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

# (c) 2016, Yanis Guenane <yanis+ansible@guenane.org>
# 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: openssl_publickey
author: "Yanis Guenane (@Spredzy)"
version_added: "2.3"
short_description: Generate an OpenSSL public key from its private key.
description:
    - "This module allows one to (re)generate OpenSSL public keys from their private keys.
       It uses the pyOpenSSL python library to interact with openssl. Keys are generated
       in PEM format. This module works only if the version of PyOpenSSL is recent enough (> 16.0.0)."
requirements:
    - "python-pyOpenSSL"
options:
    state:
        required: false
        default: "present"
        choices: [ present, absent ]
        description:
            - Whether the public key should exist or not, taking action if the state is different from what is stated.
    force:
        required: false
        default: False
        choices: [ True, False ]
        description:
            - Should the key be regenerated even it it already exists
    format:
        required: false
        default: PEM
        choices: [ PEM, OpenSSH ]
        description:
            - The format of the public key.
        version_added: "2.4"
    path:
        required: true
        description:
            - Name of the file in which the generated TLS/SSL public key will be written.
    privatekey_path:
        required: true
        description:
            - Path to the TLS/SSL private key from which to generate the public key.
    privatekey_passphrase:
        required: false
        description:
            - The passphrase for the privatekey.
        version_added: "2.4"
extends_documentation_fragment: files
'''

EXAMPLES = '''
# Generate an OpenSSL public key in PEM format.
- openssl_publickey:
    path: /etc/ssl/public/ansible.com.pem
    privatekey_path: /etc/ssl/private/ansible.com.pem

# Generate an OpenSSL public key in OpenSSH v2 format.
- openssl_publickey:
    path: /etc/ssl/public/ansible.com.pem
    privatekey_path: /etc/ssl/private/ansible.com.pem
    format: OpenSSH

# Generate an OpenSSL public key with a passphrase protected
# private key
- openssl_publickey:
    path: /etc/ssl/public/ansible.com.pem
    privatekey_path: /etc/ssl/private/ansible.com.pem
    privatekey_passphrase: ansible

# Force regenerate an OpenSSL public key if it already exists
- openssl_publickey:
    path: /etc/ssl/public/ansible.com.pem
    privatekey_path: /etc/ssl/private/ansible.com.pem
    force: True

# Remove an OpenSSL public key
- openssl_publickey:
    path: /etc/ssl/public/ansible.com.pem
    privatekey_path: /etc/ssl/private/ansible.com.pem
    state: absent
'''

RETURN = '''
privatekey:
    description: Path to the TLS/SSL private key the public key was generated from
    returned: changed or success
    type: string
    sample: /etc/ssl/private/ansible.com.pem
format:
    description: The format of the public key (PEM, OpenSSH, ...)
    returned: changed or success
    type: string
    sample: PEM
filename:
    description: Path to the generated TLS/SSL public key file
    returned: changed or success
    type: string
    sample: /etc/ssl/public/ansible.com.pem
fingerprint:
    description: The fingerprint of the public key. Fingerprint will be generated for each hashlib.algorithms available.
                 Requires PyOpenSSL >= 16.0 for meaningful output.
    returned: changed or success
    type: dict
    sample:
      md5: "84:75:71:72:8d:04:b5:6c:4d:37:6d:66:83:f5:4c:29"
      sha1: "51:cc:7c:68:5d:eb:41:43:88:7e:1a:ae:c7:f8:24:72:ee:71:f6:10"
      sha224: "b1:19:a6:6c:14:ac:33:1d:ed:18:50:d3:06:5c:b2:32:91:f1:f1:52:8c:cb:d5:75:e9:f5:9b:46"
      sha256: "41:ab:c7:cb:d5:5f:30:60:46:99:ac:d4:00:70:cf:a1:76:4f:24:5d:10:24:57:5d:51:6e:09:97:df:2f:de:c7"
      sha384: "85:39:50:4e:de:d9:19:33:40:70:ae:10:ab:59:24:19:51:c3:a2:e4:0b:1c:b1:6e:dd:b3:0c:d9:9e:6a:46:af:da:18:f8:ef:ae:2e:c0:9a:75:2c:9b:b3:0f:3a:5f:3d"
      sha512: "fd:ed:5e:39:48:5f:9f:fe:7f:25:06:3f:79:08:cd:ee:a5:e7:b3:3d:13:82:87:1f:84:e1:f5:c7:28:77:53:94:86:56:38:69:f0:d9:35:22:01:1e:a6:60:...:0f:9b"
'''

import hashlib
import os

try:
    from OpenSSL import crypto
    from cryptography.hazmat.backends import default_backend
    from cryptography.hazmat.primitives import serialization as crypto_serialization
except ImportError:
    pyopenssl_found = False
else:
    pyopenssl_found = True

from ansible.module_utils import crypto as crypto_utils
from ansible.module_utils._text import to_native
from ansible.module_utils.basic import AnsibleModule


class PublicKeyError(crypto_utils.OpenSSLObjectError):
    pass


class PublicKey(crypto_utils.OpenSSLObject):

    def __init__(self, module):
        super(PublicKey, self).__init__(
            module.params['path'],
            module.params['state'],
            module.params['force'],
            module.check_mode
        )
        self.format = module.params['format']
        self.privatekey_path = module.params['privatekey_path']
        self.privatekey_passphrase = module.params['privatekey_passphrase']
        self.privatekey = None
        self.fingerprint = {}

    def generate(self, module):
        """Generate the public key."""

