#--
# Copyright (c) 2005-2012, John Mettraux, jmettraux@gmail.com
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# Made in Japan.
#++


module Ruote

  #
  # The tracker service is used by the "listen" expression. This services
  # sees all the msg processed by a worker and triggers any
  # listener interested in a particular msg.
  #
  # Look at the ListenExpression for more details.
  #
  class Tracker

    def initialize(context)

      @context = context
    end

    # The context calls this method for each successfully processed msg
    # in the worker.
    #
    def on_msg(message)

      m_error = message['error']
      m_wfid = message['wfid'] || (message['fei']['wfid'] rescue nil)
      m_action = message['action']

      msg = m_action == 'error_intercepted' ? message['msg'] : message

      @context.storage.get_trackers['trackers'].each do |tracker_id, tracker|

        # filter msgs

        t_wfid = tracker['wfid']
        t_action = tracker['action']

        next if t_wfid && t_wfid != m_wfid
        next if t_action && t_action != m_action

        next unless does_match?(message, tracker['conditions'])

        if tracker_id == 'on_error' || tracker_id == 'on_terminate'

          fields = msg['workitem']['fields']

          next if m_action == 'error_intercepted' && fields['__error__']
          next if m_action == 'terminated' && (fields['__error__'] || fields['__terminate__'])
        end

        # prepare and emit/put 'reaction' message

        m = Ruote.fulldup(tracker['msg'])

        action = m.delete('action')

        m['wfid'] = m_wfid if m['wfid'] == 'replace'
        m['wfid'] ||= @context.wfidgen.generate

        m['workitem'] = msg['workitem'] if m['workitem'] == 'replace'

        if t_action == 'error_intercepted'
          m['workitem']['fields']['__error__'] = m_error
        elsif tracker_id == 'on_error' && m_action == 'error_intercepted'
          m['workitem']['fields']['__error__'] = m_error
        elsif tracker_id == 'on_terminate' && m_action == 'terminated'
          m['workitem']['fields']['__terminate__'] = { 'wfid' => m_wfid }
        end

        if m['variables'] == 'compile'
          fexp = Ruote::Exp::FlowExpression.fetch(@context, msg['fei'])
          m['variables'] = fexp ? fexp.compile_variables : {}
        end

        @context.storage.put_msg(action, m)
      end
    end

    # Adds a tracker (usually when a 'listen' expression gets applied).
    #
    def add_tracker(wfid, action, id, conditions, msg)

      conditions =
        conditions && conditions.remap { |(k, v), h| h[k] = Array(v) }

      doc = @context.storage.get_trackers

      doc['trackers'][id] =
        { 'wfid' => wfid,
          'action' => action,
          'id' => id,
          'conditions' => conditions,
          'msg' => msg }

      r = @context.storage.put(doc)

      add_tracker(wfid, action, id, conditions, msg) if r
        # the put failed, have to redo the work
    end

    # Removes a tracker (usually when a 'listen' expression replies to its
    # parent expression or is cancelled).
    #
    def remove_tracker(fei, doc=nil)

      doc ||= @context.storage.get_trackers

      doc['trackers'].delete(Ruote.to_storage_id(fei))

      r = @context.storage.put(doc)

      remove_tracker(fei, r) if r
        # the put failed, have to redo the work
    end

    protected

    def does_match?(msg, conditions)

      return true unless conditions

      conditions.each do |k, v|

        return false unless Array(v).find do |vv|

          # the Array(v) is for backward compatibility, although newer
          # track conditions are already stored as arrays.

          vv = Ruote.regex_or_s(vv)

          val = case k
            when 'class' then msg['error']['class']
            when 'message' then msg['error']['message']
            else msg[k]
          end

          val && (vv.is_a?(String) ? (vv == val) : vv.match(val))
        end
      end

      true
    end
  end
end