//This code is 100% based on https://github.com/jawj/OverlappingMarkerSpiderfier-Leaflet
//Huge thanks to jawj for implementing it first to make my job easy :-)

L.MarkerCluster.include({

	_2PI: Math.PI * 2,
	_circleFootSeparation: 25, //related to circumference of circle
	_circleStartAngle: Math.PI / 6,

	_spiralFootSeparation:  28, //related to size of spiral (experiment!)
	_spiralLengthStart: 11,
	_spiralLengthFactor: 5,

	_circleSpiralSwitchover: 9, //show spiral instead of circle from this marker count upwards.
								// 0 -> always spiral; Infinity -> always circle

	spiderfy: function () {
		if (this._group._spiderfied === this || this._group._inZoomAnimation) {
			return;
		}

		var childMarkers = this.getAllChildMarkers(),
			group = this._group,
			map = group._map,
			center = map.latLngToLayerPoint(this._latlng),
			positions;

		this._group._unspiderfy();
		this._group._spiderfied = this;

		//TODO Maybe: childMarkers order by distance to center

		if (childMarkers.length >= this._circleSpiralSwitchover) {
			positions = this._generatePointsSpiral(childMarkers.length, center);
		} else {
			center.y += 10; //Otherwise circles look wrong
			positions = this._generatePointsCircle(childMarkers.length, center);
		}

		this._animationSpiderfy(childMarkers, positions);
	},

	unspiderfy: function (zoomDetails) {
		/// <param Name="zoomDetails">Argument from zoomanim if being called in a zoom animation or null otherwise</param>
		if (this._group._inZoomAnimation) {
			return;
		}
		this._animationUnspiderfy(zoomDetails);

		this._group._spiderfied = null;
	},

	_generatePointsCircle: function (count, centerPt) {
		var circumference = this._group.options.spiderfyDistanceMultiplier * this._circleFootSeparation * (2 + count),
			legLength = circumference / this._2PI,  //radius from circumference
			angleStep = this._2PI / count,
			res = [],
			i, angle;

		res.length = count;

		for (i = count - 1; i >= 0; i--) {
			angle = this._circleStartAngle + i * angleStep;
			res[i] = new L.Point(centerPt.x + legLength * Math.cos(angle), centerPt.y + legLength * Math.sin(angle))._round();
		}

		return res;
	},

	_generatePointsSpiral: function (count, centerPt) {
		var legLength = this._group.options.spiderfyDistanceMultiplier * this._spiralLengthStart,
			separation = this._group.options.spiderfyDistanceMultiplier * this._spiralFootSeparation,
			lengthFactor = this._group.options.spiderfyDistanceMultiplier * this._spiralLengthFactor,
			angle = 0,
			res = [],
			i;

		res.length = count;

		for (i = count - 1; i >= 0; i--) {
			angle += separation / legLength + i * 0.0005;
			res[i] = new L.Point(centerPt.x + legLength * Math.cos(angle), centerPt.y + legLength * Math.sin(angle))._round();
			legLength += this._2PI * lengthFactor / angle;
		}
		return res;
	},

	_noanimationUnspiderfy: function () {
		var group = this._group,
			map = group._map,
			fg = group._featureGroup,
			childMarkers = this.getAllChildMarkers(),
			m, i;

		this.setOpacity(1);
		for (i = childMarkers.length - 1; i >= 0; i--) {
			m = childMarkers[i];

			fg.removeLayer(m);

			if (m._preSpiderfyLatlng) {
				m.setLatLng(m._preSpiderfyLatlng);
				delete m._preSpiderfyLatlng;
			}
			if (m.setZIndexOffset) {
				m.setZIndexOffset(0);
			}

			if (m._spiderLeg) {
				map.removeLayer(m._spiderLeg);
				delete m._spiderLeg;
			}
		}

		group._spiderfied = null;
	}
});

L.MarkerCluster.include(!L.DomUtil.TRANSITION ? {
	//Non Animated versions of everything
	_animationSpiderfy: function (childMarkers, positions) {
		var group = this._group,
			map = group._map,
			fg = group._featureGroup,
			i, m, leg, newPos;

		for (i = childMarkers.length - 1; i >= 0; i--) {
			newPos = map.layerPointToLatLng(positions[i]);
			m = childMarkers[i];

			m._preSpiderfyLatlng = m._latlng;
			m.setLatLng(newPos);
			if (m.setZIndexOffset) {
				m.setZIndexOffset(1000000); //Make these appear on top of EVERYTHING
			}

			fg.addLayer(m);

			var legOptions = this._group.options.spiderLegPolylineOptions;
			leg = new L.Polyline([this._latlng, newPos], legOptions);
			map.addLayer(leg);
			m._spiderLeg = leg;
		}
		this.setOpacity(0.3);
		group.fire('spiderfied');
	},

