Aquarium

/*

 * Copyright 2011-2012 GRNET S.A. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or

 * without modification, are permitted provided that the following

 * conditions are met:

 *

 *   1. Redistributions of source code must retain the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer.

 *

 *   2. Redistributions in binary form must reproduce the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer in the documentation and/or other materials

 *      provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

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 */

package gr.grnet.aquarium.connector.rabbitmq.service

import com.ckkloverdos.maybe.{Just, Failed, MaybeEither}

import gr.grnet.aquarium.converter.JsonTextFormat

import gr.grnet.aquarium.connector.handler._

import gr.grnet.aquarium.event.model.ExternalEventModel

import gr.grnet.aquarium.util.safeUnit

import gr.grnet.aquarium.service.EventBusService

import gr.grnet.aquarium.Aquarium

/**

 * Generic handler of events arriving to Aquarium.

 *

 * We first parse them to JSON ([[gr.grnet.aquarium.converter.JsonTextFormat]]) and an appropriate event model

 * (`E <:` [[gr.grnet.aquarium.event.model.ExternalEventModel]]),

 * then store them to DB

 * (`S <:` [[gr.grnet.aquarium.event.model.ExternalEventModel]])

 * and then forward them to business logic.

 *

 * All the above actions are given polymorphically via appropriate functions.

 *

 * @author Christos KK Loverdos <loverdos@gmail.com>

 */

class GenericPayloadHandler[E <: ExternalEventModel, S <: ExternalEventModel]

    (jsonParser: Array[Byte] ⇒ JsonTextFormat,

     onJsonParserSuccess: (Array[Byte], JsonTextFormat) ⇒ Unit,

     onJsonParserError: (Array[Byte], Throwable) ⇒ Unit,

     eventParser: JsonTextFormat ⇒ E,

     onEventParserSuccess: (Array[Byte], E) ⇒ Unit,

     onEventParserError: (Array[Byte], Throwable) ⇒ Unit,

     saveAction: E ⇒ S,

     forwardAction: S ⇒ Unit) extends PayloadHandler {

  def handlePayload(payload: Array[Byte]): HandlerResult = {

    // 1. try to parse as json

    MaybeEither { jsonParser(payload) } match {

      case Failed(e) ⇒

        safeUnit(onJsonParserError(payload, e))

        HandlerResultReject(e.getMessage)

      case Just(jsonTextFormat) ⇒

        safeUnit(onJsonParserSuccess(payload, jsonTextFormat))

        // 2. try to parse as model

        MaybeEither { eventParser(jsonTextFormat) } match {

          case Failed(e) ⇒

            safeUnit(onEventParserError(payload, e))

            HandlerResultReject(e.getMessage)

          case Just(event) ⇒

            safeUnit(onEventParserSuccess(payload, event))

            // 3. try to save to DB

            MaybeEither { saveAction(event) } match {

              case Failed(e) ⇒

                HandlerResultPanic

              case Just(s) ⇒

                // 4. try forward but it's OK if something bad happens here.

                safeUnit { forwardAction(s) }

                HandlerResultSuccess

            }

        }

    }

  }

}