/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.activation;

import java.util.Hashtable;

import java.util.Enumeration;

import java.util.Locale;

/**

 * A parameter list of a MimeType

 * as defined in RFC 2045 and 2046. The Primary type of the

 * object must already be stripped off.

 *

 * @see javax.activation.MimeType

 *

 * @since 1.6

 */

public class MimeTypeParameterList {

    private Hashtable parameters;

    /**

     * A string that holds all the special chars.

     */

    private static final String TSPECIALS = "()<>@,;:/[]?=\\\"";

    /**

     * Default constructor.

     */

    public MimeTypeParameterList() {

        parameters = new Hashtable();

    }

    /**

     * Constructs a new MimeTypeParameterList with the passed in data.

     *

     * @param parameterList an RFC 2045, 2046 compliant parameter list.

     */

    public MimeTypeParameterList(String parameterList)

                                        throws MimeTypeParseException {

        parameters = new Hashtable();

        //    now parse rawdata

        parse(parameterList);

    }

    /**

     * A routine for parsing the parameter list out of a String.

     *

     * @param parameterList an RFC 2045, 2046 compliant parameter list.

     */

    protected void parse(String parameterList) throws MimeTypeParseException {

        if (parameterList == null)

            return;

        int length = parameterList.length();

        if (length <= 0)

            return;

        int i;

        char c;

        for (i = skipWhiteSpace(parameterList, 0);

                i < length && (c = parameterList.charAt(i)) == ';';

                i = skipWhiteSpace(parameterList, i)) {

            int lastIndex;

            String name;

            String value;

            //    eat the ';'

            i++;

            //    now parse the parameter name

            //    skip whitespace

            i = skipWhiteSpace(parameterList, i);

            // tolerate trailing semicolon, even though it violates the spec

            if (i >= length)

                return;

            //    find the end of the token char run

            lastIndex = i;

            while ((i < length) && isTokenChar(parameterList.charAt(i)))

                i++;

            name = parameterList.substring(lastIndex, i).

                                                toLowerCase(Locale.ENGLISH);

            //    now parse the '=' that separates the name from the value

            i = skipWhiteSpace(parameterList, i);

            if (i >= length || parameterList.charAt(i) != '=')

                throw new MimeTypeParseException(

                    "Couldn't find the '=' that separates a " +

                    "parameter name from its value.");

            //    eat it and parse the parameter value

            i++;

            i = skipWhiteSpace(parameterList, i);

            if (i >= length)

                throw new MimeTypeParseException(

                        "Couldn't find a value for parameter named " + name);

            //    now find out whether or not we have a quoted value

            c = parameterList.charAt(i);

            if (c == '"') {

                //    yup it's quoted so eat it and capture the quoted string

                i++;

                if (i >= length)

                    throw new MimeTypeParseException(

                            "Encountered unterminated quoted parameter value.");

                lastIndex = i;

                //    find the next unescaped quote

                while (i < length) {

                    c = parameterList.charAt(i);

                    if (c == '"')

                        break;

                    if (c == '\\') {

                        //    found an escape sequence

                        //    so skip this and the

                        //    next character

                        i++;

                    }

                    i++;

                }

                if (c != '"')

                    throw new MimeTypeParseException(

                        "Encountered unterminated quoted parameter value.");

                value = unquote(parameterList.substring(lastIndex, i));

                //    eat the quote

                i++;

            } else if (isTokenChar(c)) {

                //    nope it's an ordinary token so it

                //    ends with a non-token char

                lastIndex = i;

                while (i < length && isTokenChar(parameterList.charAt(i)))

                    i++;

                value = parameterList.substring(lastIndex, i);

            } else {

                //    it ain't a value

                throw new MimeTypeParseException(

                        "Unexpected character encountered at index " + i);

            }

            //    now put the data into the hashtable

            parameters.put(name, value);

        }

        if (i < length) {

            throw new MimeTypeParseException(

                "More characters encountered in input than expected.");

        }

    }

    /**

     * Return the number of name-value pairs in this list.

     *

     * @return  the number of parameters

     */

    public int size() {

        return parameters.size();

    }

    /**

     * Determine whether or not this list is empty.

     *

     * @return  true if there are no parameters

     */

    public boolean isEmpty() {

        return parameters.isEmpty();

    }

    /**

     * Retrieve the value associated with the given name, or null if there

     * is no current association.

     *

     * @param name      the parameter name

     * @return          the parameter's value

     */

    public String get(String name) {

        return (String)parameters.get(name.trim().toLowerCase(Locale.ENGLISH));

    }

    /**

     * Set the value to be associated with the given name, replacing

     * any previous association.

     *

     * @param name      the parameter name

     * @param value     the parameter's value

     */

    public void set(String name, String value) {

        parameters.put(name.trim().toLowerCase(Locale.ENGLISH), value);

    }

    /**

     * Remove any value associated with the given name.

     *

     * @param name      the parameter name

     */

    public void remove(String name) {

        parameters.remove(name.trim().toLowerCase(Locale.ENGLISH));

    }

    /**

     * Retrieve an enumeration of all the names in this list.

     *

     * @return  an enumeration of all parameter names

     */

    public Enumeration getNames() {

        return parameters.keys();

    }

    /**

     * Return a string representation of this object.

     */

    public String toString() {

        StringBuffer buffer = new StringBuffer();

        buffer.ensureCapacity(parameters.size() * 16);

                        //    heuristic: 8 characters per field

        Enumeration keys = parameters.keys();

        while (keys.hasMoreElements()) {

            String key = (String)keys.nextElement();

            buffer.append("; ");

            buffer.append(key);

            buffer.append('=');

            buffer.append(quote((String)parameters.get(key)));

        }

        return buffer.toString();

    }

    //    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();

        while ((i < length) && Character.isWhitespace(rawdata.charAt(i)))

            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();

    }

}