/**
 * @module ol/Graticule
 */
import {degreesToStringHDMS} from './coordinate.js';
import {listen, unlistenByKey} from './events.js';
import {intersects, getCenter} from './extent.js';
import GeometryLayout from './geom/GeometryLayout.js';
import LineString from './geom/LineString.js';
import Point from './geom/Point.js';
import {meridian, parallel} from './geom/flat/geodesic.js';
import {clamp} from './math.js';
import {get as getProjection, equivalent as equivalentProjection, getTransform, transformExtent} from './proj.js';
import RenderEventType from './render/EventType.js';
import Fill from './style/Fill.js';
import Stroke from './style/Stroke.js';
import Text from './style/Text.js';


/**
 * @type {module:ol/style/Stroke}
 * @private
 * @const
 */
const DEFAULT_STROKE_STYLE = new Stroke({
  color: 'rgba(0,0,0,0.2)'
});

/**
 * TODO can be configurable
 * @type {Array.<number>}
 * @private
 */
const INTERVALS = [
  90, 45, 30, 20, 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.01, 0.005, 0.002, 0.001
];

/**
 * @typedef {Object} GraticuleLabelDataType
 * @property {module:ol/geom/Point} geom
 * @property {string} text
 */

/**
 * @typedef {Object} Options
 * @property {module:ol/PluggableMap} [map] Reference to an
 * {@link module:ol/Map~Map} object.
 * @property {number} [maxLines=100] The maximum number of meridians and
 * parallels from the center of the map. The default value of 100 means that at
 * most 200 meridians and 200 parallels will be displayed. The default value is
 * appropriate for conformal projections like Spherical Mercator. If you
 * increase the value, more lines will be drawn and the drawing performance will
 * decrease.
 * @property {module:ol/style/Stroke} [strokeStyle='rgba(0,0,0,0.2)'] The
 * stroke style to use for drawing the graticule. If not provided, a not fully
 * opaque black will be used.
 * @property {number} [targetSize=100] The target size of the graticule cells,
 * in pixels.
 * @property {boolean} [showLabels=false] Render a label with the respective
 * latitude/longitude for each graticule line.
 * @property {function(number):string} [lonLabelFormatter] Label formatter for
 * longitudes. This function is called with the longitude as argument, and
 * should return a formatted string representing the longitude. By default,
 * labels are formatted as degrees, minutes, seconds and hemisphere.
 * @property {function(number):string} [latLabelFormatter] Label formatter for
 * latitudes. This function is called with the latitude as argument, and
 * should return a formatted string representing the latitude. By default,
 * labels are formatted as degrees, minutes, seconds and hemisphere.
 * @property {number} [lonLabelPosition=0] Longitude label position in fractions
 * (0..1) of view extent. 0 means at the bottom of the viewport, 1 means at the
 * top.
 * @property {number} [latLabelPosition=1] Latitude label position in fractions
 * (0..1) of view extent. 0 means at the left of the viewport, 1 means at the
 * right.
 * @property {module:ol/style/Text} [lonLabelStyle] Longitude label text
 * style. If not provided, the following style will be used:
 * ```js
 * new Text({
 *   font: '12px Calibri,sans-serif',
 *   textBaseline: 'bottom',
 *   fill: new Fill({
 *     color: 'rgba(0,0,0,1)'
 *   }),
 *   stroke: new Stroke({
 *     color: 'rgba(255,255,255,1)',
 *     width: 3
 *   })
 * });
 * ```
 * Note that the default's `textBaseline` configuration will not work well for
 * `lonLabelPosition` configurations that position labels close to the top of
 * the viewport.
 * @property {module:ol/style/Text} [latLabelStyle] Latitude label text style.
 * If not provided, the following style will be used:
 * ```js
 * new Text({
 *   font: '12px Calibri,sans-serif',
 *   textAlign: 'end',
 *   fill: new Fill({
 *     color: 'rgba(0,0,0,1)'
 *   }),
 *   stroke: Stroke({
 *     color: 'rgba(255,255,255,1)',
 *     width: 3
 *   })
 * });
 * ```
 * Note that the default's `textAlign` configuration will not work well for
 * `latLabelPosition` configurations that position labels close to the left of
 * the viewport.
 */


/**
 * Render a grid for a coordinate system on a map.
 * @api
 */
class Graticule {

  /**
   * @param {module:ol/Graticule~Options=} opt_options Options.
   */
  constructor(opt_options) {
    const options = opt_options || {};

    /**
     * @type {module:ol/PluggableMap}
     * @private
     */
    this.map_ = null;

