/*
    * The Kuali Financial System, a comprehensive financial management system for higher education.
    * 
    * Copyright 2005-2014 The Kuali Foundation
    * 
    * This program is free software: you can redistribute it and/or modify
    * it under the terms of the GNU Affero General Public License as
    * published by the Free Software Foundation, either version 3 of the
    * License, or (at your option) any later version.
   * 
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Affero General Public License for more details.
   * 
   * You should have received a copy of the GNU Affero General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  package org.kuali.kfs.fp.document.service.impl;
  
  import java.math.BigDecimal;
  import java.sql.Date;
  import java.sql.Timestamp;
  import java.text.ParseException;
  import java.util.Calendar;
  import java.util.Collection;
  
  import org.kuali.kfs.fp.businessobject.TravelMileageRate;
  import org.kuali.kfs.fp.document.dataaccess.TravelMileageRateDao;
  import org.kuali.kfs.fp.document.service.DisbursementVoucherTravelService;
  import org.kuali.kfs.sys.service.NonTransactional;
  import org.kuali.kfs.sys.util.KfsDateUtils;
  import org.kuali.rice.core.api.datetime.DateTimeService;
  import org.kuali.rice.core.api.util.type.KualiDecimal;
  
  /**
   * This is the default implementation of the DisbursementVoucherTravelService interface.
   * Performs calculations of travel per diem and mileage amounts.
   */
  
  @NonTransactional
  public class DisbursementVoucherTravelServiceImpl implements DisbursementVoucherTravelService {
      private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(DisbursementVoucherTravelServiceImpl.class);
  
      protected TravelMileageRateDao travelMileageRateDao;
      protected DateTimeService dateTimeService;
  
      /**
       * This method calculates the per diem amount for a given period of time at the rate provided.  The per diem amount is
       * calculated as described below.
       *
       * For same day trips:
       * - Per diem is equal to 1/2 of the per diem rate provided if the difference in time between the start and end time is
       * greater than 12 hours.  An additional 1/4 of a day is added back to the amount if the trip lasted past 7:00pm.
       * - If the same day trip is less than 12 hours, the per diem amount will be zero.
       *
       * For multiple day trips:
       * - Per diem amount is equal to the full rate times the number of full days of travel.  A full day is equal to any day
       * during the trip that is not the first day or last day of the trip.
       * - For the first day of the trip,
       *   if the travel starts before noon, you receive a full day per diem,
       *   if the travel starts between noon and 5:59pm, you get a half day per diem,
       *   if the travel starts after 6:00pm, you only receive a quarter day per diem
       * - For the last day of the trip,
       *   if the travel ends before 6:00am, you only receive a quarter day per diem,
       *   if the travel ends between 6:00am and noon, you receive a half day per diem,
       *   if the travel ends after noon, you receive a full day per diem
       *
       * @param stateDateTime The starting date and time of the period the per diem amount is calculated for.
       * @param endDateTime The ending date and time of the period the per diema mount is calculated for.
       * @param rate The per diem rate used to calculate the per diem amount.
       * @return The per diem amount for the period specified, at the rate given.
       *
       * @see org.kuali.kfs.fp.document.service.DisbursementVoucherTravelService#calculatePerDiemAmount(org.kuali.kfs.fp.businessobject.DisbursementVoucherNonEmployeeTravel)
       */
      @Override
      public KualiDecimal calculatePerDiemAmount(Timestamp startDateTime, Timestamp endDateTime, KualiDecimal rate) {
          KualiDecimal perDiemAmount = KualiDecimal.ZERO;
          KualiDecimal perDiemRate = new KualiDecimal(rate.doubleValue());
  
          // make sure we have the fields needed
          if (perDiemAmount == null || startDateTime == null || endDateTime == null) {
              LOG.error("Per diem amount, Start date/time, and End date/time must all be given.");
              throw new RuntimeException("Per diem amount, Start date/time, and End date/time must all be given.");
          }
  
