/*
 * 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;

import java.util.List;
import java.util.Optional;

import nz.org.riskscape.engine.function.IdentifiedFunction;
import nz.org.riskscape.engine.function.RiskscapeFunction;
import nz.org.riskscape.engine.rl.RealizableFunction;
import nz.org.riskscape.engine.rl.RealizationContext;
import nz.org.riskscape.engine.types.Nullable;
import nz.org.riskscape.engine.types.Struct;
import nz.org.riskscape.engine.types.Struct.StructBuilder;
import nz.org.riskscape.engine.types.Struct.StructMember;
import nz.org.riskscape.problem.ResultOrProblems;
import nz.org.riskscape.engine.types.Type;
import nz.org.riskscape.rl.ast.FunctionCall;


/**
 * A dummy {@link RealizableFunction}. The backing {@link #realizedFunction} is returned by
 * {@link #realize(RealizationContext, FunctionCall, List)}.
 *
 * Other methods will proxy to same method on the backing {@link #realizedFunction} except for
 * {@link #call(java.util.List) } which will throw an exception.
 */
public class RealizableDummyFunction implements IdentifiedFunction, RealizableFunction {

  private final IdentifiedFunction realizedFunction;
  private final Type returnType;

  /**
   * The list of types that where passed to
   * {@link #realize(RealizationContext, FunctionCall, java.util.List) } if that method has been called.
   */
  public List<Type> realizedTypes;

  public RealizableDummyFunction(IdentifiedFunction realizedFunction) {
    this.realizedFunction = realizedFunction;
    Type realizedReturnType = realizedFunction.getReturnType();
    boolean nullable = Nullable.is(realizedReturnType);
    returnType = realizedReturnType.findAllowNull(Struct.class)
        .map(s -> {
          //If the return type is a struct we make a replica of it. So that Tuple.checkOwner problems
          //will exist in test code based on this RealizableDummyFunction;
          StructBuilder sb = Struct.builder();
          for (StructMember m: s.getMembers()) {
            sb.add(m.getKey(), m.getType());
          }
          return Nullable.ifTrue(nullable, sb.build());
        }).orElse(realizedReturnType);
  }



  @Override
  public ResultOrProblems<RiskscapeFunction> realize(
      RealizationContext context,
      FunctionCall functionCall,
      List<Type> argumentTypes) {
    realizedTypes = argumentTypes;
    //Just return the pre-canned realizedFunction
    return ResultOrProblems.of(realizedFunction);
  }

  @Override
  public Optional<RealizableFunction> getRealizable() {
    return Optional.of(this);
  }

  @Override
  public Object call(List<Object> args) {
    throw new UnsupportedOperationException("call is not supported. function must be realized.");
  }

  @Override
  public String getId() {
    return realizedFunction.getId();
  }

  @Override
  public List<Type> getArgumentTypes() {
    return realizedFunction.getArgumentTypes();
  }

  @Override
  public Type getReturnType() {
    return returnType;
  }

  @Override
  public String getDescription() {
    return realizedFunction.getDescription();
  }

  @Override
  public String getSource() {
    return realizedFunction.getSource();
  }

  @Override
  public Category getCategory() {
    return realizedFunction.getCategory();
  }

}
