package com.sixsq.slipstream.action;

/*
 * +=================================================================+
 * SlipStream Server (WAR)
 * =====
 * Copyright (C) 2013 SixSq Sarl (sixsq.com)
 * =====
 * 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.
 * -=================================================================-
 */

import java.io.IOException;
import java.sql.Timestamp;
import java.util.UUID;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.EnumType;
import javax.persistence.Enumerated;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;

import org.restlet.data.Form;

import com.sixsq.slipstream.persistence.PersistenceUtil;

/**
 * Parent class for one shot, asynchronous actions. These include such things as
 * a user confirming an email address or an administrator validating an account.
 *
 * Subclasses must call the method setForm only from the constructor.
 *
 */

// TODO: split the persistent part from the resource
@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public abstract class OneShotAction {

	public enum State {
		ACTIVE, DONE, ABORTED
	}

	@Id
	String uuid;

	@Enumerated(EnumType.STRING)
	private State state;

	private Timestamp lastModified;

	@Column(length=1024)
	private String encodedForm;

	protected OneShotAction() {
		this.uuid = UUID.randomUUID().toString();
		this.state = State.ACTIVE;

		encodedForm = null;

		setLastModified();
	}

	public OneShotAction(String userResourceUrl) {
		this();

		Form form = new Form();
		form.add("userResourceUrl", userResourceUrl);
		setForm(form);
	}

	public String getUuid() {
		return uuid;
	}

	public State getState() {
		return state;
	}

	public void setState(State newState) {
		if (State.ACTIVE.equals(state)) {
			if (!State.ACTIVE.equals(newState)) {
				state = newState;
				setLastModified();
			}
		}
	}

	public Timestamp getLastModified() {
        if (lastModified != null) {
            return (Timestamp) lastModified.clone();
        } else {
            return null;
        }
	}

	protected void setLastModified() {
		lastModified = new Timestamp(System.currentTimeMillis());
	}

	public Form getForm() {
		Form form = new Form(encodedForm);
		return form;
	}

	/**
	 * Method to save the state necessary to perform the action at some point in
	 * the future. This method should only be called once from the constructor.
	 * Once the form information has been set, it cannot be modified.
	 *
	 * @param form
	 */
	protected void setForm(Form form) {
		try {
			if (encodedForm == null) {
				if (form == null) {
					form = new Form();
				}
				encodedForm = form.encode();
			}
		} catch (IOException e) {
			throw new IllegalArgumentException(e.getMessage());
		}
	}

	public static OneShotAction load(String uuid) {
		EntityManager em = PersistenceUtil.createEntityManager();
		OneShotAction action = em.find(OneShotAction.class, uuid);
		em.close();
		return action;
	}

	public void update() {
		EntityManager em = PersistenceUtil.createEntityManager();
		EntityTransaction transaction = em.getTransaction();
		transaction.begin();
		em.merge(this);
		transaction.commit();
		em.close();
	}

	public void store() {
		EntityManager em = PersistenceUtil.createEntityManager();
		EntityTransaction transaction = em.getTransaction();
		transaction.begin();
		em.persist(this);
		em.flush();
		transaction.commit();
		em.close();
	}

}