// JavaScript Document
/* 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_;
 }
 // The padding in pixels beyond the viewport, where we will pre-load markers.
 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_);

 // NOTE: These two closures provide easy access to the map.
 // They are used as callbacks, not as methods.
 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_();
};

// Static constants:
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();
 // Tracking markers is expensive, so we do this only if the
 // user explicitly requested it when creating marker manager.
 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) {
   // Shifts the negative part of the rectangle. As point.x is always less
   // than grid width, only test shifted minX .. 0 part of the shown bounds.
   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) {
 // NOTE: We do not know the minimum or maximum zoom the marker was
 // added at, so we start at the absolute maximum. Whenever we successfully
 // remove a marker at a given zoom, we add it at the new grid coordinates.
 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);
     }
   }
   // For the current zoom we also need to update the map. Markers that no
   // longer are visible are removed from the map. Markers that moved into
   // the shown bounds are added to the map. This also lets us keep the count
   // of visible markers up to date.
   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);
   }
   // For the current zoom we also need to update the map. Markers that no
   // longer are visible are removed from the map. This also lets us keep the count
   // of visible markers up to date.
   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];
 
 // Crossing the prime meridian requires correction of bounds.
 if (tr.lng() < bl.lng() || ne.x < sw.x) {
   sw.x -= gw;
 }
 if (ne.x - sw.x  + 1 >= gw) {
   // Computed grid bounds are larger than the world; truncate.
   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 the move does not include new grid sections,
 // we have no work to do:
 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 {
   // Remove markers:
   me.rectangleDiff_(me.shownBounds_, newBounds, me.removeCellMarkers_);

   // Add markers:
   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++) {  // All x in R1
   // All above:
   for (var y = minY1; y <= maxY1 && y < minY2; y++) {  // y in R1 above R2
     callback(x, y);
   }
   // All below:
   for (var y = Math.max(maxY2 + 1, minY1);  // y in R1 below R2
        y <= maxY1; y++) {
     callback(x, y);
   }
 }

 for (var y = Math.max(minY1, minY2);
      y <= Math.min(maxY1, maxY2); y++) {  // All y in R2 and in R1
   // Strictly left:
   for (var x = Math.min(maxX1 + 1, minX2) - 1;
        x >= minX1; x--) {  // x in R1 left of R2
     callback(x, y);
   }
   // Strictly right:
   for (var x = Math.max(minX1, maxX2 + 1);  // x in R1 right of R2
        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;
};