/* Copyright (c) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 *
 * Author: Doug Ricket, others
 *
 * Marker manager is an interface between the map and the user, designed
 * to manage adding and removing many points when the viewport changes.
 *
 *
 * Algorithm: The MM places its markers onto a grid, similar to the map tiles.
 * When the user moves the viewport, the MM computes which grid cells have
 * entered or left the viewport, and shows or hides all the markers in those
 * cells.
 * (If the users scrolls the viewport beyond the markers that are loaded,
 * no markers will be visible until the EVENT_moveend triggers an update.)
 *
 * In practical consequences, this allows 10,000 markers to be distributed over
 * a large area, and as long as only 100-200 are visible in any given viewport,
 * the user will see good performance corresponding to the 100 visible markers,
 * rather than poor performance corresponding to the total 10,000 markers.
 *
 * Note that some code is optimized for speed over space,
 * with the goal of accommodating thousands of markers.
 *
 */
/**
 * Creates a new MarkerManager that will show/hide markers on a map.
 *
 * @constructor
 * @param {Map} map The map to manage.
 * @param {Object} opt_opts A container for optional arguments:
 * {Number} maxZoom The maximum zoom level for which to create tiles.
 * {Number} borderPadding The width in pixels beyond the map border, where markers should be display.
 * {Boolean} trackMarkers Whether or not this manager should track marker movements.
 */
function MarkerManager(map, opt_opts) {
	var me = this;
	me.map_ = map;
	me.mapZoom_ = map.getZoom();
	me.projection_ = map.getCurrentMapType().getProjection();
	opt_opts = opt_opts || {};
	me.tileSize_ = MarkerManager.DEFAULT_TILE_SIZE_;
	var maxZoom = MarkerManager.DEFAULT_MAX_ZOOM_;
	if(opt_opts.maxZoom != undefined) {
		maxZoom = opt_opts.maxZoom;
	}
	me.maxZoom_ = maxZoom;
	me.trackMarkers_ = opt_opts.trackMarkers;
	var padding;
	if (typeof opt_opts.borderPadding == "number") {
		padding = opt_opts.borderPadding;
	} else {
		padding = MarkerManager.DEFAULT_BORDER_PADDING_;
	}
	me.swPadding_ = new GSize(-padding, padding);
	me.nePadding_ = new GSize(padding, -padding);
	me.borderPadding_ = padding;
	me.gridWidth_ = [];
	me.grid_ = [];
	me.grid_[maxZoom] = [];
	me.numMarkers_ = [];
	me.numMarkers_[maxZoom] = 0;
	GEvent.bind(map, "moveend", me, me.onMapMoveEnd_);
	me.removeOverlay_ = function(marker) {
		if (!marker.isInfoWindowOpened) {
			map.removeOverlay(marker);
			me.shownMarkers_--;
		}
	};
	me.addOverlay_ = function(marker) {
		if (!marker.isInfoWindowOpened) {
			marker.isInfoWindowOpened = false;
			map.addOverlay(marker);
			me.shownMarkers_++;
		}
	};
	me.resetManager_();
	me.shownMarkers_ = 0;
	me.shownBounds_ = me.getMapGridBounds_();
};
MarkerManager.DEFAULT_TILE_SIZE_ = 1024;
MarkerManager.DEFAULT_MAX_ZOOM_ = 17;
MarkerManager.DEFAULT_BORDER_PADDING_ = 100;
MarkerManager.MERCATOR_ZOOM_LEVEL_ZERO_RANGE = 256;
/**
 * Initializes MarkerManager arrays for all zoom levels
 * Called by constructor and by clearAllMarkers
 */
MarkerManager.prototype.resetManager_ = function() {
	var me = this;
	var mapWidth = MarkerManager.MERCATOR_ZOOM_LEVEL_ZERO_RANGE;
	for (var zoom = 0; zoom <= me.maxZoom_; ++zoom) {
		me.grid_[zoom] = [];
		me.numMarkers_[zoom] = 0;
		me.gridWidth_[zoom] = Math.ceil(mapWidth/me.tileSize_);
		mapWidth <<= 1;
	}
};
/**
 * Removes all currently displayed markers
 * and calls resetManager to clear arrays
 */
MarkerManager.prototype.clearMarkers = function() {
	var me = this;
	me.processAll_(me.shownBounds_, me.removeOverlay_);
	me.resetManager_();
};
/**
 * Gets the tile coordinate for a given latlng point.
 *
 * @param {LatLng} latlng The geographical point.
 * @param {Number} zoom The zoom level.
