/*
    * Prometheus: Application Framework
    * 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.prometheus.database;
  
  import io.github.tonywasher.joceanus.metis.data.MetisDataState;
  import io.github.tonywasher.joceanus.prometheus.data.PrometheusDataItem;
  import io.github.tonywasher.joceanus.prometheus.data.PrometheusDataList;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.ListIterator;
  import java.util.Objects;
  
  /**
   * Batch control class. This controls updating data lists after the commit of the batch.
   */
  public class PrometheusBatchControl {
      /**
       * Capacity of Batch Control (0=Unlimited).
       */
      private final int theCapacity;
  
      /**
       * Number of items in this batch.
       */
      private int theItems;
  
      /**
       * The List of tables associated with this batch.
       */
      private final List<PrometheusBatchTable> theList;
  
      /**
       * The Currently active Database table.
       */
      private PrometheusTableInstance<?> theCurrTable;
  
      /**
       * The Currently active Mode.
       */
      private MetisDataState theCurrMode;
  
      /**
       * Is the current table in use.
       */
      private boolean isTableActive;
  
      /**
       * Constructor.
       *
       * @param pBatchSize the batch size
       */
      protected PrometheusBatchControl(final Integer pBatchSize) {
          /* Create the batch table list */
          theList = new ArrayList<>();
  
          /* Store capacity and capacity */
          theCapacity = pBatchSize;
      }
  
      /**
       * Is the batch full.
       *
       * @return true/false is the batch full
       */
      protected boolean isFull() {
          return theCapacity != 0
                  && theItems >= theCapacity;
      }
  
      /**
       * Is the batch active.
       *
       * @return true/false is the batch active
       */
      protected boolean isActive() {
          return theItems >= 0;
      }
  
      /**
       * Set the currently active state.
       *
       * @param pTable the Table being operated on
       * @param pMode  the Mode that is in operation
      */
     protected void setCurrentTable(final PrometheusTableInstance<?> pTable,
                                    final MetisDataState pMode) {
         /* Store details */
         theCurrTable = pTable;
         theCurrMode = pMode;
         isTableActive = false;
     }
 
     /**
      * Add item to the batch.
      */
     protected void addBatchItem() {
         /* Increment batch count */
         theItems++;
 
         /* If the current table is not active */
         if (!isTableActive) {
             /* Create the batch entry */
             final PrometheusBatchTable myTable = new PrometheusBatchTable();
 
             /* Add to the batch list */
             theList.add(myTable);
             isTableActive = true;
         }
     }
 
     /**
      * Commit the batch.
      */
     protected void commitItems() {
         /* Access iterator for the list */
 
         /* Loop through the items */
         for (PrometheusBatchTable myTable : theList) {
             /* Access the next entry */
             /* Commit batch items in the table */
             if (Objects.requireNonNull(myTable.theState) == MetisDataState.DELETED) {
                 myTable.commitDeleteBatch();
             } else {
                 myTable.commitBatch();
             }
         }
 
         /* Clear the list */
         theList.clear();
         isTableActive = false;
         theItems = 0;
     }
 
     /**
      * Table step.
      */
     private final class PrometheusBatchTable {
         /**
          * The table that is being controlled.
          */
         private final PrometheusTableInstance<?> theTable;
 
         /**
          * The State of the table.
          */
         private final MetisDataState theState;
 
         /**
          * Constructor.
          */
         private PrometheusBatchTable() {
             /* Store the details */
             theTable = theCurrTable;
             theState = theCurrMode;
         }
 
         /**
          * Mark updates in the table as committed for insert/change.
          */
         private void commitBatch() {
             /* Access the iterator */
             final Iterator<?> myIterator = theTable.getList().iterator();
 
             /* Loop through the list */
             while (myIterator.hasNext()) {
                 final PrometheusDataItem myCurr = (PrometheusDataItem) myIterator.next();
 
                 /* Ignore items that are not this type, otherwise commit and break if required */
                 if (myCurr.getState() == theState
                         && commitItem(myCurr)) {
                     break;
                 }
             }
         }
 
         /**
          * Mark updates in the table as committed for delete.
          */
         private void commitDeleteBatch() {
             /* Access the iterator */
             final PrometheusDataList<?> myList = theTable.getList();
             final ListIterator<?> myIterator = myList.listIterator(myList.size());
 
             /* Loop through the list */
             while (myIterator.hasPrevious()) {
                 final PrometheusDataItem myCurr = (PrometheusDataItem) myIterator.previous();
 
                 /* Ignore items that are not this type, otherwise commit and break if necessary */
                 final MetisDataState myState = myCurr.getState();
                 if ((myState == MetisDataState.DELETED
                         || myState == MetisDataState.DELNEW)
                         && commitItem(myCurr)) {
                     break;
                 }
             }
         }
 
         /**
          * Mark an item in the table as committed.
          *
          * @param pItem the item to commit
          * @return have we reached the end of the batch?
          */
         private boolean commitItem(final PrometheusDataItem pItem) {
             /* Access the underlying element */
             final PrometheusDataItem myBase = pItem.getBase();
 
             /* If we are handling deletions */
             if (theState == MetisDataState.DELETED) {
                 /* Unlink the underlying item */
                 myBase.unLink();
 
                 /* Remove any registration */
                 myBase.deRegister();
 
                 /* else we are handling new/changed items */
             } else {
                 /* Clear the history */
                 myBase.clearHistory();
             }
 
             /* Mark this item as clean */
             pItem.clearHistory();
 
             /* If we have to worry about batch space */
             /* Adjust batch and note if we are finished */
             return theCapacity > 0
                     && --theItems == 0;
         }
     }
 }