/*
    *    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;
  
  import java.util.Optional;
  
  import org.jspecify.annotations.Nullable;
  
  public class PagingModel {
  
      private final @Nullable Long limit;
      private final @Nullable Long offset;
      private final @Nullable Long fetchFirstRows;
  
      private PagingModel(Builder builder) {
          super();
          limit = builder.limit;
          offset = builder.offset;
          fetchFirstRows = builder.fetchFirstRows;
      }
  
      public Optional<Long> limit() {
          return Optional.ofNullable(limit);
      }
  
      public Optional<Long> offset() {
          return Optional.ofNullable(offset);
      }
  
      public Optional<Long> fetchFirstRows() {
          return Optional.ofNullable(fetchFirstRows);
      }
  
      public static class Builder {
          private @Nullable Long limit;
          private @Nullable Long offset;
          private @Nullable Long fetchFirstRows;
  
          public Builder withLimit(@Nullable Long limit) {
              this.limit = limit;
              return this;
          }
  
          public Builder withOffset(@Nullable Long offset) {
              this.offset = offset;
              return this;
          }
  
          public Builder withFetchFirstRows(@Nullable Long fetchFirstRows) {
              this.fetchFirstRows = fetchFirstRows;
              return this;
          }
  
          public Optional<PagingModel> build() {
              if (limit == null && offset == null && fetchFirstRows == null) {
                  return Optional.empty();
              }
  
              return Optional.of(new PagingModel(this));
          }
      }
  }