planetiler/planetiler-basemap/src/main/java/com/onthegomap/planetiler/basemap/layers/Waterway.java

/*
Copyright (c) 2021, MapTiler.com & OpenMapTiles contributors.
All rights reserved.

Code license: BSD 3-Clause License

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* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
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* Neither the name of the copyright holder nor the names of its
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  this software without specific prior written permission.

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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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Design license: CC-BY 4.0

See https://github.com/openmaptiles/openmaptiles/blob/master/LICENSE.md for details on usage
*/
package com.onthegomap.planetiler.basemap.layers;

import static com.onthegomap.planetiler.basemap.util.Utils.nullIfEmpty;

import com.carrotsearch.hppc.LongObjectHashMap;
import com.google.common.util.concurrent.AtomicDouble;
import com.onthegomap.planetiler.FeatureCollector;
import com.onthegomap.planetiler.FeatureMerge;
import com.onthegomap.planetiler.VectorTile;
import com.onthegomap.planetiler.basemap.BasemapProfile;
import com.onthegomap.planetiler.basemap.generated.OpenMapTilesSchema;
import com.onthegomap.planetiler.basemap.generated.Tables;
import com.onthegomap.planetiler.basemap.util.LanguageUtils;
import com.onthegomap.planetiler.basemap.util.Utils;
import com.onthegomap.planetiler.collection.Hppc;
import com.onthegomap.planetiler.config.PlanetilerConfig;
import com.onthegomap.planetiler.geo.GeometryException;
import com.onthegomap.planetiler.reader.SourceFeature;
import com.onthegomap.planetiler.reader.osm.OsmElement;
import com.onthegomap.planetiler.reader.osm.OsmReader;
import com.onthegomap.planetiler.reader.osm.OsmRelationInfo;
import com.onthegomap.planetiler.stats.Stats;
import com.onthegomap.planetiler.util.Translations;
import com.onthegomap.planetiler.util.ZoomFunction;
import java.util.List;
import java.util.Map;

/**
 * Defines the logic for generating river map elements in the {@code waterway} layer from source features.
 * <p>
 * This class is ported to Java from
 * <a href="https://github.com/openmaptiles/openmaptiles/tree/master/layers/waterway">OpenMapTiles waterway sql
 * files</a>.
 */
public class Waterway implements
  OpenMapTilesSchema.Waterway,
  Tables.OsmWaterwayLinestring.Handler,
  BasemapProfile.FeaturePostProcessor,
  BasemapProfile.NaturalEarthProcessor,
  BasemapProfile.OsmRelationPreprocessor,
  BasemapProfile.OsmAllProcessor {

  /*
   * Uses Natural Earth at lower zoom-levels and OpenStreetMap at higher zoom levels.
   *
   * For OpenStreetMap, attempts to merge disconnected linestrings with the same name
   * at lower zoom levels so that clients can more easily render the name. We also
   * limit their length at merge-time which only has visibilty into that feature in a
   * single tile, so at render-time we need to allow through features far enough outside
   * the tile boundary enough to not accidentally filter out a long river only because a
   * short segment of it goes through this tile.
   */

  private static final Map<String, Integer> CLASS_MINZOOM = Map.of(
    "river", 12,
    "canal", 12,

    "stream", 13,
    "drain", 13,
    "ditch", 13
  );
  private static final String TEMP_REL_ID_ADDR = "_relid";

  private final Translations translations;
  private final PlanetilerConfig config;
  private final Stats stats;
  private final LongObjectHashMap<AtomicDouble> riverRelationLengths = Hppc.newLongObjectHashMap();

  public Waterway(Translations translations, PlanetilerConfig config, Stats stats) {
    this.config = config;
    this.translations = translations;
    this.stats = stats;
  }

  private static final ZoomFunction.MeterToPixelThresholds MIN_PIXEL_LENGTHS = ZoomFunction.meterThresholds()
    .put(6, 500_000)
    .put(7, 400_000)
    .put(8, 300_000)
    .put(9, 8_000)
    .put(10, 4_000)
    .put(11, 1_000);

  // zoom-level 3-5 come from natural earth

  @Override
  public void processNaturalEarth(String table, SourceFeature feature, FeatureCollector features) {
    if (feature.hasTag("featurecla", "River")) {
      record ZoomRange(int min, int max) {}
      ZoomRange zoom = switch (table) {
        case "ne_110m_rivers_lake_centerlines" -> new ZoomRange(3, 3);
        case "ne_50m_rivers_lake_centerlines" -> new ZoomRange(4, 5);
        default -> null;
      };
      if (zoom != null) {
        features.line(LAYER_NAME)
          .setBufferPixels(BUFFER_SIZE)
          .setAttr(Fields.CLASS, FieldValues.CLASS_RIVER)
          .setZoomRange(zoom.min, zoom.max);
      }
    }
  }

