/*
    * 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
    *
    *      https://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.lang3.time;
  
  import java.text.DateFormat;
  import java.text.FieldPosition;
  import java.text.Format;
  import java.text.ParseException;
  import java.text.ParsePosition;
  import java.text.SimpleDateFormat;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.GregorianCalendar;
  import java.util.Locale;
  import java.util.TimeZone;
  
  /**
   * FastDateFormat is a fast and thread-safe version of {@link java.text.SimpleDateFormat}.
   *
   * <p>
   * To obtain an instance of FastDateFormat, use one of the static factory methods: {@link #getInstance(String, TimeZone, Locale)},
   * {@link #getDateInstance(int, TimeZone, Locale)}, {@link #getTimeInstance(int, TimeZone, Locale)}, or {@link #getDateTimeInstance(int, int, TimeZone, Locale)}
   * </p>
   *
   * <p>
   * Since FastDateFormat is thread safe, you can use a static member instance:
   * </p>
   * {@code
   *   private static final FastDateFormat DATE_FORMATTER = FastDateFormat.getDateTimeInstance(FastDateFormat.LONG, FastDateFormat.SHORT);
   * }
   *
   * <p>
   * This class can be used as a direct replacement to {@link SimpleDateFormat} in most formatting and parsing situations. This class is especially useful in
   * multi-threaded server environments. {@link SimpleDateFormat} is not thread-safe in any JDK version, nor will it be as Sun have closed the bug/RFE.
   * </p>
   *
   * <p>
   * All patterns are compatible with SimpleDateFormat (except time zones and some year patterns - see below).
   * </p>
   *
   * <p>
   * Since 3.2, FastDateFormat supports parsing as well as printing.
   * </p>
   *
   * <p>
   * Java 1.4 introduced a new pattern letter, {@code 'Z'}, to represent time zones in RFC822 format (for example, {@code +0800} or {@code -1100}). This pattern letter can
   * be used here (on all JDK versions).
   * </p>
   *
   * <p>
   * In addition, the pattern {@code 'ZZ'} has been made to represent ISO 8601 extended format time zones (for example, {@code +08:00} or {@code -11:00}). This introduces
   * a minor incompatibility with Java 1.4, but at a gain of useful functionality.
   * </p>
   *
   * <p>
   * Javadoc cites for the year pattern: <i>For formatting, if the number of pattern letters is 2, the year is truncated to 2 digits; otherwise it is interpreted
   * as a number.</i> Starting with Java 1.7 a pattern of 'Y' or 'YYY' will be formatted as '2003', while it was '03' in former Java versions. FastDateFormat
   * implements the behavior of Java 7.
   * </p>
   *
   * @since 2.0
   */
  public class FastDateFormat extends Format implements DateParser, DatePrinter {
  
      /**
       * Required for serialization support.
       *
       * @see java.io.Serializable
       */
      private static final long serialVersionUID = 2L;
  
      /**
       * FULL locale dependent date or time style.
       */
      public static final int FULL = DateFormat.FULL;
  
      /**
       * LONG locale dependent date or time style.
       */
      public static final int LONG = DateFormat.LONG;
  
      /**
       * MEDIUM locale dependent date or time style.
       */
     public static final int MEDIUM = DateFormat.MEDIUM;
 
     /**
      * SHORT locale dependent date or time style.
      */
     public static final int SHORT = DateFormat.SHORT;
 
     private static final AbstractFormatCache<FastDateFormat> CACHE = new AbstractFormatCache<FastDateFormat>() {
 
         @Override
         protected FastDateFormat createInstance(final String pattern, final TimeZone timeZone, final Locale locale) {
             return new FastDateFormat(pattern, timeZone, locale);
         }
     };
 
     /**
      * Clears the cache.
      */
     static void clear() {
         AbstractFormatCache.clear();
         CACHE.clearInstance();
     }
 
