#!/usr/bin/python

# Copyright: Ansible Project
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)

from __future__ import absolute_import, division, print_function
__metaclass__ = type


ANSIBLE_METADATA = {'metadata_version': '1.1',
                    'status': ['preview'],
                    'supported_by': 'community'}


DOCUMENTATION = '''
module: github_key
short_description: Manage GitHub access keys.
description:
    - Creates, removes, or updates GitHub access keys.
version_added: "2.2"
options:
  token:
    description:
      - GitHub Access Token with permission to list and create public keys.
    required: true
  name:
    description:
      - SSH key name
    required: true
  pubkey:
    description:
      - SSH public key value. Required when C(state=present).
  state:
    description:
      - Whether to remove a key, ensure that it exists, or update its value.
    choices: ['present', 'absent']
    default: 'present'
  force:
    description:
      - The default is C(yes), which will replace the existing remote key
        if it's different than C(pubkey). If C(no), the key will only be
        set if no key with the given C(name) exists.
    type: bool
    default: 'yes'

author: Robert Estelle (@erydo)
'''

RETURN = '''
deleted_keys:
    description: An array of key objects that were deleted. Only present on state=absent
    type: list
    returned: When state=absent
    sample: [{'id': 0, 'key': 'BASE64 encoded key', 'url': 'http://example.com/github key', 'created_at': 'YYYY-MM-DDTHH:MM:SZ', 'read_only': False}]
matching_keys:
    description: An array of keys matching the specified name. Only present on state=present
    type: list
    returned: When state=present
    sample: [{'id': 0, 'key': 'BASE64 encoded key', 'url': 'http://example.com/github key', 'created_at': 'YYYY-MM-DDTHH:MM:SZ', 'read_only': False}]
key:
    description: Metadata about the key just created. Only present on state=present
    type: dict
    returned: success
    sample: {'id': 0, 'key': 'BASE64 encoded key', 'url': 'http://example.com/github key', 'created_at': 'YYYY-MM-DDTHH:MM:SZ', 'read_only': False}
'''

EXAMPLES = '''
- name: Read SSH public key to authorize
  shell: cat /home/foo/.ssh/id_rsa.pub
  register: ssh_pub_key

- name: Authorize key with GitHub
  local_action:
    module: github_key
    name: Access Key for Some Machine
    token: '{{ github_access_token }}'
    pubkey: '{{ ssh_pub_key.stdout }}'
'''


import json
import re

from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.urls import fetch_url


API_BASE = 'https://api.github.com'


class GitHubResponse(object):
    def __init__(self, response, info):
        self.content = response.read()
        self.info = info

    def json(self):
        return json.loads(self.content)

    def links(self):
        links = {}
        if 'link' in self.info:
            link_header = self.info['link']
            matches = re.findall('<([^>]+)>; rel="([^"]+)"', link_header)
            for url, rel in matches:
                links[rel] = url
        return links


class GitHubSession(object):
    def __init__(self, module, token):
        self.module = module
        self.token = token

    def request(self, method, url, data=None):
        headers = {
            'Authorization': 'token %s' % self.token,
            'Content-Type': 'application/json',
            'Accept': 'application/vnd.github.v3+json',
        }
        response, info = fetch_url(
            self.module, url, method=method, data=data, headers=headers)
        if not (200 <= info['status'] < 400):
            self.module.fail_json(
                msg=(" failed to send request %s to %s: %s"
                     % (method, url, info['msg'])))
        return GitHubResponse(response, info)


def get_all_keys(session):
    url = API_BASE + '/user/keys'
    result = []
    while url:
        r = session.request('GET', url)
        result.extend(r.json())
        url = r.links().get('next')
    return result


def create_key(session, name, pubkey, check_mode):
    if check_mode:
        from datetime import datetime
        now = datetime.utcnow()
        return {
            'id': 0,
            'key': pubkey,
            'title': name,
            'url': 'http://example.com/CHECK_MODE_GITHUB_KEY',
            'created_at': datetime.strftime(now, '%Y-%m-%dT%H:%M:%SZ'),
            'read_only': False,
            'verified': False
        }
    else:
        return session.request(
            'POST',
            API_BASE + '/user/keys',
            data=json.dumps({'title': name, 'key': pubkey})).json()


def delete_keys(session, to_delete, check_mode):
    if check_mode:
        return

    for key in to_delete:
        session.request('DELETE', API_BASE + '/user/keys/%s' % key["id"])


def ensure_key_absent(session, name, check_mode):
    to_delete = [key for key in get_all_keys(session) if key['title'] == name]
    delete_keys(session, to_delete, check_mode=check_mode)

    return {'changed': bool(to_delete),
            'deleted_keys': to_delete}


def ensure_key_present(module, session, name, pubkey, force, check_mode):
    all_keys = get_all_keys(session)
    matching_keys = [k for k in all_keys if k['title'] == name]
    deleted_keys = []

    new_signature = pubkey.split(' ')[1]
    for key in all_keys:
        existing_signature = key['key'].split(' ')[1]
        if new_signature == existing_signature and key['title'] != name:
            module.fail_json(msg=(
                "another key with the same content is already registered "
                "under the name |{0}|").format(key['title']))

    if matching_keys and force and matching_keys[0]['key'].split(' ')[1] != new_signature:
        delete_keys(session, matching_keys, check_mode=check_mode)
        (deleted_keys, matching_keys) = (matching_keys, [])

    if not matching_keys:
        key = create_key(session, name, pubkey, check_mode=check_mode)
    else:
        key = matching_keys[0]

    return {
        'changed': bool(deleted_keys or not matching_keys),
        'deleted_keys': deleted_keys,
        'matching_keys': matching_keys,
        'key': key
    }


def main():
    argument_spec = {
        'token': {'required': True, 'no_log': True},
        'name': {'required': True},
        'pubkey': {},
        'state': {'choices': ['present', 'absent'], 'default': 'present'},
        'force': {'default': True, 'type': 'bool'},
    }
    module = AnsibleModule(
        argument_spec=argument_spec,
        supports_check_mode=True,
    )

    token = module.params['token']
    name = module.params['name']
    state = module.params['state']
    force = module.params['force']
    pubkey = module.params.get('pubkey')

    if pubkey:
        pubkey_parts = pubkey.split(' ')
        # Keys consist of a protocol, the key data, and an optional comment.
        if len(pubkey_parts) < 2:
            module.fail_json(msg='"pubkey" parameter has an invalid format')
    elif state == 'present':
        module.fail_json(msg='"pubkey" is required when state=present')

    session = GitHubSession(module, token)
    if state == 'present':
        result = ensure_key_present(module, session, name, pubkey, force=force,
                                    check_mode=module.check_mode)
    elif state == 'absent':
        result = ensure_key_absent(session, name, check_mode=module.check_mode)

    module.exit_json(**result)


if __name__ == '__main__':
    main()
