ElmRuntime.Render.Element = function() {
'use strict';

var Utils = ElmRuntime.use(ElmRuntime.Render.Utils);
var newElement = Utils.newElement, extract = Utils.extract,
    addTransform = Utils.addTransform, removeTransform = Utils.removeTransform,
    fromList = Utils.fromList, eq = Utils.eq;

function setProps(props, e) {
    e.style.width  = (props.width |0) + 'px';
    e.style.height = (props.height|0) + 'px';
    if (props.opacity !== 1) { e.style.opacity = props.opacity; }
    if (props.color.ctor === 'Just') {
	e.style.backgroundColor = extract(props.color._0);
    }
    if (props.tag !== '') { e.id = props.tag; }
    if (props.href !== '') {
	var a = newElement('a');
	a.href = props.href;
	a.appendChild(e);
	return a;
    }
    if (props.hover.ctor !== '_Tuple0') {
        var overCount = 0;
        e.addEventListener('mouseover', function() {
                if (overCount++ > 0) return;
                props.hover(true);
            });
        e.addEventListener('mouseout', function(evt) {
                if (e.contains(evt.toElement || evt.relatedTarget)) return;
                overCount = 0;
                props.hover(false);
            });
    }
    return e;
}

function image(props, img) {
    switch (img._0.ctor) {
    case 'Plain':   return plainImage(img._3);
    case 'Fitted':  return fittedImage(props.width, props.height, img._3);
    case 'Cropped': return croppedImage(img,props.width,props.height,img._3);
    case 'Tiled':   return tiledImage(img._3);
    }
}

function plainImage(src) {
    var img = newElement('img');
    img.src = src;
    img.name = src;
    img.style.display = "block";
    return img;
}

function tiledImage(src) {
    var div = newElement('div');
    div.style.backgroundImage = 'url(' + src + ')';
    return div;
}

function fittedImage(w, h, src) {
    var div = newElement('div');
    div.style.background = 'url(' + src + ') no-repeat center';
    div.style.webkitBackgroundSize = 'cover';
    div.style.MozBackgroundSize = 'cover';
    div.style.OBackgroundSize = 'cover';
    div.style.backgroundSize = 'cover';
    return div;
}

function croppedImage(elem, w, h, src) {
    var pos = elem._0._0;
    var e = newElement('div');
    e.style.overflow = "hidden";

    var img = newElement('img');
    img.onload = function() {
	var sw = w / elem._1, sh = h / elem._2;
	img.style.width = ((this.width * sw)|0) + 'px';
	img.style.height = ((this.height * sh)|0) + 'px';
	img.style.marginLeft = ((- pos._0 * sw)|0) + 'px';
	img.style.marginTop = ((- pos._1 * sh)|0) + 'px';
    };
    img.src = src;
    img.name = src;
    e.appendChild(img);
    return e;
}

function goIn(e) { e.style.position = 'absolute'; return e; }
function goDown(e) { return e }
function goRight(e) { e.style.styleFloat = e.style.cssFloat = "left"; return e; }
function flowWith(f, array) {
    var container = newElement('div');
    for (var i = array.length; i--; ) {
	container.appendChild(f(render(array[i])));
    }
    return container;
}

function flow(dir,elist) {
    var array = fromList(elist);
    switch(dir.ctor) {
    case "DDown":  array.reverse();
    case "DUp":    return flowWith(goDown,array);
    case "DRight": array.reverse();
    case "DLeft":  return flowWith(goRight,array);
    case "DOut":   array.reverse();
    case "DIn":    return flowWith(goIn,array);
    }
}

function toPos(pos) {
    switch(pos.ctor) {
    case "Absolute": return  pos._0 + "px";
    case "Relative": return (pos._0 * 100) + "%";
    }
}

function setPos(pos,w,h,e) {
    e.style.position = 'absolute';
    e.style.margin = 'auto';
    var transform = '';
    switch(pos.horizontal.ctor) {
    case 'P': e.style.right = toPos(pos.x); break;
    case 'Z': transform = 'translateX(' + ((-w/2)|0) + 'px) ';
    case 'N': e.style.left = toPos(pos.x); break;
    }
    switch(pos.vertical.ctor) {
    case 'N': e.style.bottom = toPos(pos.y); break;
    case 'Z': transform += 'translateY(' + ((-h/2)|0) + 'px)';
    case 'P': e.style.top = toPos(pos.y); break;
    }
    if (transform !== '') addTransform(e.style, transform);
    return e;
}

