/*
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.mail.internet;

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

/**
 * This class holds MIME parameters (attribute-value pairs).
 *
 * @version 1.7, 00/09/20
 * @author  John Mani
 */

public class ParameterList {

    private Hashtable list = new Hashtable(); // internal hashtable

    /**
     * No-arg Constructor.
     */
    public ParameterList() { 
    }

    /**
     * Constructor that takes a parameter-list string. The String
     * is parsed and the parameters are collected and stored internally.
     * A ParseException is thrown if the parse fails. 
     * Note that an empty parameter-list string is valid and will be 
     * parsed into an empty ParameterList.
     *
     * @param	s	the parameter-list string.
     * @exception	ParseException if the parse fails.
     */
    public ParameterList(String s) throws ParseException {
	HeaderTokenizer h = new HeaderTokenizer(s, HeaderTokenizer.MIME);
	HeaderTokenizer.Token tk;
	int type;
	String name;

	while (true) {
	    tk = h.next();
	    type = tk.getType();

	    if (type == HeaderTokenizer.Token.EOF) // done
		return;

	    if ((char)type == ';') {
		// expect parameter name
		tk = h.next();
		// parameter name must be a MIME Atom
		if (tk.getType() != HeaderTokenizer.Token.ATOM)
		    throw new ParseException();
		name = tk.getValue().toLowerCase();

		// expect '='
		tk = h.next();
		if ((char)tk.getType() != '=')
		    throw new ParseException();
		
		// expect parameter value
		tk = h.next();
		type = tk.getType();
		// parameter value must be a MIME Atom or Quoted String
		if (type != HeaderTokenizer.Token.ATOM &&
		    type != HeaderTokenizer.Token.QUOTEDSTRING)
		    throw new ParseException();
		
		list.put(name, tk.getValue());
	    } else
		throw new ParseException();
	}
    }

    /**
     * Return the number of parameters in this list.
     * 
     * @return  number of parameters.
     */
    public int size() {
	return list.size();
    }

    /**
     * Returns the value of the specified parameter. Note that 
     * parameter names are case-insensitive.
     *
     * @param name	parameter name.
     * @return		Value of the parameter. Returns 
     *			<code>null</code> if the parameter is not 
     *			present.
     */
    public String get(String name) {
	return (String)list.get(name.trim().toLowerCase());
    }

    /**
     * Set a parameter. If this parameter already exists, it is
     * replaced by this new value.
     *
     * @param	name 	name of the parameter.
     * @param	value	value of the parameter.
     */
    public void set(String name, String value) {
	list.put(name.trim().toLowerCase(), value);
    }

    /**
     * Removes the specified parameter from this ParameterList.
     * This method does nothing if the parameter is not present.
     *
     * @param	name	name of the parameter.
     */
    public void remove(String name) {
	list.remove(name.trim().toLowerCase());
    }

    /**
     * Return an enumeration of the names of all parameters in this
     * list.
     *
     * @return Enumeration of all parameter names in this list.
     */
    public Enumeration getNames() {
	return list.keys();
    }

    /**
     * Convert this ParameterList into a MIME String. If this is
     * an empty list, an empty string is returned.
     *
     * @return		String
     */
    public String toString() {
	return toString(0);
    }

    /**
     * Convert this ParameterList into a MIME String. If this is
     * an empty list, an empty string is returned.
     *   
     * The 'used' parameter specifies the number of character positions
     * already taken up in the field into which the resulting parameter
     * list is to be inserted. It's used to determine where to fold the
     * resulting parameter list.
     *
     * @param used      number of character positions already used, in
     *                  the field into which the parameter list is to
     *                  be inserted.
     * @return          String
     */  
    public String toString(int used) {
        StringBuffer sb = new StringBuffer();
        Enumeration e = list.keys();
 
        while (e.hasMoreElements()) {
            String name = (String)e.nextElement();
            String value = quote((String)list.get(name));
            sb.append("; ");
            used += 2;
            int len = name.length() + value.length() + 1;
            if (used + len > 76) { // overflows ...
                sb.append("\r\n\t"); // .. start new continuation line
                used = 8; // account for the starting <tab> char
            }
            sb.append(name).append('=').append(value);
        }
 
        return sb.toString();
    }
 
    // Quote a parameter value token if required.
    private String quote(String value) {
	return MimeUtility.quote(value, HeaderTokenizer.MIME);
    }
}