require 'rss'
require 'feed-normalizer'

module Agents
  class RssAgent < Agent
    include WebRequestConcern

    cannot_receive_events!
    default_schedule "every_1d"

    description do
      <<-MD
        This Agent consumes RSS feeds and emits events when they change.

        (If you want to *output* an RSS feed, use the DataOutputAgent.  Also, you can technically parse RSS and XML feeds
        with the WebsiteAgent as well.  See [this example](https://github.com/cantino/huginn/wiki/Agent-configuration-examples#itunes-trailers).)

        Options:

          * `url` - The URL of the RSS feed.
          * `clean` - Attempt to use [feed-normalizer](https://github.com/aasmith/feed-normalizer)'s' `clean!` method to cleanup HTML in the feed.  Set to `true` to use.
          * `expected_update_period_in_days` - How often you expect this RSS feed to change.  If more than this amount of time passes without an update, the Agent will mark itself as not working.
      MD
    end

    def default_options
      {
        'expected_update_period_in_days' => "5",
        'clean' => 'false',
        'url' => "https://github.com/cantino/huginn/commits/master.atom"
      }
    end

    def working?
      event_created_within?((interpolated['expected_update_period_in_days'].presence || 10).to_i) && !recent_error_logs?
    end

    def validate_options
      errors.add(:base, "url is required") unless options['url'].present?

      unless options['expected_update_period_in_days'].present? && options['expected_update_period_in_days'].to_i > 0
        errors.add(:base, "Please provide 'expected_update_period_in_days' to indicate how many days can pass without an update before this Agent is considered to not be working")
      end

      validate_web_request_options!
    end

    def check
      response = faraday.get(interpolated['url'])
      if response.success?
        feed = FeedNormalizer::FeedNormalizer.parse(response.body)
        feed.clean! if interpolated['clean'] == 'true'
        created_event_count = 0
        feed.entries.each do |entry|
          if check_and_track(entry.id)
            created_event_count += 1
            create_event(:payload => {
              :id => entry.id,
              :date_published => entry.date_published,
              :last_updated => entry.last_updated,
              :urls => entry.urls,
              :description => entry.description,
              :content => entry.content,
              :title => entry.title,
              :authors => entry.authors,
              :categories => entry.categories
            })
          end
        end
        log "Fetched #{interpolated['url']} and created #{created_event_count} event(s)."
      else
        error "Failed to fetch #{interpolated['url']}: #{response.inspect}"
      end
    end

    protected

    def check_and_track(entry_id)
      memory['seen_ids'] ||= []
      if memory['seen_ids'].include?(entry_id)
        false
      else
        memory['seen_ids'].unshift entry_id
        memory['seen_ids'].pop if memory['seen_ids'].length > 500
        true
      end
    end
  end
end