module Scrivito

  #
  # @api public
  #
  class Configuration
    #
    # Default path of a CA certification file in PEM format.
    #
    # @api public
    #
    DEFAULT_CA_FILE = File.expand_path('../../../config/ca-bundle.crt', __FILE__)

    class << self
      # Determine if current visitor is permitted to edit content.
      attr_accessor :find_user_proc

      #
      # Configures a callback to be invoked when the SDK determines whether current visitor is
      # permitted to edit content.
      #
      # If the callback is missing in the +development+ or +test+ environment, then the SDK will
      # assume, that the current visitor is {Scrivito::User.system_user}, who can always create
      # workspaces, can always read, write, publish, delete and invite to any workspace.
      #
      # If the callback is missing in any other environment (for example in +production+ or
      # +staging+), then the SDK will assume, that the current visitor is not permitted to edit
      # content.
      #
      # @api public
      #
      # @param [Proc] block proc for detemining if the current visitor is permitted to edit content
      # @yieldparam [Hash] env rack env
      # @yieldreturn [Scrivito::User] if the current visitor is permitted to edit content
      # @yieldreturn [false, nil] if the current visitor is not permitted to edit content
      #
      # @example
      #   Scrivito::Configuration.editing_auth do |env|
      #     if user_id = env['USER_ID']
      #       Scrivito::User.define(user_id)
      #     end
      #   end
      #
      def editing_auth(&block)
        if block.respond_to?(:arity) && block.arity == 1
          @editing_auth_callback = block
        else
          raise ArgumentError, 'editing_auth should have only one attribute!'
        end
      end

      def editing_auth_callback
        @editing_auth_callback || default_editing_auth_callback
      end

      # Configures how to find users for the in-place GUI.
      # @api public
      # @param [Proc] find_user_proc proc for finding a user by the user id
      # @yieldparam [String] user_id id of the user
      # @yieldreturn [Scrivito::User] if the user with the given user id was found
      # @yieldreturn [NilClass] if the user with the given user id was not found
      # @raise [Scrivito::ScrivitoError] if the proc returns neither a {Scrivito::User}, nor +nil+
      # @note This configuration key is optional. If it is not configured the in-place GUI would
      #   behave normally, but would not be able to find any users.
      # @example Return a "dummy" {Scrivito::User}
      #   Scrivito.configure do |config|
      #     config.find_user do |user_id|
      #       Scrivito::User.new(user_id)
      #     end
      #   end
      # @example Find the user with a custom user model and convert it to a {Scrivito::User}
      #   Scrivito.configure do |config|
      #     config.find_user do |user_id|
      #       my_user = MyUserModel.find(user_id)
      #       if my_user
      #         my_user.to_scrivito_user
      #       end
      #     end
      #   end
      def find_user(&find_user_proc)
        self.find_user_proc = find_user_proc
      end

      #
      # Set the path for the filesystem cache.
      #
      # +Scrivito+ makes heavy use of filesystem caching. Use this method to configure the directory
      # that should be used to store cached data. By default, +RAILS_ROOT/tmp/scrivito_cache+ will
      # be used.
      #
      # @api public
      #
      # @param path [String] Path to directory that should be used to store cached data.
      #
      # @example Configure +Scrivito+ to store its cache under +/tmp/my_cache+.
      #
      #   Scrivito.configure do |config|
      #     config.cache_path = '/tmp/my_cache'
      #   end
      #
      def cache_path=(path)
        CmsDataCache.cache_path = path
      end

      #
      # Sets the second level cache.
      #
      # If it is set, then +Scrivito+ will additionaly store its cache in both: the filesystem cache
      # and the second level cache. Also +Scrivito+ will search in the second level cache if
      # searching in the filesystem cache returns no results. If the second level cache returns
      # results, then the results will be store in the filesystem cache.
      #
      # By default it is not set.
      #
      # @api public
      #
      # @param cache_store [ActiveSupport::Cache::Store] cache store to be used as the second level
      #   cache
      #
      #  @example Use Memcached as the second level cache (https://rubygems.org/gems/dalli)
      #
      #   Scrivito.configure do |config|
      #     config.second_level_cache = ActiveSupport::Cache::DalliStore.new("localhost", "server-downstairs.localnetwork:8229")
      #   end
      #
      def second_level_cache=(cache_store)
        CmsDataCache.second_level_cache = cache_store
      end