     /**
      * Gets a date formatter instance using the specified style in the default time zone and locale.
      *
      * @param style date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @return a localized standard date formatter.
      * @throws IllegalArgumentException if the Locale has no date pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getDateInstance(final int style) {
         return CACHE.getDateInstance(style, null, null);
     }
 
     /**
      * Gets a date formatter instance using the specified style and locale in the default time zone.
      *
      * @param style  date style: {@link #FULL}, LO{@link #FULL},{@link #MEDIUM}, or {@link #SHORT}.
      * @param locale optional locale, overrides system locale.
      * @return a localized standard date formatter.
      * @throws IllegalArgumentException if the Locale has no date pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getDateInstance(final int style, final Locale locale) {
         return CACHE.getDateInstance(style, null, locale);
     }
 
     /**
      * Gets a date formatter instance using the specified style and time zone in the default locale.
      *
      * @param style    date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeZone optional time zone, overrides time zone of formatted date.
      * @return a localized standard date formatter.
      * @throws IllegalArgumentException if the Locale has no date pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getDateInstance(final int style, final TimeZone timeZone) {
         return CACHE.getDateInstance(style, timeZone, null);
     }
 
     /**
      * Gets a date formatter instance using the specified style, time zone and locale.
      *
      * @param style    date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeZone optional time zone, overrides time zone of formatted date.
      * @param locale   optional locale, overrides system locale.
      * @return a localized standard date formatter.
      * @throws IllegalArgumentException if the Locale has no date pattern defined.
      */
     public static FastDateFormat getDateInstance(final int style, final TimeZone timeZone, final Locale locale) {
         return CACHE.getDateInstance(style, timeZone, locale);
     }
 
     /**
      * Gets a date/time formatter instance using the specified style in the default time zone and locale.
      *
      * @param dateStyle date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeStyle time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @return a localized standard date/time formatter.
      * @throws IllegalArgumentException if the Locale has no date/time pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle) {
         return CACHE.getDateTimeInstance(dateStyle, timeStyle, null, null);
     }
 
     /**
      * Gets a date/time formatter instance using the specified style and locale in the default time zone.
      *
      * @param dateStyle date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeStyle time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param locale    optional locale, overrides system locale.
      * @return a localized standard date/time formatter.
      * @throws IllegalArgumentException if the Locale has no date/time pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final Locale locale) {
         return CACHE.getDateTimeInstance(dateStyle, timeStyle, null, locale);
     }
 
     /**
      * Gets a date/time formatter instance using the specified style and time zone in the default locale.
      *
      * @param dateStyle date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeStyle time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeZone  optional time zone, overrides time zone of formatted date.
      * @return a localized standard date/time formatter.
      * @throws IllegalArgumentException if the Locale has no date/time pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final TimeZone timeZone) {
         return getDateTimeInstance(dateStyle, timeStyle, timeZone, null);
     }
 
     /**
      * Gets a date/time formatter instance using the specified style, time zone and locale.
      *
      * @param dateStyle date style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeStyle time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeZone  optional time zone, overrides time zone of formatted date.
      * @param locale    optional locale, overrides system locale.
      * @return a localized standard date/time formatter.
      * @throws IllegalArgumentException if the Locale has no date/time pattern defined.
      */
     public static FastDateFormat getDateTimeInstance(final int dateStyle, final int timeStyle, final TimeZone timeZone, final Locale locale) {
         return CACHE.getDateTimeInstance(dateStyle, timeStyle, timeZone, locale);
     }
 
     /**
      * Gets a formatter instance using the default pattern in the default locale.
      *
      * @return a date/time formatter.
      */
     public static FastDateFormat getInstance() {
         return CACHE.getInstance();
     }
 
     /**
      * Gets a formatter instance using the specified pattern in the default locale and time zone.
      *
      * @param pattern {@link java.text.SimpleDateFormat} compatible pattern.
      * @return a pattern based date/time formatter.
      * @throws IllegalArgumentException if pattern is invalid.
      */
     public static FastDateFormat getInstance(final String pattern) {
         return CACHE.getInstance(pattern, null, null);
     }
 
