(function(){

	var vec2, Rect
	if ('window' in this) {
		vec2 = window.vec2
		Rect = window.Rect
	}
	else {
		vec2 = require('./vec2')
		Rect = require('./rect')
	}
	
	var Surface = function (face){
		this.width = 0
		this.height = 0
		this.faces = []
		if (face) {
			this.add(face)
		}
	}
	Surface.prototype.add = function(rect){
		this.faces.push(rect)
		this.width += rect.width()
		this.height = Math.max(this.height, rect.height())
	}
	Surface.prototype.fits_scale = function(v, scale){
		v = v.clone().mul(scale)
		return this.fits(v)
	}
	Surface.prototype.fits = function(v){
		var faces = this.faces
		var scratch
		if (this.width < v.a || this.height < v.b) {
			return null
		}
		for (var i = 0; i < faces.length; i++) {
			if (faces[i].fits(v)) {
				return faces[i]
			}
		}
		scratch = new Rect (0,0,0,0)
		for (var i = 0; i < faces.length; i++) {
			if (faces[i].y.length() < v.b) {
				continue
			}
			scratch.x.a = faces[i].x.a
			scratch.x.b = faces[i].x.b
			scratch.y.a = faces[i].y.a
			scratch.y.b = faces[i].y.b
			SEARCH: for (var j = i+1; j < faces.length; j++) {
				if (faces[j].y.a > scratch.y.a) {
					scratch.y.a = faces[j].y.a
				}
				if (faces[j].y.b < scratch.y.b) {
					scratch.y.b = faces[j].y.b
				}
				if (scratch.y.b <= scratch.y.a || scratch.y.length() < v.b) {
					break SEARCH
				}
				scratch.x.b = faces[j].x.b
				if (scratch.fits(v)) {
					return scratch
				}
			}
		}
		return null
	}
	Surface.prototype.place = function(v, index){
		var face, faces = this.faces
	}
	Surface.prototype.bounds = function(index){
		var bounds = faces[index].clone()
		var height = faces[index].height()
		bounds.first = bounds.last = index

		for (var i = index-1; i >= 0; i--) {
			var face = faces[i]
			if (face.y.length() < height) {
				continue
			}
			if (face.y.a > bounds.y.a) {
				continue
			}
			if (face.y.b < bounds.y.b) {
				continue
			}
			bounds.x.a = bounds.x.a
			bounds.first = i
		}
		
		for (var i = index+1; i < faces.length; i++) {
			var face = faces[i]
			if (face.y.length() < height) {
				continue
			}
			if (face.y.a > bounds.y.a) {
				continue
			}
			if (face.y.b < bounds.y.b) {
				continue
			}
			bounds.x.b = bounds.x.b
			bounds.last = i
		}
		return bounds
	}
	Surface.prototype.clamp = function (bounds, dimension, position, dx, dy) {
		// we start out with a set of boundaries where we know the object should fall
		// we then check if we've moved the box off any edge of the bounds
		// if so, check if the new position is valid with respect to the surface.
		// for horizontal movement, this means checking the height and boundaries of
		//   faces with adjacent indexes
		var p = position.clone(), nextIndex, nextFace, newBounds
		p.a += dx
		p.b += dy

		// left edge
		if (p.a < bounds.x.a) {
			if (bounds.first == 0) {
				p.a = bounds.x.a
			}
			else {
				nextIndex = bounds.first - 1
				nextFace = this.faces[nextIndex]
				if (nextFace.y.a <= p.b && p.b + dimension.b <= nextFace.y.b) {
					// it appears the div to the left will accomodate this element
				}
				else {
					p.a = bounds.x.a
				}
			}
		}
		// right edge
		else if (p.a + dimension.a > bounds.x.b) {
			if (bounds.last == this.faces.length-1) {
				p.a = bounds.x.b - dimension.a
			}
			else {
				nextIndex = bounds.last + 1
				nextFace = this.faces[nextIndex]
				if (nextFace.y.a <= p.b && p.b + dimension.b <= nextFace.y.b) {
					// it appears the div to the right will accomodate this element
				}
				else {
					p.a = bounds.x.b - dimension.a
				}
			}
		}
		
		// for vertical movement, this means checking the height and boundaries of
		//   elements in the set of bounds' indexes
		if (p.b < bounds.y.a) {
			for (var i = Math.min(nextIndex, bounds.first), last = Math.max(nextIndex, bounds.last); i < last; i++) {
				face = this.faces[i]
				// loop over each of the faces in the list
				// given a face, figure out if the new top-left is in its bounds
				// if so, find which one contains its right edge
				// get the lowest height of this set
				// then clamp to that lowest height
				// additionally, this is the new center-index
				// recalculate the bounds
// 				if (face.x.b < p.
// 				for (var j = bounds.first+1; j < bounds.last
			}
		}
		// bottom edge, so we can clamp here trivially
		else if (p.b + dimension.b > bounds.y.b) {
			p.b = bounds.y.b - dimension.b
		}
		// if we're able to move out of bounds in that direction, recalculate the bounds
	}
	
	if ('window' in this) {
		window.Surface = Surface
	}
	else {
		module.exports = Surface
	}
})()