Restructure omni services and add Chatwoot research snapshot

research/chatwoot/app/services/telegram/send_attachments_service.rb

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+require 'faraday/multipart'
+
+# Telegram Attachment APIs: ref: https://core.telegram.org/bots/api#inputfile
+
+# Media attachments like photos, videos can be clubbed together and sent as a media group
+# Audio can be clubbed together and send as a media group, but can't be mixed with other types
+# Documents are sent individually
+
+# We are using `HTTP URL` to send media attachments, telegram will directly download the media from the URL and send it to the user.
+# But for documents, we need to send the file as a multipart request. as telegram only support pdf and zip for the download from the URL option.
+
+# ref: `In sendDocument, sending by URL will currently only work for GIF, PDF and ZIP files.`
+# ref: `https://core.telegram.org/bots/api#senddocument`
+# ref: `https://core.telegram.org/bots/api#sendmediaGroup
+
+# The service will terminate if any of the attachment requests fail when the message has multiple attachments
+# We will create multiple messages in telegram if the message has multiple attachments (if its documents or mixed media).
+class Telegram::SendAttachmentsService
+  pattr_initialize [:message!]
+
+  def perform
+    attachment_message_id = nil
+
+    group_attachments_by_type.each do |type, attachments|
+      attachment_message_id = process_attachments_by_type(type, attachments)
+      break if attachment_message_id.nil?
+    end
+
+    attachment_message_id
+  end
+
+  private
+
+  def process_attachments_by_type(type, attachments)
+    response = send_attachments(type, attachments)
+    return extract_attachment_message_id(response) if handle_response(response)
+
+    nil
+  end
+
+  def send_attachments(type, attachments)
+    if [:media, :audio].include?(type)
+      media_group_request(channel.chat_id(message), attachments, channel.reply_to_message_id(message))
+    else
+      send_individual_attachments(attachments)
+    end
+  end
+
+  def group_attachments_by_type
+    attachments_by_type = { media: [], audio: [], document: [] }
+
+    message.attachments.each do |attachment|
+      type = attachment_type(attachment[:file_type])
+      attachment_data = { type: type, media: attachment.download_url, attachment: attachment }
+      case type
+      when 'document'
+        attachments_by_type[:document] << attachment_data
+      when 'audio'
+        attachments_by_type[:audio] << attachment_data
+      when 'photo', 'video'
+        attachments_by_type[:media] << attachment_data
+      end
+    end
+
+    attachments_by_type.reject { |_, v| v.empty? }
+  end
+
+  def attachment_type(file_type)
+    { 'audio' => 'audio', 'image' => 'photo', 'file' => 'document', 'video' => 'video' }[file_type] || 'document'
+  end
+
+  def media_group_request(chat_id, attachments, reply_to_message_id)
+    HTTParty.post("#{channel.telegram_api_url}/sendMediaGroup",
+                  body: {
+                    chat_id: chat_id,
+                    **business_connection_body,
+                    media: attachments.map { |hash| hash.except(:attachment) }.to_json,
+                    reply_to_message_id: reply_to_message_id
+                  })
+  end
+
+  def send_individual_attachments(attachments)
+    response = nil
+    attachments.map do |attachment|
+      response = document_request(channel.chat_id(message), attachment, channel.reply_to_message_id(message))
+      break unless handle_response(response)
+    end
+    response
+  end
+
+  def document_request(chat_id, attachment, reply_to_message_id)
+    temp_file_path = save_attachment_to_tempfile(attachment[:attachment])
+    response = send_file(chat_id, temp_file_path, reply_to_message_id)
+    File.delete(temp_file_path)
+    response
+  end
+
+  # Telegram picks up the file name from original field name, so we need to save the file with the original name.
+  # Hence not using Tempfile here.
+  def save_attachment_to_tempfile(attachment)
+    temp_dir = Rails.root.join('tmp/uploads', "telegram-#{attachment.message_id}")
+    FileUtils.mkdir_p(temp_dir)
+    temp_file_path = File.join(temp_dir, attachment.file.filename.to_s)
+
+    File.open(temp_file_path, 'wb') do |file|
+      attachment.file.blob.open do |blob_file|
+        IO.copy_stream(blob_file, file)
+      end
+    end
+
+    temp_file_path
+  end
+
+  def send_file(chat_id, file_path, reply_to_message_id)
+    File.open(file_path, 'rb') do |file|
+      file_name = File.basename(file_path)
+      mime_type = Marcel::MimeType.for(name: file_name) || 'application/octet-stream'
+
+      payload = { chat_id: chat_id, document: Faraday::Multipart::FilePart.new(file, mime_type, file_name) }
+      payload[:reply_to_message_id] = reply_to_message_id if reply_to_message_id
+      payload.merge!(business_connection_body)
+
+      response = multipart_post_connection.post("#{channel.telegram_api_url}/sendDocument", payload)
+      parse_faraday_response(response)
+    end
+  end
+
+  def multipart_post_connection
+    @multipart_post_connection ||= Faraday.new do |f|
+      f.request :multipart
+      f.options.timeout = 300
+      f.options.open_timeout = 60
+    end
+  end
+
+  def parse_faraday_response(response)
+    parsed = JSON.parse(response.body)
+    OpenStruct.new(success?: response.success?, parsed_response: parsed)
+  rescue JSON::ParserError
+    OpenStruct.new(success?: false, parsed_response: { 'ok' => false, 'error_code' => response.status, 'description' => response.reason_phrase })
+  end
+
+  def handle_response(response)
+    return true if response.success?
+
+    Rails.logger.error "Message Id: #{message.id}  - Error sending attachment to telegram:  #{response.parsed_response}"
+    channel.process_error(message, response)
+    false
+  end
+
+  def extract_attachment_message_id(response)
+    return unless response.success?
+
+    result = response.parsed_response['result']
+    # response will be an array if the request for media group
+    # response will be a hash if the request for document
+    result.is_a?(Array) ? result.first['message_id'] : result['message_id']
+  end
+
+  def channel
+    @channel ||= message.inbox.channel
+  end
+
+  def business_connection_id
+    @business_connection_id ||= channel.business_connection_id(message)
+  end
+
+  def business_connection_body
+    body = {}
+    body[:business_connection_id] = business_connection_id if business_connection_id
+    body
+  end
+end