/*
 * jsPlumb
 * 
 * Title:jsPlumb 1.4.1
 * 
 * Provides a way to visually connect elements on an HTML page, using either SVG, Canvas
 * elements, or VML.  
 * 
 * This file contains the code for creating and manipulating anchors.
 *
 * Copyright (c) 2010 - 2013 Simon Porritt (simon.porritt@gmail.com)
 * 
 * http://jsplumb.org
 * http://github.com/sporritt/jsplumb
 * http://code.google.com/p/jsplumb
 * 
 * Dual licensed under the MIT and GPL2 licenses.
 */
;(function() {	
    
    //
	// manages anchors for all elements.
	//
	jsPlumb.AnchorManager = function(params) {
		var _amEndpoints = {},
            continuousAnchors = {},
            continuousAnchorLocations = {},
            userDefinedContinuousAnchorLocations = {},        
            continuousAnchorOrientations = {},
            Orientation = { HORIZONTAL : "horizontal", VERTICAL : "vertical", DIAGONAL : "diagonal", IDENTITY:"identity" },
			connectionsByElementId = {},
			self = this,
            anchorLists = {},
            jsPlumbInstance = params.jsPlumbInstance,
            jpcl = jsPlumb.CurrentLibrary,
            floatingConnections = {},
            // TODO this functions uses a crude method of determining orientation between two elements.
	       // 'diagonal' should be chosen when the angle of the line between the two centers is around
	       // one of 45, 135, 225 and 315 degrees. maybe +- 15 degrees.
            // used by AnchorManager.redraw
            calculateOrientation = function(sourceId, targetId, sd, td, sourceAnchor, targetAnchor) {
        
                if (sourceId === targetId) return {
                    orientation:Orientation.IDENTITY,
                    a:["top", "top"]
                };
        
                var theta = Math.atan2((td.centery - sd.centery) , (td.centerx - sd.centerx)),
                    theta2 = Math.atan2((sd.centery - td.centery) , (sd.centerx - td.centerx)),
                    h = ((sd.left <= td.left && sd.right >= td.left) || (sd.left <= td.right && sd.right >= td.right) ||
                        (sd.left <= td.left && sd.right >= td.right) || (td.left <= sd.left && td.right >= sd.right)),
                    v = ((sd.top <= td.top && sd.bottom >= td.top) || (sd.top <= td.bottom && sd.bottom >= td.bottom) ||
                        (sd.top <= td.top && sd.bottom >= td.bottom) || (td.top <= sd.top && td.bottom >= sd.bottom)),
                    possiblyTranslateEdges = function(edges) {
                        // this function checks to see if either anchor is Continuous, and if so, runs the suggested edge
                        // through the anchor: Continuous anchors can say which faces they support, and they get to choose 
                        // whether a certain face is honoured, or, if not, which face to replace it with. the behaviour when
                        // choosing an alternate face is to try for the opposite face first, then the next one clockwise, and then
                        // the opposite of that one.
                        return [
                            sourceAnchor.isContinuous ? sourceAnchor.verifyEdge(edges[0]) : edges[0],    
                            targetAnchor.isContinuous ? targetAnchor.verifyEdge(edges[1]) : edges[1]
                        ];
                    },
                    out = {
                        orientation:Orientation.DIAGONAL,
                        theta:theta,
                        theta2:theta2
                    };                        
                
                if (! (h || v)) {                    
                    if (td.left > sd.left && td.top > sd.top)
                        out.a = ["right", "top"];
                    else if (td.left > sd.left && sd.top > td.top)
                        out.a = [ "top", "left"];
                    else if (td.left < sd.left && td.top < sd.top)
                        out.a = [ "top", "right"];
                    else if (td.left < sd.left && td.top > sd.top)
                        out.a = ["left", "top" ];                            
                }
                else if (h) {
                    out.orientation = Orientation.HORIZONTAL;
                    out.a = sd.top < td.top ? ["bottom", "top"] : ["top", "bottom"];                    
                }
                else {
                    out.orientation = Orientation.VERTICAL;
                    out.a = sd.left < td.left ? ["right", "left"] : ["left", "right"];
                }
                
                out.a = possiblyTranslateEdges(out.a);
                return out;
            },
                // used by placeAnchors function
            placeAnchorsOnLine = function(desc, elementDimensions, elementPosition,
                            connections, horizontal, otherMultiplier, reverse) {
                var a = [], step = elementDimensions[horizontal ? 0 : 1] / (connections.length + 1);
        
                for (var i = 0; i < connections.length; i++) {
                    var val = (i + 1) * step, other = otherMultiplier * elementDimensions[horizontal ? 1 : 0];
                    if (reverse)
                      val = elementDimensions[horizontal ? 0 : 1] - val;
        
                    var dx = (horizontal ? val : other), x = elementPosition[0] + dx,  xp = dx / elementDimensions[0],
                        dy = (horizontal ? other : val), y = elementPosition[1] + dy, yp = dy / elementDimensions[1];
        
                    a.push([ x, y, xp, yp, connections[i][1], connections[i][2] ]);
                }
        
