# frozen_string_literal: true

require 'yaml'
require 'json'
require 'pathname'
require_relative 'redis/queues' unless defined?(Gitlab::Redis::Queues)

# This service is run independently of the main Rails process,
# therefore the `Rails` class and its methods are unavailable.

module Gitlab
  module MailRoom
    RAILS_ROOT_DIR = Pathname.new('../..').expand_path(__dir__).freeze

    DELIVERY_METHOD_SIDEKIQ = 'sidekiq'
    DELIVERY_METHOD_WEBHOOK = 'webhook'
    INTERNAL_API_REQUEST_HEADER = 'Gitlab-Mailroom-Api-Request'
    INTERNAL_API_REQUEST_JWT_ISSUER = 'gitlab-mailroom'

    DEFAULT_CONFIG = {
      enabled: false,
      port: 143,
      ssl: false,
      start_tls: false,
      mailbox: 'inbox',
      idle_timeout: 60,
      log_path: RAILS_ROOT_DIR.join('log', 'mail_room_json.log'),
      expunge_deleted: false,
      delivery_method: DELIVERY_METHOD_SIDEKIQ
    }.freeze

    # Email specific configuration which is merged with configuration
    # fetched from YML config file.
    MAILBOX_SPECIFIC_CONFIGS = {
      incoming_email: {
        queue: 'email_receiver',
        worker: 'EmailReceiverWorker'
      },
      service_desk_email: {
        queue: 'service_desk_email_receiver',
        worker: 'ServiceDeskEmailReceiverWorker'
      }
    }.freeze

    class << self
      def enabled_configs
        @enabled_configs ||= configs.select { |_key, config| enabled?(config) }
      end

      def enabled_mailbox_types
        enabled_configs.keys.map(&:to_s)
      end

      def worker_for(mailbox_type)
        MAILBOX_SPECIFIC_CONFIGS.try(:[], mailbox_type.to_sym).try(:[], :worker).try(:safe_constantize)
      end

      private

      def enabled?(config)
        config[:enabled] && !config[:address].to_s.empty?
      end

      def configs
        MAILBOX_SPECIFIC_CONFIGS.to_h { |key, _value| [key, fetch_config(key)] }
      end

      def fetch_config(config_key)
        return {} unless File.exist?(config_file)

        config = merged_configs(config_key)

        config.merge!(redis_config) if enabled?(config)

        config[:log_path] = File.expand_path(config[:log_path], RAILS_ROOT_DIR)

        config
      end

      def merged_configs(config_key)
        yml_config = load_yaml.fetch(config_key, {})
        specific_config = MAILBOX_SPECIFIC_CONFIGS.fetch(config_key, {})
        DEFAULT_CONFIG.merge(specific_config, yml_config) do |_key, oldval, newval|
          newval.nil? ? oldval : newval
        end
      end

      def redis_config
        gitlab_redis_queues = Gitlab::Redis::Queues.new(rails_env)

        config = { redis_url: gitlab_redis_queues.url, redis_db: gitlab_redis_queues.db }

        if gitlab_redis_queues.sentinels?
          config[:sentinels] = gitlab_redis_queues.sentinels
        end

        config
      end

      def rails_env
        @rails_env ||= ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
      end

      def config_file
        ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] || File.expand_path('../../config/gitlab.yml', __dir__)
      end

      def load_yaml
        @yaml ||= YAML.load_file(config_file)[rails_env].deep_symbolize_keys
      end
    end
  end
end