#
#--
# Copyright (c) 2007, John Mettraux, OpenWFE.org
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without 
# modification, are permitted provided that the following conditions are met:
# 
# . Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.  
# 
# . 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.
# 
# . Neither the name of the "OpenWFE" nor the names of its contributors may be
#   used to endorse or promote products derived from this software without
#   specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
# POSSIBILITY OF SUCH DAMAGE.
#++
#
# $Id: definitions.rb 2725 2006-06-02 13:26:32Z jmettraux $
#

#
# "made in Japan"
#
# John Mettraux at openwfe.org
#

require 'yaml'
require 'base64'
require 'monitor'

require 'openwfe/service'
#require 'openwfe/rudefinitions'
require 'openwfe/util/scheduler'
require 'openwfe/listeners/listener'

require 'openwfe/util/sqs'


#
# some base listener implementations
#
module OpenWFE

    #
    # Polls an Amazon SQS queue for workitems
    #
    # Workitems can be instances of InFlowWorkItem or LaunchItem.
    #
    #     require 'openwfe/listeners/sqslisteners'
    #
    #     ql = OpenWFE::SqsListener("workqueue1", engine.application_context)
    #
    #     engine.add_workitem_listener(ql, "2m30s")
    #         #
    #         # thus, the engine will poll our "workqueue1" SQS queue
    #         # every 2 minutes and 30 seconds
    #
    class SqsListener < Service
        include MonitorMixin, WorkItemListener, Schedulable

        attr_reader :queue_name

        def initialize (queue_name, application_context)

            @queue_name = queue_name.to_s

            service_name = "#{self.class}::#{@queue_name}"

            super(service_name, application_context)

            linfo { "new() queue is '#{@queue_name}'" }
        end

        #
        # Will 'find' files in the work directory (by default ./work/in/),
        # extract the workitem in them and feed it back to the engine.
        #
        def trigger (params)
            synchronize do

                ldebug { "trigger()" }

                qs = SQS::QueueService.new

                qs.create_queue(@queue_name)
                    # just to be sure it is there

                while true

                    l = qs.get_messages(
                        @queue_name, :timeout => 0, :count => 255)

                    break if l.length < 1

                    l.each do |msg|

                        o = decode_object(msg)

                        handle_object(o)

                        msg.delete

                        ldebug do 
                            "trigger() " +
                            "handled successfully msg #{msg.message_id}" 
                        end
                    end
                end
            end
        end

        #
        # Extracts a workitem from the message's body.
        #
        # By default, this listeners assumes the workitem is stored in
        # its "hash form" (not directly as a Ruby InFlowWorkItem instance).
        #
        # LaunchItem instances (as hash as well) are also accepted.
        #
        def decode_object (message)

            o = Base64.decode64(message.message_body)
            o = YAML.load(o)
            o = OpenWFE::workitem_from_h(o)
            o
        end
    end

end