---
- name: Validate platform and migration settings
  ansible.builtin.assert:
    that:
      - ansible_os_family == "Debian"
      - ansible_service_mgr == "systemd"
      - ssh_port | int > 0
      - ssh_port | int <= 65535
      - ssh_legacy_port | int > 0
      - ssh_legacy_port | int <= 65535
      - ansible_port | default(22) | int == ssh_port | int or (ssh_keep_legacy_port | bool and ansible_port | default(22) | int == ssh_legacy_port | int)
    fail_msg: >-
      The inventory connection port must be either the new SSH port or the
      legacy port while the legacy listener is intentionally retained.

- name: Install hardening packages
  ansible.builtin.apt:
    name:
      - fail2ban
      - ufw
      - unattended-upgrades
    state: present
    update_cache: true
    cache_valid_time: 3600

- name: Enable UFW IPv6 support
  ansible.builtin.lineinfile:
    path: /etc/default/ufw
    regexp: '^IPV6='
    line: 'IPV6=yes'
    backup: true

- name: Set UFW default inbound policy
  community.general.ufw:
    direction: incoming
    default: "{{ ufw_default_incoming }}"

- name: Set UFW default outbound policy
  community.general.ufw:
    direction: outgoing
    default: "{{ ufw_default_outgoing }}"

- name: Set UFW default routed policy
  community.general.ufw:
    direction: routed
    default: "{{ ufw_default_routed }}"

- name: Set UFW logging level
  community.general.ufw:
    logging: "{{ ufw_logging }}"

- name: Build the SSH ports that must remain allowed during this run
  ansible.builtin.set_fact:
    hardening_ssh_ports: >-
      {{ ([ssh_port | string] + ([ssh_legacy_port | string] if ssh_keep_legacy_port | bool else [])) | unique }}

- name: Allow configured SSH listener ports before enabling UFW
  community.general.ufw:
    rule: allow
    port: "{{ item }}"
    proto: tcp
  loop: "{{ hardening_ssh_ports }}"

- name: Allow additional inventory-declared service ports
  community.general.ufw:
    rule: allow
    port: "{{ item.port | string }}"
    proto: "{{ item.proto | default('tcp') }}"
    from_ip: "{{ item.from_ip | default('any') }}"
    comment: "{{ item.comment | default(omit) }}"
  loop: "{{ ufw_allowed_rules }}"
  loop_control:
    label: "{{ item.proto | default('tcp') }}/{{ item.port }}"

- name: Enable UFW after the SSH and service allow rules are installed
  community.general.ufw:
    state: enabled
  when: ufw_enabled | bool

- name: Remove the legacy SSH firewall rule after port cutover
  community.general.ufw:
    rule: allow
    port: "{{ ssh_legacy_port | string }}"
    proto: tcp
    delete: true
  when:
    - not (ssh_keep_legacy_port | bool)
    - ssh_legacy_port | string != ssh_port | string

- name: Remove explicitly retired inventory-declared UFW rules
  community.general.ufw:
    rule: allow
    port: "{{ item.port | string }}"
    proto: "{{ item.proto | default('tcp') }}"
    from_ip: "{{ item.from_ip | default('any') }}"
    delete: true
  loop: "{{ ufw_remove_rules }}"
  loop_control:
    label: "{{ item.proto | default('tcp') }}/{{ item.port }}"

- name: Install Fail2ban SSH jail configuration
  ansible.builtin.copy:
    dest: /etc/fail2ban/jail.d/10-ansible-sshd.local
    owner: root
    group: root
    mode: "0644"
    content: |
      [DEFAULT]
      banaction = ufw
      ignoreip = 127.0.0.1/8 ::1 {{ fail2ban_ignore_ips | join(' ') }}

      [sshd]
      enabled = true
      backend = systemd
      port = {{ hardening_ssh_ports | join(',') }}
      maxretry = {{ fail2ban_ssh_maxretry }}
      findtime = {{ fail2ban_ssh_findtime }}
      bantime = {{ fail2ban_ssh_bantime }}
  notify: Restart fail2ban

