/*
 * Copyright (c) 2008-2010 Mozilla Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

package nu.validator.datatype;

import nu.validator.datatype.data.CharsetData;
import nu.validator.vendor.relaxng.datatype.DatatypeException;

public class Charset extends AbstractDatatype {

    /**
     * The singleton instance.
     */
    public static final Charset THE_INSTANCE = new Charset();

    public Charset() {
        super();
    }

    @Override
    public void checkValid(CharSequence literal) throws DatatypeException {
        if (literal.length() == 0) {
            throw newDatatypeException(
                    "The empty string is not a valid character encoding name.");
        }
        for (int i = 0; i < literal.length(); i++) {
            char c = literal.charAt(i);
            // http://tools.ietf.org/html/rfc2978
            if (!((c >= '0' && c <= '9') || (c >= 'a' && c <= 'z')
                    || (c >= 'A' && c <= 'Z') || c == '-' || c == '!'
                    || c == '#' || c == '$' || c == '%' || c == '&' || c == '\''
                    || c == '+' || c == '_' || c == '`' || c == '{' || c == '}'
                    || c == '~' || c == '^')) {
                throw newDatatypeException("Value contained ", c,
                        ", which is not a valid character in an encoding name.");
            }
        }
        String encodingName = literal.toString();
        encodingName = toAsciiLowerCase(encodingName);
        if ("replacement".equals(encodingName)
                || !CharsetData.isPreferred(encodingName)) {
            String preferred = CharsetData.preferredForLabel(encodingName);
            if (preferred == null || "replacement".equals(preferred)) {
                throw newDatatypeException("“" + encodingName
                        + "” is not a valid character encoding name.");
            }
            throw newDatatypeException("“" + encodingName
                    + "” is not a preferred encoding name."
                    + " The preferred label for this encoding is “"
                    + preferred + "”.");
        }
    }

    @Override
    public String getName() {
        return "encoding name";
    }

}