                return a;
            },
            // used by edgeSortFunctions        
            currySort = function(reverseAngles) {
                return function(a,b) {
                    var r = true;
                    if (reverseAngles) {
                        /*if (a[0][0] < b[0][0])
                            r = true;
                        else
                            r = a[0][1] > b[0][1];*/
                        r = a[0][0] < b[0][0];
                    }
                    else {
                        /*if (a[0][0] > b[0][0])
                            r= true;
                        else
                            r =a[0][1] > b[0][1];
                        */
                        r = a[0][0] > b[0][0];
                    }
                    return r === false ? -1 : 1;
                };
            },
                // used by edgeSortFunctions
            leftSort = function(a,b) {
                // first get adjusted values
                var p1 = a[0][0] < 0 ? -Math.PI - a[0][0] : Math.PI - a[0][0],
                p2 = b[0][0] < 0 ? -Math.PI - b[0][0] : Math.PI - b[0][0];
                if (p1 > p2) return 1;
                else return a[0][1] > b[0][1] ? 1 : -1;
            },
                // used by placeAnchors
            edgeSortFunctions = {
                "top":function(a, b) { return a[0] > b[0] ? 1 : -1 },
                "right":currySort(true),
                "bottom":currySort(true),
                "left":leftSort
            },
                // used by placeAnchors
            _sortHelper = function(_array, _fn) { return _array.sort(_fn); },
                // used by AnchorManager.redraw
            placeAnchors = function(elementId, _anchorLists) {		
                var cd = jsPlumbInstance.getCachedData(elementId), sS = cd.s, sO = cd.o,
                placeSomeAnchors = function(desc, elementDimensions, elementPosition, unsortedConnections, isHorizontal, otherMultiplier, orientation) {
                    if (unsortedConnections.length > 0) {
                        var sc = _sortHelper(unsortedConnections, edgeSortFunctions[desc]), // puts them in order based on the target element's pos on screen			    
                            reverse = desc === "right" || desc === "top",
                            anchors = placeAnchorsOnLine(desc, elementDimensions,
                                                     elementPosition, sc,
                                                     isHorizontal, otherMultiplier, reverse );
        
                        // takes a computed anchor position and adjusts it for parent offset and scroll, then stores it.
                        var _setAnchorLocation = function(endpoint, anchorPos) {
                            var a = jsPlumbInstance.adjustForParentOffsetAndScroll([anchorPos[0], anchorPos[1]], endpoint.canvas);
                            continuousAnchorLocations[endpoint.id] = [ a[0], a[1], anchorPos[2], anchorPos[3] ];
                            continuousAnchorOrientations[endpoint.id] = orientation;
                        };
        
                        for (var i = 0; i < anchors.length; i++) {
                            var c = anchors[i][4], weAreSource = c.endpoints[0].elementId === elementId, weAreTarget = c.endpoints[1].elementId === elementId;
                            if (weAreSource)
                                _setAnchorLocation(c.endpoints[0], anchors[i]);
                            else if (weAreTarget)
                                _setAnchorLocation(c.endpoints[1], anchors[i]);
                        }
                    }
                };
        
                placeSomeAnchors("bottom", sS, [sO.left,sO.top], _anchorLists.bottom, true, 1, [0,1]);
                placeSomeAnchors("top", sS, [sO.left,sO.top], _anchorLists.top, true, 0, [0,-1]);
                placeSomeAnchors("left", sS, [sO.left,sO.top], _anchorLists.left, false, 0, [-1,0]);
                placeSomeAnchors("right", sS, [sO.left,sO.top], _anchorLists.right, false, 1, [1,0]);
            };

        this.reset = function() {
        	_amEndpoints = {};
        	connectionsByElementId = {};
            anchorLists = {};
        };			
        this.addFloatingConnection = function(key, conn) {
            floatingConnections[key] = conn;
        };
        this.removeFloatingConnection = function(key) {
            delete floatingConnections[key];
        };                                                 
 		this.newConnection = function(conn) {
			var sourceId = conn.sourceId, targetId = conn.targetId,
				ep = conn.endpoints,
                doRegisterTarget = true,
			    registerConnection = function(otherIndex, otherEndpoint, otherAnchor, elId, c) {
					if ((sourceId == targetId) && otherAnchor.isContinuous){
                       // remove the target endpoint's canvas.  we dont need it.
                        jpcl.removeElement(ep[1].canvas);
                        doRegisterTarget = false;
                    }
					jsPlumbUtil.addToList(connectionsByElementId, elId, [c, otherEndpoint, otherAnchor.constructor == jsPlumb.DynamicAnchor]);
			    };

			registerConnection(0, ep[0], ep[0].anchor, targetId, conn);
            if (doRegisterTarget)
            	registerConnection(1, ep[1], ep[1].anchor, sourceId, conn);
		};
        var removeEndpointFromAnchorLists = function(endpoint) {
            (function(list, eId) {
                if (list) {  // transient anchors dont get entries in this list.
                    var f = function(e) { return e[4] == eId; };
                    jsPlumbUtil.removeWithFunction(list["top"], f);
                    jsPlumbUtil.removeWithFunction(list["left"], f);
                    jsPlumbUtil.removeWithFunction(list["bottom"], f);
                    jsPlumbUtil.removeWithFunction(list["right"], f);
                }
            })(anchorLists[endpoint.elementId], endpoint.id);
        };
		this.connectionDetached = function(connInfo) {
            var connection = connInfo.connection || connInfo,
			    sourceId = connInfo.sourceId,
                targetId = connInfo.targetId,
				ep = connection.endpoints,
				removeConnection = function(otherIndex, otherEndpoint, otherAnchor, elId, c) {
					if (otherAnchor.constructor == jsPlumb.FloatingAnchor) {
						// no-op
					}
					else {
						jsPlumbUtil.removeWithFunction(connectionsByElementId[elId], function(_c) {
							return _c[0].id == c.id;
						});
					}
				};
				
			removeConnection(1, ep[1], ep[1].anchor, sourceId, connection);
			removeConnection(0, ep[0], ep[0].anchor, targetId, connection);

