/*
    * 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.shardingsphere.db.protocol.firebird.packet.command.query.statement.execute.protocol.util;
  
  import lombok.Getter;
  import lombok.Setter;
  
  import java.sql.Timestamp;
  import java.time.LocalDateTime;
  
  /**
   * Firebird date and time utility class.
   */
  @Getter
  @Setter
  public final class FirebirdDateTimeUtil {
      
      static final int NANOSECONDS_PER_FRACTION = 100 * 1000;
      
      static final int FRACTIONS_PER_MILLISECOND = 10;
      
      static final int FRACTIONS_PER_SECOND = 1000 * FRACTIONS_PER_MILLISECOND;
      
      static final int FRACTIONS_PER_MINUTE = 60 * FRACTIONS_PER_SECOND;
      
      static final int FRACTIONS_PER_HOUR = 60 * FRACTIONS_PER_MINUTE;
      
      private int year;
      
      private int month;
      
      private int day;
      
      private int hour;
      
      private int minute;
      
      private int second;
      
      private int fractions;
      
      public FirebirdDateTimeUtil(final LocalDateTime localDateTime) {
          year = localDateTime.getYear();
          month = localDateTime.getMonthValue();
          day = localDateTime.getDayOfMonth();
          hour = localDateTime.getHour();
          minute = localDateTime.getMinute();
          second = localDateTime.getSecond();
          fractions = (localDateTime.getNano() / NANOSECONDS_PER_FRACTION) % FRACTIONS_PER_SECOND;
      }
      
      public FirebirdDateTimeUtil() {
          year = 0;
          month = 1;
          day = 1;
          hour = 0;
          minute = 0;
          second = 0;
          fractions = 0;
      }
      
      /**
       * Get encoded date value.
       *
       * @return encoded date as integer
       */
      public int getEncodedDate() {
          int cpMonth = month;
          int cpYear = year;
          if (cpMonth > 2) {
              cpMonth -= 3;
          } else {
              cpMonth += 9;
              cpYear -= 1;
          }
          int c = cpYear / 100;
          int ya = cpYear - 100 * c;
          return convertDate(c, ya, cpMonth);
      }
      
      /**
       * Encode {@link LocalDateTime} to an integer date representation.
       *
       * @param localDateTime the local date-time to encode
      * @return encoded date as integer
      */
     public static int getEncodedDate(final LocalDateTime localDateTime) {
         return new FirebirdDateTimeUtil(localDateTime).getEncodedDate();
     }
     
     private int convertDate(final int c, final int ya, final int cpMonth) {
         return (146097 * c) / 4
                 + (1461 * ya) / 4
                 + (153 * cpMonth + 2) / 5
                 + day + 1721119 - 2400001;
     }
     
     /**
      * Decode encoded date and set internal year, month, and day fields.
      *
      * @param encodedDate encoded date as integer
      * @return this instance with updated date fields
      */
     public FirebirdDateTimeUtil setDate(final int encodedDate) {
         int sqldate = encodedDate - 1721119 + 2400001;
         int century = (4 * sqldate - 1) / 146097;
         sqldate = 4 * sqldate - 1 - 146097 * century;
         day = sqldate / 4;
         sqldate = (4 * day + 3) / 1461;
         day = 4 * day + 3 - 1461 * sqldate;
         day = (day + 5) / 5;
         month = (5 * day - 3) / 153;
         day = 5 * day - 3 - 153 * month;
         day = (day + 5) / 5;
         year = 100 * century + sqldate;
         if (month < 10) {
             month += 3;
         } else {
             month -= 9;
             year += 1;
         }
         return this;
     }
     
     public int getEncodedTime() {
         return hour * FRACTIONS_PER_HOUR
                 + minute * FRACTIONS_PER_MINUTE
                 + second * FRACTIONS_PER_SECOND
                 + fractions;
     }
     
     /**
      * Decode encoded time and set internal hour, minute, second, and fraction fields.
      *
      * @param encodedTime encoded time as integer
      * @return this instance with updated time fields
      */
     public FirebirdDateTimeUtil setTime(final int encodedTime) {
         int fractionsInDay = encodedTime;
         hour = fractionsInDay / FRACTIONS_PER_HOUR;
         fractionsInDay -= hour * FRACTIONS_PER_HOUR;
         minute = fractionsInDay / FRACTIONS_PER_MINUTE;
         fractionsInDay -= minute * FRACTIONS_PER_MINUTE;
         second = fractionsInDay / FRACTIONS_PER_SECOND;
         fractions = fractionsInDay - second * FRACTIONS_PER_SECOND;
         return this;
     }
     
     /**
      * Convert the internal date-time fields to a {@link Timestamp}.
      *
      * @return timestamp representation of the current date-time fields
      */
     public Timestamp asTimestamp() {
         return Timestamp.valueOf(LocalDateTime.of(year, month, day, hour, minute, second, fractions));
     }
     
     /**
      * Convert encoded date value to {@link Timestamp}.
      *
      * @param encodedDate encoded date as integer
      * @return timestamp representation of the encoded date
      */
     public static Timestamp getDate(final int encodedDate) {
         return new FirebirdDateTimeUtil().setDate(encodedDate).asTimestamp();
     }
     
     /**
      * Convert encoded time value to {@link Timestamp}.
      *
      * @param encodedTime encoded time as integer
      * @return timestamp representation of the encoded time
      */
     public static Timestamp getTime(final int encodedTime) {
         return new FirebirdDateTimeUtil().setTime(encodedTime).asTimestamp();
     }
     
     /**
      * Convert encoded date and time values to {@link Timestamp}.
      *
      * @param encodedDate encoded date as integer
      * @param encodedTime encoded time as integer
      * @return timestamp representation of the encoded date and time
      */
     public static Timestamp getDateTime(final int encodedDate, final int encodedTime) {
         return new FirebirdDateTimeUtil().setDate(encodedDate).setTime(encodedTime).asTimestamp();
     }
     
     /**
      * Convert encoded date and time values with offset to {@link Timestamp}.
      *
      * @param encodedDate encoded date as integer
      * @param encodedTime encoded time as integer
      * @param offset offset value in minutes or seconds (pending implementation details)
      * @return timestamp representation of the encoded date and time with offset
      */
     public static Timestamp getDateTimeWithOffset(final int encodedDate, final int encodedTime, final int offset) {
         // TODO add time zone support
         return new FirebirdDateTimeUtil().setDate(encodedDate).setTime(encodedTime).asTimestamp();
     }
 }