      #
      # Sets the tenant name.
      # This configuration key _must_ be provided.
      #
      # @api public
      #
      def tenant=(tenant_name)
        @endpoint_uri = nil
        @tenant = tenant_name
      end

      #
      # Sets the API key.
      # This configuration key _must_ be provided.
      #
      # @api public
      #
      attr_writer :api_key

      #
      # Sets the API endpoint URL.
      # This configuration key is optional.
      # Default is +'api.scrivito.com'+.
      # If no schema is provided HTTPS is assumed.
      #
      # @api public
      #
      attr_writer :endpoint

      #
      # Gets the path of a CA certification file in PEM format.
      #
      # @return [String]
      # @api public
      #
      attr_reader :ca_file

      # Sets path of a CA certification file in PEM format.
      # The file can contain several CA certificates.
      # Certifications will be used for endpoint peer verification of various scrivito services
      # e.g. Content Read Service.
      # @api public
      def ca_file=(path)
        File.read(path) if path # Try to read the given file and fail if it doesn't exist or is not readable.
        @ca_file = path
      end

      def to_prepare
        unless Rails.configuration.cache_classes
          NamedLink.reset_cache
          BasicObj.reset_type_computer!
          BasicWidget.reset_type_computer!
        end
      end

      def tenant
        tenant = @tenant || ENV['SCRIVITO_TENANT']
        assert_configuration_key_present(:tenant, tenant)
        tenant
      end

      def api_key
        api_key = @api_key || ENV['SCRIVITO_API_KEY']
        assert_configuration_key_present(:api_key, api_key)
        api_key
      end

      def endpoint
        raise 'Missing required configuration key "endpoint"' unless @endpoint
        @endpoint
      end

      def endpoint_uri
        @endpoint_uri ||= calculate_endpoint_uri
      end

      def set_defaults!
        self.ca_file = DEFAULT_CA_FILE
        self.endpoint = 'api.scrivito.com'
        self.check_batch_size = 100
      end

      attr_accessor :choose_homepage_callback, :check_batch_size

      # Configure a callback to be invoked when the Scrivito SDK delivers the homepage.
      # The given callback will receive the rack env
      # and must return an {BasicObj Obj} to be used as the homepage.
      # If no callback is configured, {BasicObj.homepage Obj.homepage} will be used as the default.
      # @api public
      def choose_homepage(&block)
        self.choose_homepage_callback = block
      end

      def obj_formats
        @obj_formats ||= {
          '_default' => proc do |obj, user|
            {
              id: obj.id,
              obj_class_name: obj.obj_class_name,
              description_for_editor: obj.description_for_editor,
              modification: obj.modification,
              has_conflict: obj.has_conflict?,
              last_changed: obj.last_changed.utc.iso8601,
              is_binary: obj.binary?,
              restriction_messages: user.restriction_messages_for(obj)
            }
          end
        }
      end

      def register_obj_format(name, &block)
        if name.start_with? '_'
          raise InvalidFormatNameError.new('Format names starting with underscore are not allowed.')
        else
          obj_formats[name] = block
        end
      end

      # For test purposes only.
      def reset_editing_auth_callback!
        @editing_auth_callback = nil
      end

      def migration_path
        'scrivito/migrate'
      end

      private

      def default_editing_auth_callback
        if Rails.env.development? || Rails.env.test?
          ->(_) { User.system_user }
        end
      end

      def assert_configuration_key_present(key, value)
        unless value
          raise %{
            Missing the required configuration key "#{key}".

            You need to configure the "tenant" and the "api_key" in order to connect the application
            to the Scrivito backend.

            Either use the environment variables "SCRIVITO_TENANT" and "SCRIVITO_API_KEY" or set the
            keys in an initializer:

              Scrivito.configure do |config|
                config.tenant  = 'my_tenant'
                config.api_key = 'secret123'
              end

            The values of the keys can be obtained from the dashboard at https://scrivito.com.
          }
        end
      end

      def calculate_endpoint_uri
        url = endpoint
        url = "https://#{url}" unless url.match(/^http/)
        url = "#{url}/tenants/#{tenant}"
        URI.parse(url)
      end
    end

    self.set_defaults!
  end

  class InvalidFormatNameError < StandardError
  end
end