     /**
      * Gets a formatter instance using the specified pattern and locale using the default time zone.
      *
      * @param pattern {@link java.text.SimpleDateFormat} compatible pattern.
      * @param locale  optional locale, overrides system locale.
      * @return a pattern based date/time formatter.
      * @throws IllegalArgumentException if pattern is invalid.
      */
     public static FastDateFormat getInstance(final String pattern, final Locale locale) {
         return CACHE.getInstance(pattern, null, locale);
     }
 
     /**
      * Gets a formatter instance using the specified pattern and time zone.
      *
      * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern.
      * @param timeZone optional time zone, overrides time zone of formatted date.
      * @return a pattern based date/time formatter.
      * @throws IllegalArgumentException if pattern is invalid.
      */
     public static FastDateFormat getInstance(final String pattern, final TimeZone timeZone) {
         return CACHE.getInstance(pattern, timeZone, null);
     }
 
     /**
      * Gets a formatter instance using the specified pattern, time zone and locale.
      *
      * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern.
      * @param timeZone optional time zone, overrides time zone of formatted date.
      * @param locale   optional locale, overrides system locale.
      * @return a pattern based date/time formatter.
      * @throws IllegalArgumentException if pattern is invalid or {@code null}.
      */
     public static FastDateFormat getInstance(final String pattern, final TimeZone timeZone, final Locale locale) {
         return CACHE.getInstance(pattern, timeZone, locale);
     }
 
     /**
      * Gets a time formatter instance using the specified style in the default time zone and locale.
      *
      * @param style time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @return a localized standard time formatter.
      * @throws IllegalArgumentException if the Locale has no time pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getTimeInstance(final int style) {
         return CACHE.getTimeInstance(style, null, null);
     }
 
     /**
      * Gets a time formatter instance using the specified style and locale in the default time zone.
      *
      * @param style  time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param locale optional locale, overrides system locale.
      * @return a localized standard time formatter.
      * @throws IllegalArgumentException if the Locale has no time pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getTimeInstance(final int style, final Locale locale) {
         return CACHE.getTimeInstance(style, null, locale);
     }
 
     /**
      * Gets a time formatter instance using the specified style and time zone in the default locale.
      *
      * @param style    time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeZone optional time zone, overrides time zone of formatted time.
      * @return a localized standard time formatter.
      * @throws IllegalArgumentException if the Locale has no time pattern defined.
      * @since 2.1
      */
     public static FastDateFormat getTimeInstance(final int style, final TimeZone timeZone) {
         return CACHE.getTimeInstance(style, timeZone, null);
     }
 
     /**
      * Gets a time formatter instance using the specified style, time zone and locale.
      *
      * @param style    time style: {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, or {@link #SHORT}.
      * @param timeZone optional time zone, overrides time zone of formatted time.
      * @param locale   optional locale, overrides system locale.
      * @return a localized standard time formatter.
      * @throws IllegalArgumentException if the Locale has no time pattern defined.
      */
     public static FastDateFormat getTimeInstance(final int style, final TimeZone timeZone, final Locale locale) {
         return CACHE.getTimeInstance(style, timeZone, locale);
     }
 
     /** Our fast printer. */
     private final FastDatePrinter printer;
 
     /** Our fast parser. */
     private final FastDateParser parser;
 
     /**
      * Constructs a new FastDateFormat.
      *
      * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern.
      * @param timeZone non-null time zone to use.
      * @param locale   non-null locale to use.
      * @throws NullPointerException if pattern, timeZone, or locale is null.
      */
     protected FastDateFormat(final String pattern, final TimeZone timeZone, final Locale locale) {
         this(pattern, timeZone, locale, null);
     }
 
