/*
    *    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 org.mybatis.dynamic.sql.exception.InvalidSqlException;
  import org.mybatis.dynamic.sql.render.RenderedParameterInfo;
  import org.mybatis.dynamic.sql.render.RenderingContext;
  import org.mybatis.dynamic.sql.select.PagingModel;
  import org.mybatis.dynamic.sql.util.FragmentAndParameters;
  import org.mybatis.dynamic.sql.util.InternalError;
  import org.mybatis.dynamic.sql.util.Messages;
  
  public class FetchFirstPagingModelRenderer {
      private final RenderingContext renderingContext;
      private final PagingModel pagingModel;
  
      public FetchFirstPagingModelRenderer(RenderingContext renderingContext, PagingModel pagingModel) {
          this.renderingContext = renderingContext;
          this.pagingModel = pagingModel;
      }
  
      public FragmentAndParameters render() {
          return pagingModel.offset()
                  .map(this::renderWithOffset)
                  .orElseGet(this::renderFetchFirstRowsOnly);
      }
  
      private FragmentAndParameters renderWithOffset(Long offset) {
          return pagingModel.fetchFirstRows()
                  .map(ffr -> renderOffsetAndFetchFirstRows(offset, ffr))
                  .orElseGet(() -> renderOffsetOnly(offset));
      }
  
      private FragmentAndParameters renderFetchFirstRowsOnly() {
          return pagingModel.fetchFirstRows().map(this::renderFetchFirstRowsOnly)
                  .orElseThrow(() ->
                          new InvalidSqlException(Messages.getInternalErrorString(InternalError.INTERNAL_ERROR_13)));
      }
  
      private FragmentAndParameters renderFetchFirstRowsOnly(Long fetchFirstRows) {
          RenderedParameterInfo fetchFirstParameterInfo = renderingContext.calculateFetchFirstRowsParameterInfo();
          return FragmentAndParameters
                  .withFragment("fetch first " + fetchFirstParameterInfo.renderedPlaceHolder() //$NON-NLS-1$
                      + " rows only") //$NON-NLS-1$
                  .withParameter(fetchFirstParameterInfo.parameterMapKey(), fetchFirstRows)
                  .build();
      }
  
      private FragmentAndParameters renderOffsetOnly(Long offset) {
          RenderedParameterInfo offsetParameterInfo = renderingContext.calculateOffsetParameterInfo();
          return FragmentAndParameters.withFragment("offset " + offsetParameterInfo.renderedPlaceHolder() //$NON-NLS-1$
                  + " rows") //$NON-NLS-1$
                  .withParameter(offsetParameterInfo.parameterMapKey(), offset)
                  .build();
      }
  
      private FragmentAndParameters renderOffsetAndFetchFirstRows(Long offset, Long fetchFirstRows) {
          RenderedParameterInfo offsetParameterInfo = renderingContext.calculateOffsetParameterInfo();
          RenderedParameterInfo fetchFirstParameterInfo = renderingContext.calculateFetchFirstRowsParameterInfo();
          return FragmentAndParameters.withFragment("offset " + offsetParameterInfo.renderedPlaceHolder() //$NON-NLS-1$
                  + " rows fetch first " + fetchFirstParameterInfo.renderedPlaceHolder() //$NON-NLS-1$
                  + " rows only") //$NON-NLS-1$
                  .withParameter(offsetParameterInfo.parameterMapKey(), offset)
                  .withParameter(fetchFirstParameterInfo.parameterMapKey(), fetchFirstRows)
                  .build();
      }
  }