  // zoom-level 6-8 come from OSM river relations

  private record WaterwayRelation(
    long id,
    Map<String, Object> names
  ) implements OsmRelationInfo {}

  @Override
  public List<OsmRelationInfo> preprocessOsmRelation(OsmElement.Relation relation) {
    if (relation.hasTag("waterway", "river") && !Utils.nullOrEmpty(relation.getString("name"))) {
      riverRelationLengths.put(relation.id(), new AtomicDouble());
      return List.of(new WaterwayRelation(relation.id(), LanguageUtils.getNames(relation.tags(), translations)));
    }
    return null;
  }

  @Override
  public void processAllOsm(SourceFeature feature, FeatureCollector features) {
    List<OsmReader.RelationMember<WaterwayRelation>> waterways = feature.relationInfo(WaterwayRelation.class);
    if (waterways != null && !waterways.isEmpty() && feature.canBeLine()) {
      for (var waterway : waterways) {
        String role = waterway.role();
        if (Utils.nullOrEmpty(role) || "main_stream".equals(role)) {
          long relId = waterway.relation().id();
          try {
            AtomicDouble counter = riverRelationLengths.get(relId);
            if (counter != null) {
              counter.addAndGet(feature.length());
            }
          } catch (GeometryException e) {
            e.log(stats, "waterway_decode", "Unable to get waterway length for " + feature.id());
          }
          features.line(LAYER_NAME)
            .setAttr(TEMP_REL_ID_ADDR, relId)
            .setBufferPixels(BUFFER_SIZE)
            .setAttr(Fields.CLASS, FieldValues.CLASS_RIVER)
            .putAttrs(waterway.relation().names())
            .setZoomRange(6, 8)
            .setMinPixelSize(0);
        }
      }
    }
  }

  // zoom-level 9+ come from OSM river ways

  @Override
  public void process(Tables.OsmWaterwayLinestring element, FeatureCollector features) {
    String waterway = element.waterway();
    String name = nullIfEmpty(element.name());
    boolean important = "river".equals(waterway) && name != null;
    int minzoom = important ? 9 : CLASS_MINZOOM.getOrDefault(element.waterway(), 14);
    features.line(LAYER_NAME)
      .setBufferPixels(BUFFER_SIZE)
      .setAttr(Fields.CLASS, element.waterway())
      .putAttrs(LanguageUtils.getNames(element.source().tags(), translations))
      .setMinZoom(minzoom)
      // details only at higher zoom levels so that named rivers can be merged more aggressively
      .setAttrWithMinzoom(Fields.BRUNNEL, Utils.brunnel(element.isBridge(), element.isTunnel()), 12)
      .setAttrWithMinzoom(Fields.INTERMITTENT, element.isIntermittent() ? 1 : 0, 12)
      // at lower zoom levels, we'll merge linestrings and limit length/clip afterwards
      .setBufferPixelOverrides(MIN_PIXEL_LENGTHS).setMinPixelSizeBelowZoom(11, 0);
  }

  @Override
  public List<VectorTile.Feature> postProcess(int zoom, List<VectorTile.Feature> items) {
    if (zoom >= 6 && zoom <= 8) {
      // remove ways for river relations if relation is not long enough
      double minSizeAtZoom = MIN_PIXEL_LENGTHS.apply(zoom).doubleValue() / Math.pow(2, zoom) / 256d;
      for (int i = 0; i < items.size(); i++) {
        Object relIdObj = items.get(i).attrs().remove(TEMP_REL_ID_ADDR);
        if (relIdObj instanceof Long relId && riverRelationLengths.get(relId).get() < minSizeAtZoom) {
          items.set(i, null);
        }
      }
      return FeatureMerge.mergeLineStrings(
        items,
        config.minFeatureSize(zoom),
        config.tolerance(zoom),
        BUFFER_SIZE
      );
    } else if (zoom >= 9 && zoom <= 11) {
      return FeatureMerge.mergeLineStrings(
        items,
        MIN_PIXEL_LENGTHS.apply(zoom).doubleValue(),
        config.tolerance(zoom),
        BUFFER_SIZE
      );
    }
    return items;
  }
}