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Nuts'n'Bolts Utilities
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/*
 * Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 David Berkman
 *
 * This file is part of the SmallMind Code Project.
 *
 * The SmallMind Code Project is free software, you can redistribute
 * it and/or modify it under either, at your discretion...
 *
 * 1) The terms of 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.
 *
 * ...or...
 *
 * 2) The terms of the Apache License, Version 2.0.
 *
 * The SmallMind Code Project 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
 * General Public License or Apache License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * and the Apache License along with the SmallMind Code Project. If not, see
 *  or .
 *
 * Additional permission under the GNU Affero GPL version 3 section 7
 * ------------------------------------------------------------------
 * If you modify this Program, or any covered work, by linking or
 * combining it with other code, such other code is not for that reason
 * alone subject to any of the requirements of the GNU Affero GPL
 * version 3.
 */
package org.smallmind.nutsnbolts.spring.property;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

public class YamlPropertyHandler implements PropertyHandler {

  private final Map yamlMap;

  public YamlPropertyHandler (Map yamlMap) {

    this.yamlMap = yamlMap;
  }

  @Override
  public Iterator iterator () {

    return new YamlPropertyEntryIterator(yamlMap);
  }

  private static class YamlPropertyEntryIterator implements Iterator {

    private final LinkedList namedIterationList = new LinkedList<>();

    private YamlPropertyEntryIterator (Map yamlMap) {

      if ((yamlMap != null) && (!yamlMap.isEmpty())) {
        namedIterationList.push(new NamedIteration(yamlMap.entrySet().iterator()));
      }
    }

    @Override
    public boolean hasNext () {

      while (!namedIterationList.isEmpty()) {
        if (!namedIterationList.peekFirst().getIterator().hasNext()) {
          namedIterationList.pop();
        } else {

          return true;
        }
      }

      return false;
    }

    @Override
    public YamlPropertyEntry next () {

      Map.Entry entry = namedIterationList.peekFirst().getIterator().next();

      namedIterationList.peekFirst().setName(entry.getKey());

      if (entry.getValue() instanceof Map) {
        namedIterationList.push(new NamedIteration(((Map)entry.getValue()).entrySet().iterator()));

        return next();
      } else if (entry.getValue() instanceof List) {

        LinkedHashMap interpolatedMap = new LinkedHashMap<>();
        int index = 0;

        for (Object item : (List)entry.getValue()) {
          interpolatedMap.put(String.valueOf(index++), item);
        }

        namedIterationList.push(new NamedIteration(interpolatedMap.entrySet().iterator()));

        return next();
      } else {

        StringBuilder keyBuilder = new StringBuilder();
        boolean first = true;

        for (NamedIteration namedIteration : namedIterationList) {
          if (!first) {
            keyBuilder.insert(0, '.');
          }
          first = false;
          keyBuilder.insert(0, namedIteration.getName());
        }

        return new YamlPropertyEntry(keyBuilder.toString(), entry.getValue());
      }
    }

    @Override
    public void remove () {

      throw new UnsupportedOperationException();
    }
  }

  private static class NamedIteration {

    private final Iterator> iterator;
    private String name;

    private NamedIteration (Iterator> iterator) {

      this.iterator = iterator;
    }

    private String getName () {

      return name;
    }

    private void setName (String name) {

      this.name = name;
    }

    private Iterator> getIterator () {

      return iterator;
    }
  }
}