goog.provide('ol.TileGrid');
goog.provide('ol.TileGrid.createOpenStreetMap');

goog.require('goog.array');
goog.require('goog.asserts');
goog.require('goog.math.Size');
goog.require('ol.Extent');
goog.require('ol.Projection');
goog.require('ol.TileBounds');
goog.require('ol.TileCoord');



/**
 * @constructor
 * @param {!Array.<number>} resolutions Resolutions.
 * @param {ol.Extent} extent Extent.
 * @param {goog.math.Coordinate|!Array.<goog.math.Coordinate>} origin Origin.
 * @param {goog.math.Size=} opt_tileSize Tile size.
 */
ol.TileGrid = function(resolutions, extent, origin, opt_tileSize) {

  /**
   * @private
   * @type {Array.<number>}
   */
  this.resolutions_ = resolutions;
  goog.asserts.assert(goog.array.isSorted(resolutions, function(a, b) {
    return -goog.array.defaultCompare(a, b);
  }, true));

  /**
   * @private
   * @type {number}
   */
  this.numResolutions_ = this.resolutions_.length;

  /**
   * @private
   * @type {ol.Extent}
   */
  this.extent_ = extent;

  /**
   * @private
   * @type {goog.math.Coordinate}
   */
  this.origin_ = null;

  /**
   * @private
   * @type {Array.<goog.math.Coordinate>}
   */
  this.origins_ = null;

  if (origin instanceof goog.math.Coordinate) {
    this.origin_ = origin;
  } else if (goog.isArray(origin)) {
    goog.asserts.assert(origin.length == this.numResolutions_);
    this.origins_ = origin;
  } else {
    goog.asserts.assert(false);
  }

  /**
   * @private
   * @type {goog.math.Size}
   */
  this.tileSize_ = goog.isDef(opt_tileSize) ?
      opt_tileSize : new goog.math.Size(256, 256);

};


/**
 * @param {number} maxZoom Maximum zoom.
 * @return {ol.TileGrid} Tile grid.
 */
ol.TileGrid.createOpenStreetMap = function(maxZoom) {

  var resolutions = new Array(maxZoom + 1);
  var z;
  for (z = 0; z <= maxZoom; ++z) {
    resolutions[z] = ol.Projection.EPSG_3857_HALF_SIZE / (128 << z);
  }

  var extent = ol.Projection.EPSG_3857_EXTENT;
  var origin = new goog.math.Coordinate(
      -ol.Projection.EPSG_3857_HALF_SIZE, ol.Projection.EPSG_3857_HALF_SIZE);
  var tileSize = new goog.math.Size(256, 256);

  return new ol.TileGrid(resolutions, extent, origin, tileSize);

};


/**
 * @param {ol.TileCoord} tileCoord Tile coordinate.
 * @param {function(number, ol.TileBounds): boolean} callback Callback.
 */
ol.TileGrid.prototype.forEachTileCoordParent = function(tileCoord, callback) {
  var tileCoordExtent = this.getTileCoordExtent(tileCoord);
  var z = tileCoord.z - 1;
  while (z >= 0) {
    if (callback(z, this.getExtentTileBounds(z, tileCoordExtent))) {
      return;
    }
    --z;
  }
};


/**
 * @return {ol.Extent} Extent.
 */
ol.TileGrid.prototype.getExtent = function() {
  return this.extent_;
};


/**
 * @param {number} z Z.
 * @param {ol.Extent} extent Extent.
 * @return {ol.TileBounds} Tile bounds.
 */
ol.TileGrid.prototype.getExtentTileBounds = function(z, extent) {
  var min =
      this.getTileCoord(z, new goog.math.Coordinate(extent.minX, extent.minY));
  var max =
      this.getTileCoord(z, new goog.math.Coordinate(extent.maxX, extent.maxY));
  return new ol.TileBounds(min.x, min.y, max.x, max.y);
};


/**
 * @param {number} z Z.
 * @return {goog.math.Coordinate} Origin.
 */
ol.TileGrid.prototype.getOrigin = function(z) {
  if (!goog.isNull(this.origin_)) {
    return this.origin_;
  } else {
    goog.asserts.assert(!goog.isNull(this.origins_));
    goog.asserts.assert(0 <= z && z < this.origins_.length);
    return this.origins_[z];
  }
};


