package com.foxinmy.weixin4j.model.paging;
   
   import java.io.Serializable;
   
   import com.foxinmy.weixin4j.model.paging.Sort.Direction;
   
   /**
    * 分页数据(页码从1开始
    * 
   * @className Pageable
   * @author jinyu(foxinmy@gmail.com)
   * @date 2014年12月27日
   * @since JDK 1.6
   */
  public class Pageable implements Serializable {
  
  	private static final long serialVersionUID = -8051554878205756307L;
  
  	private final int page;
  	private final int size;
  	private Sort sort;
  
  	/**
  	 * 
  	 * @param page
  	 *            must not be less than one.
  	 * @param size
  	 *            must not be less than one.
  	 */
  	public Pageable(int page, int size) {
  		if (page < 1) {
  			throw new IllegalArgumentException(
  					"Page index must not be less than one!");
  		}
  		if (size < 1) {
  			throw new IllegalArgumentException(
  					"Page size must not be less than one!");
  		}
  		this.page = page;
  		this.size = size;
  	}
  
  	public Pageable(int page, int size, Direction direction,
  			String... properties) {
  		this(page, size, new Sort(direction, properties));
  	}
  
  	public Pageable(int page, int size, Sort sort) {
  		this.page = page;
  		this.size = size;
  		this.sort = sort;
  	}
  
  	/**
  	 * page=1,size=20
  	 * 
  	 * @return
  	 */
  	public static Pageable get() {
  		return new Pageable(1, 20);
  	}
  
  	public int getPageSize() {
  		return size;
  	}
  
  	public int getPageNumber() {
  		return page;
  	}
  
  	public Sort getSort() {
  		return sort;
  	}
  
  	public void setSort(Sort sort) {
  		this.sort = sort;
  	}
  
  	public int getOffset() {
  		return (page - 1) * size;
  	}
  
  	public boolean hasPrevious() {
  		return page > 1;
  	}
  
  	public Pageable next() {
  		return new Pageable(getPageNumber() + 1, getPageSize(), getSort());
  	}
  
  	public Pageable previous() {
  		return getPageNumber() == 1 ? this : new Pageable(getPageNumber() - 1,
  				getPageSize(), getSort());
  	}
  
  	public Pageable first() {
  		return new Pageable(1, getPageSize(), getSort());
  	}
  
 	@Override
 	public String toString() {
 		return "Pageable [page=" + page + ", size=" + size + ", sort=" + sort
 				+ "]";
 	}
 }