    /**
     * @type {?module:ol/events~EventsKey}
     * @private
     */
    this.postcomposeListenerKey_ = null;

    /**
     * @type {module:ol/proj/Projection}
     */
    this.projection_ = null;

    /**
     * @type {number}
     * @private
     */
    this.maxLat_ = Infinity;

    /**
     * @type {number}
     * @private
     */
    this.maxLon_ = Infinity;

    /**
     * @type {number}
     * @private
     */
    this.minLat_ = -Infinity;

    /**
     * @type {number}
     * @private
     */
    this.minLon_ = -Infinity;

    /**
     * @type {number}
     * @private
     */
    this.maxLatP_ = Infinity;

    /**
     * @type {number}
     * @private
     */
    this.maxLonP_ = Infinity;

    /**
     * @type {number}
     * @private
     */
    this.minLatP_ = -Infinity;

    /**
     * @type {number}
     * @private
     */
    this.minLonP_ = -Infinity;

    /**
     * @type {number}
     * @private
     */
    this.targetSize_ = options.targetSize !== undefined ? options.targetSize : 100;

    /**
     * @type {number}
     * @private
     */
    this.maxLines_ = options.maxLines !== undefined ? options.maxLines : 100;

    /**
     * @type {Array.<module:ol/geom/LineString>}
     * @private
     */
    this.meridians_ = [];

    /**
     * @type {Array.<module:ol/geom/LineString>}
     * @private
     */
    this.parallels_ = [];

    /**
     * @type {module:ol/style/Stroke}
     * @private
     */
    this.strokeStyle_ = options.strokeStyle !== undefined ? options.strokeStyle : DEFAULT_STROKE_STYLE;

    /**
     * @type {module:ol/proj~TransformFunction|undefined}
     * @private
     */
    this.fromLonLatTransform_ = undefined;

    /**
     * @type {module:ol/proj~TransformFunction|undefined}
     * @private
     */
    this.toLonLatTransform_ = undefined;

    /**
     * @type {module:ol/coordinate~Coordinate}
     * @private
     */
    this.projectionCenterLonLat_ = null;

    /**
     * @type {Array.<module:ol/Graticule~GraticuleLabelDataType>}
     * @private
     */
    this.meridiansLabels_ = null;

    /**
     * @type {Array.<module:ol/Graticule~GraticuleLabelDataType>}
     * @private
     */
    this.parallelsLabels_ = null;

    if (options.showLabels == true) {

      /**
       * @type {null|function(number):string}
       * @private
       */
      this.lonLabelFormatter_ = options.lonLabelFormatter == undefined ?
        degreesToStringHDMS.bind(this, 'EW') : options.lonLabelFormatter;

      /**
       * @type {function(number):string}
       * @private
       */
      this.latLabelFormatter_ = options.latLabelFormatter == undefined ?
        degreesToStringHDMS.bind(this, 'NS') : options.latLabelFormatter;

      /**
       * Longitude label position in fractions (0..1) of view extent. 0 means
       * bottom, 1 means top.
       * @type {number}
       * @private
       */
      this.lonLabelPosition_ = options.lonLabelPosition == undefined ? 0 :
        options.lonLabelPosition;

      /**
       * Latitude Label position in fractions (0..1) of view extent. 0 means left, 1
       * means right.
       * @type {number}
       * @private
       */
      this.latLabelPosition_ = options.latLabelPosition == undefined ? 1 :
        options.latLabelPosition;

      /**
       * @type {module:ol/style/Text}
       * @private
       */
      this.lonLabelStyle_ = options.lonLabelStyle !== undefined ? options.lonLabelStyle :
        new Text({
          font: '12px Calibri,sans-serif',
          textBaseline: 'bottom',
          fill: new Fill({
            color: 'rgba(0,0,0,1)'
          }),
          stroke: new Stroke({
            color: 'rgba(255,255,255,1)',
            width: 3
          })
        });

      /**
       * @type {module:ol/style/Text}
       * @private
       */
      this.latLabelStyle_ = options.latLabelStyle !== undefined ? options.latLabelStyle :
        new Text({
          font: '12px Calibri,sans-serif',
          textAlign: 'end',
          fill: new Fill({
            color: 'rgba(0,0,0,1)'
          }),
          stroke: new Stroke({
            color: 'rgba(255,255,255,1)',
            width: 3
          })
        });

