/*
    * MoneyWise: Finance Application
    * Copyright 2012-2026. Tony Washer
    *
    * 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 io.github.tonywasher.joceanus.moneywise.tax.uk;
  
  import io.github.tonywasher.joceanus.oceanus.decimal.OceanusMoney;
  import io.github.tonywasher.joceanus.oceanus.decimal.OceanusRate;
  import io.github.tonywasher.joceanus.oceanus.format.OceanusDataFormatter;
  import io.github.tonywasher.joceanus.metis.field.MetisFieldItem;
  import io.github.tonywasher.joceanus.metis.field.MetisFieldSet;
  import io.github.tonywasher.joceanus.moneywise.data.statics.MoneyWiseTaxClass;
  import io.github.tonywasher.joceanus.moneywise.tax.MoneyWiseTaxBandSet;
  import io.github.tonywasher.joceanus.moneywise.tax.MoneyWiseTaxBandSet.MoneyWiseTaxBand;
  import io.github.tonywasher.joceanus.moneywise.tax.MoneyWiseTaxResource;
  
  import java.util.Iterator;
  
  /**
   * Income Tax Scheme.
   */
  public class MoneyWiseUKIncomeScheme
          implements MetisFieldItem {
      /**
       * Local Report fields.
       */
      private static final MetisFieldSet<MoneyWiseUKIncomeScheme> FIELD_DEFS = MetisFieldSet.newFieldSet(MoneyWiseUKIncomeScheme.class);
  
      /*
       * Declare Fields.
       */
      static {
          FIELD_DEFS.declareLocalField(MoneyWiseTaxResource.SCHEME_RELIEF_AVAILABLE, MoneyWiseUKIncomeScheme::taxReliefAvailable);
      }
  
      /**
       * Tax Relief available.
       */
      private final Boolean reliefAvailable;
  
      /**
       * Constructor.
       */
      protected MoneyWiseUKIncomeScheme() {
          this(Boolean.TRUE);
      }
  
      /**
       * Constructor.
       *
       * @param pReliefAvailable Is tax relief available?
       */
      protected MoneyWiseUKIncomeScheme(final Boolean pReliefAvailable) {
          reliefAvailable = pReliefAvailable;
      }
  
      /**
       * Is tax relief available?
       *
       * @return true/false
       */
      public Boolean taxReliefAvailable() {
          return reliefAvailable;
      }
  
      /**
       * Allocate the amount to the appropriate tax bands.
       *
       * @param pConfig the taxConfig
       * @param pBasis  the taxBasis
       * @param pAmount the amount to be allocated
       * @return the tax bands
       */
      protected MoneyWiseTaxBandSet allocateToTaxBands(final MoneyWiseUKTaxConfig pConfig,
                                                       final MoneyWiseTaxClass pBasis,
                                                       final OceanusMoney pAmount) {
          /* Handle negative amounts */
          final OceanusMoney myAmount = new OceanusMoney(pAmount);
          if (!myAmount.isPositive()) {
              myAmount.setZero();
          }
  
          /* Determine the taxBand set */
          final MoneyWiseTaxBandSet myTaxBands = determineTaxBands(pConfig, pBasis, myAmount);
  
          /* Adjust allowances and taxBands */
          final OceanusMoney myRemaining = adjustAllowances(pConfig, myAmount);
         adjustTaxBands(pConfig, myRemaining);
 
         /* return the taxBands */
         return myTaxBands;
     }
 
     /**
      * Determine the taxBand set.
      *
      * @param pConfig the taxConfig
      * @param pBasis  the taxBasis
      * @param pAmount the amount to be allocated
      * @return the amount remaining
      */
     private MoneyWiseTaxBandSet determineTaxBands(final MoneyWiseUKTaxConfig pConfig,
                                                   final MoneyWiseTaxClass pBasis,
                                                   final OceanusMoney pAmount) {
         /* Create a new taxBand set */
         final MoneyWiseTaxBandSet myTaxBands = new MoneyWiseTaxBandSet();
         final OceanusMoney myRemaining = new OceanusMoney(pAmount);
 
         /* Determine allowance */
         final OceanusMoney myAllowance = new OceanusMoney(getAmountInAllowance(pConfig, myRemaining));
         if (myAllowance.isNonZero() && reliefAvailable) {
             myTaxBands.addTaxBand(new MoneyWiseTaxBand(myAllowance, OceanusRate.getWholePercentage(0)));
             myRemaining.subtractAmount(myAllowance);
         }
 
