module VideoSources
  module Youtube
    class Client
      API_BASE = 'https://www.googleapis.com/youtube/v3'

      def initialize api_key: ENV.fetch('YOUTUBE_API_KEY')
        @api_key = api_key
      end

      def videos video_ids
        return [] if video_ids.empty?

        response = connection.get('videos', part: 'snippet,statistics',
                                            id: video_ids.join(','),
                                            key: @api_key)

        JSON.parse(response.body).fetch('items', []).map do |item|
          build_video(item)
        end
      end

      def comments video_id
        comments = []
        page_token = nil

        loop do
          response = connection.get('commentThreads', {
              part: 'snippet',
              videoId: video_id,
              maxResults: 100,
              textFormat: 'plainText',
              pageToken: page_token,
              key: @api_key }.compact)

          body = JSON.parse(response.body)

          comments.concat(body.fetch('items', []).map { |item| build_comment(item) })

          page_token = body['nextPageToken']
          break if page_token.blank?
        end

        comments
      rescue Faraday::ForbiddenError
        []
      end

      private

      def connection
        @connection ||= Faraday.new(url: API_BASE) do |faraday|
          faraday.response :raise_error
        end
      end

      def build_video item
        snippet = item.fetch('snippet')
        statistics = item.fetch('statistics', { })

        { provider: 'youtube',
          code: item.fetch('id'),
          user_code: snippet['channelId'],
          title: snippet['title'].to_s,
          description: snippet['description'].to_s,
          tag_names: snippet.fetch('tags', []),
          views_count: statistics.fetch('viewCount', 0).to_i,
          uploaded_at: Time.zone.parse(snippet.fetch('publishedAt')) }
      end

      def build_comment item
        snippet =
            item
            .fetch('snippet')
            .fetch('topLevelComment')
            .fetch('snippet')

        { provider_comment_id: item.fetch('id'),
          user_code: snippet['authorChannelId']&.fetch('value', nil),
          content: snippet['textDisplay'].to_s,
          posted_at: Time.zone.parse(snippet.fetch('publishedAt')),
          reaction_count: snippet.fetch('likeCount', 0).to_i,
          comment_no: nil,
          vpos_ms: nil }
      end
    end
  end
end