     /**
      * Constructs a new FastDateFormat.
      *
      * @param pattern      {@link java.text.SimpleDateFormat} compatible pattern.
      * @param timeZone     non-null time zone to use.
      * @param locale       non-null locale to use.
      * @param centuryStart The start of the 100-year period to use as the "default century" for 2 digit year parsing. If centuryStart is null, defaults to now -
      *                     80 years.
      * @throws NullPointerException if pattern, timeZone, or locale is null.
      */
     protected FastDateFormat(final String pattern, final TimeZone timeZone, final Locale locale, final Date centuryStart) {
         printer = new FastDatePrinter(pattern, timeZone, locale);
         parser = new FastDateParser(pattern, timeZone, locale, centuryStart);
     }
 
     /**
      * Performs the formatting by applying the rules to the specified calendar.
      *
      * @param calendar the calendar to format.
      * @param buf      the buffer to format into.
      * @return the specified string buffer.
      * @deprecated Use {@link #format(Calendar, Appendable)}
      */
     @Deprecated
     protected StringBuffer applyRules(final Calendar calendar, final StringBuffer buf) {
         return printer.format(calendar, buf);
     }
 
     /**
      * Compares two objects for equality.
      *
      * @param obj the object to compare to.
      * @return {@code true} if equal.
      */
     @Override
     public boolean equals(final Object obj) {
         if (!(obj instanceof FastDateFormat)) {
             return false;
         }
         final FastDateFormat other = (FastDateFormat) obj;
         // no need to check parser, as it has same invariants as printer
         return printer.equals(other.printer);
     }
 
     /**
      * Formats a {@link Calendar} object.
      *
      * @param calendar the calendar to format.
      * @return the formatted string.
      */
     @Override
     public String format(final Calendar calendar) {
         return printer.format(calendar);
     }
 
     /**
      * Formats a {@link Calendar} object into the supplied {@link StringBuffer}.
      *
      * @param calendar the calendar to format.
      * @param buf      the buffer to format into.
      * @return the specified string buffer.
      * @since 3.5
      */
     @Override
     public <B extends Appendable> B format(final Calendar calendar, final B buf) {
         return printer.format(calendar, buf);
     }
 
     /**
      * Formats a {@link Calendar} object into the supplied {@link StringBuffer}.
      *
      * @param calendar the calendar to format.
      * @param buf      the buffer to format into.
      * @return the specified string buffer.
      * @deprecated Use {{@link #format(Calendar, Appendable)}.
      */
     @Deprecated
     @Override
     public StringBuffer format(final Calendar calendar, final StringBuffer buf) {
         return printer.format(calendar, buf);
     }
 
     /**
      * Formats a {@link Date} object using a {@link GregorianCalendar}.
      *
      * @param date the date to format.
      * @return the formatted string.
      */
     @Override
     public String format(final Date date) {
         return printer.format(date);
     }
 
     /**
      * Formats a {@link Date} object into the supplied {@link StringBuffer} using a {@link GregorianCalendar}.
      *
      * @param date the date to format.
      * @param buf  the buffer to format into.
      * @return the specified string buffer.
      * @since 3.5
      */
     @Override
     public <B extends Appendable> B format(final Date date, final B buf) {
         return printer.format(date, buf);
     }
 
     /**
      * Formats a {@link Date} object into the supplied {@link StringBuffer} using a {@link GregorianCalendar}.
      *
      * @param date the date to format.
      * @param buf  the buffer to format into.
      * @return the specified string buffer.
      * @deprecated Use {{@link #format(Date, Appendable)}.
      */
     @Deprecated
     @Override
     public StringBuffer format(final Date date, final StringBuffer buf) {
         return printer.format(date, buf);
     }
 
     /**
      * Formats a millisecond {@code long} value.
      *
      * @param millis the millisecond value to format.
      * @return the formatted string.
      * @since 2.1
      */
     @Override
     public String format(final long millis) {
         return printer.format(millis);
     }
 