	_animationUnspiderfy: function () {
		this._noanimationUnspiderfy();
	}
} : {
	//Animated versions here
	SVG_ANIMATION: (function () {
		return document.createElementNS('http://www.w3.org/2000/svg', 'animate').toString().indexOf('SVGAnimate') > -1;
	}()),

	_animationSpiderfy: function (childMarkers, positions) {
		var me = this,
			group = this._group,
			map = group._map,
			fg = group._featureGroup,
			thisLayerPos = map.latLngToLayerPoint(this._latlng),
			i, m, leg, newPos;

		//Add markers to map hidden at our center point
		for (i = childMarkers.length - 1; i >= 0; i--) {
			m = childMarkers[i];

			//If it is a marker, add it now and we'll animate it out
			if (m.setOpacity) {
				m.setZIndexOffset(1000000); //Make these appear on top of EVERYTHING
				m.clusterHide();
			
				fg.addLayer(m);

				m._setPos(thisLayerPos);
			} else {
				//Vectors just get immediately added
				fg.addLayer(m);
			}
		}

		group._forceLayout();
		group._animationStart();

		var initialLegOpacity = L.Path.SVG ? 0 : 0.3,
			xmlns = L.Path.SVG_NS;


		for (i = childMarkers.length - 1; i >= 0; i--) {
			newPos = map.layerPointToLatLng(positions[i]);
			m = childMarkers[i];

			//Move marker to new position
			m._preSpiderfyLatlng = m._latlng;
			m.setLatLng(newPos);
			
			if (m.setOpacity) {
				m.clusterShow();
			}


			//Add Legs.
			var legOptions = this._group.options.spiderLegPolylineOptions;
			if (legOptions.opacity === undefined) {
				legOptions.opacity = initialLegOpacity;
			}
			leg = new L.Polyline([me._latlng, newPos], legOptions);
			map.addLayer(leg);
			m._spiderLeg = leg;

			//Following animations don't work for canvas
			if (!L.Path.SVG || !this.SVG_ANIMATION) {
				continue;
			}

			//How this works:
			//http://stackoverflow.com/questions/5924238/how-do-you-animate-an-svg-path-in-ios
			//http://dev.opera.com/articles/view/advanced-svg-animation-techniques/

			//Animate length
			var length = leg._path.getTotalLength();
			leg._path.setAttribute("stroke-dasharray", length + "," + length);

			var anim = document.createElementNS(xmlns, "animate");
			anim.setAttribute("attributeName", "stroke-dashoffset");
			anim.setAttribute("begin", "indefinite");
			anim.setAttribute("from", length);
			anim.setAttribute("to", 0);
			anim.setAttribute("dur", 0.25);
			leg._path.appendChild(anim);
			anim.beginElement();

			//Animate opacity
			anim = document.createElementNS(xmlns, "animate");
			anim.setAttribute("attributeName", "stroke-opacity");
			anim.setAttribute("attributeName", "stroke-opacity");
			anim.setAttribute("begin", "indefinite");
			anim.setAttribute("from", 0);
			anim.setAttribute("to", 0.5);
			anim.setAttribute("dur", 0.25);
			leg._path.appendChild(anim);
			anim.beginElement();
		}
		me.setOpacity(0.3);

		//Set the opacity of the spiderLegs back to their correct value
		// The animations above override this until they complete.
		// If the initial opacity of the spiderlegs isn't 0 then they appear before the animation starts.
		if (L.Path.SVG) {
			this._group._forceLayout();

			for (i = childMarkers.length - 1; i >= 0; i--) {
				m = childMarkers[i]._spiderLeg;

				m.options.opacity = 0.5;
				m._path.setAttribute('stroke-opacity', 0.5);
			}
		}

		setTimeout(function () {
			group._animationEnd();
			group.fire('spiderfied');
		}, 200);
	},

	_animationUnspiderfy: function (zoomDetails) {
		var group = this._group,
			map = group._map,
			fg = group._featureGroup,
			thisLayerPos = zoomDetails ? map._latLngToNewLayerPoint(this._latlng, zoomDetails.zoom, zoomDetails.center) : map.latLngToLayerPoint(this._latlng),
			childMarkers = this.getAllChildMarkers(),
			svg = L.Path.SVG && this.SVG_ANIMATION,
			m, i, a;

		group._animationStart();

		//Make us visible and bring the child markers back in
		this.setOpacity(1);
		for (i = childMarkers.length - 1; i >= 0; i--) {
			m = childMarkers[i];