          // check end time is after start time
          if (endDateTime.compareTo(startDateTime) <= 0) {
              LOG.error("End date/time must be after start date/time.");
              throw new RuntimeException("End date/time must be after start date/time.");
          }
  
          Calendar startCalendar = Calendar.getInstance();
          startCalendar.setTime(startDateTime);
  
          Calendar endCalendar = Calendar.getInstance();
          endCalendar.setTime(endDateTime);
  
          double diffDays = KfsDateUtils.getDifferenceInDays(startDateTime, endDateTime);
         double diffHours = KfsDateUtils.getDifferenceInHours(startDateTime, endDateTime);
 
         // same day travel
         if (diffDays == 0) {
             // no per diem for only 12 hours or less
             if (diffHours > 12) {
                 // half day of per diem
                 perDiemAmount = perDiemRate.divide(new KualiDecimal(2));
 
                 // add in another 1/4 of a day if end time past 7:00
                 if (timeInPerDiemPeriod(endCalendar, 19, 0, 23, 59)) {
                     perDiemAmount = perDiemAmount.add(perDiemRate.divide(new KualiDecimal(4)));
                 }
             }
         }
 
         // multiple days of travel
         else {
             // must at least have 7 1/2 hours to get any per diem
             if (diffHours >= 7.5) {
                 // per diem for whole days
                 perDiemAmount = perDiemRate.multiply(new KualiDecimal(diffDays - 1));
 
                 // per diem for first day
                 if (timeInPerDiemPeriod(startCalendar, 0, 0, 11, 59)) { // Midnight to noon
                     perDiemAmount = perDiemAmount.add(perDiemRate);
                 }
                 else if (timeInPerDiemPeriod(startCalendar, 12, 0, 17, 59)) { // Noon to 5:59pm
                     perDiemAmount = perDiemAmount.add(perDiemRate.divide(new KualiDecimal(2)));
                 }
                 else if (timeInPerDiemPeriod(startCalendar, 18, 0, 23, 59)) { // 6:00pm to Midnight
                     perDiemAmount = perDiemAmount.add(perDiemRate.divide(new KualiDecimal(4)));
                 }
 
                 // per diem for end day
                 if (timeInPerDiemPeriod(endCalendar, 0, 1, 6, 0)) { // Midnight to 6:00am
                     perDiemAmount = perDiemAmount.add(perDiemRate.divide(new KualiDecimal(4)));
                 }
                 else if (timeInPerDiemPeriod(endCalendar, 6, 1, 12, 0)) { // 6:00am to noon
                     perDiemAmount = perDiemAmount.add(perDiemRate.divide(new KualiDecimal(2)));
                 }
                 else if (timeInPerDiemPeriod(endCalendar, 12, 01, 23, 59)) { // Noon to midnight
                     perDiemAmount = perDiemAmount.add(perDiemRate);
                 }
             }
         }
 
         return perDiemAmount;
     }
 
     /**
      * Checks whether the date is in a per diem period given by the start hour and end hour and minutes.
      *
      * @param cal The date being checked to see if it occurred within the defined travel per diem period.
      * @param periodStartHour The starting hour of the per diem period.
      * @param periodStartMinute The starting minute of the per diem period.
      * @param periodEndHour The ending hour of the per diem period.
      * @param periodEndMinute The ending minute of the per diem period.
      * @return True if the date passed in occurred within the period defined by the given parameters, false otherwise.
      */
     protected boolean timeInPerDiemPeriod(Calendar cal, int periodStartHour, int periodStartMinute, int periodEndHour, int periodEndMinute) {
         int hour = cal.get(Calendar.HOUR_OF_DAY);
         int minute = cal.get(Calendar.MINUTE);
 
         return (((hour > periodStartHour) || (hour == periodStartHour && minute >= periodStartMinute)) && ((hour < periodEndHour) || (hour == periodEndHour && minute <= periodEndMinute)));
     }
 
