/*
 * 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.tomcat.buildutil.translate;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.util.HashSet;
import java.util.Properties;
import java.util.Set;
import java.util.regex.Pattern;

public class Utils {

    private static final Pattern ESCAPE_LEADING_SPACE = Pattern.compile("^( )", Pattern.MULTILINE);

    private static final Set<String> KEYS_WITH_UNNECESSARY_ESCAPING = new HashSet<>();

    // Package private so it is visible to tests
    static final String PADDING = "POEDITOR_EXPORT_PADDING_DO_NOT_DELETE";

    static {
        KEYS_WITH_UNNECESSARY_ESCAPING.add("arrays.malformed.arrays");
        KEYS_WITH_UNNECESSARY_ESCAPING.add("jsp.error.attribute.deferredmix");
        KEYS_WITH_UNNECESSARY_ESCAPING.add("jsp.error.el.template.deferred");
    }


    private Utils() {
        // Utility class. Hide default constructor.
    }


    static String getLanguage(String name) {
        return name.substring(Constants.L10N_PREFIX.length(), name.length() - Constants.L10N_SUFFIX.length());
    }


    static Properties load(File f) {
        Properties props = new Properties();

        try (FileInputStream fis = new FileInputStream(f);
                Reader r = new InputStreamReader(fis, StandardCharsets.UTF_8)) {
            props.load(r);
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
        return props;
    }


    /*
     * This is the formatting applied when importing values to Tomcat from POE.
     *
     * The values have been read from POE's property files (so the input is the actual value with none of the
     * escaping required to represent that value in a property file) and are being written back out to individual files
     * in Tomcat. The padding for blank lines needs to be removed followed by the common formatting required to convert
     * a property value to the representation of that value in a file.
     */
    static String formatValueImport(String in) {
        String result;

        if (in.startsWith(PADDING)) {
            result = in.substring(PADDING.length());
        } else {
            result = in;
        }

        return formatValueCommon(result);
    }


    /*
     * Values containing "[{n}]" and "'" need to have the "'" escaped as "''". POEditor attempts to do this
     * automatically but does it for any value containing "{" or "}" leading to some unnecessary escaping. This method
     * undoes the unnecessary escaping.
     */
    static String fixUnnecessaryEscaping(String key, String value) {
        if (KEYS_WITH_UNNECESSARY_ESCAPING.contains(key)) {
            return value.replace("''", "'");
        }
        return value;
    }


    /*
     * Common formatting to convert a String value for storage as a value in a property file. Values that contain
     * line-breaks need the line-break in the value to be replaced with the correct representation of a line-break in a
     * property file. Leading space needs to be escaped with a '\' and horizontal tabs need to be converted to "\t".
     *
     * Note that a single '\' needs to be escaped both in a Java string and in a property file so if a property value
     * needs to contain a single `\` (e.g. to escape white space at the start of a line) that will appear as "\\\\" in
     * the Java code.
     */
    static String formatValueCommon(String in) {
        String result = in.replace("\n", "\\n\\\n");
        if (result.endsWith("\\n\\\n")) {
            result = result.substring(0, result.length() - 2);
        }

        result = ESCAPE_LEADING_SPACE.matcher(result).replaceAll("\\\\$1");

        result = result.replace("\t", "\\t");

        return result;
    }


    static void insertEditInstructions(Writer w) throws IOException {
        w.write(System.lineSeparator());
        w.write("# Do not edit this file directly.");
        w.write(System.lineSeparator());
        w.write("# To edit translations see: https://tomcat.apache.org/getinvolved.html#Translations");
        w.write(System.lineSeparator());
    }
}