 * @param {GSize} padding The padding used to shift the pixel coordinate. Used for expanding a bounds to include an extra padding of pixels surrounding the bounds.
 * @return {GPoint} The point in tile coordinates.
 *
 */
MarkerManager.prototype.getTilePoint_ = function(latlng, zoom, padding) {
	var pixelPoint = this.projection_.fromLatLngToPixel(latlng, zoom);
	return new GPoint(
			Math.floor((pixelPoint.x + padding.width) / this.tileSize_),
			Math.floor((pixelPoint.y + padding.height) / this.tileSize_));
};
/**
 * Finds the appropriate place to add the marker to the grid.
 * Optimized for speed; does not actually add the marker to the map.
 * Designed for batch-processing thousands of markers.
 *
 * @param {Marker} marker The marker to add.
 * @param {Number} minZoom The minimum zoom for displaying the marker.
 * @param {Number} maxZoom The maximum zoom for displaying the marker.
 */
MarkerManager.prototype.addMarkerBatch_ = function(marker, minZoom, maxZoom) {
	var mPoint = marker.getPoint();
	if (this.trackMarkers_) {
		GEvent.bind(marker, "changed", this, this.onMarkerMoved_);
	}
	GEvent.addListener(marker, "infowindowopen", function() {
		marker.isInfoWindowOpened = true;
	});
	GEvent.addListener(marker, "infowindowclose", function() {
		marker.isInfoWindowOpened = false;
	});
	var gridPoint = this.getTilePoint_(mPoint, maxZoom, GSize.ZERO);
	for (var zoom = maxZoom; zoom >= minZoom; zoom--) {
		var cell = this.getGridCellCreate_(gridPoint.x, gridPoint.y, zoom);
		cell.push(marker);
		gridPoint.x = gridPoint.x >> 1;
		gridPoint.y = gridPoint.y >> 1;
	}
};
/**
 * Returns whether or not the given point is visible in the shown bounds. This
 * is a helper method that takes care of the corner case, when shownBounds have
 * negative minX value.
 *
 * @param {Point} point a point on a grid.
 * @return {Boolean} Whether or not the given point is visible in the currently
 * shown bounds.
 */
MarkerManager.prototype.isGridPointVisible_ = function(point) {
	var me = this;
	var vertical = me.shownBounds_.minY <= point.y &&
			point.y <= me.shownBounds_.maxY;
	var minX = me.shownBounds_.minX;
	var horizontal = minX <= point.x && point.x <= me.shownBounds_.maxX;
	if (!horizontal && minX < 0) {
		var width = me.gridWidth_[me.shownBounds_.z];
		horizontal = minX + width <= point.x && point.x <= width - 1;
	}
	return vertical && horizontal;
}
/**
 * Reacts to a notification from a marker that it has moved to a new location.
 * It scans the grid all all zoom levels and moves the marker from the old grid
 * location to a new grid location.
 *
 * @param {Marker} marker The marker that moved.
 * @param {LatLng} oldPoint The old position of the marker.
 * @param {LatLng} newPoint The new position of the marker.
 */
MarkerManager.prototype.onMarkerMoved_ = function(marker, oldPoint, newPoint) {
	var me = this;
	var zoom = me.maxZoom_;
	var changed = false;
	var oldGrid = me.getTilePoint_(oldPoint, zoom, GSize.ZERO);
	var newGrid = me.getTilePoint_(newPoint, zoom, GSize.ZERO);
	while (zoom >= 0 && (oldGrid.x != newGrid.x || oldGrid.y != newGrid.y)) {
		var cell = me.getGridCellNoCreate_(oldGrid.x, oldGrid.y, zoom);
		if (cell) {
			if (me.removeFromArray(cell, marker)) {
				me.getGridCellCreate_(newGrid.x, newGrid.y, zoom).push(marker);
			}
		}
		if (zoom == me.mapZoom_) {
			if (me.isGridPointVisible_(oldGrid)) {
				if (!me.isGridPointVisible_(newGrid)) {
					me.removeOverlay_(marker);
					changed = true;
				}
			} else {
				if (me.isGridPointVisible_(newGrid)) {
					me.addOverlay_(marker);
					changed = true;
				}
			}
		}
		oldGrid.x = oldGrid.x >> 1;
		oldGrid.y = oldGrid.y >> 1;
		newGrid.x = newGrid.x >> 1;
		newGrid.y = newGrid.y >> 1;
		--zoom;
	}
	if (changed) {
		me.notifyListeners_();
	}
};
/**
 * Searches at every zoom level to find grid cell
 * that marker would be in, removes from that array if found.