            // remove from anchorLists            
            removeEndpointFromAnchorLists(connection.endpoints[0]);
            removeEndpointFromAnchorLists(connection.endpoints[1]);

            self.redraw(connection.sourceId);
            self.redraw(connection.targetId);
		};
		this.add = function(endpoint, elementId) {
			jsPlumbUtil.addToList(_amEndpoints, elementId, endpoint);
		};
		this.changeId = function(oldId, newId) {
			connectionsByElementId[newId] = connectionsByElementId[oldId];
			_amEndpoints[newId] = _amEndpoints[oldId];
			delete connectionsByElementId[oldId];
			delete _amEndpoints[oldId];	
		};
		this.getConnectionsFor = function(elementId) {
			return connectionsByElementId[elementId] || [];
		};
		this.getEndpointsFor = function(elementId) {
			return _amEndpoints[elementId] || [];
		};
		this.deleteEndpoint = function(endpoint) {
			jsPlumbUtil.removeWithFunction(_amEndpoints[endpoint.elementId], function(e) {
				return e.id == endpoint.id;
			});
            removeEndpointFromAnchorLists(endpoint);
		};
		this.clearFor = function(elementId) {
			delete _amEndpoints[elementId];
			_amEndpoints[elementId] = [];
		};
        // updates the given anchor list by either updating an existing anchor's info, or adding it. this function
        // also removes the anchor from its previous list, if the edge it is on has changed.
        // all connections found along the way (those that are connected to one of the faces this function
        // operates on) are added to the connsToPaint list, as are their endpoints. in this way we know to repaint
        // them wthout having to calculate anything else about them.
        var _updateAnchorList = function(lists, theta, order, conn, aBoolean, otherElId, idx, reverse, edgeId, elId, connsToPaint, endpointsToPaint) {        
            // first try to find the exact match, but keep track of the first index of a matching element id along the way.s
            var exactIdx = -1,
                firstMatchingElIdx = -1,
                endpoint = conn.endpoints[idx],
                endpointId = endpoint.id,
                oIdx = [1,0][idx],
                values = [ [ theta, order ], conn, aBoolean, otherElId, endpointId ],
                listToAddTo = lists[edgeId],
                listToRemoveFrom = endpoint._continuousAnchorEdge ? lists[endpoint._continuousAnchorEdge] : null;

            if (listToRemoveFrom) {
                var rIdx = jsPlumbUtil.findWithFunction(listToRemoveFrom, function(e) { return e[4] == endpointId });
                if (rIdx != -1) {
                    listToRemoveFrom.splice(rIdx, 1);
                    // get all connections from this list
                    for (var i = 0; i < listToRemoveFrom.length; i++) {
                        jsPlumbUtil.addWithFunction(connsToPaint, listToRemoveFrom[i][1], function(c) { return c.id == listToRemoveFrom[i][1].id });
                        jsPlumbUtil.addWithFunction(endpointsToPaint, listToRemoveFrom[i][1].endpoints[idx], function(e) { return e.id == listToRemoveFrom[i][1].endpoints[idx].id });
                        jsPlumbUtil.addWithFunction(endpointsToPaint, listToRemoveFrom[i][1].endpoints[oIdx], function(e) { return e.id == listToRemoveFrom[i][1].endpoints[oIdx].id });
                    }
                }
            }

            for (var i = 0; i < listToAddTo.length; i++) {
                if (params.idx == 1 && listToAddTo[i][3] === otherElId && firstMatchingElIdx == -1)
                    firstMatchingElIdx = i;
                jsPlumbUtil.addWithFunction(connsToPaint, listToAddTo[i][1], function(c) { return c.id == listToAddTo[i][1].id });                
                jsPlumbUtil.addWithFunction(endpointsToPaint, listToAddTo[i][1].endpoints[idx], function(e) { return e.id == listToAddTo[i][1].endpoints[idx].id });
                jsPlumbUtil.addWithFunction(endpointsToPaint, listToAddTo[i][1].endpoints[oIdx], function(e) { return e.id == listToAddTo[i][1].endpoints[oIdx].id });
            }
            if (exactIdx != -1) {
                listToAddTo[exactIdx] = values;
            }
            else {
                var insertIdx = reverse ? firstMatchingElIdx != -1 ? firstMatchingElIdx : 0 : listToAddTo.length; // of course we will get this from having looked through the array shortly.
                listToAddTo.splice(insertIdx, 0, values);
            }

            // store this for next time.
            endpoint._continuousAnchorEdge = edgeId;
        };
		this.redraw = function(elementId, ui, timestamp, offsetToUI, clearEdits) {
		
			if (!jsPlumbInstance.isSuspendDrawing()) {
				// get all the endpoints for this element
				var ep = _amEndpoints[elementId] || [],
					endpointConnections = connectionsByElementId[elementId] || [],
					connectionsToPaint = [],
					endpointsToPaint = [],
	                anchorsToUpdate = [];
	            
				timestamp = timestamp || jsPlumbInstance.timestamp();
				// offsetToUI are values that would have been calculated in the dragManager when registering
				// an endpoint for an element that had a parent (somewhere in the hierarchy) that had been
				// registered as draggable.
				offsetToUI = offsetToUI || {left:0, top:0};
				if (ui) {
					ui = {
						left:ui.left + offsetToUI.left,
						top:ui.top + offsetToUI.top
					}
				}
									
				// valid for one paint cycle.
				var myOffset = jsPlumbInstance.updateOffset( { elId : elementId, offset : ui, recalc : false, timestamp : timestamp }),
	                orientationCache = {};
				