/**
 * @param {number} z Z.
 * @return {number} Resolution.
 */
ol.TileGrid.prototype.getResolution = function(z) {
  goog.asserts.assert(0 <= z && z < this.numResolutions_);
  return this.resolutions_[z];
};


/**
 * @return {Array.<number>} Resolutions.
 */
ol.TileGrid.prototype.getResolutions = function() {
  return this.resolutions_;
};


/**
 * @param {number} z Z.
 * @param {goog.math.Coordinate} coordinate Coordinate.
 * @return {ol.TileCoord} Tile coordinate.
 */
ol.TileGrid.prototype.getTileCoord = function(z, coordinate) {
  var origin = this.getOrigin(z);
  var resolution = this.getResolution(z);
  var tileSize = this.getTileSize();
  var x, y;
  x = Math.floor((coordinate.x - origin.x) / (tileSize.width * resolution));
  y = Math.floor((coordinate.y - origin.y) / (tileSize.height * resolution));
  return new ol.TileCoord(z, x, y);
};


/**
 * @param {ol.TileCoord} tileCoord Tile coordinate.
 * @return {goog.math.Coordinate} Tile center.
 */
ol.TileGrid.prototype.getTileCoordCenter = function(tileCoord) {
  var origin = this.getOrigin(tileCoord.z);
  var resolution = this.getResolution(tileCoord.z);
  var tileSize = this.tileSize_;
  var x = origin.x + (tileCoord.x + 0.5) * tileSize.width * resolution;
  var y = origin.y + (tileCoord.y + 0.5) * tileSize.height * resolution;
  return new goog.math.Coordinate(x, y);
};


/**
 * @param {number} z Z.
 * @param {ol.TileBounds} tileBounds Tile bounds.
 * @return {ol.Extent} Extent.
 */
ol.TileGrid.prototype.getTileBoundsExtent = function(z, tileBounds) {
  var origin = this.getOrigin(z);
  var resolution = this.getResolution(z);
  var tileSize = this.tileSize_;
  var minX = origin.x + tileBounds.minX * tileSize.width * resolution;
  var minY = origin.y + tileBounds.minY * tileSize.height * resolution;
  var maxX = origin.x + (tileBounds.maxX + 1) * tileSize.width * resolution;
  var maxY = origin.y + (tileBounds.maxY + 1) * tileSize.height * resolution;
  return new ol.Extent(minX, minY, maxX, maxY);
};


/**
 * @param {ol.TileCoord} tileCoord Tile coordinate.
 * @return {ol.Extent} Extent.
 */
ol.TileGrid.prototype.getTileCoordExtent = function(tileCoord) {
  var origin = this.getOrigin(tileCoord.z);
  var resolution = this.getResolution(tileCoord.z);
  var tileSize = this.tileSize_;
  var minX = origin.x + tileCoord.x * tileSize.width * resolution;
  var minY = origin.y + tileCoord.y * tileSize.height * resolution;
  var maxX = minX + tileSize.width * resolution;
  var maxY = minY + tileSize.height * resolution;
  return new ol.Extent(minX, minY, maxX, maxY);
};


/**
 * @param {ol.TileCoord} tileCoord Tile coordinate.
 * @return {number} Tile resolution.
 */
ol.TileGrid.prototype.getTileCoordResolution = function(tileCoord) {
  goog.asserts.assert(0 <= tileCoord.z && tileCoord.z < this.numResolutions_);
  return this.resolutions_[tileCoord.z];
};


/**
 * @return {goog.math.Size} Tile size.
 */
ol.TileGrid.prototype.getTileSize = function() {
  return this.tileSize_;
};


/**
 * @param {number} resolution Resolution.
 * @return {number} Z.
 */
ol.TileGrid.prototype.getZForResolution = function(resolution) {
  var z;
  for (z = 0; z < this.numResolutions_; ++z) {
    if (this.resolutions_[z] == resolution) {
      return z;
    } else if (this.resolutions_[z] < resolution) {
      if (z === 0) {
        return z;
      } else if (resolution - this.resolutions_[z] <=
          this.resolutions_[z - 1] - resolution) {
        return z;
      } else {
        return z - 1;
      }
    }
  }
  return this.numResolutions_ - 1;
};