# frozen_string_literal: true
module Pragma
  module Operation
    # This is the base class all your operations should extend.
    #
    # @author Alessandro Desantis
    #
    # @abstract Subclass and override {#call} to implement an operation.
    class Base
      include Interactor

      include Authorization
      include Validation
      include Decoration

      STATUSES = {
        200 => :ok,
        201 => :created,
        202 => :accepted,
        203 => :non_authoritative_information,
        204 => :no_content,
        205 => :reset_content,
        206 => :partial_content,
        207 => :multi_status,
        208 => :already_reported,
        300 => :multiple_choices,
        301 => :moved_permanently,
        302 => :found,
        303 => :see_other,
        304 => :not_modified,
        305 => :use_proxy,
        307 => :temporary_redirect,
        400 => :bad_request,
        401 => :unauthorized,
        402 => :payment_required,
        403 => :forbidden,
        404 => :not_found,
        405 => :method_not_allowed,
        406 => :not_acceptable,
        407 => :proxy_authentication_required,
        408 => :request_timeout,
        409 => :conflict,
        410 => :gone,
        411 => :length_required,
        412 => :precondition_failed,
        413 => :request_entity_too_large,
        414 => :request_uri_too_large,
        415 => :unsupported_media_type,
        416 => :request_range_not_satisfiable,
        417 => :expectation_failed,
        418 => :im_a_teapot,
        422 => :unprocessable_entity,
        423 => :locked,
        424 => :failed_dependency,
        425 => :unordered_collection,
        426 => :upgrade_required,
        428 => :precondition_required,
        429 => :too_many_requests,
        431 => :request_header_fields_too_large,
        449 => :retry_with,
        500 => :internal_server_error,
        501 => :not_implemented,
        502 => :bad_gateway,
        503 => :service_unavailable,
        504 => :gateway_timeout,
        505 => :http_version_not_supported,
        506 => :variant_also_negotiates,
        507 => :insufficient_storage,
        509 => :bandwidth_limit_exceeded,
        510 => :not_extended,
        511 => :network_authentication_required
      }.freeze

      class << self
        def inherited(child)
          child.class_eval do
            before :setup_context
            around :handle_halt
            after :mark_result, :consolidate_status, :validate_status, :set_default_status
            after :build_links
          end
        end

        # Returns the name of this operation.
        #
        # For instance, if the operation is called +API::V1::Post::Operation::Create+, returns
        # +create+.
        #
        # @return [Symbol]
        def operation_name
          name.split('::').last
            .gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
            .gsub(/([a-z\d])([A-Z])/, '\1_\2')
            .tr('-', '_')
            .downcase
            .to_sym
        end
      end

      # Runs the operation.
      def call
        fail NotImplementedError
      end

      protected

      # Returns the params this operation is being run with.
      #
      # This is just a shortcut for +context.params+.
      #
      # @return [Hash]
      def params
        context.params
      end

      # Sets the status and resource to respond with.
      #
      # You can achieve the same result by setting +context.status+, +context.headers+ and
      # +context.resource+ wherever you want in {#call}.
      #
      # Note that calling this method doesn't halt the execution of the operation and that this
      # method can be called multiple times, overriding the previous context.
      #
      # @param status [Integer|Symbol] an HTTP status code
      # @param resource [Object] an object responding to +#to_json+
      # @param headers [Hash] HTTP headers
      # @param links [Hash] links to use for building the +Link+ header
      def respond_with(status: nil, resource: nil, headers: nil, links: nil)
        context.status = status if status
        context.resource = resource if resource
        context.headers = headers if headers
        context.links = links if links
      end

      # Same as {#respond_with}, but also halts the execution of the operation.
      #
      # @see #respond_with
      def respond_with!(*args)
        respond_with(*args)
        fail Halt
      end

      # Sets the status to respond with.
      #
      # You can achieve the same result by setting +context.status+ wherever you want in {#call}.
      #
      # Note that calling this method doesn't halt the execution of the operation and that this
      # method can be called multiple times, overriding the previous context.
      #
      # @param status [Integer|Symbol] an HTTP status code
      def head(status)
        context.status = status
      end

      # Same as {#head}, but also halts the execution of the operation.
      #
      # @param status [Integer|Symbol] an HTTP status code
      #
      # @see #head
      def head!(status)
        head status
        fail Halt
      end

      # Returns the current user.
      #
      # This is just a shortcut for +context.current_user+.
      #
      # @return [Object]
      def current_user
        context.current_user
      end

      # Returns the headers we are responding with.
      #
      # This is just a shortcut for +context.headers+.
      #
      # @return [Hash]
      def headers
        context.headers
      end

      # Returns the links we are responding with.
      #
      # This is just a shotcut for +context.links+.
      #
      # @return [Hash]
      def links
        context.links
      end

      private

      def with_hooks
        # This overrides the default behavior, which is not to run after hooks if an exception is
        # raised either in +#call+ or one of the before hooks. See:
        # https://github.com/collectiveidea/interactor/blob/master/lib/interactor/hooks.rb#L210)
        run_around_hooks do
          begin
            run_before_hooks
            yield
          ensure
            run_after_hooks
          end
        end
      end

      def setup_context
        context.params ||= {}
        context.headers = {}
        context.links = {}
      end

      def handle_halt(interactor)
        interactor.call
      rescue Halt # rubocop:disable Lint/HandleExceptions
      end

      def set_default_status
        return if context.status
        context.status = context.resource ? :ok : :no_content
      end

      def validate_status
        if context.status.is_a?(Integer)
          fail InvalidStatusError, context.status unless STATUSES.key?(context.status)
        else
          fail InvalidStatusError, context.status unless STATUSES.invert.key?(context.status.to_sym)
        end
      end

      def consolidate_status
        context.status = if context.status.is_a?(Integer)
          STATUSES[context.status]
        else
          context.status.to_sym
        end
      end

      def mark_result
        return if /\A(2|3)\d{2}\z/ =~ STATUSES.invert[context.status].to_s
        context.fail!
      end

      def build_links
        headers.delete('Link')

        link_header = context.links.each_pair.select do |relation, url|
          url && !url.empty?
        end.map do |relation, url|
          %(<#{url}>; rel="#{relation}")
        end.join(",\n  ")

        headers['Link'] = link_header unless link_header.empty?
      end
    end

    Halt = Class.new(StandardError)

    # This error is raised when an invalid status is set for an operation.
    #
    # @author Alessandro Desantis
    class InvalidStatusError < StandardError
      # Initializes the error.
      #
      # @param [Integer|Symbol] an invalid HTTP status code
      def initialize(status)
        super "'#{status}' is not a valid HTTP status code."
      end
    end
  end
end