				// actually, first we should compute the orientation of this element to all other elements to which
				// this element is connected with a continuous anchor (whether both ends of the connection have
				// a continuous anchor or just one)
	                        
	            for (var i = 0; i < endpointConnections.length; i++) {
	                var conn = endpointConnections[i][0],
						sourceId = conn.sourceId,
	                    targetId = conn.targetId,
	                    sourceContinuous = conn.endpoints[0].anchor.isContinuous,
	                    targetContinuous = conn.endpoints[1].anchor.isContinuous;
	
	                if (sourceContinuous || targetContinuous) {
		                var oKey = sourceId + "_" + targetId,
		                    oKey2 = targetId + "_" + sourceId,
		                    o = orientationCache[oKey],
		                    oIdx = conn.sourceId == elementId ? 1 : 0;
	
		                if (sourceContinuous && !anchorLists[sourceId]) anchorLists[sourceId] = { top:[], right:[], bottom:[], left:[] };
		                if (targetContinuous && !anchorLists[targetId]) anchorLists[targetId] = { top:[], right:[], bottom:[], left:[] };
	
		                if (elementId != targetId) jsPlumbInstance.updateOffset( { elId : targetId, timestamp : timestamp }); 
		                if (elementId != sourceId) jsPlumbInstance.updateOffset( { elId : sourceId, timestamp : timestamp }); 
	
		                var td = jsPlumbInstance.getCachedData(targetId),
							sd = jsPlumbInstance.getCachedData(sourceId);
	
		                if (targetId == sourceId && (sourceContinuous || targetContinuous)) {
		                    // here we may want to improve this by somehow determining the face we'd like
						    // to put the connector on.  ideally, when drawing, the face should be calculated
						    // by determining which face is closest to the point at which the mouse button
							// was released.  for now, we're putting it on the top face.                            
		                    _updateAnchorList(
                                anchorLists[sourceId], 
                                -Math.PI / 2, 
                                0, 
                                conn, 
                                false, 
                                targetId, 
                                0, false, "top", sourceId, connectionsToPaint, endpointsToPaint);
						}
		                else {
		                    if (!o) {
		                        o = calculateOrientation(sourceId, targetId, sd.o, td.o, conn.endpoints[0].anchor, conn.endpoints[1].anchor);
		                        orientationCache[oKey] = o;
		                        // this would be a performance enhancement, but the computed angles need to be clamped to
		                        //the (-PI/2 -> PI/2) range in order for the sorting to work properly.
		                    /*  orientationCache[oKey2] = {
		                            orientation:o.orientation,
		                            a:[o.a[1], o.a[0]],
		                            theta:o.theta + Math.PI,
		                            theta2:o.theta2 + Math.PI
		                        };*/
		                    }
		                    if (sourceContinuous) _updateAnchorList(anchorLists[sourceId], o.theta, 0, conn, false, targetId, 0, false, o.a[0], sourceId, connectionsToPaint, endpointsToPaint);
		                    if (targetContinuous) _updateAnchorList(anchorLists[targetId], o.theta2, -1, conn, true, sourceId, 1, true, o.a[1], targetId, connectionsToPaint, endpointsToPaint);
		                }
	
		                if (sourceContinuous) jsPlumbUtil.addWithFunction(anchorsToUpdate, sourceId, function(a) { return a === sourceId; });
		                if (targetContinuous) jsPlumbUtil.addWithFunction(anchorsToUpdate, targetId, function(a) { return a === targetId; });
		                jsPlumbUtil.addWithFunction(connectionsToPaint, conn, function(c) { return c.id == conn.id; });
		                if ((sourceContinuous && oIdx == 0) || (targetContinuous && oIdx == 1))
		                	jsPlumbUtil.addWithFunction(endpointsToPaint, conn.endpoints[oIdx], function(e) { return e.id == conn.endpoints[oIdx].id; });
		            }
	            }				
				// place Endpoints whose anchors are continuous but have no Connections
				for (var i = 0; i < ep.length; i++) {
					if (ep[i].connections.length == 0 && ep[i].anchor.isContinuous) {
						if (!anchorLists[elementId]) anchorLists[elementId] = { top:[], right:[], bottom:[], left:[] };
						_updateAnchorList(anchorLists[elementId], -Math.PI / 2, 0, {endpoints:[ep[i], ep[i]], paint:function(){}}, false, elementId, 0, false, "top", elementId, connectionsToPaint, endpointsToPaint)
						jsPlumbUtil.addWithFunction(anchorsToUpdate, elementId, function(a) { return a === elementId; })
					}
				}
	            // now place all the continuous anchors we need to;
	            for (var i = 0; i < anchorsToUpdate.length; i++) {
					placeAnchors(anchorsToUpdate[i], anchorLists[anchorsToUpdate[i]]);
				}

				// now that continuous anchors have been placed, paint all the endpoints for this element
	            // TODO performance: add the endpoint ids to a temp array, and then when iterating in the next
	            // loop, check that we didn't just paint that endpoint. we can probably shave off a few more milliseconds this way.
				for (var i = 0; i < ep.length; i++) {				
                    ep[i].paint( { timestamp : timestamp, offset : myOffset, dimensions : myOffset.s });
				}
	            // ... and any other endpoints we came across as a result of the continuous anchors.
	            for (var i = 0; i < endpointsToPaint.length; i++) {
                    var cd = jsPlumbInstance.getCachedData(endpointsToPaint[i].elementId);
                    endpointsToPaint[i].paint( { timestamp : timestamp, offset : cd, dimensions : cd.s });
				}

				// paint all the standard and "dynamic connections", which are connections whose other anchor is
				// static and therefore does need to be recomputed; we make sure that happens only one time.
	
