# lightweight Twitter api calls
class TwitterApi

  class << self

    def prettify_tweet(tweet)
      text = tweet["text"].dup
      if entities = tweet["entities"] and urls = entities["urls"]
        urls.each do |url|
          text.gsub!(url["url"], "<a target='_blank' href='#{url["expanded_url"]}'>#{url["display_url"]}</a>")
        end
      end

      text = link_hashtags_in link_handles_in text

      Rinku.auto_link(text, :all, 'target="_blank"').to_s
    end

    def user_timeline(screen_name)
      JSON.parse(twitter_get(user_timeline_uri_for screen_name))
    end

    def tweet_for(id)
      JSON.parse(twitter_get(tweet_uri_for id))
    end

    def raw_tweet_for(id)
      twitter_get(tweet_uri_for id)
    end

    def twitter_credentials_missing?
      consumer_key.blank? || consumer_secret.blank?
    end

    protected

    def link_handles_in(text)
      text.scan(/\s@(\w+)/).flatten.uniq.each do |handle|
        text.gsub!("@#{handle}", [
          "<a href='https://twitter.com/#{handle}' target='_blank'>",
            "@#{handle}",
          "</a>"
        ].join)
      end

      text
    end

    def link_hashtags_in(text)
      text.scan(/\s#(\w+)/).flatten.uniq.each do |hashtag|
        text.gsub!("##{hashtag}", [
          "<a href='https://twitter.com/search?q=%23#{hashtag}' ",
          "target='_blank'>",
            "##{hashtag}",
          "</a>"
        ].join)
      end

      text
    end

    def user_timeline_uri_for(screen_name)
      URI.parse "#{BASE_URL}/1.1/statuses/user_timeline.json?screen_name=#{screen_name}&count=50&include_rts=false&exclude_replies=true"
    end

    def tweet_uri_for(id)
      URI.parse "#{BASE_URL}/1.1/statuses/show.json?id=#{id}"
    end

    unless defined? BASE_URL
      BASE_URL = 'https://api.twitter.com'.freeze
    end

    def twitter_get(uri)
      request = Net::HTTP::Get.new(uri)
      request.add_field 'Authorization', "Bearer #{bearer_token}"
      http(uri).request(request).body
    end

    def authorization
      request = Net::HTTP::Post.new(auth_uri)

      request.add_field 'Authorization',
        "Basic #{bearer_token_credentials}"
      request.add_field 'Content-Type',
        'application/x-www-form-urlencoded;charset=UTF-8'

      request.set_form_data 'grant_type' => 'client_credentials'

      http(auth_uri).request(request).body
    end

    def bearer_token
      @access_token ||= JSON.parse(authorization).fetch('access_token')
    end

    def bearer_token_credentials
      Base64.strict_encode64(
        "#{URI::encode(consumer_key)}:#{URI::encode(consumer_secret)}"
      )
    end

    def auth_uri
      URI.parse "#{BASE_URL}/oauth2/token"
    end


    def http(uri)
      Net::HTTP.new(uri.host, uri.port).tap { |http| http.use_ssl = true }
    end

    def consumer_key
      SiteSetting.twitter_consumer_key
    end

    def consumer_secret
      SiteSetting.twitter_consumer_secret
    end

  end
end