			//Marker was added to us after we were spidified
			if (!m._preSpiderfyLatlng) {
				continue;
			}

			//Fix up the location to the real one
			m.setLatLng(m._preSpiderfyLatlng);
			delete m._preSpiderfyLatlng;
			//Hack override the location to be our center
			if (m.setOpacity) {
				m._setPos(thisLayerPos);
				m.clusterHide();
			} else {
				fg.removeLayer(m);
			}

			//Animate the spider legs back in
			if (svg) {
				a = m._spiderLeg._path.childNodes[0];
				a.setAttribute('to', a.getAttribute('from'));
				a.setAttribute('from', 0);
				a.beginElement();

				a = m._spiderLeg._path.childNodes[1];
				a.setAttribute('from', 0.5);
				a.setAttribute('to', 0);
				a.setAttribute('stroke-opacity', 0);
				a.beginElement();

				m._spiderLeg._path.setAttribute('stroke-opacity', 0);
			}
		}

		setTimeout(function () {
			//If we have only <= one child left then that marker will be shown on the map so don't remove it!
			var stillThereChildCount = 0;
			for (i = childMarkers.length - 1; i >= 0; i--) {
				m = childMarkers[i];
				if (m._spiderLeg) {
					stillThereChildCount++;
				}
			}


			for (i = childMarkers.length - 1; i >= 0; i--) {
				m = childMarkers[i];

				if (!m._spiderLeg) { //Has already been unspiderfied
					continue;
				}


				if (m.setOpacity) {
					m.clusterShow();
					m.setZIndexOffset(0);
				}

				if (stillThereChildCount > 1) {
					fg.removeLayer(m);
				}

				map.removeLayer(m._spiderLeg);
				delete m._spiderLeg;
			}
			group._animationEnd();
		}, 200);
	}
});


L.MarkerClusterGroup.include({
	//The MarkerCluster currently spiderfied (if any)
	_spiderfied: null,

	_spiderfierOnAdd: function () {
		this._map.on('click', this._unspiderfyWrapper, this);

		if (this._map.options.zoomAnimation) {
			this._map.on('zoomstart', this._unspiderfyZoomStart, this);
		}
		//Browsers without zoomAnimation or a big zoom don't fire zoomstart
		this._map.on('zoomend', this._noanimationUnspiderfy, this);

		if (L.Path.SVG && !L.Browser.touch) {
			this._map._initPathRoot();
			//Needs to happen in the pageload, not after, or animations don't work in webkit
			//  http://stackoverflow.com/questions/8455200/svg-animate-with-dynamically-added-elements
			//Disable on touch browsers as the animation messes up on a touch zoom and isn't very noticable
		}
	},

	_spiderfierOnRemove: function () {
		this._map.off('click', this._unspiderfyWrapper, this);
		this._map.off('zoomstart', this._unspiderfyZoomStart, this);
		this._map.off('zoomanim', this._unspiderfyZoomAnim, this);

		this._unspiderfy(); //Ensure that markers are back where they should be
	},


	//On zoom start we add a zoomanim handler so that we are guaranteed to be last (after markers are animated)
	//This means we can define the animation they do rather than Markers doing an animation to their actual location
	_unspiderfyZoomStart: function () {
		if (!this._map) { //May have been removed from the map by a zoomEnd handler
			return;
		}

		this._map.on('zoomanim', this._unspiderfyZoomAnim, this);
	},
	_unspiderfyZoomAnim: function (zoomDetails) {
		//Wait until the first zoomanim after the user has finished touch-zooming before running the animation
		if (L.DomUtil.hasClass(this._map._mapPane, 'leaflet-touching')) {
			return;
		}

		this._map.off('zoomanim', this._unspiderfyZoomAnim, this);
		this._unspiderfy(zoomDetails);
	},


	_unspiderfyWrapper: function () {
		/// <summary>_unspiderfy but passes no arguments</summary>
		this._unspiderfy();
	},

	_unspiderfy: function (zoomDetails) {
		if (this._spiderfied) {
			this._spiderfied.unspiderfy(zoomDetails);
		}
	},

	_noanimationUnspiderfy: function () {
		if (this._spiderfied) {
			this._spiderfied._noanimationUnspiderfy();
		}
	},

	//If the given layer is currently being spiderfied then we unspiderfy it so it isn't on the map anymore etc
	_unspiderfyLayer: function (layer) {
		if (layer._spiderLeg) {
			this._featureGroup.removeLayer(layer);

			layer.setOpacity(1);
			//Position will be fixed up immediately in _animationUnspiderfy
			layer.setZIndexOffset(0);

			this._map.removeLayer(layer._spiderLeg);
			delete layer._spiderLeg;
		}
	}
});