/*
 * RiskScape™ Copyright New Zealand Institute for Earth Science Limited
 * (Earth Sciences New Zealand) is distributed for research purposes only
 * under the terms of AGPLv3.
 *
 * RiskScape™ Copyright 2026 New Zealand Institute for Earth Science
 * Limited (Earth Sciences New Zealand). All rights reserved. Source code
 * available under the AGPLv3.
 * 
 * This program is free software: you can redistribute it and/or modify it under
 *  the terms of the GNU Affero General Public License as published by the Free
 *  Software Foundation, either version 3 of the License, or (at your option) any
 *  later version.
 * 
 * This program is distributed for RESEARCH PURPOSES ONLY, in the hope that it will
 * be useful for research and education initiatives.
 * 
 * If you are not a researcher, or you are a researcher who wishes to use this
 * program on terms other than AGPLv3 (including those who wish to restrict the
 * distribution of any source code created using this program), please contact:
 * https://riskscape.org.nz
 * 
 * This program is distributed WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Affero General Public License for more details.  You should have received a copy
 * of the GNU Affero General Public License along with this program.  If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * By way of summary only, under the AGPLv3:
 *     • Permissions of this strongest copyleft license are conditioned
 *       on making available complete source code of licensed works and
 *       modifications, which include larger works using a licensed work,
 *       under the same license.
 *     • Copyright and license notices must be preserved.
 *     • Contributors provide an express grant of patent rights.
 *     • When a modified version is used to provide a service over a
 *       network, the complete source code of the modified version must be made
 *       available.
 */
package nz.org.riskscape.engine.defaults.data;

import java.util.List;
import java.util.Optional;
import java.util.function.Function;

import org.geotools.api.referencing.crs.CoordinateReferenceSystem;
import org.geotools.geometry.jts.ReferencedEnvelope;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.Point;

import lombok.Getter;
import lombok.RequiredArgsConstructor;
import nz.org.riskscape.engine.Tuple;
import nz.org.riskscape.engine.coverage.TypedCoverage;
import nz.org.riskscape.engine.geo.IntersectionIndex;
import nz.org.riskscape.engine.types.Struct.StructMember;
import nz.org.riskscape.engine.types.Type;
import nz.org.riskscape.engine.util.Pair;

/**
 * A {@link TypedCoverage} that composites multiple coverages together by spatial location.
 * Each underlying coverage is indexed by its envelope, and when sampled, the mosaic returns
 * the max value from all of the intersecting coverages.
 */
@RequiredArgsConstructor
public class MosaicCoverage implements TypedCoverage {

  /**
   * Index of tuples, where each tuple contains a coverage and its spatial extent
   */
  private final IntersectionIndex coverages;

  /**
   * The member of each tuple that contains the TypedCoverage
   */
  private final StructMember coverageMember;

  @Getter
  private final Type type;

  @Override
  public Object evaluate(Point point) {
    List<Tuple> pointIntersections = coverages.findPointIntersections(point);

    Double max = null;
    // Try each intersecting coverage - pick the max (but should be configurable)
    for (Tuple tuple : pointIntersections) {
      TypedCoverage coverage = (TypedCoverage) tuple.fetch(coverageMember);
      Double value = (Double) coverage.evaluate(point);

      if (value != null) {
        if (max == null) {
          max = value;
        } else {
          max = Math.max(max, value);
        }
      }
    }

    // this will be the biggest value we saw, or the default of null (so no data)
    return max;
  }

  @Override
  public Optional<Function<Geometry, List<Pair<Geometry, Object>>>> getEvaluateIntersectionOp() {
    return Optional.empty();
  }

  @Override
  public Optional<Function<Geometry, List<? extends Object>>> getEvaluateIntersectingValuesOp() {
    return Optional.empty();
  }

  @Override
  public CoordinateReferenceSystem getCoordinateReferenceSystem() {
    return coverages.getReferencedEnvelope().getCoordinateReferenceSystem();
  }

  @Override
  public Optional<ReferencedEnvelope> getEnvelope() {
    return Optional.of(coverages.getReferencedEnvelope());
  }
}
