---
# Copyright (c) 2025 Gravitino LLC
# MIT License

- name: Detect distribution type
  ansible.builtin.set_fact:
    is_ubuntu: "{{ ansible_distribution == 'Ubuntu' }}"
    is_debian: "{{ ansible_distribution == 'Debian' }}"
    is_rocky: "{{ ansible_distribution == 'Rocky' }}"
    is_redhat: "{{ ansible_os_family == 'RedHat' }}"
    ubuntu_version: "{{ ansible_distribution_version if ansible_distribution == 'Ubuntu' else '' }}"
    debian_version: "{{ ansible_distribution_major_version if ansible_distribution == 'Debian' else '' }}"
  tags:
    - openssh
    - facts

- name: Display Ubuntu ESM notice for older LTS versions
  ansible.builtin.debug:
    msg:
      - "WARNING: Ubuntu {{ ubuntu_version }} is in Extended Security Maintenance (ESM)."
      - "Consider upgrading to a newer LTS or enabling Ubuntu Pro for continued security updates."
      - "ESM support for {{ ubuntu_version }} ends in {{ '2026' if ubuntu_version == '16.04' else '2028' }}."
  when:
    - is_ubuntu
    - ubuntu_version in ['16.04', '18.04']
  tags:
    - openssh
    - security

- name: Display Ubuntu non-LTS short lifecycle notice
  ansible.builtin.debug:
    msg:
      - "INFO: Ubuntu {{ ubuntu_version }} is a non-LTS release with a 9-month support window."
      - "This release will reach end-of-life and stop receiving security updates."
      - "For production use, we recommend upgrading to the latest Ubuntu LTS release."
  when:
    - is_ubuntu
    - ubuntu_version in ['24.10', '25.04', '25.10']
  tags:
    - openssh
    - security

- name: Display Debian EOL warning for old-old-stable
  ansible.builtin.debug:
    msg:
      - "WARNING: Debian {{ debian_version }} ({{ ansible_distribution_release }}) may be past EOL or in LTS."
      - "OpenSSH {{ openssh_version | default('unknown') }} has limited modern security features."
      - "Consider upgrading to Debian Bullseye (11) or newer for better security."
  when:
    - is_debian
    - debian_version | int < 11
  tags:
    - openssh
    - security

- name: Install OpenSSH server (Debian/Ubuntu)
  ansible.builtin.apt:
    name: openssh-server
    state: "{{ openssh_server_state }}"
    update_cache: true
    cache_valid_time: 3600
  become: true
  when: is_debian or is_ubuntu
  tags:
    - openssh
    - packages

- name: Install OpenSSH server (RedHat/Rocky)
  ansible.builtin.dnf:
    name: openssh-server
    state: "{{ openssh_server_state }}"
    update_cache: true
  become: true
  when: is_redhat
  tags:
    - openssh
    - packages

- name: Generate SSH host keys (RedHat/Rocky/Fedora)
  ansible.builtin.command: ssh-keygen -A
  when: is_redhat
  changed_when: false
  become: true
  tags:
    - openssh
    - init

- name: Detect OpenSSH version
  ansible.builtin.command: ssh -V
  register: openssh_version_output
  changed_when: false
  failed_when: false
  tags:
    - openssh
    - facts

- name: Parse OpenSSH version number
  ansible.builtin.set_fact:
    openssh_version_string: "{{ openssh_version_output.stderr | regex_search('OpenSSH_([0-9]+\\.[0-9]+)', '\\1') | first }}"
  when: openssh_version_output.rc == 0
  tags:
    - openssh
    - facts

- name: Set OpenSSH version as float for comparison
  ansible.builtin.set_fact:
    openssh_version: "{{ openssh_version_string | float }}"
  when: openssh_version_string is defined
  tags:
    - openssh
    - facts

- name: Set OpenSSH capability flags
  ansible.builtin.set_fact:
    # Core capabilities for backwards compatibility
    openssh_has_disable_forwarding: "{{ openssh_version is defined and openssh_version is version('7.4', '>=') }}"
    openssh_has_ca_signature_algorithms: "{{ openssh_version is defined and openssh_version is version('7.9', '>=') }}"
    openssh_has_fido2: "{{ openssh_version is defined and openssh_version is version('8.2', '>=') }}"
    openssh_has_include: "{{ openssh_version is defined and openssh_version is version('8.2', '>=') }}"
    openssh_has_log_verbose: "{{ openssh_version is defined and openssh_version is version('8.5', '>=') }}"
    openssh_has_required_rsa_size: "{{ openssh_version is defined and openssh_version is version('9.3', '>=') }}"
    openssh_has_persourcepenalties: "{{ openssh_version is defined and openssh_version is version('9.8', '>=') }}"
    openssh_has_mlkem: "{{ openssh_version is defined and openssh_version is version('9.9', '>=') }}"
    # Algorithm support flags
    openssh_has_rsa_sha2: "{{ openssh_version is defined and openssh_version is version('7.2', '>=') }}"
    openssh_has_modern_kex: "{{ openssh_version is defined and openssh_version is version('7.4', '>=') }}"
    # Security restriction flags
    openssh_blocks_dsa_ca: "{{ openssh_version is defined and openssh_version is version('7.9', '>=') }}"
    openssh_removes_dsa: "{{ openssh_version is defined and openssh_version is version('9.6', '>=') }}"
    openssh_dh_disabled_default: "{{ openssh_version is defined and openssh_version is version('10.0', '>=') }}"
  tags:
    - openssh
    - facts

