/*******************************************************************************
 * Copyright (c) 2014 EclipseSource and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    EclipseSource - initial API and implementation
 ******************************************************************************/
package com.eclipsesource.tabris.tracking;

import static com.eclipsesource.tabris.internal.Clauses.when;
import static com.eclipsesource.tabris.internal.Clauses.whenNull;

import java.io.Serializable;

import com.eclipsesource.tabris.ui.Page;


/**
 * <p>
 * A {@link TrackingEvent} will be generated by a {@link Tracking} instance and dispatched to a {@link Tracker}. The
 * event contains information regarding the event, the user and the environment.
 * </p>
 * <p>
 * <b>Please note:</b> You not get in touch with a {@link TrackingEvent} unless you will implement your own
 * {@link Tracker}.
 * </p>
 *
 * @see Tracker
 *
 * @since 1.4
 */
@SuppressWarnings("restriction")
public class TrackingEvent implements Serializable {

  /**
   * <p>
   * The {@link EventType} describes the type of the event.
   *  </p>
   */
  public static enum EventType {

    /**
     * <p>
     * A page view event describe when a {@link Page} in the Tabris UI is activated. The id of the page will be in the
     * event's details object. See {@link TrackingEvent#getDetail()}.
     * </p>
     */
    PAGE_VIEW,

    /**
     * <p>
     * An action event describes the Action in a Tabris UI that was executed. The id of the action will be in the
     * event's details object. See {@link TrackingEvent#getDetail()}.
     * </p>
     */
    ACTION,

    /**
     * <p>
     * A search event describes the search in a Tabris UI that was triggered. The query of the search will be in the
     * event's details object. See {@link TrackingEvent#getDetail()}.
     * </p>
     */
    SEARCH,

    /**
     * <p>
     * An order event describes the order that was submitted. The {@link Order} object will be in the
     * event's details object. See {@link TrackingEvent#getDetail()}.
     * </p>
     */
    ORDER,

    /**
     * <p>
     * A simple event describes a custom event that submitted. The id of the event will be in the
     * event's details object. See {@link TrackingEvent#getDetail()}.
     * </p>
     */
    EVENT
  }

  private final EventType type;
  private final TrackingInfo info;
  private final Object detail;
  private final long timestamp;

  public TrackingEvent( EventType type, TrackingInfo info, Object detail, long timestamp ) {
    validateArguments( type, info, detail, timestamp );
    this.type = type;
    this.info = info;
    this.detail = detail;
    this.timestamp = timestamp;
  }

  private void validateArguments( EventType type, TrackingInfo info, Object detail, long timestamp ) {
    whenNull( type ).throwIllegalArgument( "EventType must not be null." );
    whenNull( info ).throwIllegalArgument( "TrackingInfo must not be null." );
    whenNull( detail ).throwIllegalArgument( "Detail must not be null." );
    when( timestamp < 0 ).throwIllegalArgument( "Timestamp must be > 0 but was " + timestamp );
  }

  /**
   * <p>
   * Returns the type of the event.
   * </p>
   */
  public EventType getType() {
    return type;
  }

  /**
   * <p>
   * Returns the {@link TrackingInfo} of the event.
   * </p>
   */
  public TrackingInfo getInfo() {
    return info;
  }

  /**
   * <p>
   * Returns the details of the event. May be different depending on the type of the event.
   * </p>
   */
  public Object getDetail() {
    return detail;
  }

  /**
   * <p>
   * Returns the timestamp of the event. Will be taken from the server time.
   * </p>
   */
  public long getTimestamp() {
    return timestamp;
  }

}