#!/usr/bin/python
# -*- coding: utf-8 -*-

# Copyright (c) 2019, George Rawlinson <george@rawlinson.net.nz>
# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
# SPDX-License-Identifier: GPL-3.0-or-later

from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

DOCUMENTATION = r"""
module: pacman_key
author:
  - George Rawlinson (@grawlinson)
version_added: "3.2.0"
short_description: Manage pacman's list of trusted keys
description:
  - Add or remove gpg keys from the pacman keyring.
notes:
  - Use full-length key ID (40 characters).
  - Keys will be verified when using O(data), O(file), or O(url) unless O(verify) is overridden.
  - Keys will be locally signed after being imported into the keyring.
  - If the key ID exists in the keyring, the key will not be added unless O(force_update) is specified.
  - O(data), O(file), O(url), and O(keyserver) are mutually exclusive.
requirements:
  - gpg
  - pacman-key
extends_documentation_fragment:
  - community.general.attributes
attributes:
  check_mode:
    support: full
  diff_mode:
    support: none
options:
  id:
    description:
      - The 40 character identifier of the key.
      - Including this allows check mode to correctly report the changed state.
      - Do not specify a subkey ID, instead specify the primary key ID.
    required: true
    type: str
  data:
    description:
      - The keyfile contents to add to the keyring.
      - Must be of C(PGP PUBLIC KEY BLOCK) type.
    type: str
  file:
    description:
      - The path to a keyfile on the remote server to add to the keyring.
      - Remote file must be of C(PGP PUBLIC KEY BLOCK) type.
    type: path
  url:
    description:
      - The URL to retrieve keyfile from.
      - Remote file must be of C(PGP PUBLIC KEY BLOCK) type.
    type: str
  keyserver:
    description:
      - The keyserver used to retrieve key from.
    type: str
  verify:
    description:
      - Whether or not to verify the keyfile's key ID against specified key ID.
    type: bool
    default: true
  force_update:
    description:
      - This forces the key to be updated if it already exists in the keyring.
    type: bool
    default: false
  keyring:
    description:
      - The full path to the keyring folder on the remote server.
      - If not specified, module will use pacman's default (V(/etc/pacman.d/gnupg)).
      - Useful if the remote system requires an alternative gnupg directory.
    type: path
    default: /etc/pacman.d/gnupg
  state:
    description:
      - Ensures that the key is present (added), trusted (signed and not expired) or absent (revoked).
    default: present
    choices: [absent, present, trusted]
    type: str
"""

EXAMPLES = r"""
- name: Import a key via local file
  community.general.pacman_key:
    id: 01234567890ABCDE01234567890ABCDE12345678
    data: "{{ lookup('file', 'keyfile.asc') }}"
    state: present

- name: Import a key via remote file
  community.general.pacman_key:
    id: 01234567890ABCDE01234567890ABCDE12345678
    file: /tmp/keyfile.asc
    state: present

- name: Import a key via url
  community.general.pacman_key:
    id: 01234567890ABCDE01234567890ABCDE12345678
    url: https://domain.tld/keys/keyfile.asc
    state: present

- name: Import a key via keyserver
  community.general.pacman_key:
    id: 01234567890ABCDE01234567890ABCDE12345678
    keyserver: keyserver.domain.tld

- name: Import a key into an alternative keyring
  community.general.pacman_key:
    id: 01234567890ABCDE01234567890ABCDE12345678
    file: /tmp/keyfile.asc
    keyring: /etc/pacman.d/gnupg-alternative

- name: Remove a key from the keyring
  community.general.pacman_key:
    id: 01234567890ABCDE01234567890ABCDE12345678
    state: absent
"""

RETURN = r""" # """

import os.path
import tempfile
from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.urls import fetch_url
from ansible.module_utils.common.text.converters import to_native


class GpgListResult(object):
    """Wraps gpg --list-* output."""

    def __init__(self, line):
        self._parts = line.split(':')

    @property
    def kind(self):
        return self._parts[0]

