/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package org.apache.commons.text.translate;

import java.io.IOException;

import java.io.Writer;

import org.apache.commons.lang3.CharUtils;

import org.apache.commons.lang3.StringUtils;

/**

 * This class holds inner classes for escaping/unescaping Comma Separated Values.

 * <p>

 * In general the use a high level API like <a href="https://commons.apache.org/proper/commons-csv/">Apache Commons

 * CSV</a> should be preferred over these low level classes.

 * </p>

 *

 * @see <a href="https://commons.apache.org/proper/commons-csv/apidocs/index.html">Apache Commons CSV</a>

 */

public final class CsvTranslators {

    /** Comma character. */

    private static final char CSV_DELIMITER = ',';

    /** Quote character. */

    private static final char CSV_QUOTE = '"';

    /** Quote character converted to string. */

    private static final String CSV_QUOTE_STR = String.valueOf(CSV_QUOTE);

    /** Escaped quote string. */

    private static final String CSV_ESCAPED_QUOTE_STR = CSV_QUOTE_STR + CSV_QUOTE_STR;

    /** CSV key characters in an array. */

    private static final char[] CSV_SEARCH_CHARS =

            new char[] {CSV_DELIMITER, CSV_QUOTE, CharUtils.CR, CharUtils.LF};

    /** Hidden constructor. */

    private CsvTranslators() { }

    /**

     * Translator for escaping Comma Separated Values.

     */

    public static class CsvEscaper extends SinglePassTranslator {

        @Override

        void translateWhole(final CharSequence input, final Writer out) throws IOException {

            final String inputSting = input.toString();

            if (StringUtils.containsNone(inputSting, CSV_SEARCH_CHARS)) {

                out.write(inputSting);

            } else {

                // input needs quoting

                out.write(CSV_QUOTE);

                out.write(StringUtils.replace(inputSting, CSV_QUOTE_STR, CSV_ESCAPED_QUOTE_STR));

                out.write(CSV_QUOTE);

            }

        }

    }

    /**

     * Translator for unescaping escaped Comma Separated Value entries.

     */

    public static class CsvUnescaper extends SinglePassTranslator {

        @Override

        void translateWhole(final CharSequence input, final Writer out) throws IOException {

            // is input not quoted?

            if (input.charAt(0) != CSV_QUOTE || input.charAt(input.length() - 1) != CSV_QUOTE) {

                out.write(input.toString());

                return;

            }

            // strip quotes

            final String quoteless = input.subSequence(1, input.length() - 1).toString();

            if (StringUtils.containsAny(quoteless, CSV_SEARCH_CHARS)) {

                // deal with escaped quotes; ie) ""

                out.write(StringUtils.replace(quoteless, CSV_ESCAPED_QUOTE_STR, CSV_QUOTE_STR));

            } else {

                out.write(quoteless);

            }

        }

    }

}