module Agents
  class TwitterFavorites < Agent
    include TwitterConcern

    can_dry_run!
    cannot_receive_events!

    description <<~MD
      The Twitter Favorites List Agent follows the favorites list of a specified Twitter user.

      #{twitter_dependencies_missing if dependencies_missing?}

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

      You must also provide the `username` of the Twitter user, `number` of latest tweets to monitor and `history' as number of tweets that will be held in memory.

      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.

      Set `starting_at` to the date/time (eg. `Mon Jun 02 00:38:12 +0000 2014`) you want to start receiving tweets from (default: agent's `created_at`)
    MD

    event_description <<~MD
      Events are the raw JSON provided by the [Twitter API v1.1](https://dev.twitter.com/docs/api/1.1/get/favorites/list) with slight modifications.   They should look something like this:

      #{tweet_event_description('full_text')}
    MD

    default_schedule "every_1h"

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

    def default_options
      {
        'username' => 'tectonic',
        'number' => '10',
        'history' => '100',
        'expected_update_period_in_days' => '2'
      }
    end

    def validate_options
      errors.add(:base, "username is required") unless options[:username].present?
      errors.add(:base, "number is required") unless options[:number].present?
      errors.add(:base, "history is required") unless options[:history].present?
      errors.add(
        :base,
        "expected_update_period_in_days is required"
      ) unless options[:expected_update_period_in_days].present?

      if options[:starting_at].present?
        begin
          Time.parse(options[:starting_at])
        rescue StandardError
          errors.add(:base, "Error parsing starting_at")
        end
      end
    end

    def starting_at
      if interpolated[:starting_at].present?
        begin
          Time.parse(interpolated[:starting_at])
        rescue StandardError
        end
      end || created_at || Time.now # for dry-running
    end

    def check
      opts = { count: interpolated[:number], tweet_mode: 'extended' }
      tweets = twitter.favorites(interpolated[:username], opts)
      memory[:last_seen] ||= []

      tweets.sort_by(&:id).each do |tweet|
        next if memory[:last_seen].include?(tweet.id) || tweet.created_at < starting_at

        memory[:last_seen].push(tweet.id)
        memory[:last_seen].shift if memory[:last_seen].length > interpolated[:history].to_i
        create_event(payload: format_tweet(tweet))
      end
    end
  end
end