/*
    *    Copyright 2016-2026 the original author or authors.
    *
    *    Licensed under the Apache License, Version 2.0 (the "License");
    *    you may not use this file except in compliance with the License.
    *    You may obtain a copy of the License at
    *
    *       https://www.apache.org/licenses/LICENSE-2.0
    *
   *    Unless required by applicable law or agreed to in writing, software
   *    distributed under the License is distributed on an "AS IS" BASIS,
   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *    See the License for the specific language governing permissions and
   *    limitations under the License.
   */
  package org.mybatis.dynamic.sql.where.render;
  
  import java.util.List;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  
  import org.mybatis.dynamic.sql.AndOrCriteriaGroup;
  import org.mybatis.dynamic.sql.ColumnAndConditionCriterion;
  import org.mybatis.dynamic.sql.CriteriaGroup;
  import org.mybatis.dynamic.sql.ExistsCriterion;
  import org.mybatis.dynamic.sql.ExistsPredicate;
  import org.mybatis.dynamic.sql.NotCriterion;
  import org.mybatis.dynamic.sql.NullCriterion;
  import org.mybatis.dynamic.sql.SqlCriterion;
  import org.mybatis.dynamic.sql.SqlCriterionVisitor;
  import org.mybatis.dynamic.sql.render.RenderingContext;
  import org.mybatis.dynamic.sql.select.render.SubQueryRenderer;
  import org.mybatis.dynamic.sql.util.FragmentAndParameters;
  import org.mybatis.dynamic.sql.util.FragmentCollector;
  
  /**
   * Renders a {@link SqlCriterion} to a {@link RenderedCriterion}. The process is complex because all conditions
   * may or may not be a candidate for rendering. For example, "isEqualWhenPresent" will not render when the value
   * is null. It is also complex because SqlCriterion may or may not include sub-criteria.
   *
   * <p>Rendering is a recursive process. The renderer will recurse into each sub-criteria - which may also
   * contain further sub-criteria - until all possible sub-criteria are rendered into a single fragment. So, for example,
   * the fragment may end up looking like:
   *
   * <pre>
   *     col1 = ? and (col2 = ? or (col3 = ? and col4 = ?))
   * </pre>
   *
   * <p>It is also possible that the end result will be empty if all criteria and sub-criteria are not valid for
   * rendering.
   *
   * @author Jeff Butler
   */
  public class CriterionRenderer implements SqlCriterionVisitor<Optional<RenderedCriterion>> {
      private final RenderingContext renderingContext;
  
      public CriterionRenderer(RenderingContext renderingContext) {
          this.renderingContext = Objects.requireNonNull(renderingContext);
      }
  
      @Override
      public <T> Optional<RenderedCriterion> visit(ColumnAndConditionCriterion<T> criterion) {
          Optional<FragmentAndParameters> initialCriterion = renderColumnAndCondition(criterion);
          List<RenderedCriterion> renderedSubCriteria = renderSubCriteria(criterion.subCriteria());
  
          return initialCriterion.map(fp -> calculateRenderedCriterion(fp, renderedSubCriteria, this::calculateFragment))
                  .orElseGet(() -> calculateRenderedCriterion(renderedSubCriteria, this::calculateFragment));
      }
  
      @Override
      public Optional<RenderedCriterion> visit(ExistsCriterion criterion) {
          FragmentAndParameters initialCriterion = renderExists(criterion);
          List<RenderedCriterion> renderedSubCriteria = renderSubCriteria(criterion.subCriteria());
  
          return calculateRenderedCriterion(initialCriterion, renderedSubCriteria, this::calculateFragment);
      }
  
      @Override
      public Optional<RenderedCriterion> visit(CriteriaGroup criterion) {
          return renderCriteriaGroup(criterion, this::calculateFragment);
      }
  
      @Override
      public Optional<RenderedCriterion> visit(NotCriterion criterion) {
          return renderCriteriaGroup(criterion, this::calculateNotFragment);
      }
  
      @Override
      public Optional<RenderedCriterion> visit(NullCriterion criterion) {
          return Optional.empty();
      }
  
      private Optional<RenderedCriterion> renderCriteriaGroup(CriteriaGroup criterion,
                                                              Function<FragmentCollector, String> fragmentCalculator) {
          return render(criterion.initialCriterion(), criterion.subCriteria(), fragmentCalculator);
      }
  
     public Optional<RenderedCriterion> render(SqlCriterion initialCriterion, List<AndOrCriteriaGroup> subCriteria,
                                               Function<FragmentCollector, String> fragmentCalculator) {
         Optional<FragmentAndParameters> fragmentAndParameters = initialCriterion.accept(this)
                 .map(RenderedCriterion::fragmentAndParameters);
         List<RenderedCriterion> renderedSubCriteria = renderSubCriteria(subCriteria);
 
         return fragmentAndParameters.map(fp -> calculateRenderedCriterion(fp, renderedSubCriteria, fragmentCalculator))
                 .orElseGet(() -> calculateRenderedCriterion(renderedSubCriteria, fragmentCalculator));
     }
 
     private <T> Optional<FragmentAndParameters> renderColumnAndCondition(ColumnAndConditionCriterion<T> criterion) {
         if (criterion.condition().shouldRender(renderingContext)) {
             return Optional.of(renderCondition(criterion));
         } else {
             criterion.condition().renderingSkipped();
             return Optional.empty();
         }
     }
 
