Fix sending File objects in nested objects in sendMediaGroup

lib/telegram/bot/client/request_body_formatter.rb

@@ -0,0 +1,48 @@
+require 'json'
+
+module Telegram
+  module Bot
+    class Client
+      # Encodes nested hashes and arrays as json and extract File objects from them
+      # to the top level. Top-level File objects are handled by httpclient.
+      # More details: https://core.telegram.org/bots/api#sending-files
+      module RequestBodyFormatter
+        extend self
+
+        def format(body, action)
+          body = body.dup
+          if action.to_s == 'sendMediaGroup'
+            body = extract_files_from_array!(body, :media)
+          end
+          body.each do |key, val|
+            body[key] = val.to_json if val.is_a?(Hash) || val.is_a?(Array)
+          end
+        end
+
+        private
+
+        def extract_files_from_array!(body, field_name)
+          field_name = [field_name.to_sym, field_name.to_s].find { |x| body.key?(x) }
+          return body unless field_name && body[field_name].is_a?(Array)
+          files = {}
+          body[field_name] = body[field_name].map { |x| extract_files_from_hash(x, files) }
+          body.merge!(files)
+        end
+
+        # Replace File objects with `attach` URIs. File objects are added into `files` hash.
+        def extract_files_from_hash(hash, files)
+          return hash unless hash.is_a?(Hash)
+          hash.transform_values do |value|
+            if value.is_a?(File)
+              arg_name = "_file#{files.size}"
+              files[arg_name] = value
+              "attach://#{arg_name}"
+            else
+              value
+            end
+          end
+        end
+      end
+    end
+  end
+end