				// TODO we could have compiled a list of these in the first pass through connections; might save some time.
				for (var i = 0; i < endpointConnections.length; i++) {
					var otherEndpoint = endpointConnections[i][1];
					if (otherEndpoint.anchor.constructor == jsPlumb.DynamicAnchor) {			 							
						otherEndpoint.paint({ elementWithPrecedence:elementId });								
	                    jsPlumbUtil.addWithFunction(connectionsToPaint, endpointConnections[i][0], function(c) { return c.id == endpointConnections[i][0].id; });
						// all the connections for the other endpoint now need to be repainted
						for (var k = 0; k < otherEndpoint.connections.length; k++) {
							if (otherEndpoint.connections[k] !== endpointConnections[i][0])							
	                            jsPlumbUtil.addWithFunction(connectionsToPaint, otherEndpoint.connections[k], function(c) { return c.id == otherEndpoint.connections[k].id; });
						}
					} else if (otherEndpoint.anchor.constructor == jsPlumb.Anchor) {					
	                    jsPlumbUtil.addWithFunction(connectionsToPaint, endpointConnections[i][0], function(c) { return c.id == endpointConnections[i][0].id; });
					}
				}
				// paint current floating connection for this element, if there is one.
				var fc = floatingConnections[elementId];
				if (fc) 
					fc.paint({timestamp:timestamp, recalc:false, elId:elementId});
				                
				// paint all the connections
				for (var i = 0; i < connectionsToPaint.length; i++) {
					connectionsToPaint[i].paint({elId:elementId, timestamp:timestamp, recalc:false, clearEdits:clearEdits});
				}
			}
		};
		this.rehomeEndpoint = function(currentId, element) {
			var eps = _amEndpoints[currentId] || [], 
				elementId = jsPlumbInstance.getId(element);
			if (elementId !== currentId) {
				for (var i = 0; i < eps.length; i++) {
					self.add(eps[i], elementId);
				}
				eps.splice(0, eps.length);
			}
		};
        
        var ContinuousAnchor = function(anchorParams) {
            jsPlumbUtil.EventGenerator.apply(this);
            this.type = "Continuous";
            this.isDynamic = true;
            this.isContinuous = true;
            var faces = anchorParams.faces || ["top", "right", "bottom", "left"],
                clockwise = !(anchorParams.clockwise === false),
                availableFaces = { },
                opposites = { "top":"bottom", "right":"left","left":"right","bottom":"top" },
                clockwiseOptions = { "top":"right", "right":"bottom","left":"top","bottom":"left" },
                antiClockwiseOptions = { "top":"left", "right":"top","left":"bottom","bottom":"right" },
                secondBest = clockwise ? clockwiseOptions : antiClockwiseOptions,
                lastChoice = clockwise ? antiClockwiseOptions : clockwiseOptions,
                cssClass = anchorParams.cssClass || "";
            
            for (var i = 0; i < faces.length; i++) { availableFaces[faces[i]] = true; }
          
            // if the given edge is suported, returns it. otherwise looks for a substitute that _is_
            // supported. if none supported we also return the request edge.
            this.verifyEdge = function(edge) {
                if (availableFaces[edge]) return edge;
                else if (availableFaces[opposites[edge]]) return opposites[edge];
                else if (availableFaces[secondBest[edge]]) return secondBest[edge];
                else if (availableFaces[lastChoice[edge]]) return lastChoice[edge];
                return edge; // we have to give them something.
            };
            
            this.compute = function(params) {
                return userDefinedContinuousAnchorLocations[params.element.id] || continuousAnchorLocations[params.element.id] || [0,0];
            };
            this.getCurrentLocation = function(endpoint) {
                return userDefinedContinuousAnchorLocations[endpoint.id] || continuousAnchorLocations[endpoint.id] || [0,0];
            };
            this.getOrientation = function(endpoint) {
                return continuousAnchorOrientations[endpoint.id] || [0,0];
            };
            this.clearUserDefinedLocation = function() { 
                delete userDefinedContinuousAnchorLocations[anchorParams.elementId]; 
            };
            this.setUserDefinedLocation = function(loc) { 
                userDefinedContinuousAnchorLocations[anchorParams.elementId] = loc; 
            };            
            this.getCssClass = function() { return cssClass; };
            this.setCssClass = function(c) { cssClass = c; };
        };        
        
        // continuous anchors
        jsPlumbInstance.continuousAnchorFactory = {
            get:function(params) {
                var existing = continuousAnchors[params.elementId];
                if (!existing) {
                    existing = new ContinuousAnchor(params);                    
                    continuousAnchors[params.elementId] = existing;
                }
                return existing;
            }
        };
	};
    
    /**
     * Anchors model a position on some element at which an Endpoint may be located.  They began as a first class citizen of jsPlumb, ie. a user
     * was required to create these themselves, but over time this has been replaced by the concept of referring to them either by name (eg. "TopMiddle"),
     * or by an array describing their coordinates (eg. [ 0, 0.5, 0, -1 ], which is the same as "TopMiddle").  jsPlumb now handles all of the
     * creation of Anchors without user intervention.
     */
    jsPlumb.Anchor = function(params) {
        var self = this;
        this.x = params.x || 0;
        this.y = params.y || 0;
        this.elementId = params.elementId;        

        jsPlumbUtil.EventGenerator.apply(this);
        
        var orientation = params.orientation || [ 0, 0 ],
            jsPlumbInstance = params.jsPlumbInstance,
            lastTimestamp = null, lastReturnValue = null, userDefinedLocation = null,
            cssClass = params.cssClass || "";

        this.getCssClass = function() { return cssClass; };
        
        this.offsets = params.offsets || [ 0, 0 ];
        self.timestamp = null;        
        this.compute = function(params) {
            
            var xy = params.xy, wh = params.wh, element = params.element, timestamp = params.timestamp;                    
            if(params.clearUserDefinedLocation)
                userDefinedLocation = null;
            
            if (timestamp && timestamp === self.timestamp)
                return lastReturnValue;        
            