      this.meridiansLabels_ = [];
      this.parallelsLabels_ = [];
    }

    this.setMap(options.map !== undefined ? options.map : null);
  }

  /**
   * @param {number} lon Longitude.
   * @param {number} minLat Minimal latitude.
   * @param {number} maxLat Maximal latitude.
   * @param {number} squaredTolerance Squared tolerance.
   * @param {module:ol/extent~Extent} extent Extent.
   * @param {number} index Index.
   * @return {number} Index.
   * @private
   */
  addMeridian_(lon, minLat, maxLat, squaredTolerance, extent, index) {
    const lineString = this.getMeridian_(lon, minLat, maxLat, squaredTolerance, index);
    if (intersects(lineString.getExtent(), extent)) {
      if (this.meridiansLabels_) {
        const textPoint = this.getMeridianPoint_(lineString, extent, index);
        this.meridiansLabels_[index] = {
          geom: textPoint,
          text: this.lonLabelFormatter_(lon)
        };
      }
      this.meridians_[index++] = lineString;
    }
    return index;
  }

  /**
   * @param {module:ol/geom/LineString} lineString Meridian
   * @param {module:ol/extent~Extent} extent Extent.
   * @param {number} index Index.
   * @return {module:ol/geom/Point} Meridian point.
   * @private
   */
  getMeridianPoint_(lineString, extent, index) {
    const flatCoordinates = lineString.getFlatCoordinates();
    const clampedBottom = Math.max(extent[1], flatCoordinates[1]);
    const clampedTop = Math.min(extent[3], flatCoordinates[flatCoordinates.length - 1]);
    const lat = clamp(
      extent[1] + Math.abs(extent[1] - extent[3]) * this.lonLabelPosition_,
      clampedBottom, clampedTop);
    const coordinate = [flatCoordinates[0], lat];
    let point;
    if (index in this.meridiansLabels_) {
      point = this.meridiansLabels_[index];
      point.setCoordinates(coordinate);
    } else {
      point = new Point(coordinate);
    }
    return point;
  }

  /**
   * @param {number} lat Latitude.
   * @param {number} minLon Minimal longitude.
   * @param {number} maxLon Maximal longitude.
   * @param {number} squaredTolerance Squared tolerance.
   * @param {module:ol/extent~Extent} extent Extent.
   * @param {number} index Index.
   * @return {number} Index.
   * @private
   */
  addParallel_(lat, minLon, maxLon, squaredTolerance, extent, index) {
    const lineString = this.getParallel_(lat, minLon, maxLon, squaredTolerance, index);
    if (intersects(lineString.getExtent(), extent)) {
      if (this.parallelsLabels_) {
        const textPoint = this.getParallelPoint_(lineString, extent, index);
        this.parallelsLabels_[index] = {
          geom: textPoint,
          text: this.latLabelFormatter_(lat)
        };
      }
      this.parallels_[index++] = lineString;
    }
    return index;
  }

  /**
   * @param {module:ol/geom/LineString} lineString Parallels.
   * @param {module:ol/extent~Extent} extent Extent.
   * @param {number} index Index.
   * @return {module:ol/geom/Point} Parallel point.
   * @private
   */
  getParallelPoint_(lineString, extent, index) {
    const flatCoordinates = lineString.getFlatCoordinates();
    const clampedLeft = Math.max(extent[0], flatCoordinates[0]);
    const clampedRight = Math.min(extent[2], flatCoordinates[flatCoordinates.length - 2]);
    const lon = clamp(
      extent[0] + Math.abs(extent[0] - extent[2]) * this.latLabelPosition_,
      clampedLeft, clampedRight);
    const coordinate = [lon, flatCoordinates[1]];
    let point;
    if (index in this.parallelsLabels_) {
      point = this.parallelsLabels_[index];
      point.setCoordinates(coordinate);
    } else {
      point = new Point(coordinate);
    }
    return point;
  }

  /**
   * @param {module:ol/extent~Extent} extent Extent.
   * @param {module:ol/coordinate~Coordinate} center Center.
   * @param {number} resolution Resolution.
   * @param {number} squaredTolerance Squared tolerance.
   * @private
   */
  createGraticule_(extent, center, resolution, squaredTolerance) {

    const interval = this.getInterval_(resolution);
    if (interval == -1) {
      this.meridians_.length = this.parallels_.length = 0;
      if (this.meridiansLabels_) {
        this.meridiansLabels_.length = 0;
      }
      if (this.parallelsLabels_) {
        this.parallelsLabels_.length = 0;
      }
      return;
    }

    const centerLonLat = this.toLonLatTransform_(center);
    let centerLon = centerLonLat[0];
    let centerLat = centerLonLat[1];
    const maxLines = this.maxLines_;
    let cnt, idx, lat, lon;

    let validExtent = [
      Math.max(extent[0], this.minLonP_),
      Math.max(extent[1], this.minLatP_),
      Math.min(extent[2], this.maxLonP_),
      Math.min(extent[3], this.maxLatP_)
    ];

    validExtent = transformExtent(validExtent, this.projection_, 'EPSG:4326');
    const maxLat = validExtent[3];
    const maxLon = validExtent[2];
    const minLat = validExtent[1];
    const minLon = validExtent[0];

