module BoxView
  class Session

    PATH = '/sessions'

    class << self

      attr_accessor :expiration_date, :duration, :retry_after, :is_downloadable

      # Description:
      # => The getter method for the duration that a session will last.
      # No Params!
      # Note:
      # => Raises an error if the duration is nil when retrieved.
      def duration
        raise BoxView::Errors::DurationNotFound if @duration.nil?
        @duration
      end

      # Description:
      # => The getter method for the expiration date that a session will last.
      # No Params!
      # Note:
      # => Raises an error if the expiration date is nil when retrieved.
      def expiration_date
        raise BoxView::Errors::ExpirationDateNotFound if @expiration_date.nil?
        @expiration_date
      end

      ### BEGIN Session HTTP Request ###

      # Description:
      # => Creates a session for viewing the HTML ready document
      # Note:
      # => No Required Params!
      # => params can be defined elsewhere.
      # => document id must be defined.
      def create(options = {})
        BoxView.document_id = options[:document_id] if options[:document_id]
        @duration = options[:duration] if options[:duration]
        @expiration_date = options[:expiration_date] if options[:expiration_date]
        @is_downloadable = options[:is_downloadable] if options[:is_downloadable]
        response = BoxView.post session_path, body: json_data, headers: BoxView.headers
        response_handler response
        return response
      end

      ### END Session HTTP Request ###

      # Description:
      # => A path that is used for all session related requests.
      # No Params!
      def session_path
        "#{BoxView::BASE_PATH}#{PATH}"
      end

      # Description:
      # => Convenience method to make the session last for a thousand years
      # No Params!
      def never_expire
        @expiration_date = Time.now + (365.25 * 24 * 60 * 60 * 1000).to_i
      end

      # Description:
      # => A convenience method to return the viewer url that can be used after generating a session.
      # Note:
      # => No Required Params!
      # => Defaults to using a generated session_id.
      def viewer_url(session_id = nil)
        unless session_id then session_id = BoxView.session_id end
        "#{BoxView.base_uri}#{session_path}/#{session_id}/view?theme=light"
      end

      # Description:
      # => A convenience method to return the asset url that is used in viewerjs.
      # Optional Params:
      # => session_id
      # Note:
      # => No Required Params!
      # => Defaults to using a generated session_id.
      def viewerjs_url(session_id = nil)
        unless session_id then session_id = BoxView.session_id end
        "#{BoxView.base_uri}#{session_path}/#{session_id}/assets"
      end

      # Description:
      # => Convenience method to open the viewer url in a default browser.
      # Optional Params:
      # => A url to open in a default browser.
      # Note:
      # => No Required Params!
      # => A session must have been generated in order for a url to be generated.
      def view(link = nil)
        unless link then link = viewer_url end
        if RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/
          system "start #{link}"
        elsif RbConfig::CONFIG['host_os'] =~ /darwin/
          system "open #{link}"
        elsif RbConfig::CONFIG['host_os'] =~ /linux|bsd/
          system "xdg-open #{link}"
        end
      end

      private

      # Description:
      # => Response handler for the create request of a session.
      # No Params!
      def response_handler(response)
        case response.code
        when 201 # Done converting
          parsed = JSON.parse response.body
          @session_id = parsed["id"]
          BoxView.session_id = @session_id
        when 202 # Session not ready yet
          @retry_after = response.headers['retry-after']
        when 400 # An error occurred while converting the document or the document does not exist
          raise BoxView::Errors::DocumentConversionFailed
        else
          raise BoxView::Errors::SessionNotGenerated
        end
      end

      # Description:
      # => The JSON data that is sent in the create request of a session.
      # No Params!
      def json_data # Does a duration or an expiration date need to exist?
        data = {}
        data[:document_id] = BoxView.document_id
        data[:is_downloadable] = is_downloadable if is_downloadable
        if !@duration.nil? && @expiration_date.nil? # duration
          data[:duration] = duration
        elsif @duration.nil? && !@expiration_date.nil? # expiration
          data[:expires_at] = expiration_date
        elsif !@duration.nil? && !@expiration_date.nil? # both, use expiration date
          data[:expires_at] = expiration_date
        else
          # Default will be used
        end
        return data.to_json
      end
    end
  end
end