---
- name: Rollback impress to a previous version
  hosts: webserver
  become: yes
  become_user: impress
  vars:
    remote_project_root: "/srv/impress"
    ruby_version: "3.3.7"
  tasks:
    - name: Read the second-to-most-recent version
      command:
        chdir: "{{ remote_project_root }}/versions"
        cmd: bash -c 'ls | tail -n 2 | head -n 1'
      register: new_app_version

    - name: Print out the new version name
      debug:
        msg: "Rolling back to version: {{ new_app_version.stdout }}"

    - name: Save new remote folder path to a variable
      set_fact:
        remote_app_root: "{{ remote_project_root }}/versions/{{ new_app_version.stdout }}"

    - name: Configure Bundler to run in deployment mode
      command:
        chdir: "{{ remote_app_root }}"
        cmd: /opt/ruby-{{ ruby_version }}/bin/bundle config set --local deployment true

    # This ensures that, while attempting our current deploy, we don't
    # accidentally delete gems out from under the currently-running version.
    # NOTE: From reading the docs, I thiink this is the default behavior, but
    # I can't be sure? Rather than deep-dive to find out, I'd rather just set
    # it, to be clear about the default(?) behavior we're depending on.
    - name: Configure Bundler to *not* clean up old gems when installing
      command:
        chdir: "{{ remote_app_root }}"
        cmd: /opt/ruby-{{ ruby_version }}/bin/bundle config set --local clean false

    # NOTE: Bundler recommends this, and they're pretty smart about it: if the
    # Gemfile changes, this shouldn't disrupt the currently-running version,
    # because we won't clean up its now-unused gems yet, and if we upgrade a
    # gem it'll install *both* versions of the gem until we clean up.
    - name: Configure Bundler to use the bundle folder shared by all app versions
      command:
        chdir: "{{ remote_app_root }}"
        cmd: "/opt/ruby-{{ ruby_version }}/bin/bundle config set --local path {{ remote_project_root}}/shared/bundle"

    - name: Run `bundle install` to install dependencies in remote folder
      command:
        chdir: "{{ remote_app_root }}"
        # The `--local` flag instructs Bundler to use the cached dependencies
        # in `vendor/cache`, instead of reading from the web, which is much
        # faster and more reliable!
        cmd: /opt/ruby-{{ ruby_version }}/bin/bundle install --local

    - name: Update the `current` folder to point to the new version
      file:
        src: "{{ remote_app_root }}"
        dest: /srv/impress/current
        state: link

    # NOTE: This uses the passwordless sudo rule we set up in deploy:setup.
    # We write it as a command rather than using the built-in `systemd` Ansible
    # module, to make sure we're invoking it exactly as we wrote in that rule.
    #
    # NOTE: We use `sudo` instead of `become_user: root`, because we don't have
    # permission to *become* the root user; we only have permission to run this
    # one command as them.
    - name: Restart the app
      become: no
      command: sudo systemctl restart impress