            if (userDefinedLocation != null) {
                lastReturnValue = userDefinedLocation;
            }
            else {                
                
                lastReturnValue = [ xy[0] + (self.x * wh[0]) + self.offsets[0], xy[1] + (self.y * wh[1]) + self.offsets[1] ];                    
                // adjust loc if there is an offsetParent
                lastReturnValue = jsPlumbInstance.adjustForParentOffsetAndScroll(lastReturnValue, element.canvas);
            }
            
            self.timestamp = timestamp;
            return lastReturnValue;
        };

        this.getOrientation = function(_endpoint) { return orientation; };

        this.equals = function(anchor) {
            if (!anchor) return false;
            var ao = anchor.getOrientation();
            var o = this.getOrientation();
            return this.x == anchor.x && this.y == anchor.y
                    && this.offsets[0] == anchor.offsets[0]
                    && this.offsets[1] == anchor.offsets[1]
                    && o[0] == ao[0] && o[1] == ao[1];
        };

        this.getCurrentLocation = function() { return lastReturnValue; };
        
        this.getUserDefinedLocation = function() { 
            return userDefinedLocation;
        };
        
        this.setUserDefinedLocation = function(l) {
            userDefinedLocation = l;
        };
        this.clearUserDefinedLocation = function() {
            userDefinedLocation = null;
        };
    };

    /**
     * An Anchor that floats. its orientation is computed dynamically from
     * its position relative to the anchor it is floating relative to.  It is used when creating 
     * a connection through drag and drop.
     * 
     * TODO FloatingAnchor could totally be refactored to extend Anchor just slightly.
     */
    jsPlumb.FloatingAnchor = function(params) {
        
        jsPlumb.Anchor.apply(this, arguments);

        // this is the anchor that this floating anchor is referenced to for
        // purposes of calculating the orientation.
        var ref = params.reference,
            jpcl = jsPlumb.CurrentLibrary,
            jsPlumbInstance = params.jsPlumbInstance,
            // the canvas this refers to.
            refCanvas = params.referenceCanvas,
            size = jpcl.getSize(jpcl.getElementObject(refCanvas)),                

        // these are used to store the current relative position of our
        // anchor wrt the reference anchor. they only indicate
        // direction, so have a value of 1 or -1 (or, very rarely, 0). these
        // values are written by the compute method, and read
        // by the getOrientation method.
        xDir = 0, yDir = 0,
        // temporary member used to store an orientation when the floating
        // anchor is hovering over another anchor.
        orientation = null,
        _lastResult = null;

        // set these to 0 each; they are used by certain types of connectors in the loopback case,
        // when the connector is trying to clear the element it is on. but for floating anchor it's not
        // very important.
        this.x = 0; this.y = 0;

        this.isFloating = true;

        this.compute = function(params) {
            var xy = params.xy, element = params.element,
            result = [ xy[0] + (size[0] / 2), xy[1] + (size[1] / 2) ]; // return origin of the element. we may wish to improve this so that any object can be the drag proxy.
                        
            // adjust loc if there is an offsetParent
            result = jsPlumbInstance.adjustForParentOffsetAndScroll(result, element.canvas);
            
            _lastResult = result;
            return result;
        };

        this.getOrientation = function(_endpoint) {
            if (orientation) return orientation;
            else {
                var o = ref.getOrientation(_endpoint);
                // here we take into account the orientation of the other
                // anchor: if it declares zero for some direction, we declare zero too. this might not be the most awesome. perhaps we can come
                // up with a better way. it's just so that the line we draw looks like it makes sense. maybe this wont make sense.
                return [ Math.abs(o[0]) * xDir * -1,
                        Math.abs(o[1]) * yDir * -1 ];
            }
        };

        /**
         * notification the endpoint associated with this anchor is hovering
         * over another anchor; we want to assume that anchor's orientation
         * for the duration of the hover.
         */
        this.over = function(anchor) { 
            orientation = anchor.getOrientation(); 
        };

        /**
         * notification the endpoint associated with this anchor is no
         * longer hovering over another anchor; we should resume calculating
         * orientation as we normally do.
         */
        this.out = function() { orientation = null; };

        this.getCurrentLocation = function() { return _lastResult; };
    };

    /* 
     * A DynamicAnchor is an Anchor that contains a list of other Anchors, which it cycles
     * through at compute time to find the one that is located closest to
     * the center of the target element, and returns that Anchor's compute
     * method result. this causes endpoints to follow each other with
     * respect to the orientation of their target elements, which is a useful
     * feature for some applications.
     * 
     */
    jsPlumb.DynamicAnchor = function(params) {
        jsPlumb.Anchor.apply(this, arguments);
        
        this.isSelective = true;
        this.isDynamic = true;			
        var _anchors = [], self = this,            
            _convert = function(anchor) { 
                return anchor.constructor == jsPlumb.Anchor ? anchor: params.jsPlumbInstance.makeAnchor(anchor, params.elementId, params.jsPlumbInstance); 
            };

        for (var i = 0; i < params.anchors.length; i++) 
            _anchors[i] = _convert(params.anchors[i]);			
        this.addAnchor = function(anchor) { _anchors.push(_convert(anchor)); };
        this.getAnchors = function() { return _anchors; };
        this.locked = false;
        var _curAnchor = _anchors.length > 0 ? _anchors[0] : null,
            _curIndex = _anchors.length > 0 ? 0 : -1,
            _lastAnchor = _curAnchor,
            self = this,
        
