chore: Whatsapp templates fix for 360 dialog (#3479)

Fixes: #3426

app/services/whatsapp/send_on_whatsapp_service.rb

@@ -6,6 +6,71 @@ class Whatsapp::SendOnWhatsappService < Base::SendOnChannelService
   end
 
   def perform_reply
-    channel.send_message(message.conversation.contact_inbox.source_id, message)
+    # can reply checks if 24 hour limit has passed.
+    if message.conversation.can_reply?
+      send_on_whatsapp
+    else
+      send_template_message
+    end
+  end
+
+  def send_template_message
+    name, namespace, lang_code, processed_parameters = processable_channel_message_template
+    return if name.blank?
+
+    message_id = channel.send_template(message.conversation.contact_inbox.source_id, {
+                                         name: name,
+                                         namespace: namespace,
+                                         lang_code: lang_code,
+                                         parameters: processed_parameters
+                                       })
+    message.update!(source_id: message_id) if message_id.present?
+  end
+
+  def processable_channel_message_template
+    # see if we can match the message content to a template
+    # An example template may look like "Your package has been shipped. It will be delivered in {{1}} business days.
+    # We want to iterate over these templates with our message body and see if we can fit it to any of the templates
+    # Then we use regex to parse the template varibles and convert them into the proper payload
+    channel.message_templates.each do |template|
+      match_obj = template_match_object(template)
+      next if match_obj.blank?
+
+      # we have a match, now we need to parse the template variables and convert them into the wa recommended format
+      processed_parameters = match_obj.captures.map { |x| { type: 'text', text: x } }
+
+      # no need to look up further end the search
+      return [template['name'], template['namespace'], template['language'], processed_parameters]
+    end
+    [nil, nil, nil, nil]
+  end
+
+  def template_match_object(template)
+    body_object = validated_body_object(template)
+    return if body_object.blank?
+
+    template_match_regex = build_template_match_regex(body_object['text'])
+    message.content.match(template_match_regex)
+  end
+
+  def build_template_match_regex(template_text)
+    # Converts the whatsapp template to a comparable regex string to check against the message content
+    # the variables are of the format {{num}} ex:{{1}}
+    template_match_string = "^#{template_text.gsub(/{{\d}}/, '(.*)')}$"
+    Regexp.new template_match_string
+  end
+
+  def validated_body_object(template)
+    # we don't care if its not approved template
+    return if template['status'] != 'approved'
+
+    # we only care about text body object in template. if not present we discard the template
+    # we don't support other forms of templates
+    template['components'].find { |obj| obj['type'] == 'BODY' && obj.key?('text') }
+  end
+
+  def send_on_whatsapp
+    message_id = channel.send_message(message.conversation.contact_inbox.source_id, message)
+    message.update!(source_id: message_id) if message_id.present?
   end
 end