/*
    *    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 org.jspecify.annotations.Nullable;
  import org.mybatis.dynamic.sql.common.OrderByModel;
  import org.mybatis.dynamic.sql.common.OrderByRenderer;
  import org.mybatis.dynamic.sql.render.RenderingContext;
  import org.mybatis.dynamic.sql.render.RenderingStrategy;
  import org.mybatis.dynamic.sql.select.MultiSelectModel;
  import org.mybatis.dynamic.sql.select.PagingModel;
  import org.mybatis.dynamic.sql.select.SelectModel;
  import org.mybatis.dynamic.sql.select.UnionQuery;
  import org.mybatis.dynamic.sql.util.FragmentAndParameters;
  import org.mybatis.dynamic.sql.util.FragmentCollector;
  
  public class MultiSelectRenderer {
      private final MultiSelectModel multiSelectModel;
      private final RenderingContext renderingContext;
  
      private MultiSelectRenderer(Builder builder) {
          multiSelectModel = Objects.requireNonNull(builder.multiSelectModel);
          renderingContext = RenderingContext
                  .withRenderingStrategy(Objects.requireNonNull(builder.renderingStrategy))
                  .withStatementConfiguration(multiSelectModel.statementConfiguration())
                  .build();
      }
  
      public SelectStatementProvider render() {
          FragmentAndParameters initialSelect = renderSelect(multiSelectModel.initialSelect());
  
          FragmentCollector fragmentCollector = multiSelectModel
                  .unionQueries()
                  .map(this::renderSelect)
                  .collect(FragmentCollector.collect(initialSelect));
  
          renderOrderBy().ifPresent(fragmentCollector::add);
          renderPagingModel().ifPresent(fragmentCollector::add);
  
          return toSelectStatementProvider(fragmentCollector);
      }
  
      private SelectStatementProvider toSelectStatementProvider(FragmentCollector fragmentCollector) {
          return DefaultSelectStatementProvider
                  .withSelectStatement(fragmentCollector.collectFragments(Collectors.joining(" "))) //$NON-NLS-1$
                  .withParameters(fragmentCollector.parameters())
                  .build();
      }
  
      private FragmentAndParameters renderSelect(SelectModel selectModel) {
          return SubQueryRenderer.withSelectModel(selectModel)
                  .withRenderingContext(renderingContext)
                  .withPrefix("(") //$NON-NLS-1$
                  .withSuffix(")") //$NON-NLS-1$
                  .build()
                  .render();
      }
  
      private FragmentAndParameters renderSelect(UnionQuery unionQuery) {
          return SubQueryRenderer.withSelectModel(unionQuery.selectModel())
                  .withRenderingContext(renderingContext)
                  .withPrefix(unionQuery.connector() + " (") //$NON-NLS-1$
                  .withSuffix(")") //$NON-NLS-1$
                  .build()
                  .render();
      }
  
      private Optional<FragmentAndParameters> renderOrderBy() {
          return multiSelectModel.orderByModel().map(this::renderOrderBy);
      }
  
      private FragmentAndParameters renderOrderBy(OrderByModel orderByModel) {
          return new OrderByRenderer(renderingContext).render(orderByModel);
      }
  
      private Optional<FragmentAndParameters> renderPagingModel() {
          return multiSelectModel.pagingModel().map(this::renderPagingModel);
      }
  
      private FragmentAndParameters renderPagingModel(PagingModel pagingModel) {
          return new PagingModelRenderer.Builder()
                  .withPagingModel(pagingModel)
                 .withRenderingContext(renderingContext)
                 .build()
                 .render();
     }
 
     public static Builder withMultiSelectModel(MultiSelectModel multiSelectModel) {
         return new Builder().withMultiSelectModel(multiSelectModel);
     }
 
     public static class Builder {
         private @Nullable RenderingStrategy renderingStrategy;
         private @Nullable MultiSelectModel multiSelectModel;
 
         public Builder withRenderingStrategy(RenderingStrategy renderingStrategy) {
             this.renderingStrategy = renderingStrategy;
             return this;
         }
 
         public Builder withMultiSelectModel(MultiSelectModel multiSelectModel) {
             this.multiSelectModel = multiSelectModel;
             return this;
         }
 
         public MultiSelectRenderer build() {
             return new MultiSelectRenderer(this);
         }
     }
 }