/*
	The MIT License
	
	Copyright (c) 2007 Thomas Robinson
	
	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:
	
	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.
	
	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.
*/

function Exposer(width, height) {
    var scale_factor = 0.95;

	this.calc = function(orig_rects) {
		var new_rects = [];
		for (var i = 0; i < orig_rects.length; i++) {
	        new_rects[i] = {
				x: orig_rects[i].x,
				y: orig_rects[i].y,
				w: orig_rects[i].w,
				h: orig_rects[i].h
			};
		}

	    while (localSearch(new_rects))
			for (var k = 0; k < new_rects.length; ++k)
				scaleAroundCenter(new_rects[k], scale_factor);
		
		for (var k = 0; k < new_rects.length; ++k)
			scaleAroundCenter(new_rects[k], scale_factor);
			
		return new_rects;
	};
    calculateOverlap = function(rects, j, x, y)
	{
		var x1 = x;
		var y1 = y;
		var x2 = x1 + rects[j].w;
		var y2 = y1 + rects[j].h;

		var result = -0.01;

		for (var i = 0; i < rects.length; i++) {
			if (i == j) {
				continue;
			}
			
			var x1O = Math.max(rects[i].x, x1);
			var x2O = Math.min(rects[i].x+rects[i].w, x2);
			var xOverlap = 0;
			if (x1O <= x2O) {
				xOverlap = x2O - x1O;
			}

			var y1O = Math.max(rects[i].y, y1);
			var y2O = Math.min(rects[i].y+rects[i].h, y2);
			var yOverlap = 0;
			if (y1O <= y2O) {
				yOverlap = y2O - y1O;
			}
			result += xOverlap * yOverlap;
		}
		return result;
	};
    findBestHorizontalPosition = function(rects, j, best)
	{
		var y1 = rects[j].y;
		var y2 = rects[j].y + rects[j].h;

		var bestOverlap = 1e34;
		best.x = rects[j].x;
		var w = rects[j].w;

	    // For every other div excluding itself
		for (var i = 0; i < rects.length; i++) {
			if (i == j) {
				continue;
			}

	        // If they overlap vertically
			if (rects[i].y < y2 && rects[i].y + rects[i].h > y1) {
	            // If there's room on the left, check just next to it
				if (rects[i].x - w >= 0) {
					var overlap = calculateOverlap(rects, j, rects[i].x - w, y1);
					if (overlap < bestOverlap) {
						best.x = rects[i].x - w;
						bestOverlap = overlap;
					}
				}
	            // If there's room on the right, check just next to it
				if (rects[i].x + rects[i].w + w < width) {
					var overlap = calculateOverlap(rects, j, rects[i].x + rects[i].w, y1);
					if (overlap < bestOverlap) {
						best.x = rects[i].x + rects[i].w;
						bestOverlap = overlap;
					}
				}
			}
		}

		// Test left and right side of desktop as well... 
		var overlap = calculateOverlap(rects, j, 0, y1);
		if (overlap < bestOverlap) {
			best.x = 0;
			bestOverlap = overlap;
		}

		overlap = calculateOverlap(rects, j, width - w, y1);
		if (overlap < bestOverlap) {
			best.x = width - w;
			bestOverlap = overlap;
		}
		return bestOverlap;
	};
    findBestVerticalPosition = function(rects, j, best)
	{
		var x1 = rects[j].x;
		var x2 = rects[j].x + rects[j].w;

		var bestOverlap = 1e34;
		best.y = rects[j].y;
		var h = rects[j].h;

		for (var i = 0; i < rects.length; i++) {
			if (i == j) {
				continue;
			}

			if (rects[i].x < x2 && rects[i].x + rects[i].w > x1) {
				if (rects[i].y - h >= 0 && rects[i].y < height) {
					var overlap = calculateOverlap(rects, j, x1, rects[i].y - h);
					if (overlap < bestOverlap) {
						best.y = rects[i].y - h;
						bestOverlap = overlap;
					}
				}
				if (rects[i].y + rects[i].h > 0 && rects[i].y + rects[i].h + h < height) {
					var overlap = calculateOverlap(rects, j, x1, rects[i].y + rects[i].h);
					if (overlap < bestOverlap) {
						best.y = rects[i].y + rects[i].h;
						bestOverlap = overlap;
					}
				}
			}
		}

		// Test top and bottom of desktop as well... 
		var overlap = calculateOverlap(rects, j, x1, 0);
		if (overlap < bestOverlap) {
			best.y = 0;
			bestOverlap = overlap;
		}

		overlap = calculateOverlap(rects, j, x1, height - h);
		if (overlap < bestOverlap) {
			best.y = height - h;
			bestOverlap = overlap;
		}

		return bestOverlap;
	};
    localSearch = function(rects)
	{
		var improvement = false;
		do {
	        improvement = false;
			for (var i = 0; i < rects.length; i++) {
				var improved = false;
				do {
					improved = false;
					var newPos = {};
					var oldOverlap = calculateOverlap(rects, i, rects[i].x, rects[i].y);
					var overlapH = findBestHorizontalPosition(rects, i, newPos);
					var overlapV = findBestVerticalPosition(rects, i, newPos);
					if (overlapH < oldOverlap-0.1 || overlapV < oldOverlap-0.1) {
						improved = true;
						improvement = true;
						if (overlapV > overlapH) {
							rects[i].x = newPos.x;
						} else {
							rects[i].y = newPos.y;
						}
					}
				} while (improved);
			}
		} while (improvement);

		var totalOverlap = 0.0;
		for (var i = 0; i < rects.length; i++) {
			totalOverlap += calculateOverlap(rects, i, rects[i].x, rects[i].y);
		}
		return (totalOverlap > 0.1);
	};
	scaleAroundCenter = function(rect, factor) {
	    var centerX = rect.x + (rect.w / 2);
	    var centerY = rect.y + (rect.h / 2);
	    rect.w = Math.round(factor * rect.w);
	    rect.h = Math.round(factor * rect.h);
	    rect.x = centerX - (rect.w / 2);
	    rect.y = centerY - (rect.h / 2);
	};
}