/*
 * 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.steps;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

import com.google.common.collect.Range;

import nz.org.riskscape.engine.Engine;
import nz.org.riskscape.engine.pipeline.RealizationInput;
import nz.org.riskscape.engine.pipeline.Realized;
import nz.org.riskscape.engine.pipeline.RealizedStep;
import nz.org.riskscape.engine.problem.GeneralProblems;
import nz.org.riskscape.engine.projection.UnionProjector;
import nz.org.riskscape.problem.Problem;
import nz.org.riskscape.problem.Problem.Severity;
import nz.org.riskscape.problem.ResultOrProblems;

public class UnionStep extends BaseStep<UnionStep.Parameters> {

  public static class Parameters {

    @Input
    public List<RealizedStep> inputs;

    //Injected field
    public RealizationInput rInput;
  }

  public UnionStep(Engine engine) {
    // union step takes 2 or more inputs, all of which are unnamed
    super(engine, Range.atLeast(2), Collections.emptyList());
  }

  @Override
  public ResultOrProblems<? extends Realized> realize(Parameters parameters) {
    return UnionProjector.realize(parameters.rInput.getRealizationContext().getTypeSet(), parameters.inputs.stream()
        .map(input -> input.getProduces())
        .collect(Collectors.toList())
      );
  }

  @Override
  protected ResultOrProblems<UnionStep.Parameters> bindInputs(RealizationInput input, UnionStep.Parameters parameters) {
    List<RealizedStep> inputs = input.getDependencies();

    List<Problem> problems = new ArrayList<>();
    if (inputs.size() < 2) {
      // we expect >= 2 inputs, but allow the user to specify only 1 input for testing/debugging
      Problem arityError = GeneralProblems.get().badArity(Input.class, this, getInputArity(), inputs.size());
      if (inputs.size() == 1) {
        problems.add(arityError.withSeverity(Severity.WARNING));
      } else {
        return ResultOrProblems.failed(arityError);
      }
    }
    parameters.inputs = inputs;
    return ResultOrProblems.of(parameters, problems);
  }
}
