/*
 * 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.net.ftp.parser;

import java.text.DateFormatSymbols;
import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

import org.apache.commons.net.ftp.Configurable;
import org.apache.commons.net.ftp.FTPClientConfig;

Default implementation of the  FTPTimestampParser interface also implements the  Configurable interface to allow the parsing to be configured from the outside. 
See Also:
ConfigurableFTPFileEntryParserImpl
Since:
1.4/**
 * Default implementation of the {@link  FTPTimestampParser  FTPTimestampParser}
 * interface also implements the {@link  org.apache.commons.net.ftp.Configurable  Configurable}
 * interface to allow the parsing to be configured from the outside.
 *
 * @see ConfigurableFTPFileEntryParserImpl
 * @since 1.4
 */
public class FTPTimestampParserImpl implements
        FTPTimestampParser, Configurable
{


    
The date format for all dates, except possibly recent dates. Assumed to include the year. /** The date format for all dates, except possibly recent dates. Assumed to include the year. */
    private SimpleDateFormat defaultDateFormat;
    /* The index in CALENDAR_UNITS of the smallest time unit in defaultDateFormat */
    private int defaultDateSmallestUnitIndex;

    
The format used for recent dates (which don't have the year). May be null. /** The format used for recent dates (which don't have the year). May be null. */
    private SimpleDateFormat recentDateFormat;
    /* The index in CALENDAR_UNITS of the smallest time unit in recentDateFormat */
    private int recentDateSmallestUnitIndex;

    private boolean lenientFutureDates = false;

    /*
     * List of units in order of increasing significance.
     * This allows the code to clear all units in the Calendar until it
     * reaches the least significant unit in the parse string.
     * The date formats are analysed to find the least significant
     * unit (e.g. Minutes or Milliseconds) and the appropriate index to
     * the array is saved.
     * This is done by searching the array for the unit specifier,
     * and returning the index. When clearing the Calendar units,
     * the code loops through the array until the previous entry.
     * e.g. for MINUTE it would clear MILLISECOND and SECOND
     */
    private static final int[] CALENDAR_UNITS = {
        Calendar.MILLISECOND,
        Calendar.SECOND,
        Calendar.MINUTE,
        Calendar.HOUR_OF_DAY,
        Calendar.DAY_OF_MONTH,
        Calendar.MONTH,
        Calendar.YEAR};

    /*
     * Return the index to the array representing the least significant
     * unit found in the date format.
     * Default is 0 (to avoid dropping precision)
     */
    private static int getEntry(SimpleDateFormat dateFormat) {
        if (dateFormat == null) {
            return 0;
        }
        final String FORMAT_CHARS="SsmHdM";
        final String pattern = dateFormat.toPattern();
        for(char ch : FORMAT_CHARS.toCharArray()) {
            if (pattern.indexOf(ch) != -1){ // found the character
                switch(ch) {
                case 'S':
                    return indexOf(Calendar.MILLISECOND);
                case 's':
                    return indexOf(Calendar.SECOND);
                case 'm':
                    return indexOf(Calendar.MINUTE);
                case 'H':
                    return indexOf(Calendar.HOUR_OF_DAY);
                case 'd':
                    return indexOf(Calendar.DAY_OF_MONTH);
                case 'M':
                    return indexOf(Calendar.MONTH);
                }
            }
        }
        return 0;
    }

    /*
     * Find the entry in the CALENDAR_UNITS array.
     */
    private static int indexOf(int calendarUnit) {
        int i;
        for(i = 0; i <CALENDAR_UNITS.length; i++) {
            if (calendarUnit == CALENDAR_UNITS[i]) {
                return i;
            }
        }
        return 0;
    }

    /*
     * Sets the Calendar precision (used by FTPFile#toFormattedDate) by clearing
     * the immediately preceeding unit (if any).
     * Unfortunately the clear(int) method results in setting all other units.
     */
    private static void setPrecision(int index, Calendar working) {
        if (index <= 0) { // e.g. MILLISECONDS
            return;
        }
        final int field = CALENDAR_UNITS[index-1];
        // Just in case the analysis is wrong, stop clearing if
        // field value is not the default.
        final int value = working.get(field);
        if (value != 0) { // don't reset if it has a value
//            new Throwable("Unexpected value "+value).printStackTrace(); // DEBUG
        } else {
            working.clear(field); // reset just the required field
        }
    }

