/*
 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
 * 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
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 */

package jdk.javadoc.internal.doclets.formats.html.markup;

import jdk.javadoc.internal.doclets.toolkit.Content;

import java.io.IOException;
import java.io.Writer;

A representation of HTML entities.
/**
 * A representation of HTML entities.
 */
public class Entity extends Content {
    public static final Entity LESS_THAN = new Entity("<");
    public static final Entity GREATER_THAN = new Entity(">");
    public static final Entity AMPERSAND = new Entity("&");
    public static final Entity NO_BREAK_SPACE = new Entity(" ");
    public static final Entity ZERO_WIDTH_SPACE = new Entity("​") {
        @Override
        public int charCount() {
            return 0;
        }
    };

    public final String text;

    private Entity(String text) {
        this.text = text;
    }

    @Override
    public void add(Content content) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void add(CharSequence stringContent) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean write(Writer writer, boolean atNewline) throws IOException {
        writer.write(text);
        return false;
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @Override
    public int charCount() {
        return 1;
    }


    
Escapes the special HTML characters in a given string using the appropriate
entities.
Params:
s – the string to escape
Returns:
the string with all of the HTML characters escaped/**
     * Escapes the special HTML characters in a given string using the appropriate
     * entities.
     *
     * @param s the string to escape
     * @return the string with all of the HTML characters escaped
     */
    static String escapeHtmlChars(CharSequence s) {
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            switch (ch) {
                // only start building a new string if we need to
                case '<': case '>': case '&':
                    StringBuilder sb = new StringBuilder(s.subSequence(0, i));
                    escapeHtmlChars(s, i, sb);
                    return sb.toString();
            }
        }
        return s.toString();
    }

    
Escapes the special HTML characters in a given string using the appropriate
entities, appending the results into a string builder.
Params:
s – the string
sb – the string builder/**
     * Escapes the special HTML characters in a given string using the appropriate
     * entities, appending the results into a string builder.
     *
     * @param s the string
     * @param sb the string builder
     */
    static void escapeHtmlChars(CharSequence s, StringBuilder sb) {
        escapeHtmlChars(s, 0, sb);
    }

    private static void escapeHtmlChars(CharSequence s, int start, StringBuilder sb) {
        for (int i = start ; i < s.length(); i++) {
            char ch = s.charAt(i);
            switch (ch) {
                case '<': sb.append(Entity.LESS_THAN.text);     break;
                case '>': sb.append(Entity.GREATER_THAN.text);  break;
                case '&': sb.append(Entity.AMPERSAND.text);     break;
                default:  sb.append(ch);                        break;
            }
        }
    }

}