---
- name: Validate target_node variable
  hosts: localhost
  gather_facts: false

  tasks:
    - name: Require target_node
      ansible.builtin.fail:
        msg: "Use: ansible-playbook decommission-slurm-node.yml -e target_node=<hostname> [-e decom_reason='reason']"
      when: target_node is not defined

    - name: Ensure target_node is in inventory
      ansible.builtin.fail:
        msg: "target_node={{ target_node }} is not in Ansible inventory"
      when: target_node not in groups['all']


- name: Drain target node and wait for jobs to leave
  hosts: slurm_controller
  become: true
  gather_facts: false

  vars:
    decom_reason_effective: "{{ decom_reason | default('decommission by Ansible') }}"
    decom_wait_retries_effective: "{{ decom_wait_retries | default(120) }}"
    decom_wait_delay_effective: "{{ decom_wait_delay | default(10) }}"

  tasks:
    - name: Show current target node state
      ansible.builtin.shell: |
        set -euo pipefail
        sinfo -N -n {{ target_node }} || true
        scontrol show node {{ target_node }} || true
      args:
        executable: /bin/bash
      register: node_state_before
      changed_when: false

    - name: Print current target node state
      ansible.builtin.debug:
        var: node_state_before.stdout_lines

    - name: Drain target node
      ansible.builtin.command:
        cmd: scontrol update NodeName={{ target_node }} State=DRAIN Reason="{{ decom_reason_effective }}"
      changed_when: true

    - name: Wait until no jobs are running on target node
      ansible.builtin.shell: |
        set -euo pipefail
        squeue -h -w {{ target_node }} || true
      args:
        executable: /bin/bash
      register: jobs_on_node
      retries: "{{ decom_wait_retries_effective | int }}"
      delay: "{{ decom_wait_delay_effective | int }}"
      until: jobs_on_node.stdout | trim == ""
      changed_when: false

    - name: Show drained node state
      ansible.builtin.shell: |
        set -euo pipefail
        sinfo -N -n {{ target_node }} || true
        scontrol show node {{ target_node }} | grep -E "NodeName=|State=|Reason=" || true
      args:
        executable: /bin/bash
      register: node_state_drained
      changed_when: false

    - name: Print drained node state
      ansible.builtin.debug:
        var: node_state_drained.stdout_lines


- name: Stop Slurm worker service on target node
  hosts: "{{ target_node }}"
  become: true
  gather_facts: false

  tasks:
    - name: Stop slurmd
      ansible.builtin.systemd:
        name: slurmd
        state: stopped
        enabled: false
      when:
        - inventory_hostname in groups.get('slurm_compute', []) or inventory_hostname in groups.get('slurm_gpu', [])

    - name: Show slurmd state
      ansible.builtin.shell: |
        systemctl is-enabled slurmd 2>/dev/null || true
        systemctl is-active slurmd 2>/dev/null || true
      args:
        executable: /bin/bash
      register: slurmd_state_after
      changed_when: false

    - name: Print slurmd state
      ansible.builtin.debug:
        var: slurmd_state_after.stdout_lines


- name: Mark node down in Slurm controller
  hosts: slurm_controller
  become: true
  gather_facts: false

  tasks:
    - name: Mark target node DOWN after service stop
      ansible.builtin.command:
        cmd: scontrol update NodeName={{ target_node }} State=DOWN Reason="decommissioned"
      changed_when: true

    - name: Show final node state
      ansible.builtin.shell: |
        set -euo pipefail
        sinfo -N -n {{ target_node }} || true
        scontrol show node {{ target_node }} | grep -E "NodeName=|State=|Reason=" || true
      args:
        executable: /bin/bash
      register: final_node_state
      changed_when: false

    - name: Print final node state
      ansible.builtin.debug:
        var: final_node_state.stdout_lines