     private FragmentAndParameters renderExists(ExistsCriterion criterion) {
         ExistsPredicate existsPredicate = criterion.existsPredicate();
         return SubQueryRenderer.withSelectModel(existsPredicate.selectModelBuilder().build())
                 .withRenderingContext(renderingContext)
                 .withPrefix(existsPredicate.operator() + " (") //$NON-NLS-1$
                 .withSuffix(")") //$NON-NLS-1$
                 .build()
                 .render();
     }
 
     private List<RenderedCriterion> renderSubCriteria(List<AndOrCriteriaGroup> subCriteria) {
         return subCriteria.stream().map(this::renderAndOrCriteriaGroup)
                 .flatMap(Optional::stream)
                 .toList();
     }
 
     private Optional<RenderedCriterion> renderAndOrCriteriaGroup(AndOrCriteriaGroup criterion) {
         return render(criterion.initialCriterion(), criterion.subCriteria(), this::calculateFragment)
                 .map(rc -> rc.withConnector(criterion.connector()));
     }
 
     private Optional<RenderedCriterion> calculateRenderedCriterion(FragmentAndParameters initialCriterion,
             List<RenderedCriterion> renderedSubCriteria, Function<FragmentCollector, String> fragmentCalculator) {
         return Optional.of(calculateRenderedCriterion(
                 collectSqlFragments(initialCriterion, renderedSubCriteria), fragmentCalculator));
     }
 
     private RenderedCriterion calculateRenderedCriterion(FragmentCollector fragmentCollector,
                                                          Function<FragmentCollector, String> fragmentCalculator) {
         FragmentAndParameters fragmentAndParameters = FragmentAndParameters
                 .withFragment(fragmentCalculator.apply(fragmentCollector))
                 .withParameters(fragmentCollector.parameters())
                 .build();
 
         return new RenderedCriterion.Builder()
                 .withFragmentAndParameters(fragmentAndParameters)
                 .build();
     }
 
     private Optional<RenderedCriterion> calculateRenderedCriterion(List<RenderedCriterion> renderedSubCriteria,
             Function<FragmentCollector, String> fragmentCalculator) {
         return collectSqlFragments(renderedSubCriteria).map(fc -> calculateRenderedCriterion(fc, fragmentCalculator));
     }
 
     private <T> FragmentAndParameters renderCondition(ColumnAndConditionCriterion<T> criterion) {
         return new ColumnAndConditionRenderer.Builder<T>()
                 .withColumn(criterion.column())
                 .withCondition(criterion.condition())
                 .withRenderingContext(renderingContext)
                 .build()
                 .render();
     }
 
     /**
      * This method encapsulates the logic of building a collection of fragments from an initial condition
      * and a list of rendered sub criteria. In this overload we know there is an initial condition
      * and there may be subcriteria. The collector will contain the initial condition and any rendered subcriteria
      * in order.
      *
      * @param initialCondition - may not be null. If there is no initial condition, then use the other overload
      * @param renderedSubCriteria - a list of previously rendered sub criteria. The sub criteria will all
      *                            have connectors (either an AND or an OR)
      * @return a fragment collector whose fragments represent the final calculated list of fragments and parameters.
      *     The fragment collector can be used to calculate the single composed fragment - either as a where clause, or
      *     a valid rendered sub criteria in the case of a recursive call.
      */
     private FragmentCollector collectSqlFragments(FragmentAndParameters initialCondition,
                                                   List<RenderedCriterion> renderedSubCriteria) {
         return renderedSubCriteria.stream()
                 .map(RenderedCriterion::fragmentAndParametersWithConnector)
                 .collect(FragmentCollector.collect(initialCondition));
     }
 
     /**
      * This method encapsulates the logic of building a collection of fragments from a list of rendered sub criteria.
      * In this overload we take the initial condition to be the first element in the subcriteria list.
      * The collector will contain the rendered subcriteria in order. However, the connector from the first rendered
      * sub criterion will be removed. This to avoid generating an invalid where clause like "where and a < 3"
      *
      * @param renderedSubCriteria - a list of previously rendered sub criteria. The sub criteria will all
      *                            have connectors (either an AND or an OR)
      * @return a fragment collector whose fragments represent the final calculated list of fragments and parameters.
      *     The fragment collector can be used to calculate the single composed fragment - either as a where clause, or
      *     a valid rendered sub criteria in the case of a recursive call.
      */
     private Optional<FragmentCollector> collectSqlFragments(List<RenderedCriterion> renderedSubCriteria) {
         if (renderedSubCriteria.isEmpty()) {
             return Optional.empty();
         }
 
         FragmentAndParameters firstCondition = renderedSubCriteria.get(0).fragmentAndParameters();
 
         FragmentCollector fc = renderedSubCriteria.stream()
                 .skip(1)
                 .map(RenderedCriterion::fragmentAndParametersWithConnector)
                 .collect(FragmentCollector.collect(firstCondition));
 
         return Optional.of(fc);
     }
 
     private String calculateFragment(FragmentCollector collector) {
         if (collector.hasMultipleFragments()) {
             return collector.collectFragments(
                     Collectors.joining(" ", "(", ")")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
         } else {
             return collector.firstFragment().orElse(""); //$NON-NLS-1$
         }
     }
 
     private String calculateNotFragment(FragmentCollector collector) {
         if (collector.hasMultipleFragments()) {
             return collector.collectFragments(
                     Collectors.joining(" ", "not (", ")")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
         } else {
             return collector.firstFragment().map(s -> "not " + s).orElse(""); //$NON-NLS-1$ //$NON-NLS-2$
         }
     }
 }