    
The only constructor for this class.
/**
     * The only constructor for this class.
     */
    public FTPTimestampParserImpl() {
        setDefaultDateFormat(DEFAULT_SDF, null);
        setRecentDateFormat(DEFAULT_RECENT_SDF, null);
    }

    
Implements the one  method in the  FTPTimestampParser interface according to this algorithm: If the recentDateFormat member has been defined, try to parse the supplied string with that. If that parse fails, or if the recentDateFormat member has not been defined, attempt to parse with the defaultDateFormat member. If that fails, throw a ParseException. This method assumes that the server time is the same as the local time. 
Params:
timestampStr – The timestamp to be parsed
See Also:
parseTimestamp(String, Calendar)
Returns:
a Calendar with the parsed timestamp/**
     * Implements the one {@link  FTPTimestampParser#parseTimestamp(String)  method}
     * in the {@link  FTPTimestampParser  FTPTimestampParser} interface
     * according to this algorithm:
     *
     * If the recentDateFormat member has been defined, try to parse the
     * supplied string with that.  If that parse fails, or if the recentDateFormat
     * member has not been defined, attempt to parse with the defaultDateFormat
     * member.  If that fails, throw a ParseException.
     *
     * This method assumes that the server time is the same as the local time.
     *
     * @see FTPTimestampParserImpl#parseTimestamp(String, Calendar)
     *
     * @param timestampStr The timestamp to be parsed
     * @return a Calendar with the parsed timestamp
     */
    @Override
    public Calendar parseTimestamp(String timestampStr) throws ParseException {
        Calendar now = Calendar.getInstance();
        return parseTimestamp(timestampStr, now);
    }

    
If the recentDateFormat member has been defined, try to parse the supplied string with that. If that parse fails, or if the recentDateFormat member has not been defined, attempt to parse with the defaultDateFormat member. If that fails, throw a ParseException. This method allows a Calendar instance to be passed in which represents the current (system) time. 
Params:
timestampStr – The timestamp to be parsed
serverTime – The current time for the server
Throws:
ParseException – if timestamp cannot be parsed
See Also:
FTPTimestampParser.parseTimestamp(String)
Returns:
the calendar
Since:
1.5/**
     * If the recentDateFormat member has been defined, try to parse the
     * supplied string with that.  If that parse fails, or if the recentDateFormat
     * member has not been defined, attempt to parse with the defaultDateFormat
     * member.  If that fails, throw a ParseException.
     *
     * This method allows a {@link Calendar} instance to be passed in which represents the
     * current (system) time.
     *
     * @see FTPTimestampParser#parseTimestamp(String)
     * @param timestampStr The timestamp to be parsed
     * @param serverTime The current time for the server
     * @return the calendar
     * @throws ParseException if timestamp cannot be parsed
     * @since 1.5
     */
    public Calendar parseTimestamp(String timestampStr, Calendar serverTime) throws ParseException {
        Calendar working = (Calendar) serverTime.clone();
        working.setTimeZone(getServerTimeZone()); // is this needed?

        Date parsed = null;

        if (recentDateFormat != null) {
            Calendar now = (Calendar) serverTime.clone();// Copy this, because we may change it
            now.setTimeZone(this.getServerTimeZone());
            if (lenientFutureDates) {
                // add a day to "now" so that "slop" doesn't cause a date
                // slightly in the future to roll back a full year.  (Bug 35181 => NET-83)
                now.add(Calendar.DAY_OF_MONTH, 1);
            }
            // The Java SimpleDateFormat class uses the epoch year 1970 if not present in the input
            // As 1970 was not a leap year, it cannot parse "Feb 29" correctly.
            // Java 1.5+ returns Mar 1 1970
            // Temporarily add the current year to the short date time
            // to cope with short-date leap year strings.
            // Since Feb 29 is more that 6 months from the end of the year, this should be OK for
            // all instances of short dates which are +- 6 months from current date.
            // TODO this won't always work for systems that use short dates +0/-12months
            // e.g. if today is Jan 1 2001 and the short date is Feb 29
            String year = Integer.toString(now.get(Calendar.YEAR));
            String timeStampStrPlusYear = timestampStr + " " + year;
            SimpleDateFormat hackFormatter = new SimpleDateFormat(recentDateFormat.toPattern() + " yyyy",
                    recentDateFormat.getDateFormatSymbols());
            hackFormatter.setLenient(false);
            hackFormatter.setTimeZone(recentDateFormat.getTimeZone());
            ParsePosition pp = new ParsePosition(0);
            parsed = hackFormatter.parse(timeStampStrPlusYear, pp);
            // Check if we parsed the full string, if so it must have been a short date originally
            if (parsed != null && pp.getIndex() == timeStampStrPlusYear.length()) {
                working.setTime(parsed);
                if (working.after(now)) { // must have been last year instead
                    working.add(Calendar.YEAR, -1);
                }
                setPrecision(recentDateSmallestUnitIndex, working);
                return working;
            }
        }

