require "diaspora_federation/logging"

require "diaspora_federation/callbacks"
require "diaspora_federation/properties_dsl"
require "diaspora_federation/entity"
require "diaspora_federation/validators"

require "diaspora_federation/fetcher"

require "diaspora_federation/signing"
require "diaspora_federation/entities"

require "diaspora_federation/discovery"
require "diaspora_federation/salmon"

# diaspora* federation library
module DiasporaFederation
  extend Logging

  @callbacks = Callbacks.new %i(
    fetch_person_for_webfinger
    fetch_person_for_hcard
    save_person_after_webfinger
    fetch_private_key_by_id
    fetch_private_key_by_post_guid
    fetch_public_key_by_id
    fetch_public_key_by_post_guid
    post_author_is_local?
  )

  class << self
    # {Callbacks} instance with defined callbacks
    # @see Callbacks#on
    # @see Callbacks#trigger
    #
    attr_reader :callbacks

    # the pod url
    #
    # @example with uri
    #   config.server_uri = URI("http://localhost:3000/")
    # @example with configured pod_uri
    #   config.server_uri = AppConfig.pod_uri
    attr_accessor :server_uri

    # Set the bundle of certificate authorities (CA) certificates
    #
    # @example
    #   config.certificate_authorities = AppConfig.environment.certificate_authorities.get
    attr_accessor :certificate_authorities

    # configure the federation library
    #
    # @example
    #   DiasporaFederation.configure do |config|
    #     config.server_uri = URI("http://localhost:3000/")
    #
    #     config.define_callbacks do
    #       # callback configuration
    #     end
    #   end
    def configure
      yield self
    end

    # define the callbacks
    #
    # @example
    #   config.define_callbacks do
    #     on :some_event do |arg1|
    #       # do something
    #     end
    #   end
    #
    # @param [Proc] block the callbacks to define
    def define_callbacks(&block)
      @callbacks.instance_eval(&block)
    end

    # validates if the engine is configured correctly
    #
    # called from after_initialize
    # @raise [ConfigurationError] if the configuration is incomplete or invalid
    def validate_config
      configuration_error "server_uri: Missing or invalid" unless @server_uri.respond_to? :host

      unless defined?(::Rails) && !::Rails.env.production?
        configuration_error "certificate_authorities: Not configured" if @certificate_authorities.nil?
        unless File.file? @certificate_authorities
          configuration_error "certificate_authorities: File not found: #{@certificate_authorities}"
        end
      end

      unless @callbacks.definition_complete?
        configuration_error "Missing handlers for #{@callbacks.missing_handlers.join(', ')}"
      end

      logger.info "successfully configured the federation library"
    end

    private

    def configuration_error(message)
      logger.fatal("diaspora federation configuration error: #{message}")
      raise ConfigurationError, message
    end
  end

  # raised, if the engine is not configured correctly
  class ConfigurationError < RuntimeError
  end
end