 * Also removes marker with removeOverlay if visible.
 * @param {GMarker} marker The marker to delete.
 */
MarkerManager.prototype.removeMarker = function(marker) {
	var me = this;
	var zoom = me.maxZoom_;
	var changed = false;
	var point = marker.getPoint();
	var grid = me.getTilePoint_(point, zoom, GSize.ZERO);
	while (zoom >= 0) {
		var cell = me.getGridCellNoCreate_(grid.x, grid.y, zoom);
		if (cell) {
			me.removeFromArray(cell, marker);
		}
		if (zoom == me.mapZoom_) {
			if (me.isGridPointVisible_(grid)) {
					me.removeOverlay_(marker);
					changed = true;
			}
		}
		grid.x = grid.x >> 1;
		grid.y = grid.y >> 1;
		--zoom;
	}
	if (changed) {
		me.notifyListeners_();
	}
};
/**
 * Add many markers at once.
 * Does not actually update the map, just the internal grid.
 *
 * @param {Array of Marker} markers The markers to add.
 * @param {Number} minZoom The minimum zoom level to display the markers.
 * @param {Number} opt_maxZoom The maximum zoom level to display the markers.
 */
MarkerManager.prototype.addMarkers = function(markers, minZoom, opt_maxZoom) {
	var maxZoom = this.getOptMaxZoom_(opt_maxZoom);
	for (var i = markers.length - 1; i >= 0; i--) {
		this.addMarkerBatch_(markers[i], minZoom, maxZoom);
	}
	this.numMarkers_[minZoom] += markers.length;
};
/**
 * Returns the value of the optional maximum zoom. This method is defined so
 * that we have just one place where optional maximum zoom is calculated.
 *
 * @param {Number} opt_maxZoom The optinal maximum zoom.
 * @return The maximum zoom.
 */
MarkerManager.prototype.getOptMaxZoom_ = function(opt_maxZoom) {
	return opt_maxZoom != undefined ? opt_maxZoom : this.maxZoom_;
}
/**
 * Calculates the total number of markers potentially visible at a given
 * zoom level.
 *
 * @param {Number} zoom The zoom level to check.
 */
MarkerManager.prototype.getMarkerCount = function(zoom) {
	var total = 0;
	for (var z = 0; z <= zoom; z++) {
		total += this.numMarkers_[z];
	}
	return total;
};
/**
 * Add a single marker to the map.
 *
 * @param {Marker} marker The marker to add.
 * @param {Number} minZoom The minimum zoom level to display the marker.
 * @param {Number} opt_maxZoom The maximum zoom level to display the marker.
 */
MarkerManager.prototype.addMarker = function(marker, minZoom, opt_maxZoom) {
	var me = this;
	var maxZoom = this.getOptMaxZoom_(opt_maxZoom);
	me.addMarkerBatch_(marker, minZoom, maxZoom);
	var gridPoint = me.getTilePoint_(marker.getPoint(), me.mapZoom_, GSize.ZERO);
	if(me.isGridPointVisible_(gridPoint) &&
		minZoom <= me.shownBounds_.z &&
		me.shownBounds_.z <= maxZoom ) {
		me.addOverlay_(marker);
		me.notifyListeners_();
	}
	this.numMarkers_[minZoom]++;
};
/**
 * Returns true if this bounds (inclusively) contains the given point.
 * @param {Point} point The point to test.
 * @return {Boolean} This Bounds contains the given Point.
 */
GBounds.prototype.containsPoint = function(point) {
	var outer = this;
	return (outer.minX <= point.x &&
					outer.maxX >= point.x &&
					outer.minY <= point.y &&
					outer.maxY >= point.y);
}
/**
 * Get a cell in the grid, creating it first if necessary.
 *
 * Optimization candidate
 *
 * @param {Number} x The x coordinate of the cell.
 * @param {Number} y The y coordinate of the cell.
 * @param {Number} z The z coordinate of the cell.
 * @return {Array} The cell in the array.
 */
MarkerManager.prototype.getGridCellCreate_ = function(x, y, z) {
	var grid = this.grid_[z];
	if (x < 0) {
		x += this.gridWidth_[z];
	}
	var gridCol = grid[x];
	if (!gridCol) {
		gridCol = grid[x] = [];
		return gridCol[y] = [];
	}
	var gridCell = gridCol[y];
	if (!gridCell) {
		return gridCol[y] = [];
	}
	return gridCell;
};
/**
 * Get a cell in the grid, returning undefined if it does not exist.
 *
 * NOTE: Optimized for speed -- otherwise could combine with getGridCellCreate_.