            // helper method to calculate the distance between the centers of the two elements.
            _distance = function(anchor, cx, cy, xy, wh) {
                var ax = xy[0] + (anchor.x * wh[0]), ay = xy[1] + (anchor.y * wh[1]),				
                    acx = xy[0] + (wh[0] / 2), acy = xy[1] + (wh[1] / 2);
                return (Math.sqrt(Math.pow(cx - ax, 2) + Math.pow(cy - ay, 2)) +
                        Math.sqrt(Math.pow(acx - ax, 2) + Math.pow(acy - ay, 2)));
            },        
            // default method uses distance between element centers.  you can provide your own method in the dynamic anchor
            // constructor (and also to jsPlumb.makeDynamicAnchor). the arguments to it are four arrays: 
            // xy - xy loc of the anchor's element
            // wh - anchor's element's dimensions
            // txy - xy loc of the element of the other anchor in the connection
            // twh - dimensions of the element of the other anchor in the connection.
            // anchors - the list of selectable anchors
            _anchorSelector = params.selector || function(xy, wh, txy, twh, anchors) {
                var cx = txy[0] + (twh[0] / 2), cy = txy[1] + (twh[1] / 2);
                var minIdx = -1, minDist = Infinity;
                for ( var i = 0; i < anchors.length; i++) {
                    var d = _distance(anchors[i], cx, cy, xy, wh);
                    if (d < minDist) {
                        minIdx = i + 0;
                        minDist = d;
                    }
                }
                return anchors[minIdx];
            };
        
        this.compute = function(params) {				
            var xy = params.xy, wh = params.wh, timestamp = params.timestamp, txy = params.txy, twh = params.twh;				
            
            if(params.clearUserDefinedLocation)
                userDefinedLocation = null;
            
            var udl = self.getUserDefinedLocation();
            if (udl != null) {
                return udl;
            }
            
            // if anchor is locked or an opposite element was not given, we
            // maintain our state. anchor will be locked
            // if it is the source of a drag and drop.
            if (self.locked || txy == null || twh == null)
                return _curAnchor.compute(params);				
            else
                params.timestamp = null; // otherwise clear this, i think. we want the anchor to compute.
            
            _curAnchor = _anchorSelector(xy, wh, txy, twh, _anchors);
            self.x = _curAnchor.x;
            self.y = _curAnchor.y;        

            if (_curAnchor != _lastAnchor)
                self.fire("anchorChanged", _curAnchor);

            _lastAnchor = _curAnchor;
            
            return _curAnchor.compute(params);
        };

        this.getCurrentLocation = function() {
            return self.getUserDefinedLocation() || (_curAnchor != null ? _curAnchor.getCurrentLocation() : null);
        };

        this.getOrientation = function(_endpoint) { return _curAnchor != null ? _curAnchor.getOrientation(_endpoint) : [ 0, 0 ]; };
        this.over = function(anchor) { if (_curAnchor != null) _curAnchor.over(anchor); };
        this.out = function() { if (_curAnchor != null) _curAnchor.out(); };

        this.getCssClass = function() { return (_curAnchor && _curAnchor.getCssClass()) || ""; };
    };            
    
// -------- basic anchors ------------------    
    var _curryAnchor = function(x, y, ox, oy, type, fnInit) {
        jsPlumb.Anchors[type] = function(params) {
            var a = params.jsPlumbInstance.makeAnchor([ x, y, ox, oy, 0, 0 ], params.elementId, params.jsPlumbInstance);
            a.type = type;
            if (fnInit) fnInit(a, params);
            return a;
        };
    };
    	
	_curryAnchor(0.5, 0, 0,-1, "TopCenter");
    _curryAnchor(0.5, 1, 0, 1, "BottomCenter");
    _curryAnchor(0, 0.5, -1, 0, "LeftMiddle");
    _curryAnchor(1, 0.5, 1, 0, "RightMiddle");
    // from 1.4.1: Top, Right, Bottom, Left
    _curryAnchor(0.5, 0, 0,-1, "Top");
    _curryAnchor(0.5, 1, 0, 1, "Bottom");
    _curryAnchor(0, 0.5, -1, 0, "Left");
    _curryAnchor(1, 0.5, 1, 0, "Right");
    _curryAnchor(0.5, 0.5, 0, 0, "Center");
    _curryAnchor(1, 0, 0,-1, "TopRight");
    _curryAnchor(1, 1, 0, 1, "BottomRight");
    _curryAnchor(0, 0, 0, -1, "TopLeft");
    _curryAnchor(0, 1, 0, 1, "BottomLeft");
    
// ------- dynamic anchors -------------------    
			
    // default dynamic anchors chooses from Top, Right, Bottom, Left
	jsPlumb.Defaults.DynamicAnchors = function(params) {
		return params.jsPlumbInstance.makeAnchors(["TopCenter", "RightMiddle", "BottomCenter", "LeftMiddle"], params.elementId, params.jsPlumbInstance);
	};
    
    // default dynamic anchors bound to name 'AutoDefault'
	jsPlumb.Anchors["AutoDefault"]  = function(params) { 
		var a = params.jsPlumbInstance.makeDynamicAnchor(jsPlumb.Defaults.DynamicAnchors(params));
		a.type = "AutoDefault";
		return a;
	};	
    
// ------- continuous anchors -------------------    
    
    var _curryContinuousAnchor = function(type, faces) {
        jsPlumb.Anchors[type] = function(params) {
            var a = params.jsPlumbInstance.makeAnchor(["Continuous", { faces:faces }], params.elementId, params.jsPlumbInstance);
            a.type = type;
            return a;
        };
    };
    
    jsPlumb.Anchors["Continuous"] = function(params) {
		return params.jsPlumbInstance.continuousAnchorFactory.get(params);
	};
                
