package org.aegee.runanddine.pathfinder;

import java.sql.*;
import java.util.LinkedList;
import java.util.List;

import org.aegee.runanddine.util.model.MySQLModelManager;

/**
 * Manages persistent OptGroup models
 */
public class OptGroupManager extends MySQLModelManager<OptGroup> {
    /**
     * Singleton instance of opt group manager
     */
    private static OptGroupManager instance = null;
    
    /**
     * Init OptGroupManager
     * (private because of singleton pattern)
     */
    private OptGroupManager()
    {
        super();
        this.table = "opt_groups";
    }
    
    /**
     * Return singleton instance of OptGroupManager
     * @return Singleton instance of OptGroupManager
     */
    public static OptGroupManager getInstance() {
        // create singleton instance if it does not exist
        if (OptGroupManager.instance == null) {
            OptGroupManager.instance = new OptGroupManager();
        }
        
        return OptGroupManager.instance;
    }
    
    /**
     * Get list of all existing OptGroups for given RunAndDine
     * @param runAndDineId ID of RunAndDine
     * @return List of all existing OptGroups for given RunAndDine
     */
    public List<OptGroup> getAllByRunAndDineId(int runAndDineId) {
        try {
            List<OptGroup> models = new LinkedList<OptGroup>();
            // select all models for RunAndDine
            PreparedStatement stmt = this.con.prepareStatement("SELECT id, serialized_object FROM " + this.table + " WHERE rad_id=?");
            // bind RunAndDine ID
            stmt.setInt(1, runAndDineId);
            ResultSet rs  = stmt.executeQuery();
            
            while (rs.next()) {
                // deserialize model
                OptGroup model = this.readObject(rs.getBytes("serialized_object"));
                model.setId(rs.getInt("id"));
                // add model to list
                models.add(model);
            }

            rs.close();
            stmt.close();

            return models;
        } catch (SQLException e) {
            e.printStackTrace(System.err);
            return null;
        }
    }
    
    /**
     * Stores new model or updates existing one
     * @param model Model to be saved/updated
     */
    @Override
    public void save(OptGroup model) {
        try {
            // update model
            if (this.hasModel(model.getId())) {
                PreparedStatement stmt = this.con.prepareStatement("UPDATE " + this.table + " SET serialized_object=?, rad_id=? WHERE id=?");
                // bind values
                stmt.setObject(1, model);
                stmt.setInt(2, model.getRunAndDineId());
                stmt.setInt(3, model.getId());
                // execute update
                stmt.executeUpdate();    
                stmt.close();
            // save new model
            } else {
                PreparedStatement stmt = this.con.prepareStatement("INSERT INTO " + this.table + " (serialized_object, rad_id) VALUES (?, ?)");
                // bind values to statement
                stmt.setObject(1, model);
                stmt.setInt(2, model.getRunAndDineId());
                // execute insert
                stmt.executeUpdate();
                // retrieve auto increment id
                ResultSet rs = stmt.getGeneratedKeys();
                rs.next();
                model.setId(rs.getInt(1));
                rs.close();
                stmt.close();
            }
        } catch (SQLException e) {
            e.printStackTrace(System.err);
        }
    }
    
    /**
     * Create empty OptGroup
     * @return Empty OptGroup
     */
    public OptGroup newObject() {
        throw new UnsupportedOperationException();
    }
}