     /**
      * Formats a millisecond {@code long} value into the supplied {@link StringBuffer}.
      *
      * @param millis the millisecond value to format.
      * @param buf    the buffer to format into.
      * @return the specified string buffer.
      * @since 3.5
      */
     @Override
     public <B extends Appendable> B format(final long millis, final B buf) {
         return printer.format(millis, buf);
     }
 
     /**
      * Formats a millisecond {@code long} value into the supplied {@link StringBuffer}.
      *
      * @param millis the millisecond value to format.
      * @param buf    the buffer to format into.
      * @return the specified string buffer.
      * @since 2.1
      * @deprecated Use {{@link #format(long, Appendable)}.
      */
     @Deprecated
     @Override
     public StringBuffer format(final long millis, final StringBuffer buf) {
         return printer.format(millis, buf);
     }
 
     /**
      * Formats a {@link Date}, {@link Calendar} or {@link Long} (milliseconds) object. This method is an implementation of
      * {@link Format#format(Object, StringBuffer, FieldPosition)}
      *
      * @param obj        the object to format.
      * @param toAppendTo the buffer to append to.
      * @param pos        the position, ignored.
      * @return the given buffer.
      */
     @Override
     public StringBuffer format(final Object obj, final StringBuffer toAppendTo, final FieldPosition pos) {
         return toAppendTo.append(printer.format(obj));
     }
 
     /**
      * Gets the locale used by this formatter.
      *
      * @return the locale.
      */
     @Override
     public Locale getLocale() {
         return printer.getLocale();
     }
 
     /**
      * Gets an estimate for the maximum string length that the formatter will produce.
      *
      * <p>
      * The actual formatted length will almost always be less than or equal to this amount.
      * </p>
      *
      * @return the maximum formatted length.
      */
     public int getMaxLengthEstimate() {
         return printer.getMaxLengthEstimate();
     }
 
     /**
      * Gets the pattern used by this formatter.
      *
      * @return the pattern, {@link java.text.SimpleDateFormat} compatible.
      */
     @Override
     public String getPattern() {
         return printer.getPattern();
     }
 
     /**
      * Gets the time zone used by this formatter.
      *
      * <p>
      * This zone is always used for {@link Date} formatting.
      * </p>
      *
      * @return the time zone.
      */
     @Override
     public TimeZone getTimeZone() {
         return printer.getTimeZone();
     }
 
     /**
      * Returns a hash code compatible with equals.
      *
      * @return a hash code compatible with equals.
      */
     @Override
     public int hashCode() {
         return printer.hashCode();
     }
 
     /*
      * (non-Javadoc)
      *
      * @see DateParser#parse(String)
      */
     @Override
     public Date parse(final String source) throws ParseException {
         return parser.parse(source);
     }
 
     /*
      * (non-Javadoc)
      *
      * @see DateParser#parse(String, java.text.ParsePosition)
      */
     @Override
     public Date parse(final String source, final ParsePosition pos) {
         return parser.parse(source, pos);
     }
 
     /*
      * (non-Javadoc)
      *
      * @see org.apache.commons.lang3.time.DateParser#parse(String, java.text.ParsePosition, java.util.Calendar)
      */
     @Override
     public boolean parse(final String source, final ParsePosition pos, final Calendar calendar) {
         return parser.parse(source, pos, calendar);
     }
 
     /*
      * (non-Javadoc)
      *
      * @see java.text.Format#parseObject(String, java.text.ParsePosition)
      */
     @Override
     public Object parseObject(final String source, final ParsePosition pos) {
         return parser.parseObject(source, pos);
     }
 
     /**
      * Gets a debugging string version of this formatter.
      *
      * @return a debug string.
      */
     @Override
     public String toString() {
         return "FastDateFormat[" + printer.getPattern() + "," + printer.getLocale() + "," + printer.getTimeZone().getID() + "]";
     }
 }