    // Create meridians

    centerLon = Math.floor(centerLon / interval) * interval;
    lon = clamp(centerLon, this.minLon_, this.maxLon_);

    idx = this.addMeridian_(lon, minLat, maxLat, squaredTolerance, extent, 0);

    cnt = 0;
    while (lon != this.minLon_ && cnt++ < maxLines) {
      lon = Math.max(lon - interval, this.minLon_);
      idx = this.addMeridian_(lon, minLat, maxLat, squaredTolerance, extent, idx);
    }

    lon = clamp(centerLon, this.minLon_, this.maxLon_);

    cnt = 0;
    while (lon != this.maxLon_ && cnt++ < maxLines) {
      lon = Math.min(lon + interval, this.maxLon_);
      idx = this.addMeridian_(lon, minLat, maxLat, squaredTolerance, extent, idx);
    }

    this.meridians_.length = idx;
    if (this.meridiansLabels_) {
      this.meridiansLabels_.length = idx;
    }

    // Create parallels

    centerLat = Math.floor(centerLat / interval) * interval;
    lat = clamp(centerLat, this.minLat_, this.maxLat_);

    idx = this.addParallel_(lat, minLon, maxLon, squaredTolerance, extent, 0);

    cnt = 0;
    while (lat != this.minLat_ && cnt++ < maxLines) {
      lat = Math.max(lat - interval, this.minLat_);
      idx = this.addParallel_(lat, minLon, maxLon, squaredTolerance, extent, idx);
    }

    lat = clamp(centerLat, this.minLat_, this.maxLat_);

    cnt = 0;
    while (lat != this.maxLat_ && cnt++ < maxLines) {
      lat = Math.min(lat + interval, this.maxLat_);
      idx = this.addParallel_(lat, minLon, maxLon, squaredTolerance, extent, idx);
    }

    this.parallels_.length = idx;
    if (this.parallelsLabels_) {
      this.parallelsLabels_.length = idx;
    }

  }

  /**
   * @param {number} resolution Resolution.
   * @return {number} The interval in degrees.
   * @private
   */
  getInterval_(resolution) {
    const centerLon = this.projectionCenterLonLat_[0];
    const centerLat = this.projectionCenterLonLat_[1];
    let interval = -1;
    const target = Math.pow(this.targetSize_ * resolution, 2);
    /** @type {Array.<number>} **/
    const p1 = [];
    /** @type {Array.<number>} **/
    const p2 = [];
    for (let i = 0, ii = INTERVALS.length; i < ii; ++i) {
      const delta = INTERVALS[i] / 2;
      p1[0] = centerLon - delta;
      p1[1] = centerLat - delta;
      p2[0] = centerLon + delta;
      p2[1] = centerLat + delta;
      this.fromLonLatTransform_(p1, p1);
      this.fromLonLatTransform_(p2, p2);
      const dist = Math.pow(p2[0] - p1[0], 2) + Math.pow(p2[1] - p1[1], 2);
      if (dist <= target) {
        break;
      }
      interval = INTERVALS[i];
    }
    return interval;
  }

  /**
   * Get the map associated with this graticule.
   * @return {module:ol/PluggableMap} The map.
   * @api
   */
  getMap() {
    return this.map_;
  }

  /**
   * @param {number} lon Longitude.
   * @param {number} minLat Minimal latitude.
   * @param {number} maxLat Maximal latitude.
   * @param {number} squaredTolerance Squared tolerance.
   * @return {module:ol/geom/LineString} The meridian line string.
   * @param {number} index Index.
   * @private
   */
  getMeridian_(lon, minLat, maxLat, squaredTolerance, index) {
    const flatCoordinates = meridian(lon, minLat, maxLat, this.projection_, squaredTolerance);
    let lineString = this.meridians_[index];
    if (!lineString) {
      lineString = this.meridians_[index] = new LineString(flatCoordinates, GeometryLayout.XY);
    } else {
      lineString.setFlatCoordinates(GeometryLayout.XY, flatCoordinates);
      lineString.changed();
    }
    return lineString;
  }

  /**
   * Get the list of meridians.  Meridians are lines of equal longitude.
   * @return {Array.<module:ol/geom/LineString>} The meridians.
   * @api
   */
  getMeridians() {
    return this.meridians_;
  }

