/PersisterService/src/main/java/org/pasut/persister/MongoPersisterService.java

package org.pasut.persister;

import java.util.List;
import java.util.UUID;

import org.pasut.persister.operators.Operator;

import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBObject;
import com.mongodb.Mongo;

public class MongoPersisterService implements PersisterService {
	private final Mongo mongo;
	private final DB db;
	private final GsonMongoMapper mapper = new GsonMongoMapper();
	private final ExampleFactory factory = new ExampleFactory();
	
	public MongoPersisterService(String dbName, String host, int port){
		try {
			mongo = new Mongo(host,port);
			db = mongo.getDB(dbName);	
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	public <T> T insert(T object) {
		DBCollection collection = db.getCollection(getCollectionName(object.getClass()));
		DBObject dbObject = mapper.toDbObject(object);
		if(dbObject.get("_id")==null){
			dbObject.put("_id", UUID.randomUUID().toString());
			collection.insert(dbObject);
		}
		else{
			collection.save(dbObject);
		}
		@SuppressWarnings("unchecked")
		T newObject = (T)mapper.fromDbObject(dbObject, object.getClass());
		return newObject;
	}

	public <T> List<T> find(Class<T> clazz) {
		DBCollection collection = db.getCollection(getCollectionName(clazz));
		List<DBObject> list = collection.find().toArray();
		return mapper.fromDbObject(list, clazz);
	}

	public <T> List<T> find(T example, String[] properties) {
		DBCollection collection = db.getCollection(getCollectionName(example.getClass()));
		List<DBObject> list = collection.find(factory.createExample(example,properties)).toArray();

		@SuppressWarnings("unchecked")
		List<T> result = (List<T>)mapper.fromDbObject(list, example.getClass());
		return result;
	}

	public <T> T update(T object) {
		DBCollection collection = db.getCollection(getCollectionName(object.getClass()));
		DBObject dbObject = mapper.toDbObject(object);
		collection.save(dbObject);
		@SuppressWarnings("unchecked")
		T newObject = (T)mapper.fromDbObject(dbObject, object.getClass());
		return newObject;
	}
	
	private <T> String getCollectionName(Class<T> clazz){
		Entity annotation = clazz.getAnnotation(Entity.class);
		if(annotation==null) throw new PersistenceException(clazz);
		return annotation.value();
	}
	public <T> long count(Class<T> clazz) {
		DBCollection collection = db.getCollection(getCollectionName(clazz));
		return collection.count();
	}
	public <T> long count(T example, String[] properties) {
		DBCollection collection = db.getCollection(getCollectionName(example.getClass()));
		return collection.count(factory.createExample(example,properties));
	}
	@SuppressWarnings("unchecked")
	public <T> T findOne(T example, String[] properties) {
		DBCollection collection = db.getCollection(getCollectionName(example.getClass()));
		DBObject dbObject = collection.findOne(factory.createExample(example,properties));
		if(dbObject==null) return null;
		return (T) mapper.fromDbObject(dbObject, example.getClass());
	}
	public <T> List<T> find(Class<T> clazz, Operator... operators) {
		DBCollection collection = db.getCollection(getCollectionName(clazz));
		BasicDBObjectBuilder builder = createObjectBuilder(operators);
		List<DBObject> list = collection.find(builder.get()).toArray();
		return mapper.fromDbObject(list, clazz);
	}
	public <T> T findOne(Class<T> clazz, Operator... operators) {
		DBCollection collection = db.getCollection(getCollectionName(clazz));
		BasicDBObjectBuilder builder = createObjectBuilder(operators);
		DBObject res = collection.findOne(builder.get());
		return mapper.fromDbObject(res, clazz);
	}
	
	private BasicDBObjectBuilder createObjectBuilder(Operator[] operators){
		BasicDBObjectBuilder builder = BasicDBObjectBuilder.start();
		for(Operator operator : operators){
			operator.perform(builder);
		}
		return builder;
	}

}