    @property
    def valid(self):
        return self._parts[1]

    @property
    def is_fully_valid(self):
        return self.valid == 'f'

    @property
    def key(self):
        return self._parts[4]

    @property
    def user_id(self):
        return self._parts[9]


def gpg_get_first(lines, kind, attr):
    for line in lines:
        glr = GpgListResult(line)
        if glr.kind == kind:
            return getattr(glr, attr)


def gpg_gather_all(lines, kind, attr):
    result = []
    for line in lines:
        glr = GpgListResult(line)
        if glr.kind == kind:
            result.append(getattr(glr, attr))
    return result


class PacmanKey(object):
    def __init__(self, module):
        self.module = module
        # obtain binary paths for gpg & pacman-key
        self.gpg_binary = module.get_bin_path('gpg', required=True)
        self.pacman_key_binary = module.get_bin_path('pacman-key', required=True)

        # obtain module parameters
        keyid = module.params['id']
        url = module.params['url']
        data = module.params['data']
        file = module.params['file']
        keyserver = module.params['keyserver']
        verify = module.params['verify']
        force_update = module.params['force_update']
        keyring = module.params['keyring']
        state = module.params['state']
        self.keylength = 40

        # sanitise key ID & check if key exists in the keyring
        keyid = self.sanitise_keyid(keyid)
        key_validity = self.key_validity(keyring, keyid)
        key_present = len(key_validity) > 0
        key_valid = any(key_validity)

        # check mode
        if module.check_mode:
            if state in ['present', 'trusted']:
                changed = (key_present and force_update) or not key_present
                if not changed and state == 'trusted':
                    changed = not (key_valid and self.key_is_trusted(keyring, keyid))
                module.exit_json(changed=changed)
            if state == 'absent':
                module.exit_json(changed=key_present)

        if state in ['present', 'trusted']:
            trusted = key_valid and self.key_is_trusted(keyring, keyid)
            if not force_update:
                if (state == 'present' and key_present) or (state == 'trusted' and trusted):
                    module.exit_json(changed=False)
            changed = False
            if data:
                file = self.save_key(data)
                self.add_key(keyring, file, keyid, verify)
                changed = True
            elif file:
                self.add_key(keyring, file, keyid, verify)
                changed = True
            elif url:
                data = self.fetch_key(url)
                file = self.save_key(data)
                self.add_key(keyring, file, keyid, verify)
                changed = True
            elif keyserver:
                self.recv_key(keyring, keyid, keyserver)
                changed = True
            if changed or (state == 'trusted' and not trusted):
                self.lsign_key(keyring=keyring, keyid=keyid)
                changed = True
            module.exit_json(changed=changed)
        elif state == 'absent':
            if key_present:
                self.remove_key(keyring, keyid)
                module.exit_json(changed=True)
            module.exit_json(changed=False)

    def gpg(self, args, keyring=None, **kwargs):
        cmd = [self.gpg_binary]
        if keyring:
            cmd.append(f'--homedir={keyring}')
        cmd.extend(['--no-permission-warning', '--with-colons', '--quiet', '--batch', '--no-tty'])
        return self.module.run_command(cmd + args, **kwargs)

    def pacman_key(self, args, keyring, **kwargs):
        return self.module.run_command(
            [self.pacman_key_binary, '--gpgdir', keyring] + args,
            **kwargs,
        )

    def pacman_machine_key(self, keyring):
        unused_rc, stdout, unused_stderr = self.gpg(['--list-secret-key'], keyring=keyring)
        return gpg_get_first(stdout.splitlines(), 'sec', 'key')

    def is_hexadecimal(self, string):
        """Check if a given string is valid hexadecimal"""
        try:
            int(string, 16)
        except ValueError:
            return False
        return True

    def sanitise_keyid(self, keyid):
        """Sanitise given key ID.