function container(pos,elem) {
    var e = render(elem);
    setPos(pos, elem.props.width, elem.props.height, e);
    var div = newElement('div');
    div.style.position = 'relative';
    div.style.overflow = 'hidden';
    div.appendChild(e);
    return div;
}

function rawHtml(html) {
    var e = newElement('div');
    e.innerHTML = html;
    return e;
}

function render(elem) { return setProps(elem.props, makeElement(elem)); }
function makeElement(e) {
    var elem = e.element;
    switch(elem.ctor) {
    case 'Image':     return image(e.props, elem);
    case 'Flow':      return flow(elem._0, elem._1);
    case 'Container': return container(elem._0, elem._1);
    case 'Spacer':    return newElement('div');
    case 'RawHtml':   return rawHtml(elem._0);
    case 'Custom':    return elem.render(elem.model);
    }
}

function update(node, curr, next) {
    if (node.tagName === 'A') { node = node.firstChild; }
    if (curr.props.id === next.props.id) return updateProps(node, curr, next);
    if (curr.element.ctor !== next.element.ctor) {
	node.parentNode.replaceChild(render(next),node);
	return true;
    }
    var nextE = next.element, currE = curr.element;
    switch(nextE.ctor) {
    case "Spacer": break;
    case "RawHtml":
        if (nextE._0 !== currE._0) node.innerHTML = nextE._0;
        break;
    case "Image":
	if (nextE._0.ctor === 'Plain') {
	    if (nextE._3 !== currE._3) node.src = nextE._3;
	} else if (!eq(nextE,currE) ||
		   next.props.width !== curr.props.width ||
		   next.props.height !== curr.props.height) {
	    node.parentNode.replaceChild(render(next),node);
	    return true;
	}
	break;
    case "Flow":
        var arr = fromList(nextE._1);
        for (var i = arr.length; i--; ) { arr[i] = arr[i].element.ctor; }
	if (nextE._0.ctor !== currE._0.ctor) {
	    node.parentNode.replaceChild(render(next),node);
	    return true;
	}
	var nexts = fromList(nextE._1);
	var kids = node.childNodes;
	if (nexts.length !== kids.length) {
	    node.parentNode.replaceChild(render(next),node);
	    return true;
	}
	var currs = fromList(currE._1);
	var goDir = function(x) { return x; };
	switch(nextE._0.ctor) {
	case "DDown":  case "DUp":   goDir = goDown; break;
	case "DRight": case "DLeft": goDir = goRight; break;
	case "DOut":   case "DIn":   goDir = goIn; break;
	}
	for (var i = kids.length; i-- ;) {
	    update(kids[i],currs[i],nexts[i]);
	    goDir(kids[i]);
	}
	break;
    case "Container":
	var inner = node.firstChild;
	if (!update(inner, currE._1, nextE._1)) {
	    if (nextE._0.horizontal.ctor !== currE._0.horizontal.ctor) {
		inner.style.left = inner.style.right = 'none';
		removeTransform(inner.style);
	    }
	    if (nextE._0.vertical.ctor !== currE._0.vertical.ctor) {
		inner.style.top = inner.style.bottom = 'none';
		removeTransform(inner.style);
	    }
	}
	setPos(nextE._0, nextE._1.props.width, nextE._1.props.height, inner);
	break;
    case "Custom":
	if (currE.type === nextE.type) {
	    var done = nextE.update(node, currE.model, nextE.model);
	    if (done) return;
	} else {
	    return node.parentNode.replaceChild(render(next), node);
	}
    }
    updateProps(node, curr, next);
}

function updateProps(node, curr, next) {
    var props = next.props, currP = curr.props, e = node;
    if (props.width !== currP.width)   e.style.width  = (props.width |0) + 'px';
    if (props.height !== currP.height) e.style.height = (props.height|0) + 'px';
    if (props.opacity !== 1 && props.opacity !== currP.opacity) {
	e.style.opacity = props.opacity;
    }
    var nextColor = (props.color.ctor === 'Just' ?
		     extract(props.color._0) : 'transparent');
    if (e.style.backgroundColor !== nextColor) {
        e.style.backgroundColor = nextColor;
    }
    if (props.tag !== currP.tag) { e.id = props.tag; }
    if (props.href !== currP.href) {
	if (currP.href === '') {
	    var a = newElement('a');
	    a.href = props.href;
	    a.appendChild(e);
	    e.parentNode.replaceChild(a,e);
	} else {
	    node.parentNode.href = props.href;
	}
    }
}

return { render:render, update:update };

};