#!/usr/bin/python

PIP = None
VIRTUALENV = None
ENV = None


def _get_full_name(name, version=None):
    return name if version is None else name + '==' + version


def _find_pip():
    paths = ['/usr/local/bin', '/usr/bin']

    if ENV:
        paths = [os.path.join(ENV, 'bin')] + paths

    for p in paths:
        pe = p + '/pip'
        if os.path.exists(pe):
            return pe

    module.fail_json(msg='pip is not installed')


def _find_virtualenv():
    paths = ['/usr/local/bin', '/usr/bin']

    for p in paths:
        ve = p + '/virtualenv'
        if os.path.exists(ve):
            return ve

    module.fail_json(msg='virtualenv is not installed')


def _ensure_virtualenv():
    if os.path.exists(os.path.join(ENV, 'bin', 'activate')):
        return 0, '', ''
    else:
        return _run('%s %s' % (VIRTUALENV, ENV))


def _is_package_installed(name, version=None):
    rc, status_stdout, status_stderr = _run('%s freeze' % PIP)
    return _get_full_name(name, version).lower() in status_stdout.lower()


def _run(cmd):
    # returns (rc, stdout, stderr) from shell command
    process = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE, shell=True)
    stdout, stderr = process.communicate()
    return (process.returncode, stdout, stderr)


def main():
    arg_spec = dict(
        state=dict(default='present', choices=['absent', 'present', 'latest']),
        name=dict(default=None, required=False),
        version=dict(default=None, required=False),
        requirements=dict(default=None, required=False),
        virtualenv=dict(default=None, required=False)
    )

    module = AnsibleModule(argument_spec=arg_spec)

    global PIP
    global VIRTUALENV
    global ENV

    rc = 0
    err = ''
    out = ''

    ENV = module.params['virtualenv']
    PIP = _find_pip()

    if ENV:
        VIRTUALENV = _find_virtualenv()

        rc_venv, out_venv, err_venv = _ensure_virtualenv()

        rc += rc_venv
        out += out_venv
        err += err_venv

    state = module.params['state']
    name = module.params['name']
    version = module.params['version']
    requirements = module.params['requirements']
    command_map = dict(present='install', absent='uninstall', latest='install')

    if state == 'latest' and version is not None:
        module.fail_json(msg='If `state` is set to `latest` the `version` '
                             'paramater must not be specified.')

    if state == 'latest' and requirements is not None:
        module.fail_json(msg='If `state` is set to `latest` the `requirements` '
                             'paramater must not be specified.')

    if name is not None and '==' in name:
        module.fail_json(msg='It looks like you specified the version number '
                             'in the library name. Use the `version` parameter '
                             'to specify versio instead')

    if version is not None and name is None:
        module.fail_json(msg='The `version` parameter must be used with the '
                             '`name` parameter and not with the `requirements` '
                             'paramter')

    if name is None and requirements is None:
        module.fail_json(msg='You must specify a python library name via '
                             'the `name` parameter or a requirements file via '
                             'the `requirements` paramter')

    if name and requirements:
        module.fail_json(msg='Both `name` and `requirements` were specified. '
                             'Specify only the python library name via the '
                             '`name` parameter or a requirements file via the '
                             '`requirements` parameter')

    cmd = None
    installed = None

    if requirements:
        cmd = '%s %s -r %s --use-mirrors' % (PIP, command_map[state], requirements)
        rc_pip, out_pip, err_pip = _run(cmd)

        rc += rc_pip
        out += out_pip
        err += err_pip

        def did_install(out):
            return 'Successfully installed' in out

        changed = ((did_install(out) and state == 'present') or
                   (not did_install(out) and state == 'absent'))

    if name and state == 'latest':
        cmd = '%s %s %s --upgrade' % (PIP, command_map[state], name)

        rc_pip, out_pip, err_pip = _run(cmd)

        rc += rc_pip
        out += out_pip
        err += err_pip

        changed = 'Successfully installed' in out_pip

    elif name:
        installed = _is_package_installed(name, version)

        changed = ((installed and state == 'absent') or
                   (not installed and state == 'present'))

        if changed:
            full_name = _get_full_name(name, version) if state == 'present' else name

            cmd = '%s %s %s' % (PIP, command_map[state], full_name)

            if state == 'absent':
                cmd = cmd + ' -y'
            else:
                cmd = cmd + ' --use-mirrors'

            rc_pip, out_pip, err_pip = _run(cmd)

            rc += rc_pip
            out += out_pip
            err += err_pip

    if rc != 0:
        module.fail_json(msg=err, cmd=cmd)

    module.exit_json(changed=changed, cmd=cmd, name=name, version=version,
                     state=state, requirements=requirements, virtualenv=ENV)

# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>

main()