feat: Support sending and receiving attachments in Slack Integration (#3022)

- Process incoming slack attachments
- Send attachments from chatwoot to slack

lib/integrations/slack/incoming_message_builder.rb

@@ -79,7 +79,7 @@ class Integrations::Slack::IncomingMessageBuilder
   def create_message
     return unless conversation
 
-    conversation.messages.create(
+    @message = conversation.messages.create(
       message_type: :outgoing,
       account_id: conversation.account_id,
       inbox_id: conversation.inbox_id,
@@ -89,10 +89,46 @@ class Integrations::Slack::IncomingMessageBuilder
       sender: sender
     )
 
+    process_attachments(params[:event][:files]) if params[:event][:files].present?
+
     { status: 'success' }
   end
 
   def slack_client
     @slack_client ||= Slack::Web::Client.new(token: @integration_hook.access_token)
   end
+
+  # TODO: move process attachment for facebook instagram and slack in one place
+  # https://api.slack.com/messaging/files
+  def process_attachments(attachments)
+    attachments.each do |attachment|
+      tempfile = Down::NetHttp.download(attachment[:url_private], headers: { 'Authorization' => "Bearer #{integration_hook.access_token}" })
+
+      attachment_params = {
+        file_type: file_type(attachment),
+        account_id: @message.account_id,
+        external_url: attachment[:url_private],
+        file: {
+          io: tempfile,
+          filename: tempfile.original_filename,
+          content_type: tempfile.content_type
+        }
+      }
+
+      attachment_obj = @message.attachments.new(attachment_params)
+      attachment_obj.file.content_type = attachment[:mimetype]
+      attachment_obj.save!
+    end
+  end
+
+  def file_type(attachment)
+    return if attachment[:mimetype] == 'text/plain'
+
+    case attachment[:filetype]
+    when 'png', 'jpeg', 'gif', 'bmp', 'tiff', 'jpg'
+      :image
+    when 'pdf'
+      :file
+    end
+  end
 end