        ParsePosition pp = new ParsePosition(0);
        parsed = defaultDateFormat.parse(timestampStr, pp);
        // note, length checks are mandatory for us since
        // SimpleDateFormat methods will succeed if less than
        // full string is matched.  They will also accept,
        // despite "leniency" setting, a two-digit number as
        // a valid year (e.g. 22:04 will parse as 22 A.D.)
        // so could mistakenly confuse an hour with a year,
        // if we don't insist on full length parsing.
        if (parsed != null && pp.getIndex() == timestampStr.length()) {
            working.setTime(parsed);
        } else {
            throw new ParseException(
                    "Timestamp '"+timestampStr+"' could not be parsed using a server time of "
                        +serverTime.getTime().toString(),
                    pp.getErrorIndex());
        }
        setPrecision(defaultDateSmallestUnitIndex, working);
        return working;
    }

    
Returns:
Returns the defaultDateFormat./**
     * @return Returns the defaultDateFormat.
     */
    public SimpleDateFormat getDefaultDateFormat() {
        return defaultDateFormat;
    }
    
Returns:
Returns the defaultDateFormat pattern string./**
     * @return Returns the defaultDateFormat pattern string.
     */
    public String getDefaultDateFormatString() {
        return defaultDateFormat.toPattern();
    }
    
Params:
format – The defaultDateFormat to be set.
dfs – the symbols to use (may be null)/**
     * @param format The defaultDateFormat to be set.
     * @param dfs the symbols to use (may be null)
     */
    private void setDefaultDateFormat(String format, DateFormatSymbols dfs) {
        if (format != null) {
            if (dfs != null) {
                this.defaultDateFormat = new SimpleDateFormat(format, dfs);
            } else {
                this.defaultDateFormat = new SimpleDateFormat(format);
            }
            this.defaultDateFormat.setLenient(false);
        } else {
            this.defaultDateFormat = null;
        }
        this.defaultDateSmallestUnitIndex = getEntry(this.defaultDateFormat);
    }
    
Returns:
Returns the recentDateFormat./**
     * @return Returns the recentDateFormat.
     */
    public SimpleDateFormat getRecentDateFormat() {
        return recentDateFormat;
    }
    
Returns:
Returns the recentDateFormat./**
     * @return Returns the recentDateFormat.
     */
    public String getRecentDateFormatString() {
        return recentDateFormat.toPattern();
    }
    
Params:
format – The recentDateFormat to set.
dfs – the symbols to use (may be null)/**
     * @param format The recentDateFormat to set.
     * @param dfs the symbols to use (may be null)
     */
    private void setRecentDateFormat(String format, DateFormatSymbols dfs) {
        if (format != null) {
            if (dfs != null) {
                this.recentDateFormat = new SimpleDateFormat(format, dfs);
            } else {
                this.recentDateFormat = new SimpleDateFormat(format);
            }
            this.recentDateFormat.setLenient(false);
        } else {
            this.recentDateFormat = null;
        }
        this.recentDateSmallestUnitIndex = getEntry(this.recentDateFormat);
    }

    
Returns:
returns an array of 12 strings representing the short
month names used by this parse./**
     * @return returns an array of 12 strings representing the short
     * month names used by this parse.
     */
    public String[] getShortMonths() {
        return defaultDateFormat.getDateFormatSymbols().getShortMonths();
    }


