require 'logstash-logger'
require 'retriable'
require 'slack-notifier'

module Maltese
  class ::InternalServerError < StandardError; end
  class ::BadGatewayError < StandardError; end

  class Sitemap
    attr_reader :sitemap_bucket, :rack_env, :access_key, :secret_key, :region, :slack_webhook_url, :logger

    # load ENV variables from .env file if it exists
    env_file = File.expand_path("../../../.env", __FILE__)
    if File.exist?(env_file)
      require 'dotenv'
      Dotenv.overload env_file
    end

    # load ENV variables from container environment if json file exists
    # see https://github.com/phusion/baseimage-docker#envvar_dumps
    env_json_file = "/etc/container_environment.json"
    if File.size?(env_json_file).to_i > 2
      env_vars = JSON.parse(File.read(env_json_file))
      env_vars.each { |k, v| ENV[k] = v }
    end

    # icon for Slack messages
    SLACK_ICON_URL = "https://raw.githubusercontent.com/datacite/homepage/master/source/images/fabrica.png"

    def initialize(attributes={})
      @sitemap_bucket = attributes[:sitemap_bucket].presence || "search.test.datacite.org"
      @rack_env = attributes[:rack_env].presence || ENV['RACK_ENV'] || "stage"
      @access_key = attributes[:access_key].presence || ENV['AWS_ACCESS_KEY_ID']
      @secret_key = attributes[:secret_key].presence || ENV['AWS_SECRET_ACCESS_KEY']
      @region = attributes[:region].presence || ENV['AWS_REGION']
      @slack_webhook_url = attributes[:slack_webhook_url].presence || ENV['SLACK_WEBHOOK_URL']

      @logger = LogStashLogger.new(type: :stdout)
    end

    def sitemap_url
      rack_env == "production" ? "https://commons.datacite.org/" : "https://commons.stage.datacite.org/"
    end

    def slack_title
      rack_env == "production" ? "DataCite Fabrica" : "DataCite Fabrica Stage"
    end

    def sitemaps_path
      "sitemaps/"
    end

    def search_path
      rack_env == "production" ? "https://api.datacite.org/dois?" : "https://api.stage.datacite.org/dois?"
    end

    def timeout
      60
    end

    def job_batch_size
      1000
    end

    def sitemap
      @sitemap ||= SitemapGenerator::LinkSet.new(
        default_host: sitemap_url,
        sitemaps_host: sitemap_url,
        sitemaps_path: sitemaps_path,
        adapter: s3_adapter,
        finalize: false)
    end

    def s3_adapter
      SitemapGenerator::AwsSdkAdapter.new(sitemap_bucket,
                                      aws_access_key_id: access_key,
                                      aws_secret_access_key: secret_key,
                                      aws_region: region)
    end

    def queue_jobs(options={})
      total = get_total(options)

      if total.nil?
        logger.error "An error occured."
      elsif total > 0
        process_data(options.merge(total: total, url: get_query_url))
      else
        logger.info "No works found."
      end

      # return number of works queued
      total.to_i
    end

    def get_total(options={})
      query_url = get_query_url(options.merge(size: 1))

      result = Maremma.get(query_url, options)
      result.body.dig("meta", "total")
    end

    def get_query_url(options={})
      options[:size] = options[:size] || job_batch_size

      params = { 
        "fields[dois]" => "doi,updated",
        "exclude-registration-agencies" => "true",
        "page[scroll]" => "7m",
        "page[size]" => options[:size]
      }
      search_path + URI.encode_www_form(params)
    end

    def process_data(options = {})
      options[:start_time] = Time.now
      link_count = 0

      # walk through paginated results
      while options[:url] do
        begin
          response = nil

          # speed up tests
          base_interval = rack_env == "test" ? 0.1 : 10

          # retry on temporal errors (status codes 408, 500 and 502)
          Retriable.retriable(base_interval: base_interval, multiplier: 2) do
            response = get_data(options[:url])

            raise Timeout::Error, "A timeout error occured for URL #{options[:url]}." if response.status == 408
            raise InternalServerError, "An internal server error occured for URL #{options[:url]}." if response.status == 500
            raise BadGatewayError, "A bad gateway error occured for URL #{options[:url]}." if response.status == 502
          end

          if response.status == 200
            link_count = parse_data(response)
            logger.info "#{(link_count + sitemap.sitemap_index.total_link_count).to_s(:delimited)} DOIs parsed."
            options[:url] = response.body.dig("links", "next")
          else
            logger.error "An error occured for URL #{options[:url]}."
            logger.error "Error: #{response.body.fetch("errors").inspect}" if response.body.fetch("errors", nil).present?
            options[:url] = nil
          end
        rescue => exception
          logger.error "Error: #{exception.message}"
          fields = [
            { title: "Error", value: exception.message },
            { title: "Number of DOIs", value: sitemap.sitemap_index.total_link_count.to_s(:delimited), short: true },
            { title: "Number of Sitemaps", value: sitemap.sitemap_index.link_count.to_s(:delimited), short: true },
            { title: "Time Taken", value: "#{((Time.now - options[:start_time])/ 60.0).ceil} min", short: true }
          ]
          send_notification_to_slack(nil, title: slack_title + ": Sitemaps Not Updated", level: "danger", fields: fields) unless rack_env == "test"
          options[:url] = nil
        ensure
          # don't loop when testing
          break if rack_env == "test"
        end  
      end

      push_data(options)
    end

    def get_data(url)
      Maremma.get(url, timeout: 300)
    end

    def parse_data(result)
      Array.wrap(result.body.fetch("data", nil)).each do |item|
        loc = "/doi.org/" + item.dig("attributes", "doi")
        sitemap.add loc, changefreq: "weekly", lastmod: item.dig("attributes", "updated")
      end
      sitemap.sitemap.link_count
    end

    def push_data(options={})
      sitemap.finalize!
      options[:start_time] ||= Time.now
      sitemap.sitemap_index.stats_summary(:time_taken => Time.now - options[:start_time])
      
      fields = [
        { title: "URL", value: sitemap.sitemap_index_url },
        { title: "Number of DOIs", value: sitemap.sitemap_index.total_link_count.to_s(:delimited), short: true },
        { title: "Number of Sitemaps", value: sitemap.sitemap_index.link_count.to_s(:delimited), short: true },
        { title: "Time Taken", value: "#{((Time.now - options[:start_time])/ 60.0).ceil} min", short: true }
      ]
      send_notification_to_slack(nil, title: slack_title + ": Sitemaps Updated", level: "good", fields: fields) unless rack_env == "test"
      sitemap.sitemap.link_count
    end

    def send_notification_to_slack(text, options={})
      return nil unless slack_webhook_url.present?

      attachment = {
        title: options[:title] || "Fabrica Message",
        text: text,
        color: options[:level] || "good",
        fields: options[:fields]
      }.compact

      begin
        notifier = Slack::Notifier.new(slack_webhook_url,
                                       username: "Fabrica",
                                       icon_url: SLACK_ICON_URL)
        response = notifier.ping attachments: [attachment]
        response.first.body
      rescue => exception
        logger.error exception.message
      end
    end
  end
end