/*
 * 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.catalina.util;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.Properties;
import java.util.TimeZone;

/**
 * Converts dates to strings using the same format specifiers as strftime Notes:
 * <ul>
 * <li>This does not mimic strftime perfectly. Certain strftime commands, are not supported, and will convert as if they
 * were literals.</li>
 * <li>Certain complicated commands, like those dealing with the week of the year probably don't have exactly the same
 * behavior as strftime.</li>
 * <li>These limitations are due to use SimpleDateTime. If the conversion was done manually, all these limitations could
 * be eliminated.</li>
 * <li>The interface looks like a subset of DateFormat. Maybe someday someone will make this class extend
 * DateFormat.</li>
 * </ul>
 *
 * @author Bip Thelin
 * @author Dan Sandberg
 */
public class Strftime {
    protected static final Properties translate;
    protected final SimpleDateFormat simpleDateFormat;

    /*
     * Initialize our pattern translation
     */
    static {
        translate = new Properties();
        translate.put("a", "EEE");
        translate.put("A", "EEEE");
        translate.put("b", "MMM");
        translate.put("B", "MMMM");
        translate.put("c", "EEE MMM d HH:mm:ss yyyy");

        // There's no way to specify the century in SimpleDateFormat. We don't want to hard-code
        // 20 since this could be wrong for the pre-2000 files.
        // translate.put("C", "20");
        translate.put("d", "dd");
        translate.put("D", "MM/dd/yy");
        translate.put("e", "dd"); // will show as '03' instead of ' 3'
        translate.put("F", "yyyy-MM-dd");
        translate.put("g", "yy");
        translate.put("G", "yyyy");
        translate.put("H", "HH");
        translate.put("h", "MMM");
        translate.put("I", "hh");
        translate.put("j", "DDD");
        translate.put("k", "HH"); // will show as '07' instead of ' 7'
        translate.put("l", "hh"); // will show as '07' instead of ' 7'
        translate.put("m", "MM");
        translate.put("M", "mm");
        translate.put("n", "\n");
        translate.put("p", "a");
        translate.put("P", "a"); // will show as pm instead of PM
        translate.put("r", "hh:mm:ss a");
        translate.put("R", "HH:mm");
        // There's no way to specify this with SimpleDateFormat
        // translate.put("s","seconds since epoch");
        translate.put("S", "ss");
        translate.put("t", "\t");
        translate.put("T", "HH:mm:ss");
        // There's no way to specify this with SimpleDateFormat
        // translate.put("u","day of week ( 1-7 )");

        // There's no way to specify this with SimpleDateFormat
        // translate.put("U","week in year with first Sunday as first day...");

        translate.put("V", "ww"); // I'm not sure this is always exactly the same

        // There's no way to specify this with SimpleDateFormat
        // translate.put("W","week in year with first Monday as first day...");

        // There's no way to specify this with SimpleDateFormat
        // translate.put("w","E");
        translate.put("X", "HH:mm:ss");
        translate.put("x", "MM/dd/yy");
        translate.put("y", "yy");
        translate.put("Y", "yyyy");
        translate.put("Z", "z");
        translate.put("z", "Z");
        translate.put("%", "%");
    }


    /**
     * Create an instance of this date formatting class
     *
     * @param origFormat the strftime-style formatting string
     * @param locale     the locale to use for locale-specific conversions
     */
    public Strftime(String origFormat, Locale locale) {
        String convertedFormat = convertDateFormat(origFormat);
        simpleDateFormat = new SimpleDateFormat(convertedFormat, locale);
    }

    /**
     * Format the date according to the strftime-style string given in the constructor.
     *
     * @param date the date to format
     *
     * @return the formatted date
     */
    public String format(Date date) {
        return simpleDateFormat.format(date);
    }

    /**
     * Get the timezone used for formatting conversions
     *
     * @return the timezone
     */
    public TimeZone getTimeZone() {
        return simpleDateFormat.getTimeZone();
    }

    /**
     * Change the timezone used to format dates
     *
     * @param timeZone The new time zone
     *
     * @see SimpleDateFormat#setTimeZone
     */
    public void setTimeZone(TimeZone timeZone) {
        simpleDateFormat.setTimeZone(timeZone);
    }

    /**
     * Search the provided pattern and get the C standard Date/Time formatting rules and convert them to the Java
     * equivalent.
     *
     * @param pattern The pattern to search
     *
     * @return The modified pattern
     */
    protected String convertDateFormat(String pattern) {
        boolean inside = false;
        boolean mark = false;
        boolean modifiedCommand = false;

        StringBuilder buf = new StringBuilder();

        for (int i = 0; i < pattern.length(); i++) {
            char c = pattern.charAt(i);

            if (c == '%' && !mark) {
                mark = true;
            } else {
                if (mark) {
                    if (modifiedCommand) {
                        // don't do anything--we just wanted to skip a char
                        modifiedCommand = false;
                        mark = false;
                    } else {
                        inside = translateCommand(buf, pattern, i, inside);
                        // It's a modifier code
                        if (c == 'O' || c == 'E') {
                            modifiedCommand = true;
                        } else {
                            mark = false;
                        }
                    }
                } else {
                    if (!inside && c != ' ') {
                        // We start a literal, which we need to quote
                        buf.append('\'');
                        inside = true;
                    }

                    buf.append(c);
                }
            }
        }

        if (buf.length() > 0) {
            char lastChar = buf.charAt(buf.length() - 1);

            if (lastChar != '\'' && inside) {
                buf.append('\'');
            }
        }
        return buf.toString();
    }

    protected String quote(String str, boolean insideQuotes) {
        String retVal = str;
        if (!insideQuotes) {
            retVal = '\'' + retVal + '\'';
        }
        return retVal;
    }

    /**
     * Try to get the Java Date/Time formatting associated with the C standard provided.
     *
     * @param buf       The buffer
     * @param pattern   The date/time pattern
     * @param index     The char index
     * @param oldInside Flag value
     *
     * @return True if new is inside buffer
     */
    protected boolean translateCommand(StringBuilder buf, String pattern, int index, boolean oldInside) {
        char firstChar = pattern.charAt(index);
        boolean newInside = oldInside;

        // O and E are modifiers, they mean to present an alternative representation of the next char
        // we just handle the next char as if the O or E wasn't there
        if (firstChar == 'O' || firstChar == 'E') {
            if (index + 1 < pattern.length()) {
                newInside = translateCommand(buf, pattern, index + 1, oldInside);
            } else {
                buf.append(quote("%" + firstChar, oldInside));
            }
        } else {
            String command = translate.getProperty(String.valueOf(firstChar));

            // If we don't find a format, treat it as a literal--That's what apache does
            if (command == null) {
                buf.append(quote("%" + firstChar, oldInside));
            } else {
                // If we were inside quotes, close the quotes
                if (oldInside) {
                    buf.append('\'');
                }
                buf.append(command);
                newInside = false;
            }
        }
        return newInside;
    }
}
