module Agents
  class TwitterStreamAgent < Agent
    include TwitterConcern

    cannot_receive_events!

    description <<-MD
      The TwitterStreamAgent follows the Twitter stream in real time, watching for certain keywords, or filters, that you provide.

      To follow the Twitter stream, provide an array of `filters`.  Multiple words in a filter must all show up in a tweet, but are independent of order.
      If you provide an array instead of a filter, the first entry will be considered primary and any additional values will be treated as aliases.

      To be able to use this Agent you need to authenticate with Twitter in the [Services](/services) section first.

      Set `expected_update_period_in_days` to the maximum amount of time that you'd expect to pass between Events being created by this Agent.

      `generate` should be either `events` or `counts`.  If set to `counts`, it will output event summaries whenever the Agent is scheduled.
    MD

    event_description <<-MD
      When in `counts` mode, TwitterStreamAgent events look like:

          {
            "filter": "hello world",
            "count": 25,
            "time": 3456785456
          }

      When in `events` mode, TwitterStreamAgent events look like:

          {
            "filter": "selectorgadget",
             ... every Tweet field, including ...
            "text": "something",
            "user": {
              "name": "Mr. Someone",
              "screen_name": "Someone",
              "location": "Vancouver BC Canada",
              "description":  "...",
              "followers_count": 486,
              "friends_count": 1983,
              "created_at": "Mon Aug 29 23:38:14 +0000 2011",
              "time_zone": "Pacific Time (US & Canada)",
              "statuses_count": 3807,
              "lang": "en"
            },
            "retweet_count": 0,
            "entities": ...
            "lang": "en"
          }
    MD

    default_schedule "11pm"

    def validate_options
      unless options['filters'].present? &&
             options['expected_update_period_in_days'].present? &&
             options['generate'].present?
        errors.add(:base, "expected_update_period_in_days, generate, and filters are required fields")
      end
    end

    def working?
      event_created_within?(interpolated['expected_update_period_in_days']) && !recent_error_logs?
    end

    def default_options
      {
        'filters' => %w[keyword1 keyword2],
        'expected_update_period_in_days' => "2",
        'generate' => "events"
      }
    end

    def process_tweet(filter, status)
      filter = lookup_filter(filter)

      if filter
        if interpolated['generate'] == "counts"
          # Avoid memory pollution by reloading the Agent.
          agent = Agent.find(id)
          agent.memory['filter_counts'] ||= {}
          agent.memory['filter_counts'][filter] ||= 0
          agent.memory['filter_counts'][filter] += 1
          remove_unused_keys!(agent, 'filter_counts')
          agent.save!
        else
          create_event :payload => status.merge('filter' => filter)
        end
      end
    end

    def check
      if interpolated['generate'] == "counts" && memory['filter_counts'] && memory['filter_counts'].length > 0
        memory['filter_counts'].each do |filter, count|
          create_event :payload => { 'filter' => filter, 'count' => count, 'time' => Time.now.to_i }
        end
      end
      memory['filter_counts'] = {}
    end

    protected

    def lookup_filter(filter)
      interpolated['filters'].each do |known_filter|
        if known_filter == filter
          return filter
        elsif known_filter.is_a?(Array)
          if known_filter.include?(filter)
            return known_filter.first
          end
        end
      end
    end

    def remove_unused_keys!(agent, base)
      if agent.memory[base]
        (agent.memory[base].keys - agent.interpolated['filters'].map {|f| f.is_a?(Array) ? f.first.to_s : f.to_s }).each do |removed_key|
          agent.memory[base].delete(removed_key)
        end
      end
    end
  end
end