/*
    *    Copyright 2016-2025 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.select.render;
  
  import java.util.Objects;
  import java.util.Optional;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import org.mybatis.dynamic.sql.BasicColumn;
  import org.mybatis.dynamic.sql.render.RenderingContext;
  import org.mybatis.dynamic.sql.select.caseexpression.SimpleCaseModel;
  import org.mybatis.dynamic.sql.select.caseexpression.SimpleCaseWhenCondition;
  import org.mybatis.dynamic.sql.util.FragmentAndParameters;
  import org.mybatis.dynamic.sql.util.FragmentCollector;
  
  public class SimpleCaseRenderer<T> {
      private final SimpleCaseModel<T> simpleCaseModel;
      private final RenderingContext renderingContext;
      private final SimpleCaseWhenConditionRenderer<T> whenConditionRenderer;
  
      public SimpleCaseRenderer(SimpleCaseModel<T> simpleCaseModel, RenderingContext renderingContext) {
          this.simpleCaseModel = Objects.requireNonNull(simpleCaseModel);
          this.renderingContext = Objects.requireNonNull(renderingContext);
          whenConditionRenderer = new SimpleCaseWhenConditionRenderer<>(renderingContext, simpleCaseModel.column());
      }
  
      public FragmentAndParameters render() {
          FragmentCollector fc = new FragmentCollector();
          fc.add(renderCase());
          fc.add(renderWhenConditions());
          renderElse().ifPresent(fc::add);
          fc.add(renderEnd());
          return fc.toFragmentAndParameters(Collectors.joining(" ")); //$NON-NLS-1$
      }
  
      private FragmentAndParameters renderCase() {
          return simpleCaseModel.column().alias()
                  .map(FragmentAndParameters::fromFragment)
                  .orElseGet(() -> simpleCaseModel.column().render(renderingContext))
                  .mapFragment(f -> "case " + f); //$NON-NLS-1$
      }
  
      private FragmentAndParameters renderWhenConditions() {
          return simpleCaseModel.whenConditions().map(this::renderWhenCondition)
                  .collect(FragmentCollector.collect())
                  .toFragmentAndParameters(Collectors.joining(" ")); //$NON-NLS-1$
      }
  
      private FragmentAndParameters renderWhenCondition(SimpleCaseWhenCondition<T> whenCondition) {
          return Stream.of(
                  renderWhen(),
                  renderConditions(whenCondition),
                  renderThen(whenCondition)
          ).collect(FragmentCollector.collect())
                  .toFragmentAndParameters(Collectors.joining(" ")); //$NON-NLS-1$
      }
  
      private FragmentAndParameters renderWhen() {
          return FragmentAndParameters.fromFragment("when"); //$NON-NLS-1$
      }
  
      private FragmentAndParameters renderConditions(SimpleCaseWhenCondition<T> whenCondition) {
          return whenCondition.accept(whenConditionRenderer);
      }
  
      private FragmentAndParameters renderThen(SimpleCaseWhenCondition<T> whenCondition) {
          return whenCondition.thenValue().render(renderingContext)
                  .mapFragment(f -> "then " + f); //$NON-NLS-1$
      }
  
      private Optional<FragmentAndParameters> renderElse() {
          return simpleCaseModel.elseValue().map(this::renderElse);
      }
  
      private FragmentAndParameters renderElse(BasicColumn elseValue) {
          return elseValue.render(renderingContext).mapFragment(f -> "else " + f); //$NON-NLS-1$
      }
  
      private FragmentAndParameters renderEnd() {
          return FragmentAndParameters.fromFragment("end"); //$NON-NLS-1$
      }
  }