 *
 * @param {Number} x The x coordinate of the cell.
 * @param {Number} y The y coordinate of the cell.
 * @param {Number} z The z coordinate of the cell.
 * @return {Array} The cell in the array.
 */
MarkerManager.prototype.getGridCellNoCreate_ = function(x, y, z) {
	var grid = this.grid_[z];
	if (x < 0) {
		x += this.gridWidth_[z];
	}
	var gridCol = grid[x];
	return gridCol ? gridCol[y] : undefined;
};
/**
 * Turns at geographical bounds into a grid-space bounds.
 *
 * @param {LatLngBounds} bounds The geographical bounds.
 * @param {Number} zoom The zoom level of the bounds.
 * @param {GSize} swPadding The padding in pixels to extend beyond the
 * given bounds.
 * @param {GSize} nePadding The padding in pixels to extend beyond the
 * given bounds.
 * @return {GBounds} The bounds in grid space.
 */
MarkerManager.prototype.getGridBounds_ = function(bounds, zoom, swPadding, nePadding) {
	zoom = Math.min(zoom, this.maxZoom_);
	var bl = bounds.getSouthWest();
	var tr = bounds.getNorthEast();
	var sw = this.getTilePoint_(bl, zoom, swPadding);
	var ne = this.getTilePoint_(tr, zoom, nePadding);
	var gw = this.gridWidth_[zoom];
	if (tr.lng() < bl.lng() || ne.x < sw.x) {
		sw.x -= gw;
	}
	if (ne.x - sw.x + 1 >= gw) {
		sw.x = 0;
		ne.x = gw - 1;
	}
	var gridBounds = new GBounds([sw, ne]);
	gridBounds.z = zoom;
	return gridBounds;
};
/**
 * Gets the grid-space bounds for the current map viewport.
 *
 * @return {Bounds} The bounds in grid space.
 */
MarkerManager.prototype.getMapGridBounds_ = function() {
	var me = this;
	return me.getGridBounds_(me.map_.getBounds(), me.mapZoom_, me.swPadding_, me.nePadding_);
};
/**
 * Event listener for map:movend.
 * NOTE: Use a timeout so that the user is not blocked
 * from moving the map.
 *
 */
MarkerManager.prototype.onMapMoveEnd_ = function() {
	var me = this;
	me.objectSetTimeout_(this, this.updateMarkers_, 0);
};
/**
 * Call a function or evaluate an expression after a specified number of
 * milliseconds.
 *
 * Equivalent to the standard window.setTimeout function, but the given
 * function executes as a method of this instance. So the function passed to
 * objectSetTimeout can contain references to this.
 * objectSetTimeout(this, function() { alert(this.x) }, 1000);
 *
 * @param {Object} object The target object.
 * @param {Function} command The command to run.
 * @param {Number} milliseconds The delay.
 * @return {Boolean} Success.
 */
MarkerManager.prototype.objectSetTimeout_ = function(object, command, milliseconds) {
	return window.setTimeout(function() {
		command.call(object);
	}, milliseconds);
};
/**
 * Refresh forces the marker-manager into a good state.
 * <ol>
 * <li>If never before initialized, shows all the markers.</li>
 * <li>If previously initialized, removes and re-adds all markers.</li>
 * </ol>
 */
MarkerManager.prototype.refresh = function() {
	var me = this;
	if (me.shownMarkers_ > 0) {
		me.processAll_(me.shownBounds_, me.removeOverlay_);
	}
	me.processAll_(me.shownBounds_, me.addOverlay_);
	me.notifyListeners_();
};
/**
 * After the viewport may have changed, add or remove markers as needed.
 */
MarkerManager.prototype.updateMarkers_ = function() {
	var me = this;
	me.mapZoom_ = this.map_.getZoom();
	var newBounds = me.getMapGridBounds_();
	if (newBounds.equals(me.shownBounds_) && newBounds.z == me.shownBounds_.z) {
		return;
	}
	if (newBounds.z != me.shownBounds_.z) {
		me.processAll_(me.shownBounds_, me.removeOverlay_);
		me.processAll_(newBounds, me.addOverlay_);
	} else {
		me.rectangleDiff_(me.shownBounds_, newBounds, me.removeCellMarkers_);
		me.rectangleDiff_(newBounds, me.shownBounds_, me.addCellMarkers_);
	}
	me.shownBounds_ = newBounds;
	me.notifyListeners_();
};
/**
 * Notify listeners when the state of what is displayed changes.
