package bookstoreapp.clientside;

import java.io.*;
import java.sql.*;
import java.util.*;

public class Inventory
{

	public static void main(String[] args) throws Exception
	{
		Class.forName("com.ibm.db2.jcc.DB2Driver");
		
		String url = "jdbc:derby:net://localhost:1527/bookstoredb";
		url += ":user=bookstore;password=aaa;";		
		url += "retrieveMessagesFromServerOnGetMessage=true;";
		Connection con = DriverManager.getConnection(url);
		
		processCommands(con);
		
		con.close();
	}
	
	public static void processCommands(Connection con) throws Exception
	{
		boolean end = false;
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		Statement stmt = con.createStatement();
			
		while (!end) {
			System.out.print("> ");
			String cmd = in.readLine();
			
			if (cmd.equals("quit"))
				end = true;
			else if (cmd.startsWith("list"))
				listBooks(stmt);
			else if (cmd.startsWith("add"))
				updateQuantity(stmt, cmd, true);
			else if (cmd.startsWith("remove")) 
				updateQuantity(stmt, cmd, false);
		}
		
		stmt.close();
	}
	
	protected static void listBooks(Statement stmt) throws Exception
	{
		ResultSet rs = stmt.executeQuery("SELECT * FROM books");
		while (rs.next()) {
			System.out.print(rs.getString(1) + ", ");
			System.out.print(rs.getString(2) + ", ");
			System.out.print(rs.getString(3) + ", ");
			System.out.print(rs.getString(4) + ", ");
			System.out.print(rs.getString(5) + ", ");
			System.out.println(rs.getString(6));
		}
		rs.close();
	}
	
	protected static void updateQuantity(Statement stmt, String cmd, boolean add) throws Exception
	{
		StringTokenizer st = new StringTokenizer(cmd);
		st.nextToken(); // skip first token
		String id = st.nextToken();
		String quantity = st.nextToken();
		
		String query = "update books set quantity=quantity";
		query += (add) ? "+" : "-";
		query += quantity;
		query += " where id=" + id;
		stmt.executeUpdate(query);
		System.out.println("Updated");
	}
	
}