    _curryContinuousAnchor("ContinuousLeft", ["left"]);    
    _curryContinuousAnchor("ContinuousTop", ["top"]);                 
    _curryContinuousAnchor("ContinuousBottom", ["bottom"]);                 
    _curryContinuousAnchor("ContinuousRight", ["right"]); 
    
// ------- position assign anchors -------------------    
    
    // this anchor type lets you assign the position at connection time.
	jsPlumb.Anchors["Assign"] = _curryAnchor(0, 0, 0, 0, "Assign", function(anchor, params) {
		// find what to use as the "position finder". the user may have supplied a String which represents
		// the id of a position finder in jsPlumb.AnchorPositionFinders, or the user may have supplied the
		// position finder as a function.  we find out what to use and then set it on the anchor.
		var pf = params.position || "Fixed";
		anchor.positionFinder = pf.constructor == String ? params.jsPlumbInstance.AnchorPositionFinders[pf] : pf;
		// always set the constructor params; the position finder might need them later (the Grid one does,
		// for example)
		anchor.constructorParams = params;
	});	

    // these are the default anchor positions finders, which are used by the makeTarget function.  supplying
    // a position finder argument to that function allows you to specify where the resulting anchor will
    // be located
	jsPlumb.AnchorPositionFinders = {
		"Fixed": function(dp, ep, es, params) {
			return [ (dp.left - ep.left) / es[0], (dp.top - ep.top) / es[1] ];	
		},
		"Grid":function(dp, ep, es, params) {
			var dx = dp.left - ep.left, dy = dp.top - ep.top,
				gx = es[0] / (params.grid[0]), gy = es[1] / (params.grid[1]),
				mx = Math.floor(dx / gx), my = Math.floor(dy / gy);
			return [ ((mx * gx) + (gx / 2)) / es[0], ((my * gy) + (gy / 2)) / es[1] ];
		}
	};
    
// ------- perimeter anchors -------------------    
		
	jsPlumb.Anchors["Perimeter"] = function(params) {
		params = params || {};
		var anchorCount = params.anchorCount || 60,
			shape = params.shape;
		
		if (!shape) throw new Error("no shape supplied to Perimeter Anchor type");		
		
		var _circle = function() {
                var r = 0.5, step = Math.PI * 2 / anchorCount, current = 0, a = [];
                for (var i = 0; i < anchorCount; i++) {
                    var x = r + (r * Math.sin(current)),
                        y = r + (r * Math.cos(current));                                
                    a.push( [ x, y, 0, 0 ] );
                    current += step;
                }
                return a;	
            },
            _path = function(segments) {
                var anchorsPerFace = anchorCount / segments.length, a = [],
                    _computeFace = function(x1, y1, x2, y2, fractionalLength) {
                        anchorsPerFace = anchorCount * fractionalLength;
                        var dx = (x2 - x1) / anchorsPerFace, dy = (y2 - y1) / anchorsPerFace;
                        for (var i = 0; i < anchorsPerFace; i++) {
                            a.push( [
                                x1 + (dx * i),
                                y1 + (dy * i),
                                0,
                                0
                            ]);
                        }
                    };
								
                for (var i = 0; i < segments.length; i++)
                    _computeFace.apply(null, segments[i]);
														
                return a;					
            },
			_shape = function(faces) {												
                var s = [];
                for (var i = 0; i < faces.length; i++) {
                    s.push([faces[i][0], faces[i][1], faces[i][2], faces[i][3], 1 / faces.length]);
                }
                return _path(s);
			},
			_rectangle = function() {
				return _shape([
					[ 0, 0, 1, 0 ], [ 1, 0, 1, 1 ], [ 1, 1, 0, 1 ], [ 0, 1, 0, 0 ]
				]);		
			};
		
		var _shapes = {
			"Circle":_circle,
			"Ellipse":_circle,
			"Diamond":function() {
				return _shape([
						[ 0.5, 0, 1, 0.5 ], [ 1, 0.5, 0.5, 1 ], [ 0.5, 1, 0, 0.5 ], [ 0, 0.5, 0.5, 0 ]
				]);
			},
			"Rectangle":_rectangle,
			"Square":_rectangle,
			"Triangle":function() {
				return _shape([
						[ 0.5, 0, 1, 1 ], [ 1, 1, 0, 1 ], [ 0, 1, 0.5, 0]
				]);	
			},
			"Path":function(params) {
                var points = params.points, p = [], tl = 0;
				for (var i = 0; i < points.length - 1; i++) {
                    var l = Math.sqrt(Math.pow(points[i][2] - points[i][0]) + Math.pow(points[i][3] - points[i][1]));
                    tl += l;
					p.push([points[i][0], points[i][1], points[i+1][0], points[i+1][1], l]);						
				}
                for (var i = 0; i < p.length; i++) {
                    p[i][4] = p[i][4] / tl;
                }
				return _path(p);
			}
		},
        _rotate = function(points, amountInDegrees) {
            var o = [], theta = amountInDegrees / 180 * Math.PI ;
            for (var i = 0; i < points.length; i++) {
                var _x = points[i][0] - 0.5,
                    _y = points[i][1] - 0.5;
                    
                o.push([
                    0.5 + ((_x * Math.cos(theta)) - (_y * Math.sin(theta))),
                    0.5 + ((_x * Math.sin(theta)) + (_y * Math.cos(theta))),
                    points[i][2],
                    points[i][3]
                ]);
            }
            return o;
        };
		
		if (!_shapes[shape]) throw new Error("Shape [" + shape + "] is unknown by Perimeter Anchor type");
		
		var da = _shapes[shape](params);
        if (params.rotation) da = _rotate(da, params.rotation);
        var a = params.jsPlumbInstance.makeDynamicAnchor(da);
		a.type = "Perimeter";
		return a;
	};
})();