/*
 * Copyright (c) 2011 OJC Technologies.  All rights reserved.
 * @author: Jake Smith
 */

function ProximityHelper(pageX, pageY) {
    this.x = pageX;
    this.y = pageY;
    this.ABOVE = 1;
    this.BELOW = 2;
    this.RIGHT = 3;
    this.LEFT = 4;
    this.WITHIN = 0;
    this.ERR = -1;
    
    this.getInfoFromRelation = function(terminalNodes) {
        var relation, properNode, index, firstNode, lastNode;
        firstNode = terminalNodes[0];
        lastNode = terminalNodes[terminalNodes.length - 1];
        if (this.clickedAbove(firstNode)) { 
            relation = this.ABOVE;
            properNode = firstNode;
            index = 0;
        } else if (this.clickedToLeft(terminalNodes)) {
            relation = this.LEFT;
            properNode = firstNode;
            index = 0;
        } else if (this.clickedBelow(lastNode)) {
            relation = this.BELOW;
            properNode = lastNode;
            index = properNode.nodeValue.length;
        } else { 
            relation = this.RIGHT;
            properNode = lastNode;
            index = properNode.nodeValue.length;
        }
        return new Array(relation, properNode, index);
    }
    
    //-----------------------//
    //  "Private" functions  //
    //-----------------------//
    
    this.clickedAbove = function(textNode) {
        var bounds, top;
        bounds = this.getBoundingRectFor(textNode);
        top = Math.round(bounds.top);
        return this.y < top;
    }
    
    this.clickedBelow = function(textNode) {
        var bounds, bottom;
        bounds = this.getBoundingRectFor(textNode);
        bottom = Math.round(bounds.bottom);
        return this.y > bottom;
    }
    
    this.getBoundingRectFor = function(textNode) {
        var span, bounds;
        span = makeTempSpan(textNode);
        textNode.parentNode.replaceChild(span, textNode);
        bounds = span.getBoundingClientRect();
        span.parentNode.replaceChild(textNode, span);
        return bounds;
    }
    
    this.clickedToLeft = function(terminalNodes) {
        var i, j, rects, r, tempSpan, parent, currNode;
        for (i = 0; i < terminalNodes.length; i += 1) {
            currNode = terminalNodes[i];
            parent = currNode.parentNode;
            tempSpan = makeTempSpan(currNode);
            parent.replaceChild(tempSpan, currNode);
            rects = tempSpan.getClientRects();
            for (j = 0; j < rects.length; j += 1) {
                r = rects[j];
                if (inVerticalBounds(r, this.y)) {
                    if (toLeftOf(r, this.x)) {
                        parent.replaceChild(currNode, tempSpan);
                        return true;
                    }
                }
            }
            parent.replaceChild(currNode, tempSpan);
        }
        return false;
    }
} // ProximityHelper(pageX, pageY)

function inVerticalBounds(rect, y) {
    var top, bottom
    top = Math.round(rect.top) + window.scrollY;
    bottom = Math.round(rect.bottom) + window.scrollY;
    return top < y && y < bottom;
}

function toLeftOf(rect, x) {
    var leftEdge = rect.left + window.scrollX;
    return x < leftEdge;
}