    
Returns:
Returns the serverTimeZone used by this parser./**
     * @return Returns the serverTimeZone used by this parser.
     */
    public TimeZone getServerTimeZone() {
        return this.defaultDateFormat.getTimeZone();
    }
    
sets a TimeZone represented by the supplied ID string into all
of the parsers used by this server.
Params:
serverTimeZone – Time Id java.util.TimeZone id used by
the ftp server.  If null the client's local time zone is assumed./**
     * sets a TimeZone represented by the supplied ID string into all
     * of the parsers used by this server.
     * @param serverTimeZone Time Id java.util.TimeZone id used by
     * the ftp server.  If null the client's local time zone is assumed.
     */
    private void setServerTimeZone(String serverTimeZoneId) {
        TimeZone serverTimeZone = TimeZone.getDefault();
        if (serverTimeZoneId != null) {
            serverTimeZone = TimeZone.getTimeZone(serverTimeZoneId);
        }
        this.defaultDateFormat.setTimeZone(serverTimeZone);
        if (this.recentDateFormat != null) {
            this.recentDateFormat.setTimeZone(serverTimeZone);
        }
    }

    
Implementation of the  Configurable interface. Configures this FTPTimestampParser according
to the following logic:
 Set up the defaultDateFormat and optionally the recentDateFormat to values supplied in the config based on month names configured as follows: 

If a shortMonthString has been supplied in the config, use that to parse  parse timestamps.
Otherwise, if a serverLanguageCode has been supplied in the config, use the month names represented by that language to parse timestamps.
otherwise use default English month names
 Finally if a serverTimeZoneId has been supplied via the config, set that into all date formats that have been configured. 
/**
     * Implementation of the {@link  Configurable  Configurable}
     * interface. Configures this <code>FTPTimestampParser</code> according
     * to the following logic:
     * <p>
     * Set up the {@link  FTPClientConfig#setDefaultDateFormatStr(java.lang.String) defaultDateFormat}
     * and optionally the {@link  FTPClientConfig#setRecentDateFormatStr(String) recentDateFormat}
     * to values supplied in the config based on month names configured as follows:
     * </p>
     * <ul>
     * <li>If a {@link  FTPClientConfig#setShortMonthNames(String) shortMonthString}
     * has been supplied in the <code>config</code>, use that to parse  parse timestamps.</li>
     * <li>Otherwise, if a {@link  FTPClientConfig#setServerLanguageCode(String) serverLanguageCode}
     * has been supplied in the <code>config</code>, use the month names represented
     * by that {@link  FTPClientConfig#lookupDateFormatSymbols(String) language}
     * to parse timestamps.</li>
     * <li>otherwise use default English month names</li>
     * </ul><p>
     * Finally if a {@link  org.apache.commons.net.ftp.FTPClientConfig#setServerTimeZoneId(String) serverTimeZoneId}
     * has been supplied via the config, set that into all date formats that have
     * been configured.
     * </p>
     */
    @Override
    public void configure(FTPClientConfig config) {
        DateFormatSymbols dfs = null;

        String languageCode = config.getServerLanguageCode();
        String shortmonths = config.getShortMonthNames();
        if (shortmonths != null) {
            dfs = FTPClientConfig.getDateFormatSymbols(shortmonths);
        } else if (languageCode != null) {
            dfs = FTPClientConfig.lookupDateFormatSymbols(languageCode);
        } else {
            dfs = FTPClientConfig.lookupDateFormatSymbols("en");
        }


        String recentFormatString = config.getRecentDateFormatStr();
        setRecentDateFormat(recentFormatString, dfs);

        String defaultFormatString = config.getDefaultDateFormatStr();
        if (defaultFormatString == null) {
            throw new IllegalArgumentException("defaultFormatString cannot be null");
        }
        setDefaultDateFormat(defaultFormatString, dfs);

        setServerTimeZone(config.getServerTimeZoneId());

        this.lenientFutureDates = config.isLenientFutureDates();
    }
    
Returns:
Returns the lenientFutureDates./**
     * @return Returns the lenientFutureDates.
     */
    boolean isLenientFutureDates() {
        return lenientFutureDates;
    }
    
Params:
lenientFutureDates – The lenientFutureDates to set./**
     * @param lenientFutureDates The lenientFutureDates to set.
     */
    void setLenientFutureDates(boolean lenientFutureDates) {
        this.lenientFutureDates = lenientFutureDates;
    }
}