- name: get the default python version
  command: "{{ ansible_python_interpreter }} -V"
  register: default_python_version

- name: find the default python
  command: which python
  register: which_python

- name: find the default pip
  command: which pip
  register: which_pip

- name: preserve the default python
  command: cp -av "{{ which_python.stdout }}" "{{ which_python.stdout }}.default"

- name: preserve the default pip
  command: cp -av "{{ which_pip.stdout }}" "{{ which_pip.stdout }}.default"

# using the apt module prevents autoremove from working, so call apt-get via shell instead
- name: install mercurial (apt)
  shell: apt-get -y update && apt-get -y install mercurial
  when: ansible_pkg_mgr == 'apt'

- name: install mercurial (dnf)
  dnf:
    name: mercurial
  when: ansible_pkg_mgr == 'dnf'

- name: install mercurial (yum)
  yum:
    name: mercurial
  when: ansible_pkg_mgr == 'yum'

- name: install mercurial (pkgng)
  pkgng:
    name: mercurial
  when: ansible_pkg_mgr == 'pkgng'

- name: preserve the updated python
  command: cp -av "{{ which_python.stdout }}" "{{ which_python.stdout }}.updated"

- name: preserve the updated pip
  command: cp -av "{{ which_pip.stdout }}" "{{ which_pip.stdout }}.updated"

- name: locate mercurial
  command: which hg
  register: which_hg

- name: get the mercurial interpreter
  command: head -n 1 "{{ which_hg.stdout }}"
  register: hg_interpreter

- name: stat the mercurial interpreter
  stat:
    path: "{{ hg_interpreter.stdout[2:] }}"
  register: stat_hg_interpreter

- name: bypass the mercurial python interpreter symlink (if needed)
  lineinfile:
    path: "{{ which_hg.stdout }}"
    regexp: "^#!.*$"
    line: "#!{{ stat_hg_interpreter.stat.lnk_source }}"
  when: stat_hg_interpreter.stat.islnk

- name: restore the default python
  command: cp -av "{{ which_python.stdout }}.default" "{{ which_python.stdout }}"

- name: restore the default pip
  command: cp -av "{{ which_pip.stdout }}.default" "{{ which_pip.stdout }}"

- name: get the current python version
  command: "{{ ansible_python_interpreter }} -V"
  register: current_python_version

- name: verify the python version has not changed
  assert:
    that:
      - default_python_version.stdout == current_python_version.stdout