Add resource framework: Base, CRUD mixins, and shared drafts/attachments/payments concerns

lib/fiken/resources/concerns/attachments.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require "faraday/multipart"
+
+module Fiken
+  module Resources
+    module Concerns
+      # /<parent>/attachments — list (where supported) and multipart upload.
+      class Attachments < Resource::Base
+        def initialize(client, company_slug, parent_path, listable: true)
+          super(client, company_slug)
+          @parent_path = parent_path
+          @listable = listable
+        end
+
+        def base_path
+          "#{@parent_path}/attachments"
+        end
+
+        def list
+          raise Error, "this resource does not support listing attachments" unless @listable
+
+          get_collection(base_path, {})
+        end
+
+        # Upload a file. Provide either path: (a filename on disk) or io: + filename:.
+        # Extra Fiken fields (e.g. comment:, attachToPayment:) are passed as form fields.
+        def add(path: nil, io: nil, filename: nil, content_type: "application/octet-stream", **fields)
+          parts = { "file" => build_file_part(path, io, filename, content_type) }
+          fields.each { |key, value| parts[key.to_s] = value.to_s unless value.nil? }
+          build_created(connection.post_multipart(base_path, parts))
+        end
+      end
+    end
+  end
+end