  }); 
  return e;
}



module.exports = {
  ENode: ENode,
  el: el,
  html: el.bind(null, "html"),
  head: el.bind(null, "head"),
  title: el.bind(null, "title"),
  script: el.bind(null, "script"),
  link: el.bind(null, "link"),
  meta: el.bind(null, "meta"),
  body: el.bind(null, "body"),
  div: el.bind(null, "div"),
  span: el.bind(null, "span"),
  a: el.bind(null, "a"),
  p: el.bind(null, "p"),
  b: el.bind(null, "b"),
  i: el.bind(null, "i"),
  br: el.bind(null, "br"),
  ol: el.bind(null, "ol"),
  ul: el.bind(null, "ul"),
  li: el.bind(null, "li"),
  em: el.bind(null, "em"),
  img: el.bind(null, "img"),
  font: el.bind(null, "font"),
  h1: el.bind(null, "h1"),
  h2: el.bind(null, "h2"),
  h3: el.bind(null, "h3"),
  h4: el.bind(null, "h4"),
  h5: el.bind(null, "h5"),
  h6: el.bind(null, "h6"),
  hr: el.bind(null, "hr"),
  blockquote: el.bind(null, "blockquote"),
  button: el.bind(null, "button"),
  nav: el.bind(null, "nav"),
  canvas: el.bind(null, "canvas"),
  caption: el.bind(null, "caption"),
  indentationChar: function(c){
    if (type(c) === "string" && c.length > 0){
      PRETTY_INDENTATION = c;
    }
    return PRETTY_INDENTATION;
  }
};