module Agents
    class EventFormattingAgent < Agent
        cannot_be_scheduled!

        description <<-MD
            Event Formatting Agent allows you to format your events in any way you prefer.
            For example if you have an event like 

                {
                  :high => {
                    :celsius => "18",
                    :fahreinheit => "64"
                            },
                  :conditions => "Rain showers",
                  :data   => "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
                }


            And other agents which are receiving this event, say, Twilio Agent  expects `message` key , and Digest Email Agent which expects a `subject` key, then you can reformat this event by filling `Instructions` in the following way.

                 message => "Today's conditions look like <$.conditions> and high temperaure is going to be <$.high.celsius> degree Celsius.""
                 subject => "$.data"

            JSONPaths must be between < and > . Make sure you dont use these symbols anywhere else. You can add as many keys as you like.

            Event generated by Event Formatting Agent will be like

                {
                  :message => "Today's conditions look like Rain showers and high temperaure is going to be 18 degree Celsius"
                  :subject => "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
                }

            `Mode` can only be `merge` or `clean`. If you want to retain original contents of events and only add add new keys, then use `merge` mode else use `clean` mode.

        MD

        event_description <<-MD

            User defined
        MD

        def validate_options
            errors.add(:base,"instructions,mode,skip_agent and skip_created_at , all need to be present.") unless options[:instructions].present? and options[:mode].present? and options[:skip_agent].present? and options[:skip_created_at].present?
        end

        def default_options
            {
                :instructions => {
                    :message =>  "You received a text <$.text> from <$.fields.from>",
                    :content => "Looks like the weather is going to be <$.fields.weather>"},
                :mode    => "clean",
                :skip_agent => "false",
                :skip_created_at => "false"
            }
        end

        def working?
            true
        end

        def value_constructor(value,payload)
            value.gsub(/<[^>]+>/).each {|jsonpath| Utils.values_at(payload,jsonpath[1..-2]).first.to_s}
        end

        def receive(incoming_events)
            incoming_events.each do |event|
                formatted_event = options[:mode].to_s == "merge" ? event.payload : {}
                options[:instructions].each_pair {|key,value| formatted_event[key] = value_constructor value, event.payload}
                formatted_event[:agent] = Agent.find(event.agent_id).type.slice!(8..-1) unless options[:skip_agent].to_s == "true" 
                formatted_event[:created_at] = event.created_at unless options[:skip_created_at].to_s == "true"
                create_event :payload => formatted_event
            end
        end
    end
end