---
- name: Setup robot
  hosts: raspbot
  become: true

  vars:
    docker_users:
      - "{{ robot_user }}"

  pre_tasks:
    - name: Enable SPI via raspi-config
      command: raspi-config nonint do_spi 0
      changed_when: false

    # Real-time scheduling setup per
    # https://control.ros.org/kilted/doc/ros2_control/controller_manager/doc/userdoc.html#determinism
    - name: Create realtime group
      group:
        name: realtime
        state: present

    - name: Add robot user to realtime group
      user:
        name: "{{ robot_user }}"
        groups: realtime
        append: true

    - name: Configure real-time scheduling limits
      copy:
        dest: /etc/security/limits.d/99-realtime.conf
        content: |
          @realtime soft rtprio 99
          @realtime soft priority 99
          @realtime soft memlock unlimited
          @realtime hard rtprio 99
          @realtime hard priority 99
          @realtime hard memlock unlimited
        owner: root
        group: root
        mode: '0644'

    # - name: Install low-latency kernel for improved RT performance
    #   apt:
    #     name: linux-lowlatency
    #     state: present
    #     update_cache: true

    # I2C Fast Mode (400 kHz) reduces SSD1306 OLED frame transfers from ~95 ms
    # to ~24 ms, shrinking the window in which the kernel I2C adapter lock blocks
    # motor writes on the shared /dev/i2c-1 bus.
    - name: Set I2C bus speed to 400 kHz
      lineinfile:
        path: /boot/firmware/config.txt
        regexp: '^dtparam=i2c_arm_baudrate='
        line: 'dtparam=i2c_arm_baudrate=400000'
      notify: Reboot required

  handlers:
    - name: Reboot required
      debug:
        msg: "config.txt updated — reboot the Pi to apply I2C speed change"

  roles:
    - geerlingguy.docker