package lessionman;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import db.dbconn;

public class classlession_operation {
    /**
     * 功能:得到所有錄入了成績的班級與課程數據
     * 輸入:class_id為班級ID號,lession_id為課程ID號
     * 輸出:有成績的班級與課程數據記錄集
     */
    public ResultSet getCoreClassLessionRs(int class_id,int lession_id){
        String sqlString=null;//SQL語句字符串
        Statement sql=null;//SQL語句對象
        ResultSet rs=null;//結果記錄集
        dbconn dbconnOBject=new dbconn();//數據庫連接對象
        Connection dbconn=dbconnOBject.getDBConn();//得到數據庫連接
        if(dbconn==null) return null;//連接失敗
        sqlString="select distinct core.lession_id as lession_id," +
        		"class.class_name as class_name,student.class_id as class_id," +
        		"lession.lession_name from core,student,lession,class" +
        		" where core.student_id=student.student_id and" +
        		" student.class_id=class.class_id and lession.lession_id=core.lession_id";
        if(class_id!=0)
            sqlString=sqlString+" and student.class_id="+class_id+"" +
            		" and class.class_id="+class_id;
        if(lession_id!=0)
            sqlString=sqlString+" and lession.lession_id="+lession_id+"" +
            		" and core.lession_id="+lession_id;
        sqlString=sqlString+" order by class_id";
        try{
            sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
            rs=sql.executeQuery(sqlString);       
        }catch(Exception e){
            System.out.println(e);
        }
        return rs;
    }
    /**
     * 功能:得到班級的某課程的封存狀態
     * 輸入:class_id為班級ID號,lession_id為課程ID號
     * 輸出:封存狀態字符串
     * 提示：只在班級的所有學生的成績都得到封存才算是成功封存狀態
     */
    public String getClassLessionCloseStatus(int class_id,int lession_id){
        String returnString=new String("");
        String sqlString=null;//SQL語句字符串
        Statement sql=null;//SQL語句對象
        ResultSet rs=null;//結果記錄集
        dbconn dbconnOBject=new dbconn();//數據庫連接對象
        Connection dbconn=dbconnOBject.getDBConn();//得到數據庫連接
        if(dbconn==null) return returnString;//連接失敗
        if(class_id==0||lession_id==0)//輸入參數不合法
            return returnString;
        sqlString="select distinct core.lession_id as lession_id,student.class_id as class_id," +
        		"core.close_status as close_status from core,student " +
        		"where core.student_id=student.student_id and student.class_id="+class_id+
        		" and core.lession_id="+lession_id;
        try{
            sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
            rs=sql.executeQuery(sqlString); 
            rs.last();
            int rowCount=rs.getRow();
            rs.beforeFirst();
            switch(rowCount){
            	case 0:
            	    returnString="沒有此班級此課程的成績數據";break;
            	case 1://查到一條記錄,從字段中取狀態
            	    rs.next();
                    switch(rs.getInt("close_status")){
                    	case 0:
                    	    returnString="未封存";break;
                    	case 1:
                    	    returnString="已封存";break;
                    	case 2:
                    	    returnString="部分封存";break;
                    	default:
                    	    returnString="未知";break;
                    }
                    break;
                case 2://查到2條,說明封存未完全
                    returnString="部分封存";break;
                default:
                    returnString="未知";break;
            }
        }catch(Exception e){
            System.out.println(e);
            returnString="未知";
        }
        return returnString;         
    }
    /**
     * 功能:置某班某課程的狀態為封存
     * 輸入:class_id為班級ID號,lession_id為課程ID號
     * 輸出:返回1表成功，返回2表數據連接參數配置不正確或連接數據庫失敗或數據庫操作失敗，
     * 返回4表輸入參數不正確;
     */
    public int classLessionCloseSave(int class_id,int lession_id){
        String sqlString=null;//SQL語句字符串
        Statement sql=null;//SQL語句對象
        ResultSet rs=null;//結果記錄集
        dbconn dbconnOBject=new dbconn();//數據庫連接對象
        Connection dbconn=dbconnOBject.getDBConn();//得到數據庫連接
        if(dbconn==null) return 2;//連接失敗
        if(class_id==0||lession_id==0)//輸入參數不合法
            return 4;
        //-------更新狀態為封存----------
        sqlString="update core set close_status=1" +
        		" where lession_id=? and student_id in" +
        		" (select student_id from student where class_id=?)";
        try{
            PreparedStatement preSQLUpdate=dbconn.prepareStatement(sqlString);
            preSQLUpdate.setInt(1,lession_id);
            preSQLUpdate.setInt(2,class_id);
            preSQLUpdate.executeUpdate();
            return 1;
        }catch(Exception e){
            System.out.print(e);
            return 2;
        }   
    }
    /**
     * 功能:置某班某課程的狀態為解封
     * 輸入:class_id為班級ID號,lession_id為課程ID號
     * 輸出:返回1表成功，返回2表數據連接參數配置不正確或連接數據庫失敗或數據庫操作失敗，
     * 返回4表輸入參數不正確;
     */
    public int classLessionOpenSave(int class_id,int lession_id){
        String sqlString=null;//SQL語句字符串
        Statement sql=null;//SQL語句對象
        ResultSet rs=null;//結果記錄集
        dbconn dbconnOBject=new dbconn();//數據庫連接對象
        Connection dbconn=dbconnOBject.getDBConn();//得到數據庫連接
        if(dbconn==null) return 2;//連接失敗
        if(class_id==0||lession_id==0)//輸入參數不合法
            return 4;
        //-------更新狀態為解封----------
        sqlString="update core set close_status=0" +
        		" where lession_id=? and student_id in" +
        		" (select student_id from student where class_id=?)";
        try{
            PreparedStatement preSQLUpdate=dbconn.prepareStatement(sqlString);
            preSQLUpdate.setInt(1,lession_id);
            preSQLUpdate.setInt(2,class_id);
            preSQLUpdate.executeUpdate();
            return 1;
        }catch(Exception e){
            System.out.print(e);
            return 2;
        }   
    }
}