  /**
   * @param {number} lat Latitude.
   * @param {number} minLon Minimal longitude.
   * @param {number} maxLon Maximal longitude.
   * @param {number} squaredTolerance Squared tolerance.
   * @return {module:ol/geom/LineString} The parallel line string.
   * @param {number} index Index.
   * @private
   */
  getParallel_(lat, minLon, maxLon, squaredTolerance, index) {
    const flatCoordinates = parallel(lat, minLon, maxLon, this.projection_, squaredTolerance);
    let lineString = this.parallels_[index];
    if (!lineString) {
      lineString = new LineString(flatCoordinates, GeometryLayout.XY);
    } else {
      lineString.setFlatCoordinates(GeometryLayout.XY, flatCoordinates);
      lineString.changed();
    }
    return lineString;
  }

  /**
   * Get the list of parallels.  Parallels are lines of equal latitude.
   * @return {Array.<module:ol/geom/LineString>} The parallels.
   * @api
   */
  getParallels() {
    return this.parallels_;
  }

  /**
   * @param {module:ol/render/Event} e Event.
   * @private
   */
  handlePostCompose_(e) {
    const vectorContext = e.vectorContext;
    const frameState = e.frameState;
    const extent = frameState.extent;
    const viewState = frameState.viewState;
    const center = viewState.center;
    const projection = viewState.projection;
    const resolution = viewState.resolution;
    const pixelRatio = frameState.pixelRatio;
    const squaredTolerance =
        resolution * resolution / (4 * pixelRatio * pixelRatio);

    const updateProjectionInfo = !this.projection_ ||
        !equivalentProjection(this.projection_, projection);

    if (updateProjectionInfo) {
      this.updateProjectionInfo_(projection);
    }

    this.createGraticule_(extent, center, resolution, squaredTolerance);

    // Draw the lines
    vectorContext.setFillStrokeStyle(null, this.strokeStyle_);
    let i, l, line;
    for (i = 0, l = this.meridians_.length; i < l; ++i) {
      line = this.meridians_[i];
      vectorContext.drawGeometry(line);
    }
    for (i = 0, l = this.parallels_.length; i < l; ++i) {
      line = this.parallels_[i];
      vectorContext.drawGeometry(line);
    }
    let labelData;
    if (this.meridiansLabels_) {
      for (i = 0, l = this.meridiansLabels_.length; i < l; ++i) {
        labelData = this.meridiansLabels_[i];
        this.lonLabelStyle_.setText(labelData.text);
        vectorContext.setTextStyle(this.lonLabelStyle_);
        vectorContext.drawGeometry(labelData.geom);
      }
    }
    if (this.parallelsLabels_) {
      for (i = 0, l = this.parallelsLabels_.length; i < l; ++i) {
        labelData = this.parallelsLabels_[i];
        this.latLabelStyle_.setText(labelData.text);
        vectorContext.setTextStyle(this.latLabelStyle_);
        vectorContext.drawGeometry(labelData.geom);
      }
    }
  }

  /**
   * @param {module:ol/proj/Projection} projection Projection.
   * @private
   */
  updateProjectionInfo_(projection) {
    const epsg4326Projection = getProjection('EPSG:4326');

    const worldExtent = projection.getWorldExtent();
    const worldExtentP = transformExtent(worldExtent, epsg4326Projection, projection);

    this.maxLat_ = worldExtent[3];
    this.maxLon_ = worldExtent[2];
    this.minLat_ = worldExtent[1];
    this.minLon_ = worldExtent[0];

    this.maxLatP_ = worldExtentP[3];
    this.maxLonP_ = worldExtentP[2];
    this.minLatP_ = worldExtentP[1];
    this.minLonP_ = worldExtentP[0];

    this.fromLonLatTransform_ = getTransform(epsg4326Projection, projection);

    this.toLonLatTransform_ = getTransform(projection, epsg4326Projection);

    this.projectionCenterLonLat_ = this.toLonLatTransform_(getCenter(projection.getExtent()));

    this.projection_ = projection;
  }

  /**
   * Set the map for this graticule.  The graticule will be rendered on the
   * provided map.
   * @param {module:ol/PluggableMap} map Map.
   * @api
   */
  setMap(map) {
    if (this.map_) {
      unlistenByKey(this.postcomposeListenerKey_);
      this.postcomposeListenerKey_ = null;
      this.map_.render();
    }
    if (map) {
      this.postcomposeListenerKey_ = listen(map, RenderEventType.POSTCOMPOSE, this.handlePostCompose_, this);
      map.render();
    }
    this.map_ = map;
  }
}

export default Graticule;