/*
 * @(#)MimeTypeParameterList.java	1.5 01/11/29
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.awt.datatransfer;

import java.util.Hashtable;
import java.util.Enumeration;


/**
 * An object that encapsualtes the parameter list of a MimeType
 * as defined in RFC 2045 and 2046.
 */
class MimeTypeParameterList implements Cloneable {

    /**
     * Default constructor.
     */
    public MimeTypeParameterList() {
        parameters = new Hashtable();
    }

    public MimeTypeParameterList(String rawdata) throws MimeTypeParseException {
        parameters = new Hashtable();
        
        //    now parse rawdata
        parse(rawdata);
    }
    
    private MimeTypeParameterList(Hashtable ht) throws CloneNotSupportedException {
	parameters = (Hashtable)ht.clone();
    }

    /**
     * A routine for parsing the parameter list out of a String.
     */
    protected void parse(String rawdata) throws MimeTypeParseException {
        int length = rawdata.length();
        if(length > 0) {
            int currentIndex = skipWhiteSpace(rawdata, 0);
            int lastIndex = 0;
            
            if(currentIndex < length) {
                char currentChar = rawdata.charAt(currentIndex);
                while ((currentIndex < length) && (currentChar == ';')) {
                    String name;
                    String value;
                    boolean foundit;
                    
                    //    eat the ';'
                    ++currentIndex;
                    
                    //    now parse the parameter name
                    
                    //    skip whitespace
                    currentIndex = skipWhiteSpace(rawdata, currentIndex);
                    
                    if(currentIndex < length) {
                        //    find the end of the token char run
                        lastIndex = currentIndex;
                        currentChar = rawdata.charAt(currentIndex);
                        while((currentIndex < length) && isTokenChar(currentChar)) {
                            ++currentIndex;
                            currentChar = rawdata.charAt(currentIndex);
                        }
                        name = rawdata.substring(lastIndex, currentIndex).toLowerCase();
                        
                        //    now parse the '=' that separates the name from the value
                        
                        //    skip whitespace
                        currentIndex = skipWhiteSpace(rawdata, currentIndex);
                        
                        if((currentIndex < length) && (rawdata.charAt(currentIndex) == '='))  {
                            //    eat it and parse the parameter value
                            ++currentIndex;
                            
                            //    skip whitespace
                            currentIndex = skipWhiteSpace(rawdata, currentIndex);
                            
                            if(currentIndex < length) {
                                //    now find out whether or not we have a quoted value
                                currentChar = rawdata.charAt(currentIndex);
                                if(currentChar == '"') {
                                    //    yup it's quoted so eat it and capture the quoted string
                                    ++currentIndex;
                                    lastIndex = currentIndex;
                                    
                                    if(currentIndex < length) {
                                        //    find the next unescqped quote
                                        foundit = false;
                                        while((currentIndex < length) && !foundit) {
                                            currentChar = rawdata.charAt(currentIndex);
                                            if(currentChar == '\\') {
                                                //    found an escape sequence so pass this and the next character
                                                currentIndex += 2;
                                            } else if(currentChar == '"') {
                                                //    foundit!
                                                foundit = true;
                                            } else {
                                                ++currentIndex;
                                            }
                                        }
                                        if(currentChar == '"') {
                                            value = unquote(rawdata.substring(lastIndex, currentIndex));
                                            //    eat the quote
                                            ++currentIndex;
                                        } else {
                                            throw new MimeTypeParseException("Encountered unterminated quoted parameter value.");
                                        }
                                    } else {
                                        throw new MimeTypeParseException("Encountered unterminated quoted parameter value.");
                                    }
                                } else if(isTokenChar(currentChar)) {
                                    //    nope it's an ordinary token so it ends with a non-token char
                                    lastIndex = currentIndex;
                                    foundit = false;
                                    while((currentIndex < length) && !foundit) {
                                        currentChar = rawdata.charAt(currentIndex);
                                        
                                        if(isTokenChar(currentChar)) {
                                            ++currentIndex;
                                        } else {
                                            foundit = true;
                                        }
                                    }
                                    value = rawdata.substring(lastIndex, currentIndex);
                                } else {
                                    //    it ain't a value
                                    throw new MimeTypeParseException("Unexpected character encountered at index " + currentIndex);
                                }
                                
