---
- name: Preflight checks
  block:
    - name: Collecting all nebula_internal_ip_addr values
      set_fact:
        sorted_ips: >-
          {{ hostvars
             | dict2items
             | selectattr('value.nebula_internal_ip_addr', 'defined')
             | map(attribute='value.nebula_internal_ip_addr')
             | list
             | sort
          }}

    - name: Initialize duplicated_ips list
      set_fact:
        duplicated_ips: []

    - name: Looking for duplicate IP addresses
      set_fact:
        duplicated_ips: "{{ duplicated_ips + [item] }}"
      loop: "{{ sorted_ips | unique }}"
      when: "sorted_ips | select('equalto', item) | list | length > 1"

    - name: Fail if duplicate IP addresses are found
      fail:
        msg: "You have one or more hosts with duplicate IP addresses assigned: {{ duplicated_ips }}"
      when: duplicated_ips | length > 0
  run_once: true