- name: Enable and start Fail2ban
  ansible.builtin.service:
    name: fail2ban
    enabled: true
    state: started

- name: Detect active systemd SSH socket
  ansible.builtin.command: systemctl is-active --quiet ssh.socket
  register: hardening_ssh_socket
  changed_when: false
  failed_when: false

- name: Detect active systemd SSH service
  ansible.builtin.command: systemctl is-active --quiet ssh.service
  register: hardening_ssh_service
  changed_when: false
  failed_when: false

- name: Ensure the SSH socket override directory exists
  ansible.builtin.file:
    path: /etc/systemd/system/ssh.socket.d
    state: directory
    owner: root
    group: root
    mode: "0755"
  when: hardening_ssh_socket.rc == 0

- name: Set SSH socket listener ports when socket activation is active
  ansible.builtin.copy:
    dest: /etc/systemd/system/ssh.socket.d/zz-ansible-ports.conf
    owner: root
    group: root
    mode: "0644"
    content: |
      [Socket]
      ListenStream=
      {% for port in hardening_ssh_ports %}
      ListenStream={{ port }}
      {% endfor %}
  when: hardening_ssh_socket.rc == 0
  notify: Apply SSH changes

- name: Install SSH hardening drop-in
  ansible.builtin.copy:
    dest: /etc/ssh/sshd_config.d/00-ansible-hardening.conf
    owner: root
    group: root
    mode: "0644"
    content: |
      Port {{ ssh_port }}
      {% if ssh_keep_legacy_port | bool and ssh_legacy_port | int != ssh_port | int %}Port {{ ssh_legacy_port }}
      {% endif %}PermitRootLogin no
      PubkeyAuthentication yes
      PasswordAuthentication {{ 'yes' if ssh_password_authentication | bool else 'no' }}
      KbdInteractiveAuthentication {{ 'yes' if ssh_kbd_interactive_authentication | bool else 'no' }}
      PermitEmptyPasswords no
      MaxAuthTries {{ ssh_max_auth_tries }}
      LoginGraceTime {{ ssh_login_grace_time }}
      X11Forwarding no
    validate: /usr/sbin/sshd -t -f %s
    backup: true
  notify: Apply SSH changes

- name: Apply pending service configuration changes
  ansible.builtin.meta: flush_handlers

- name: Read effective SSH configuration
  ansible.builtin.command: /usr/sbin/sshd -T
  register: effective_sshd
  changed_when: false

- name: Verify effective SSH hardening and listener ports
  ansible.builtin.assert:
    that:
      - "'permitrootlogin no' in effective_sshd.stdout_lines"
      - "'passwordauthentication ' + ('yes' if ssh_password_authentication | bool else 'no') in effective_sshd.stdout_lines"
      - "'pubkeyauthentication yes' in effective_sshd.stdout_lines"
      - "'port ' + (ssh_port | string) in effective_sshd.stdout_lines"
      - ssh_port | int == ssh_legacy_port | int or (ssh_keep_legacy_port | bool) == (('port ' + (ssh_legacy_port | string)) in effective_sshd.stdout_lines)

- name: Wait for the new SSH listener locally on the host
  ansible.builtin.wait_for:
    host: 127.0.0.1
    port: "{{ ssh_port }}"
    state: started
    timeout: 30

- name: Confirm the legacy SSH listener is closed after cutover
  ansible.builtin.wait_for:
    host: 127.0.0.1
    port: "{{ ssh_legacy_port }}"
    state: stopped
    timeout: 10
  when:
    - not (ssh_keep_legacy_port | bool)
    - ssh_legacy_port | int != ssh_port | int

- name: Confirm Fail2ban has the SSH jail active
  ansible.builtin.command: fail2ban-client status sshd
  register: fail2ban_sshd_status
  changed_when: false
  failed_when: fail2ban_sshd_status.rc != 0