                                //    now put the data into the hashtable
                                parameters.put(name, value);
                            } else {
                                throw new MimeTypeParseException("Couldn't find a value for parameter named " + name);
                            }
                        } else {
                            throw new MimeTypeParseException("Couldn't find the '=' that separates a parameter name from its value.");
                        }
                    } else {
                        throw new MimeTypeParseException("Couldn't find parameter name");
                    }
                    
                    //    setup the next iteration
                    currentIndex = skipWhiteSpace(rawdata, currentIndex);
                    if(currentIndex < length) {
                        currentChar = rawdata.charAt(currentIndex);
                    }
                }
                if(currentIndex < length) {
                    throw new MimeTypeParseException("More characters encountered in input than expected.");
                }
            }
        }
    }

    /**
     * return the number of name-value pairs in this list.
     */
    public int size() {
        return parameters.size();
    }

    /**
     * Determine whether or not this list is empty.
     */
    public boolean isEmpty() {
        return parameters.isEmpty();
    }

    /**
     * Retrieve the value associated with the given name, or null if there
     * is no current association.
     */
    public String get(String name) {
        return (String)parameters.get(name.trim().toLowerCase());
    }

    /**
     * Set the value to be associated with the given name, replacing
     * any previous association.
     */
    public void set(String name, String value) {
        parameters.put(name.trim().toLowerCase(), value);
    }

    /**
     * Remove any value associated with the given name.
     */
    public void remove(String name) {
        parameters.remove(name.trim().toLowerCase());
    }

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

    public String toString() {
        StringBuffer buffer = new StringBuffer();
        buffer.ensureCapacity(parameters.size() * 16);    //    heuristic: 8 characters per field
        
        Enumeration keys = parameters.keys();
        while(keys.hasMoreElements())
        {
            buffer.append("; ");
            
            String key = (String)keys.nextElement();
            buffer.append(key);
            buffer.append('=');
               buffer.append(quote((String)parameters.get(key)));
        }
        
        return buffer.toString();
    }

    /**
     * @return a clone of this object
     */

     public Object clone() throws CloneNotSupportedException {
	return new MimeTypeParameterList(parameters); // clones hashtable ...
     }

    private Hashtable parameters;
    
    //    below here be scary parsing related things

    /**
     * Determine whether or not a given character belongs to a legal token.
     */
    private static boolean isTokenChar(char c) {
        return ((c > 040) && (c < 0177)) && (TSPECIALS.indexOf(c) < 0);
    }

    /**
     * return the index of the first non white space character in
     * rawdata at or after index i.
     */
    private static int skipWhiteSpace(String rawdata, int i) {
        int length = rawdata.length();
        if (i < length) {
            char c =  rawdata.charAt(i);
            while ((i < length) && Character.isWhitespace(c)) {
                ++i;
                c = rawdata.charAt(i);
            }
        }
        
        return i;
    }
    
    /**
     * A routine that knows how and when to quote and escape the given value.
     */
    private static String quote(String value) {
        boolean needsQuotes = false;
        
        //    check to see if we actually have to quote this thing
        int length = value.length();
        for(int i = 0; (i < length) && !needsQuotes; ++i) {
            needsQuotes = !isTokenChar(value.charAt(i));
        }
        
        if(needsQuotes) {
            StringBuffer buffer = new StringBuffer();
            buffer.ensureCapacity((int)(length * 1.5));
            
            //    add the initial quote
            buffer.append('"');
            
            //    add the properly escaped text
            for(int i = 0; i < length; ++i) {
                char c = value.charAt(i);
                if((c == '\\') || (c == '"')) {
                    buffer.append('\\');
                }
                buffer.append(c);
            }
            
            //    add the closing quote
            buffer.append('"');
            
            return buffer.toString();
        }
        else
        {
            return value;
        }
    }
    
    /**
     * A routine that knows how to strip the quotes and escape sequences from the given value.
     */
    private static String unquote(String value) {
        int valueLength = value.length();
        StringBuffer buffer = new StringBuffer();
        buffer.ensureCapacity(valueLength);
        
        boolean escaped = false;
        for(int i = 0; i < valueLength; ++i) {
            char currentChar = value.charAt(i);
            if(!escaped && (currentChar != '\\')) {
                buffer.append(currentChar);
            } else if(escaped) {
                buffer.append(currentChar);
                escaped = false;
            } else {
                escaped = true;
            }
        }
        
        return buffer.toString();
    }
    
    /**
     * A string that holds all the special chars.
     */
    private static final String TSPECIALS = "()<>@,;:\\\"/[]?=";

}