        Strips whitespace, uppercases all characters, and strips leading `0X`.
        """
        sanitised_keyid = keyid.strip().upper().replace(' ', '').replace('0X', '')
        if len(sanitised_keyid) != self.keylength:
            self.module.fail_json(msg="key ID is not full-length: %s" % sanitised_keyid)
        if not self.is_hexadecimal(sanitised_keyid):
            self.module.fail_json(msg="key ID is not hexadecimal: %s" % sanitised_keyid)
        return sanitised_keyid

    def fetch_key(self, url):
        """Downloads a key from url"""
        response, info = fetch_url(self.module, url)
        if info['status'] != 200:
            self.module.fail_json(msg="failed to fetch key at %s, error was %s" % (url, info['msg']))
        return to_native(response.read())

    def recv_key(self, keyring, keyid, keyserver):
        """Receives key via keyserver"""
        self.pacman_key(['--keyserver', keyserver, '--recv-keys', keyid], keyring=keyring, check_rc=True)

    def lsign_key(self, keyring, keyid):
        """Locally sign key"""
        self.pacman_key(['--lsign-key', keyid], keyring=keyring, check_rc=True)

    def save_key(self, data):
        "Saves key data to a temporary file"
        tmpfd, tmpname = tempfile.mkstemp()
        self.module.add_cleanup_file(tmpname)
        tmpfile = os.fdopen(tmpfd, "w")
        tmpfile.write(data)
        tmpfile.close()
        return tmpname

    def add_key(self, keyring, keyfile, keyid, verify):
        """Add key to pacman's keyring"""
        if verify:
            self.verify_keyfile(keyfile, keyid)
        self.pacman_key(['--add', keyfile], keyring=keyring, check_rc=True)

    def remove_key(self, keyring, keyid):
        """Remove key from pacman's keyring"""
        self.pacman_key(['--delete', keyid], keyring=keyring, check_rc=True)

    def verify_keyfile(self, keyfile, keyid):
        """Verify that keyfile matches the specified key ID"""
        if keyfile is None:
            self.module.fail_json(msg="expected a key, got none")
        elif keyid is None:
            self.module.fail_json(msg="expected a key ID, got none")

        rc, stdout, stderr = self.gpg(
            ['--with-fingerprint', '--show-keys', keyfile],
            check_rc=True,
        )

        extracted_keyid = gpg_get_first(stdout.splitlines(), 'fpr', 'user_id')
        if extracted_keyid != keyid:
            self.module.fail_json(msg="key ID does not match. expected %s, got %s" % (keyid, extracted_keyid))

    def key_validity(self, keyring, keyid):
        "Check if the key ID is in pacman's keyring and not expired"
        rc, stdout, stderr = self.gpg(['--no-default-keyring', '--list-keys', keyid], keyring=keyring, check_rc=False)
        if rc != 0:
            if stderr.find("No public key") >= 0:
                return []
            else:
                self.module.fail_json(msg="gpg returned an error: %s" % stderr)
        return gpg_gather_all(stdout.splitlines(), 'uid', 'is_fully_valid')

    def key_is_trusted(self, keyring, keyid):
        """Check if key is signed and not expired."""
        unused_rc, stdout, unused_stderr = self.gpg(['--check-signatures', keyid], keyring=keyring)
        return self.pacman_machine_key(keyring) in gpg_gather_all(stdout.splitlines(), 'sig', 'key')


def main():
    module = AnsibleModule(
        argument_spec=dict(
            id=dict(type='str', required=True),
            data=dict(type='str'),
            file=dict(type='path'),
            url=dict(type='str'),
            keyserver=dict(type='str'),
            verify=dict(type='bool', default=True),
            force_update=dict(type='bool', default=False),
            keyring=dict(type='path', default='/etc/pacman.d/gnupg'),
            state=dict(
                type='str',
                default='present',
                choices=['absent', 'present', 'trusted'],
            ),
        ),
        supports_check_mode=True,
        mutually_exclusive=(('data', 'file', 'url', 'keyserver'),),
        required_if=[('state', 'present', ('data', 'file', 'url', 'keyserver'), True)],
    )
    PacmanKey(module)


if __name__ == '__main__':
    main()