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package org.springframework.data.domain;

import java.lang.reflect.Field;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.springframework.core.convert.converter.Converter;
import org.springframework.util.ReflectionUtils;
import org.springframework.web.util.UriComponentsBuilder;

/**
 * @see org.springframework.data.domain.Page
 * @see org.springframework.data.domain.SliceImpl
 * @see org.springframework.hateoas.Link
 */
public class PageImplCustom extends PageImpl {
  private static final long serialVersionUID = -5021629657557291345L;
  private boolean direction;
  private UriComponentsBuilder builder;
  private Map link = new LinkedHashMap();
  private static final Field PAGEABLE = ReflectionUtils.findField(PageImpl.class, "pageable");
  private static final Field TOTAL = ReflectionUtils.findField(PageImpl.class, "total");

  static {
    ReflectionUtils.makeAccessible(PAGEABLE);
    ReflectionUtils.makeAccessible(TOTAL);
  }

  public PageImplCustom() {
    this(Collections.emptyList(), null, 0, null);
  }

  public PageImplCustom(List content, Pageable pageable, long total, UriComponentsBuilder builder) {
    super(content, pageable, total);
    this.direction = pageable instanceof OffsetRequest && ((OffsetRequest) pageable).hasDirection();
    this.builder = builder;
  }

  @Override
  public boolean hasNext() {
    return this.direction ? true : super.hasNext();
  }

  @Override
  public boolean hasPrevious() {
    return this.direction ? true : super.hasPrevious();
  }

  @Override
  public int getTotalPages() {
    return this.direction ? 0 : super.getTotalPages();
  }

  public boolean isMore() {
    return this.direction ? !(getNumberOfElements() == getTotalElements()) : (!isLast() && !isFirst());
  }

  public Map getLink() {
    Object pageable = ReflectionUtils.getField(PAGEABLE, this);
    boolean offset = pageable instanceof OffsetRequest;
    String pageParameterName = offset ? ((OffsetRequest) pageable).getPageParameterName() : "page";
    String sizeParameterName = offset ? ((OffsetRequest) pageable).getSizeParameterName() : "size";
    String nextParameterName = offset ? ((OffsetRequest) pageable).getNextParameterName() : "next";
    String prevParameterName = offset ? ((OffsetRequest) pageable).getPrevParameterName() : "prev";
    if (this.builder != null) {
      this.builder.scheme(null).host(null).port(null).replaceQueryParam(sizeParameterName, getSize());
      if (this.direction) {
        this.builder.replaceQueryParam(nextParameterName, "").replaceQueryParam(prevParameterName);
      }
      this.link.put(nextParameterName, this.builder.replaceQueryParam(pageParameterName, hasNext() ? nextPageable().getPageNumber() : getNumber()).build().toUriString());

      if (this.direction) {
        this.builder.replaceQueryParam(nextParameterName).replaceQueryParam(prevParameterName, "");
      }
      this.link.put(prevParameterName, this.builder.replaceQueryParam(pageParameterName, hasPrevious() ? previousPageable().getPageNumber() : getNumber()).build().toUriString());
    }
    return this.link;
  }

  @Override
  public  Page map(Converter converter) {
    Object pageable = ReflectionUtils.getField(PAGEABLE, this);
    return new PageImplCustom(getConvertedContent(converter), (pageable instanceof Pageable ? (Pageable) pageable : null), getTotalElements(), this.builder);
  }

  public Page page(Pageable pageable) {
    return new PageImplCustom(getContent(), pageable, getTotalElements(), this.builder);
  }

  public void setTotalElements(long totalElements) {
    ReflectionUtils.setField(TOTAL, this, totalElements);
  }

  @Override
  public int hashCode() {
    return super.hashCode();
  }

  @Override
  public boolean equals(Object obj) {
    return super.equals(obj);
  }
}