package me.prettyprint.cassandra.serializers;

import static me.prettyprint.hector.api.ddl.ComparatorType.BYTESTYPE;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import me.prettyprint.hector.api.Serializer;
import me.prettyprint.hector.api.ddl.ComparatorType;

/**
 * A base class for serializer implementations. Takes care of the default
 * implementations of to/fromBytesList and to/fromBytesMap. Extenders of this
 * class only need to implement the toBytes and fromBytes.
 * 
 * @author Ed Anuff
 * 
 * @param <T>
 */
public abstract class AbstractSerializer<T> implements Serializer<T> {

  @Override
  public abstract ByteBuffer toByteBuffer(T obj);

  @Override
  public byte[] toBytes(T obj) {
    ByteBuffer bb = toByteBuffer(obj);
    byte[] bytes = new byte[bb.remaining()];
    bb.get(bytes, 0, bytes.length);
    return bytes;
  }

  @Override
  public T fromBytes(byte[] bytes) {
    return fromByteBuffer(ByteBuffer.wrap(bytes));
  }

  /*
   * public ByteBuffer toByteBuffer(T obj) { return
   * ByteBuffer.wrap(toBytes(obj)); }
   * 
   * public ByteBuffer toByteBuffer(T obj, ByteBuffer byteBuffer, int offset,
   * int length) { byteBuffer.put(toBytes(obj), offset, length); return
   * byteBuffer; }
   */

  @Override
  public abstract T fromByteBuffer(ByteBuffer byteBuffer);

  /*
   * public T fromByteBuffer(ByteBuffer byteBuffer) { return
   * fromBytes(byteBuffer.array()); }
   * 
   * public T fromByteBuffer(ByteBuffer byteBuffer, int offset, int length) {
   * return fromBytes(Arrays.copyOfRange(byteBuffer.array(), offset, length)); }
   */

  @Override
  public Set<ByteBuffer> toBytesSet(List<T> list) {
    Set<ByteBuffer> bytesList = new HashSet<ByteBuffer>(
        computeInitialHashSize(list.size()));
    for (T s : list) {
      bytesList.add(toByteBuffer(s));
    }
    return bytesList;
  }

  @Override
  public List<T> fromBytesSet(Set<ByteBuffer> set) {
    List<T> objList = new ArrayList<T>(set.size());
    for (ByteBuffer b : set) {
      objList.add(fromByteBuffer(b));
    }
    return objList;
  }

  @Override
  public List<ByteBuffer> toBytesList(List<T> list) {
    List<ByteBuffer> bytesList = new ArrayList<ByteBuffer>(list.size());
    for (T s : list) {
      bytesList.add(toByteBuffer(s));
    }
    return bytesList;
  }

  @Override
  public List<T> fromBytesList(List<ByteBuffer> list) {
    List<T> objList = new ArrayList<T>(list.size());
    for (ByteBuffer s : list) {
      objList.add(fromByteBuffer(s));
    }
    return objList;
  }

  @Override
  public <V> Map<ByteBuffer, V> toBytesMap(Map<T, V> map) {
    Map<ByteBuffer, V> bytesMap = new LinkedHashMap<ByteBuffer, V>(
        computeInitialHashSize(map.size()));
    for (Entry<T, V> entry : map.entrySet()) {
      bytesMap.put(toByteBuffer(entry.getKey()), entry.getValue());
    }
    return bytesMap;
  }

  @Override
  public <V> Map<T, V> fromBytesMap(Map<ByteBuffer, V> map) {
    Map<T, V> objMap = new LinkedHashMap<T, V>(
        computeInitialHashSize(map.size()));
    for (Entry<ByteBuffer, V> entry : map.entrySet()) {
      objMap.put(fromByteBuffer(entry.getKey()), entry.getValue());
    }
    return objMap;
  }

  public int computeInitialHashSize(int initialSize) {
    return ((int) (initialSize / 0.75)) + 1;
  }

  public ComparatorType getComparatorType() {
    return BYTESTYPE;
  }
}