- name: Filter unsupported algorithms for older OpenSSH versions
  ansible.builtin.set_fact:
    openssh_host_key_algorithms: "{{ openssh_host_key_algorithms | reject('match', '^sk-') | list }}"
    openssh_pubkey_accepted_key_types: "{{ openssh_pubkey_accepted_key_types | reject('match', '^sk-') | list }}"
    openssh_ca_signature_algorithms: "{{ openssh_ca_signature_algorithms | reject('match', '^sk-') | list }}"
  when:
    - openssh_version is defined
    - openssh_version is version('8.2', '<')
  tags:
    - openssh
    - facts

- name: Display OpenSSH version and capabilities
  ansible.builtin.debug:
    msg:
      - "OpenSSH version: {{ openssh_version | default('unknown') }}"
      - "Distribution: {{ ansible_distribution }} {{ ansible_distribution_version }}"
      - "Core capabilities:"
      - "  - DisableForwarding: {{ openssh_has_disable_forwarding | default(false) }}"
      - "  - CASignatureAlgorithms: {{ openssh_has_ca_signature_algorithms | default(false) }}"
      - "  - FIDO2 support: {{ openssh_has_fido2 | default(false) }}"
      - "  - Include directive: {{ openssh_has_include | default(false) }}"
      - "Advanced capabilities:"
      - "  - LogVerbose: {{ openssh_has_log_verbose | default(false) }}"
      - "  - RequiredRSASize: {{ openssh_has_required_rsa_size | default(false) }}"
      - "  - PerSourcePenalties: {{ openssh_has_persourcepenalties | default(false) }}"
      - "  - ML-KEM (Post-Quantum): {{ openssh_has_mlkem | default(false) }}"
  when: openssh_version is defined
  tags:
    - openssh
    - facts

- name: Verify moduli file has strong DH groups (3072-bit minimum)
  ansible.builtin.shell: |
    set -o pipefail
    awk '$5 >= 3071' /etc/ssh/moduli > /etc/ssh/moduli.tmp
    if [ -s /etc/ssh/moduli.tmp ]; then
      mv /etc/ssh/moduli.tmp /etc/ssh/moduli
    else
      rm -f /etc/ssh/moduli.tmp
    fi
  args:
    executable: /bin/bash
  become: true
  when: openssh_verify_moduli | default(true)
  changed_when: false
  tags:
    - openssh
    - security
    - hardening

- name: Validate host key strengths
  ansible.builtin.shell: |
    set -o pipefail
    for key in {{ openssh_host_keys | join(' ') }}; do
      if [ -f "${key}" ]; then
        if [[ "${key}" == *rsa* ]]; then
          bits=$(ssh-keygen -lf "${key}" | awk '{print $1}')
          if [ "${bits}" -lt 3072 ]; then
            echo "WARNING: ${key} is only ${bits} bits (minimum 3072 recommended)"
          fi
        fi
      fi
    done
  args:
    executable: /bin/bash
  become: true
  register: hostkey_validation
  changed_when: false
  failed_when: false
  tags:
    - openssh
    - security
    - validation

- name: Display host key validation results
  ansible.builtin.debug:
    msg: "{{ hostkey_validation.stdout_lines }}"
  when:
    - hostkey_validation.stdout_lines is defined
    - hostkey_validation.stdout_lines | length > 0
  tags:
    - openssh
    - security

- name: Configure OpenSSH server
  ansible.builtin.template:
    src: sshd_config.j2
    dest: /etc/ssh/sshd_config
    owner: root
    group: root
    mode: "0644"
    validate: /usr/sbin/sshd -t -f %s
    backup: true
  become: true
  notify: restart openssh
  tags:
    - openssh
    - configuration

- name: Ensure SSH directory exists for root
  ansible.builtin.file:
    path: /root/.ssh
    state: directory
    owner: root
    group: root
    mode: "0700"
  become: true
  when: openssh_permit_root_login != "no"
  tags:
    - openssh
    - security

- name: Enable and start OpenSSH service
  ansible.builtin.systemd:
    name: "{{ 'sshd' if is_redhat else 'ssh' }}"
    enabled: "{{ openssh_service_enabled }}"
    state: "{{ openssh_service_state }}"
    daemon_reload: true
  become: true
  tags:
    - openssh
    - service