feat: Add bulk imports API for contacts (#1724)

app/jobs/data_import_job.rb

@@ -0,0 +1,46 @@
+# TODO: logic is written tailored to contact import since its the only import available
+# let's break this logic and clean this up in future
+
+class DataImportJob < ApplicationJob
+  queue_as :low
+
+  def perform(data_import)
+    contacts = []
+    data_import.update!(status: :processing)
+    csv = CSV.parse(data_import.import_file.download, headers: true)
+    csv.each { |row| contacts << build_contact(row.to_h.with_indifferent_access, data_import.account) }
+    result = Contact.import contacts, on_duplicate_key_update: :all, batch_size: 1000
+    data_import.update!(status: :completed, processed_records: csv.length - result.failed_instances.length, total_records: csv.length)
+  end
+
+  private
+
+  def build_contact(params, account)
+    # TODO: rather than doing the find or initialize individually lets fetch objects in bulk and update them in memory
+    contact = init_contact(params, account)
+
+    contact.name = params[:name] if params[:name].present?
+    contact.assign_attributes(custom_attributes: contact.custom_attributes.merge(params.except(:identifier, :email, :name)))
+
+    # since callbacks aren't triggered lets ensure a pubsub token
+    contact.pubsub_token ||= SecureRandom.base58(24)
+    contact
+  end
+
+  def get_identified_contacts(params, account)
+    identifier_contact = account.contacts.find_by(identifier: params[:identifier]) if params[:identifier]
+    email_contact = account.contacts.find_by(email: params[:email]) if params[:email]
+    [identifier_contact, email_contact]
+  end
+
+  def init_contact(params, account)
+    identifier_contact, email_contact = get_identified_contacts(params, account)
+
+    # intiating the new contact / contact attributes only by ensuring the identifier or email duplication errors won't occur
+    contact = identifier_contact
+    contact&.email = params[:email] if params[:email].present? && email_contact.blank?
+    contact ||= email_contact
+    contact ||= account.contacts.new(params.slice(:email, :identifier))
+    contact
+  end
+end