/*
 * 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.pipeline;

import java.util.List;
import java.util.Map;
import java.util.function.Consumer;

import nz.org.riskscape.engine.bind.Parameter;
import nz.org.riskscape.engine.rl.RealizationContext;
import nz.org.riskscape.problem.Problem;
import nz.org.riskscape.rl.ast.AST;
import nz.org.riskscape.rl.ast.Expression;
import nz.org.riskscape.rl.ast.PipelineDeclaration;

/**
 * Methods for converting {@link PipelineDeclaration}s in to {@link RealizedPipeline}s
 */
public interface PipelineRealizer {

  /**
   * Common handling for populating an unbound parameter from an expression, with some specific handling for realizing
   * expressions or binding expressions straight-to the parameterMap
   *
   * @param context for realizing constants
   * @param parameter the parameter to bind
   * @param value the expression being bound
   * @param parameters map to populate
   * @param problemConsumer where to put errors with realizing constants
   */
  static void populateUnboundFromExpression(
      RealizationContext context,
      Parameter parameter,
      AST value,
      Map<String, List<?>> parameters,
      Consumer<List<Problem>> problemConsumer
  ) {

    if (AST.class.isAssignableFrom(parameter.getType())) {
      parameters.put(parameter.getName(), List.of(value));
    } else if (value instanceof Expression expr){
      Object constant = context.getExpressionRealizer()
          .realizeConstant(expr)
          .map(re -> re.evaluateConstant())
          .orElse(problemConsumer, null);

      if (constant != null) {
        if (constant instanceof List<?> list) {
          parameters.put(parameter.getName(), list);
        } else {
          parameters.put(parameter.getName(), List.of(constant));
        }
      }
    } else {
      // this will probably fail, but will hopefully give a reasonable error message? Maybe we need to convert it to a
      // string instead?
      parameters.put(parameter.getName(), List.of(value));
    }
  }

  /**
   * Realizes a {@link PipelineDeclaration} in to a {@link RealizedPipeline}.  A realized
   * pipeline is effectively 'compiled' at this point to the extent that we know the various functions exist and that it
   * is type safe.  It can now be handed over to a {@link PipelineExecutor} for execution.
   */
  RealizedPipeline realize(ExecutionContext context, PipelineDeclaration pipeline);

  /**
   * Incremental version of {@link #realize(ExecutionContext, PipelineDeclaration)} that realizes a pipeline "on top" of
   * another pipeline, e.g. new steps should be added in on top of the existing pipeline.
   *
   * This method is here to support {@link Step}s that want to realize some kind of sub pipeline that gets executed as
   * part of the parent.
   */
  RealizedPipeline realize(RealizedPipeline addTo, PipelineDeclaration pipeline);
}