         /* Loop through the taxBands */
         final Iterator<MoneyWiseTaxBand> myIterator = taxBandIterator(pConfig, pBasis);
         while (myRemaining.isNonZero()
                 && myIterator.hasNext()) {
             /* Determine amount in band */
             final MoneyWiseTaxBand myBand = myIterator.next();
             OceanusMoney myAmount = getAmountInBand(myBand.getAmount(), myRemaining);
 
             /* Add any held-over allowance */
             if (!reliefAvailable && myAllowance.isNonZero()) {
                 myAmount = new OceanusMoney(myAmount);
                 myAmount.addAmount(myAllowance);
                 myAllowance.setZero();
             }
 
             /* allocate band and adjust */
             myTaxBands.addTaxBand(new MoneyWiseTaxBand(myAmount, myBand.getRate()));
             myRemaining.subtractAmount(myAmount);
         }
 
         /* Return the taxBands */
         return myTaxBands;
     }
 
     /**
      * Obtain the taxBand iterator.
      *
      * @param pConfig the taxConfig
      * @param pBasis  the taxBasis
      * @return the iterator
      */
     protected Iterator<MoneyWiseTaxBand> taxBandIterator(final MoneyWiseUKTaxConfig pConfig,
                                                          final MoneyWiseTaxClass pBasis) {
         return pConfig.getTaxBands().iterator();
     }
 
     /**
      * Obtain the taxFree amount.
      *
      * @param pConfig the taxConfig
      * @param pAmount the amount that is to be adjusted
      * @return the amount remaining
      */
     protected OceanusMoney getAmountInAllowance(final MoneyWiseUKTaxConfig pConfig,
                                                 final OceanusMoney pAmount) {
         /* Obtain the amount covered by the allowance */
         return getAmountInBand(pConfig.getAllowance(), pAmount);
     }
 
     /**
      * Adjust Allowances.
      *
      * @param pConfig the taxConfig
      * @param pAmount the amount that is to be adjusted
      * @return the amount remaining
      */
     protected OceanusMoney adjustAllowances(final MoneyWiseUKTaxConfig pConfig,
                                             final OceanusMoney pAmount) {
         /* Adjust the basic allowance */
         return adjustForAllowance(pConfig.getAllowance(), pAmount);
     }
 
     /**
      * Adjust TaxBands.
      *
      * @param pConfig the taxConfig
      * @param pAmount the amount that is to be adjusted
      */
     protected void adjustTaxBands(final MoneyWiseUKTaxConfig pConfig,
                                   final OceanusMoney pAmount) {
         /* Loop through the taxBands */
         OceanusMoney myRemaining = pAmount;
         for (MoneyWiseTaxBand myBand : pConfig.getTaxBands()) {
             /* If we have nothing left to adjust, we have finished */
             if (myRemaining.isZero()
                     || myBand.getAmount() == null) {
                 break;
             }
 
             /* Adjust the band */
             myRemaining = adjustForAllowance(myBand.getAmount(), myRemaining);
         }
     }
 
     /**
      * Adjust For an allowance/band.
      *
      * @param pAllowance the allowance
      * @param pAmount    the amount that is to be adjusted
      * @return the amount remaining
      */
     protected OceanusMoney adjustForAllowance(final OceanusMoney pAllowance,
                                               final OceanusMoney pAmount) {
         /* Take a copy of the amount */
         final OceanusMoney myRemaining = new OceanusMoney(pAmount);
 
         /* If we have exhausted the allowance */
         if (myRemaining.compareTo(pAllowance) > 0) {
             /* Subtract allowance */
             myRemaining.subtractAmount(pAllowance);
             pAllowance.setZero();
 
             /* else the allowance covers everything */
         } else {
             /* adjust the allowance */
             pAllowance.subtractAmount(myRemaining);
             myRemaining.setZero();
         }
 
         /* return the remaining amount */
         return myRemaining;
     }
 
     /**
      * Obtain the amount of income that falls in a band.
      *
      * @param pBand   the band
      * @param pAmount the amount available
      * @return the amount within the band
      */
     protected static OceanusMoney getAmountInBand(final OceanusMoney pBand,
                                                   final OceanusMoney pAmount) {
         /* Return the lesser of the two */
         return pBand != null && pAmount.compareTo(pBand) > 0
                 ? pBand
                 : pAmount;
     }
 
     @Override
     public MetisFieldSet<? extends MoneyWiseUKIncomeScheme> getDataFieldSet() {
         return FIELD_DEFS;
     }
 
     @Override
     public String formatObject(final OceanusDataFormatter pFormatter) {
         return getDataFieldSet().getName();
     }
 }