 */
MarkerManager.prototype.notifyListeners_ = function() {
	GEvent.trigger(this, "changed", this.shownBounds_, this.shownMarkers_);
};
/**
 * Process all markers in the bounds provided, using a callback.
 *
 * @param {Bounds} bounds The bounds in grid space.
 * @param {Function} callback The function to call for each marker.
 */
MarkerManager.prototype.processAll_ = function(bounds, callback) {
	for (var x = bounds.minX; x <= bounds.maxX; x++) {
		for (var y = bounds.minY; y <= bounds.maxY; y++) {
			this.processCellMarkers_(x, y, bounds.z, callback);
		}
	}
};
/**
 * Process all markers in the grid cell, using a callback.
 *
 * @param {Number} x The x coordinate of the cell.
 * @param {Number} y The y coordinate of the cell.
 * @param {Number} z The z coordinate of the cell.
 * @param {Function} callback The function to call for each marker.
 */
MarkerManager.prototype.processCellMarkers_ = function(x, y, z, callback) {
	var cell = this.getGridCellNoCreate_(x, y, z);
	if (cell) {
		for (var i = cell.length - 1; i >= 0; i--) {
			callback(cell[i]);
		}
	}
};
/**
 * Remove all markers in a grid cell.
 *
 * @param {Number} x The x coordinate of the cell.
 * @param {Number} y The y coordinate of the cell.
 * @param {Number} z The z coordinate of the cell.
 */
MarkerManager.prototype.removeCellMarkers_ = function(x, y, z) {
	this.processCellMarkers_(x, y, z, this.removeOverlay_);
};
/**
 * Add all markers in a grid cell.
 *
 * @param {Number} x The x coordinate of the cell.
 * @param {Number} y The y coordinate of the cell.
 * @param {Number} z The z coordinate of the cell.
 */
MarkerManager.prototype.addCellMarkers_ = function(x, y, z) {
	this.processCellMarkers_(x, y, z, this.addOverlay_);
};
/**
 * Use the rectangleDiffCoords function to process all grid cells
 * that are in bounds1 but not bounds2, using a callback, and using
 * the current MarkerManager object as the instance.
 *
 * Pass the z parameter to the callback in addition to x and y.
 *
 * @param {Bounds} bounds1 The bounds of all points we may process.
 * @param {Bounds} bounds2 The bounds of points to exclude.
 * @param {Function} callback The callback function to call for each grid coordinate (x, y, z).
 */
MarkerManager.prototype.rectangleDiff_ = function(bounds1, bounds2, callback) {
	var me = this;
	me.rectangleDiffCoords(bounds1, bounds2, function(x, y) {
		callback.apply(me, [x, y, bounds1.z]);
	});
};
/**
 * Calls the function for all points in bounds1, not in bounds2
 *
 * @param {Bounds} bounds1 The bounds of all points we may process.
 * @param {Bounds} bounds2 The bounds of points to exclude.
 * @param {Function} callback The callback function to call for each grid coordinate.
 */
MarkerManager.prototype.rectangleDiffCoords = function(bounds1, bounds2, callback) {
	var minX1 = bounds1.minX;
	var minY1 = bounds1.minY;
	var maxX1 = bounds1.maxX;
	var maxY1 = bounds1.maxY;
	var minX2 = bounds2.minX;
	var minY2 = bounds2.minY;
	var maxX2 = bounds2.maxX;
	var maxY2 = bounds2.maxY;
	for (var x = minX1; x <= maxX1; x++) {
		for (var y = minY1; y <= maxY1 && y < minY2; y++) {
			callback(x, y);
		}
		for (var y = Math.max(maxY2 + 1, minY1);
				y <= maxY1; y++) {
			callback(x, y);
		}
	}
	for (var y = Math.max(minY1, minY2);
			y <= Math.min(maxY1, maxY2); y++) {
		for (var x = Math.min(maxX1 + 1, minX2) - 1;
				x >= minX1; x--) {
			callback(x, y);
		}
		for (var x = Math.max(minX1, maxX2 + 1);
				x <= maxX1; x++) {
			callback(x, y);
		}
	}
};
/**
 * Removes value from array. O(N).
 *
 * @param {Array} array The array to modify.
 * @param {any} value The value to remove.
 * @param {Boolean} opt_notype Flag to disable type checking in equality.
 * @return {Number} The number of instances of value that were removed.
 */
MarkerManager.prototype.removeFromArray = function(array, value, opt_notype) {
	var shift = 0;
	for (var i = 0; i < array.length; ++i) {
		if (array[i] === value || (opt_notype && array[i] == value)) {
			array.splice(i--, 1);
			shift++;
		}
	}
	return shift;
};