package edu.uci.ics.hivesterix.serde.lazy.objectinspector;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;

/**
 * ObjectInspectorFactory is the primary way to create new ObjectInspector
 * instances.
 * 
 * SerDe classes should call the static functions in this library to create an
 * ObjectInspector to return to the caller of SerDe2.getObjectInspector().
 * 
 * The reason of having caches here is that ObjectInspectors do not have an
 * internal state - so ObjectInspectors with the same construction parameters
 * should result in exactly the same ObjectInspector.
 */

public final class LazyObjectInspectorFactory {

	static ConcurrentHashMap<ArrayList<Object>, LazyColumnarObjectInspector> cachedLazyColumnarObjectInspector = new ConcurrentHashMap<ArrayList<Object>, LazyColumnarObjectInspector>();

	static ConcurrentHashMap<ArrayList<Object>, LazyStructObjectInspector> cachedLazyStructObjectInspector = new ConcurrentHashMap<ArrayList<Object>, LazyStructObjectInspector>();

	static ConcurrentHashMap<ArrayList<Object>, LazyListObjectInspector> cachedLazyListObjectInspector = new ConcurrentHashMap<ArrayList<Object>, LazyListObjectInspector>();

	static ConcurrentHashMap<ArrayList<Object>, LazyMapObjectInspector> cachedLazyMapObjectInspector = new ConcurrentHashMap<ArrayList<Object>, LazyMapObjectInspector>();

	public static LazyColumnarObjectInspector getLazyColumnarObjectInspector(
			List<String> structFieldNames,
			List<ObjectInspector> structFieldObjectInspectors) {
		ArrayList<Object> signature = new ArrayList<Object>();
		signature.add(structFieldNames);
		signature.add(structFieldObjectInspectors);
		LazyColumnarObjectInspector result = cachedLazyColumnarObjectInspector
				.get(signature);
		if (result == null) {
			result = new LazyColumnarObjectInspector(structFieldNames,
					structFieldObjectInspectors);
			cachedLazyColumnarObjectInspector.put(signature, result);
		}
		return result;
	}

	public static LazyStructObjectInspector getLazyStructObjectInspector(
			List<String> structFieldNames,
			List<ObjectInspector> structFieldObjectInspectors) {
		ArrayList<Object> signature = new ArrayList<Object>();
		signature.add(structFieldNames);
		signature.add(structFieldObjectInspectors);
		LazyStructObjectInspector result = cachedLazyStructObjectInspector
				.get(signature);
		if (result == null) {
			result = new LazyStructObjectInspector(structFieldNames,
					structFieldObjectInspectors);
			cachedLazyStructObjectInspector.put(signature, result);
		}
		return result;
	}

	public static LazyListObjectInspector getLazyListObjectInspector(
			ObjectInspector listElementInspector) {
		ArrayList<Object> signature = new ArrayList<Object>();
		signature.add(listElementInspector);
		LazyListObjectInspector result = cachedLazyListObjectInspector
				.get(signature);
		if (result == null) {
			result = new LazyListObjectInspector(listElementInspector);
			cachedLazyListObjectInspector.put(signature, result);
		}
		return result;
	}

	public static LazyMapObjectInspector getLazyMapObjectInspector(
			ObjectInspector keyInspector, ObjectInspector valueInspector) {
		ArrayList<Object> signature = new ArrayList<Object>();
		signature.add(keyInspector);
		signature.add(valueInspector);
		LazyMapObjectInspector result = cachedLazyMapObjectInspector
				.get(signature);
		if (result == null) {
			result = new LazyMapObjectInspector(keyInspector, valueInspector);
			cachedLazyMapObjectInspector.put(signature, result);
		}
		return result;
	}

	private LazyObjectInspectorFactory() {
		// prevent instantiation
	}
}