package cn.itcast.oa.util;

import java.util.ArrayList;
import java.util.List;

import cn.itcast.oa.base.DaoSupport;
import cn.itcast.oa.domain.PageBean;

import com.opensymphony.xwork2.ActionContext;

/**
 * 用于辅助拼接HQL语句_工具
 * 
 * @author 
 * @version V1.0
 */
@SuppressWarnings({ "rawtypes" })
public class QueryHelper {
  private String fromClause;// From子句
  private String whereClause = "";// Where子句
  private String orderByClause = "";// OrderBy子句

  private List<Object> parameters = new ArrayList<Object>();// 参数列表

  /**
   * 生成From子句
   * 
   * @param clazz
   * @param alias
   *            别名
   */
  public QueryHelper(Class clazz, String alias) {
    fromClause = " from " + clazz.getSimpleName() + " " + alias;// from User u
  }

  /**
   * 拼接Where子句
   * 
   * @param condition
   * @param params
   */
  public QueryHelper addCondition(String condition, Object... params) {
    // 拼接
    if (whereClause.length() == 0) {
      whereClause = " where " + condition;// from User u where ?
    } else {
      whereClause += " and " + condition;// from User u where ?,and ?
    }

    // 参数
    if (params != null) {
      for (Object obj : params) {
        parameters.add(obj);
      }
    }
    return this;
  }

  /**
   * 如果第一个参数为true,则拼接Where子句
   * 
   * @param append
   * @param condition
   * @param params
   */
  public QueryHelper addCondition(boolean append, String condition, Object... params) {
    if (append) {
      addCondition(condition, params);
    }
    return this;
  }

  /**
   * 拼接OrderBy子句
   * 
   * @param propertyName
   *            参于排序的属性名
   * @param asc
   *            true表示升序(1,2,3),false表示降序(3,2,1)
   */
  public QueryHelper addOrderProperty(String propertyName, boolean asc) {
    if (orderByClause.length() == 0) {
      orderByClause = " Order by " + propertyName + (asc ? " asc " : " desc ");// from User u where ? order by ? asc/desc
    } else {
      orderByClause += " , " + propertyName + (asc ? " asc " : " desc ");// from User u where ? order by ? asc/desc,? asc/desc
    }
    return this;
  }

  /**
   * 如果第一个参数为true,则拼接OrderBy子句
   * 
   * @param append
   * @param propertyName
   * @param asc
   */
  public QueryHelper addOrderProperty(boolean append, String propertyName, boolean asc) {
    if (append) {
      addOrderProperty(propertyName, asc);
    }
    return this;
  }

  /**
   * 获取生成用于查询数据列表的HQL语句
   * 
   * @return
   */
  public String getListQueryHql() {
    return fromClause + whereClause + orderByClause;
  }

  /**
   * 获取生成用于查询总记录数的HQL语句
   * 
   * @return
   */
  public String getCountQueryHql() {
    return " select count(*) " + fromClause + whereClause;
  }

  /**
   * 获取HQL中的参数值列表
   * 
   * @return
   */
  public List<Object> getParameters() {
    return parameters;
  }

  /**
   * 查询分页信息,并放到值栈栈顶
   * @param service
   * @param pageNum
   * @param pageSize
   */
  public void preparePageBean(DaoSupport<?> service,int pageNum, int pageSize) {
    PageBean pageBean = service.getPageBean(pageNum, pageSize, this);
    ActionContext.getContext().getValueStack().push(pageBean);
  }

}