        if not os.path.exists(self.privatekey_path):
            raise PublicKeyError(
                'The private key %s does not exist' % self.privatekey_path
            )

        if not self.check(module, perms_required=False) or self.force:
            try:
                if self.format == 'OpenSSH':
                    privatekey_content = open(self.privatekey_path, 'rb').read()
                    key = crypto_serialization.load_pem_private_key(privatekey_content,
                                                                    password=self.privatekey_passphrase,
                                                                    backend=default_backend())
                    publickey_content = key.public_key().public_bytes(
                        crypto_serialization.Encoding.OpenSSH,
                        crypto_serialization.PublicFormat.OpenSSH
                    )
                else:
                    self.privatekey = crypto_utils.load_privatekey(
                        self.privatekey_path, self.privatekey_passphrase
                    )
                    publickey_content = crypto.dump_publickey(crypto.FILETYPE_PEM, self.privatekey)

                with open(self.path, 'wb') as publickey_file:
                    publickey_file.write(publickey_content)

                self.changed = True
            except (IOError, OSError) as exc:
                raise PublicKeyError(exc)
            except AttributeError as exc:
                self.remove()
                raise PublicKeyError('You need to have PyOpenSSL>=16.0.0 to generate public keys')

        self.fingerprint = crypto_utils.get_fingerprint(
            self.privatekey_path,
            self.privatekey_passphrase
        )
        file_args = module.load_file_common_arguments(module.params)
        if module.set_fs_attributes_if_different(file_args, False):
            self.changed = True

    def check(self, module, perms_required=True):
        """Ensure the resource is in its desired state."""

        state_and_perms = super(PublicKey, self).check(module, perms_required)

        def _check_privatekey():
            if not os.path.exists(self.privatekey_path):
                return False

            try:
                publickey_content = open(self.path, 'rb').read()
                if self.format == 'OpenSSH':
                    current_publickey = crypto_serialization.load_ssh_public_key(publickey_content, backend=default_backend())
                    publickey_content = current_publickey.public_bytes(crypto_serialization.Encoding.PEM,
                                                                       crypto_serialization.PublicFormat.SubjectPublicKeyInfo)
                current_publickey = crypto.dump_publickey(
                    crypto.FILETYPE_ASN1,
                    crypto.load_publickey(crypto.FILETYPE_PEM, publickey_content)
                )
            except (crypto.Error, ValueError):
                return False

            desired_publickey = crypto.dump_publickey(
                crypto.FILETYPE_ASN1,
                crypto_utils.load_privatekey(self.privatekey_path, self.privatekey_passphrase)
            )

            return current_publickey == desired_publickey

        if not state_and_perms:
            return state_and_perms

        return _check_privatekey()

    def dump(self):
        """Serialize the object into a dictionary."""

        result = {
            'privatekey': self.privatekey_path,
            'filename': self.path,
            'format': self.format,
            'changed': self.changed,
            'fingerprint': self.fingerprint,
        }

        return result


def main():

    module = AnsibleModule(
        argument_spec=dict(
            state=dict(default='present', choices=['present', 'absent'], type='str'),
            force=dict(default=False, type='bool'),
            path=dict(required=True, type='path'),
            privatekey_path=dict(type='path'),
            format=dict(type='str', choices=['PEM', 'OpenSSH'], default='PEM'),
            privatekey_passphrase=dict(type='path', no_log=True),
        ),
        supports_check_mode=True,
        add_file_common_args=True,
        required_if=[('state', 'present', ['privatekey_path'])]
    )

    if not pyopenssl_found:
        module.fail_json(msg='the python pyOpenSSL module is required')

    base_dir = os.path.dirname(module.params['path'])
    if not os.path.isdir(base_dir):
        module.fail_json(
            name=base_dir,
            msg='The directory %s does not exist or the file is not a directory' % base_dir
        )

    public_key = PublicKey(module)

    if public_key.state == 'present':

        if module.check_mode:
            result = public_key.dump()
            result['changed'] = module.params['force'] or not public_key.check(module)
            module.exit_json(**result)

        try:
            public_key.generate(module)
        except PublicKeyError as exc:
            module.fail_json(msg=to_native(exc))
    else:

        if module.check_mode:
            result = public_key.dump()
            result['changed'] = os.path.exists(module.params['path'])
            module.exit_json(**result)

        try:
            public_key.remove()
        except PublicKeyError as exc:
            module.fail_json(msg=to_native(exc))

    result = public_key.dump()

    module.exit_json(**result)


if __name__ == '__main__':
    main()
