package edu.vt.marian.WebGate;

import java.io.*;
import java.net.*;
import java.util.*;
import edu.vt.marian.common.*;




/** Class name: preference
	Class description: this class represent the preferences of this user, there
		may be many preferences in the future, the design of this class make it
		easy to add new preferences.
	Author: Jianxin Zhao
	Finished time: ????, 1998
	Known bugs: none
	Platform: jdk1.1.5 under UNIX
*/

public class preference
{
	/** this is just for debugging
	*/
	Debug debug;

	/** this vector contains all the preference informations
	*/
	private Vector pres;


	/** this constructor will create a preference object, the object is empty 
		upon creation
	*/
	public preference(Debug debug)
	{
		// first initialize data members
		init();

		this.debug = debug;
	}


	/** this constructor will create a preference object from the specified
		directory
	*/
	public preference(String dir, Debug debug)
	{
		// first initialize data members
		init();

		this.debug = debug;

		// we only save the preference of a user to a file at this time
		File preference_config = new File(dir);

		// read preferences from the file
		BufferedReader br;
		
		try
		{
			FileReader fr = new FileReader(preference_config);
			br = new BufferedReader(fr);

			// first read out number of preferences 
			int number_preference = Integer.parseInt(br.readLine());

			// then read out each preference
			int i;
			name_value_pair nvp;
			for (i = 0; i < number_preference; i++)
			{
				nvp = new name_value_pair(br, debug);
				pres.addElement(nvp);
			}
			br.close();
		}
		catch (IOException e3) 
		{
			debug.dumpTrace("class preference: error reading data from " +  preference_config.getAbsolutePath());
		}
	}


	/** this constructor will create a preference object from the specified
		directory
	*/
	public preference(BufferedReader br, Debug debug)
	{
		// first initialize data members
		init();

		this.debug = debug;

		try
		{
			// first read out number of preferences 
			int number_preference = Integer.parseInt(br.readLine());

			// then read out each preference
			int i;
			name_value_pair nvp;
			for (i = 0; i < number_preference; i++)
			{
				nvp = new name_value_pair(br, debug);
				pres.addElement(nvp);
			}
		}
		catch (IOException e3) 
		{
			debug.dumpTrace("class preference: constructor 2, error reading data from file");
		}
	}

	
	/** this constructor will create a preference object from a stream, this
		might be helpful for remote manage in the future. (not implemented yet)
	*/
	public preference(DataInputStream dis, Debug debug)
	{
	}


	/** this method will return the value of the specified preference
	*/
	public String get_value(String name)
	{
		int i;
		name_value_pair nvp;

		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			if (nvp.get_name().equals(name))
			{
				// a match is found, return it's value
				return nvp.get_value();
			}
		}

		// no match is found
		return null;
	}


	/** this method will return all the preference names currently in this
		object
	*/
	public Vector get_names()
	{
		int i;
		name_value_pair nvp;
		Vector names = new Vector();

		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			names.addElement(nvp.get_name());
		}

		return names;
	}


	/** this method will add the preference with the specified value to 
		this object
	*/
	public String add(String name, String value)
	{
		int i;
		name_value_pair nvp;

		// first search to see if this preference exists in our current 
		// preferences
		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			if (nvp.get_name().equals(name))
			{
				// already exist, cann't add it
				return "this preference already exists";
			}
		}

		// this is a new preference, so add it
		nvp = new name_value_pair(name, value, debug);
		pres.addElement(nvp);
		return "OK";
	}


	/** this method will set the specified preference to the specified value 
	*/
	public String set(String name, String value)
	{
		int i;
		name_value_pair nvp;

		// first search to see if this preference exists in our current 
		// preferences
		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			if (nvp.get_name().equals(name))
			{
				// exist, set it's value
				nvp.set_value(value);
				return "OK";
			}
		}

		// this is a new preference, cann't set it's value directly
		return "no such preference";
	}


	/** this method will delete the specified preference 
	*/
	public String delete(String name)
	{
		int i;
		name_value_pair nvp;

		// first search to see if this preference exists in our current 
		// preferences
		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			if (nvp.get_name().equals(name))
			{
				// exist, delete it
				pres.removeElementAt(i);
				return "OK";
			}
		}

		// we couldn't found such preference 
		return "no such preference";
	}


	/** this method will print the content of this object to the stream, this 
		might be helpful for remote management in the future. (not implemented yet)
	*/
	public String to_stream(DataOutputStream dos)
	{
		return null; // not implemented yet
	}


	/** this method will save the content of this object to the specified
		directory
	*/
	public String save(String dir)
	{
		FileOutputStream fos = null;
        try
        {
			fos = new FileOutputStream(dir, false);             
        }
        catch (IOException e3)
        {
			debug.dumpTrace("class preference: error opening preference config file to write");
        }
		PrintWriter pw = new PrintWriter(fos);

		// first write number of preferences
        pw.println(pres.size());

		// then write out each preference
		int i;
		name_value_pair nvp = null;
		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			nvp.to_stream(pw);
		}
		pw.flush();
		pw.close();
		return "OK";
	}


	/** this method will save the content of this object to the specified
		directory
	*/
	public String save(PrintWriter pw)
	{
		// first write number of preferences
        pw.println(pres.size());

		// then write out each preference
		int i;
		name_value_pair nvp = null;
		for (i = 0; i < pres.size(); i++)
		{
			nvp = (name_value_pair) pres.elementAt(i);
			nvp.to_stream(pw);
		}
		return "OK";
	}

	
	/** this method will initialize the data members of this object
	*/
	private void init()
	{
		debug = null;
		pres = new Vector();
	}
}