     /**
      * This method calculates the mileage amount based on the total mileage traveled and the using the reimbursement rate
      * applicable to when the trip started.
      *
      * For this method, a collection of mileage rates is retrieved, where each mileage rate is defined by a mileage limit.
      * This collection is iterated over to determine which mileage rate will be used for calculating the total mileage
      * amount due.
      *
      * @param totalMileage The total mileage traveled that will be reimbursed for.
      * @param travelStartDate The start date of the travel, which will be used to retrieve the mileage reimbursement rate.
      * @return The total reimbursement due to the traveler for the mileage traveled.
      *
      * @see org.kuali.kfs.fp.document.service.DisbursementVoucherTravelService#calculateMileageAmount(org.kuali.kfs.fp.businessobject.DisbursementVoucherNonEmployeeTravel)
      */
     @Override
     public KualiDecimal calculateMileageAmount(Integer totalMileage, Timestamp travelStartDate) {
         KualiDecimal mileageAmount = KualiDecimal.ZERO;
 
         if (totalMileage == null || travelStartDate == null) {
             LOG.error("Total Mileage and Travel Start Date must be given.");
             throw new RuntimeException("Total Mileage and Travel Start Date must be given.");
         }
 
         // convert timestamp to sql date
         Date effectiveDate = null;
         try {
             effectiveDate = dateTimeService.convertToSqlDate(travelStartDate);
         } catch (ParseException e) {
             LOG.error("Unable to parse travel start date into sql date " + travelStartDate, e);
             throw new RuntimeException("Unable to parse travel start date into sql date ", e);
         }
 
         // retrieve mileage rates
         Collection<TravelMileageRate> mileageRates = travelMileageRateDao.retrieveMostEffectiveMileageRates(effectiveDate);
 
         if (mileageRates == null || mileageRates.isEmpty()) {
             LOG.error("Unable to retreive mileage rates.");
             throw new RuntimeException("Unable to retreive mileage rates.");
         }
 
         int mileage = totalMileage.intValue();
         int mileageRemaining = mileage;
 
         /**
          * Iterate over mileage rates sorted in descending order by the mileage limit amount. For all miles over the mileage limit
          * amount, the rate times those number of miles over is added to the mileage amount.
          */
         for ( TravelMileageRate rate : mileageRates ) {
             int mileageLimitAmount = rate.getMileageLimitAmount().intValue();
             if (mileageRemaining > mileageLimitAmount) {
                 BigDecimal numMiles = new BigDecimal(mileageRemaining - mileageLimitAmount);
                 BigDecimal rateForMiles = numMiles.multiply(rate.getMileageRate()).setScale(KualiDecimal.SCALE, KualiDecimal.ROUND_BEHAVIOR);
                 mileageAmount = mileageAmount.add(new KualiDecimal(rateForMiles));
                 mileageRemaining = mileageLimitAmount;
             }
 
         }
 
         return mileageAmount;
     }
 
     /**
      * Gets the travelMileageRateDao attribute.
      * @return Returns the travelMileageRateDao.
      */
     public TravelMileageRateDao getTravelMileageRateDao() {
         return travelMileageRateDao;
     }
 
     /**
      * Sets the travelMileageRateDao attribute.
      * @param travelMileageRateDao The travelMileageRateDao to set.
      */
     public void setTravelMileageRateDao(TravelMileageRateDao travelMileageRateDao) {
         this.travelMileageRateDao = travelMileageRateDao;
     }
 
     /**
      * Gets the dateTimeService attribute.
      * @return Returns the dateTimeService.
      */
     public DateTimeService getDateTimeService() {
         return dateTimeService;
     }
 
     /**
      * Sets the dateTimeService attribute.
      * @param dateTimeService The dateTimeService to set.
      */
     public void setDateTimeService(DateTimeService dateTimeService) {
         this.dateTimeService = dateTimeService;
     }
 }