/*
 * 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.function.lang;

import java.util.Arrays;
import java.util.List;

import nz.org.riskscape.engine.ArgsProblems;
import nz.org.riskscape.engine.function.ArgumentList;
import nz.org.riskscape.engine.function.BaseRealizableFunction;
import nz.org.riskscape.engine.function.RiskscapeFunction;
import nz.org.riskscape.engine.rl.RealizationContext;
import nz.org.riskscape.engine.types.EmptyList;
import nz.org.riskscape.engine.types.Nullable;
import nz.org.riskscape.engine.types.RSList;
import nz.org.riskscape.engine.types.Type;
import nz.org.riskscape.engine.types.Types;
import nz.org.riskscape.engine.types.ancestor.AncestorType;
import nz.org.riskscape.problem.ProblemException;
import nz.org.riskscape.problem.ResultOrProblems;
import nz.org.riskscape.rl.ast.FunctionCall;
import nz.org.riskscape.util.ListUtils;

public class AppendList extends BaseRealizableFunction {

  public AppendList() {
    super(
      ArgumentList.create(
          "list", Nullable.of(RSList.LIST_ANYTHING),
          "element", Nullable.ANYTHING
      ),
      RSList.LIST_ANYTHING
    );
  }

  @Override
  public ResultOrProblems<RiskscapeFunction> realize(RealizationContext context, FunctionCall functionCall,
      List<Type> givenTypes) {

    if (givenTypes.size() != arguments.size()) {
      return ResultOrProblems.failed(ArgsProblems.get().wrongNumber(arguments.size(), givenTypes.size()));
    }

    return ProblemException.catching(() -> {
      Type appendToType = Nullable.strip(givenTypes.get(0));
      Type elementType = givenTypes.get(1);
      if (appendToType == EmptyList.INSTANCE) {
        return RiskscapeFunction.create(this, givenTypes, RSList.create(elementType), args -> {
          Object element = args.get(1);
          return Arrays.asList(element);
        });
      } else {
        RSList listType = Types.findOrThrow(functionCall.getArguments().get(0), RSList.LIST_ANYTHING,
            Nullable.strip(givenTypes.get(0)));

        // work out the common type
        AncestorType ancestorType = context.getTypeSet().computeAncestorType(
          listType.getContainedType(),
          elementType
        ).orElse(AncestorType.of(Types.ANYTHING));

        RSList listReturnType = RSList.create(ancestorType.getType());

        // we need an ancestor type to convert the list if necessary.
        // e.g if we have a list of integer and are appending a float
        AncestorType listAncestorType = context.getTypeSet().computeAncestorType(listType, listReturnType)
            .orElse(AncestorType.of(RSList.LIST_ANYTHING));

        return RiskscapeFunction.create(this, givenTypes, listReturnType, args -> {
          List<?> list = (List<?>) args.get(0);
          Object element = ancestorType.getConvert().apply(args.get(1));

          if (list == null) {
            return Arrays.asList(element);
          }
          list = (List<?>)listAncestorType.getConvert().apply(list);

          // TODO probably want to consider whether some sort of immutable list type might be better here
          // to allow lists to be linked, which will work better with the immutable style of rl
          return ListUtils.append(list, element);
        });
      }

    });

  }
}
