/*
    *  Copyright 2001-2005 Stephen Colebourne
    *
    *  Licensed 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.joda.time.chrono.gj;
  
  /**
   * A reference Gregorian chronology implementation, intended for testing
   * purposes only. Correctness is favored over performance. The key functions
   * for date calculations are based on ones provided in "Calendrical
   * Calculations", ISBN 0-521-77752-6.
   *
   * @author Brian S O'Neill
   */
  public final class TestGregorianChronology extends TestGJChronology {
      /**
       * Constructs with an epoch of 1970-01-01.
       */
      public TestGregorianChronology() {
          super(1970, 1, 1);
      }
  
      public TestGregorianChronology(int epochYear, int epochMonth, int epochDay) {
          super(epochYear, epochMonth, epochDay);
      }
  
      public String toString() {
          return "TestGregorianChronology";
      }
  
      long millisPerYear() {
          return (long)(365.2425 * MILLIS_PER_DAY);
      }
  
      long millisPerMonth() {
          return (long)(365.2425 * MILLIS_PER_DAY / 12);
      }
  
      boolean isLeapYear(int year) {
          if (mod(year, 4) == 0) {
              int t = (int)mod(year, 400);
              if (t != 100 && t != 200 && t != 300) {
                  return true;
              }
          }
          return false;
      }
  
      /**
       * @return days from 0001-01-01
       */
      long fixedFromGJ(int year, int monthOfYear, int dayOfMonth) {
          long year_m1 = year - 1;
          long f = 365 * year_m1 + div(year_m1, 4) - div(year_m1, 100)
              + div(year_m1, 400) + div(367 * monthOfYear - 362, 12) + dayOfMonth;
          if (monthOfYear > 2) {
              f += isLeapYear(year) ? -1 : -2;
          }
          return f;
      }
  
      /**
       * @param date days from 0001-01-01
       * @return gj year
       */
      int gjYearFromFixed(long date) {
          long d0 = date - 1;
          long n400 = div(d0, 146097);
          long d1 = mod(d0, 146097);
          long n100 = div(d1, 36524);
          long d2 = mod(d1, 36524);
          long n4 = div(d2, 1461);
          long d3 = mod(d2, 1461);
          long n1 = div(d3, 365);
          long year = 400 * n400 + 100 * n100 + 4 * n4 + n1;
          if (!(n100 == 4 || n1 == 4)) {
              year += 1;
          }
  
          int year_i = (int)year;
          if (year_i == year) {
              return year_i;
          } else {
              throw new RuntimeException("year cannot be cast to an int: " + year);
          }
      }
  
      /**
      * @param date days from 0001-01-01
      * @return gj year, monthOfYear, dayOfMonth
      */
     int[] gjFromFixed(long date) {
         int year = gjYearFromFixed(date);
         long priorDays = date - fixedFromGJ(year, 1, 1);
         long correction;
         if (date < fixedFromGJ(year, 3, 1)) {
             correction = 0;
         } else if (isLeapYear(year)) {
             correction = 1;
         } else {
             correction = 2;
         }
         int monthOfYear = (int)div(12 * (priorDays + correction) + 373, 367);
         int day = (int)(date - fixedFromGJ(year, monthOfYear, 1) + 1);
 
         return new int[]{year, monthOfYear, day};
     }
 
     long fixedFromISO(int weekyear, int weekOfWeekyear, int dayOfWeek) {
         return nthWeekday(weekOfWeekyear, 0, weekyear - 1, 12, 28) + dayOfWeek;
     }
 
     /**
      * @param date days from 0001-01-01
      * @return iso weekyear, weekOfWeekyear, dayOfWeek (1=Monday to 7)
      */
     int[] isoFromFixed(long date) {
         int weekyear = gjYearFromFixed(date - 3);
         if (date >= fixedFromISO(weekyear + 1, 1, 1)) {
             weekyear += 1;
         }
         int weekOfWeekyear = (int)(div(date - fixedFromISO(weekyear, 1, 1), 7) + 1);
         int dayOfWeek = (int)amod(date, 7);
         return new int[]{weekyear, weekOfWeekyear, dayOfWeek};
     }
 }