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

# acertmgr - acme api v2 functions (implements RFC8555)
# Copyright (c) Rudolf Mayerhofer, 2019.
# available under the ISC license, see LICENSE

import copy
import json
import re
import time

from acertmgr import tools
from acertmgr.authority.acme import ACMEAuthority as AbstractACMEAuthority
from acertmgr.tools import log

# Maximum age for nonce values (Boulder invalidates them after some time, so we use a low value of 2 minutes here)
MAX_NONCE_AGE = 120


class ACMEAuthority(AbstractACMEAuthority):
    # @brief Init class with config
    # @param config Configuration data
    # @param key Account key data
    def __init__(self, config, key):
        AbstractACMEAuthority.__init__(self, config, key)
        # Initialize config vars
        self.ca = config['authority']
        self.tos_agreed = str(config.get('authority_tos_agreement')).lower() == 'true'
        contact_email = config.get('authority_contact_email')
        if contact_email is None:
            self.contact = None
        elif isinstance(contact_email, list):
            self.contact = ["mailto:{}".format(contact) for contact in contact_email]
        else:
            self.contact = ["mailto:{}".format(contact_email)]

        # Initialize runtime vars
        code, self.directory, _ = self._request_url(self.ca + '/directory')
        if code >= 400 or not self.directory:
            self.directory = {
                "meta": {},
                "newAccount": "{}/acme/new-acct".format(self.ca),
                "newNonce": "{}/acme/new-nonce".format(self.ca),
                "newOrder": "{}/acme/new-order".format(self.ca),
                "revokeCert": "{}/acme/revoke-cert".format(self.ca),
            }
            log("API directory retrieval failed ({}). Guessed necessary values: {}".format(code, self.directory),
                warning=True)
        self.nonce = None
        self.nonce_time = 0

        self.algorithm, jwk = tools.get_key_alg_and_jwk(key)
        self.account_protected = {
            "alg": self.algorithm,
            "jwk": jwk
        }
        self.account_id = None  # will be updated to correct value during account registration

    # @brief fetch a given url
    def _request_url(self, url, data=None, raw_result=False):
        header = {'Content-Type': 'application/jose+json'}
        if data:
            # Always encode data to bytes
            data = data.encode('utf-8')
        try:
            resp = tools.get_url(url, data, header)
        except IOError as e:
            body = getattr(e, "read", e.__str__)()
            if getattr(body, 'decode', None):
                # Decode function available? Use it to get a proper str
                body = body.decode('utf-8')
            return getattr(e, "code", 999), body, {}

        # Store next Replay-Nonce if it is in the header
        if 'Replay-Nonce' in resp.headers:
            self.nonce = resp.headers['Replay-Nonce']
            self.nonce_time = time.time()

        body = resp.read()
        if getattr(body, 'decode', None):
            # Decode function available? Use it to get a proper str
            body = body.decode('utf-8')
        if not raw_result and len(body) > 0:
            try:
                body = json.loads(body)
            except json.JSONDecodeError as e:
                raise ValueError('Could not parse non-raw result (expected JSON)', e)

        return resp.getcode(), body, resp.headers

    # @brief fetch an url with a signed request
    def _request_acme_url(self, url, payload=None, protected=None, raw_result=False):
        if not protected:
            protected = {}

        if payload:
            payload64 = tools.bytes_to_base64url(json.dumps(payload).encode('utf8'))
        else:
            payload64 = ""  # for POST-as-GET

        # Request a new nonce if there is none in cache
        if not self.nonce or time.time() > self.nonce_time + MAX_NONCE_AGE:
            self._request_url(self.directory['newNonce'])
        # Set request nonce to current cache value
        protected["nonce"] = self.nonce
        # Reset nonce cache as we are using it's current value
        self.nonce = None

        protected["url"] = url
        if self.algorithm:
            protected["alg"] = self.algorithm
        if self.account_id:
            protected["kid"] = self.account_id
        protected64 = tools.bytes_to_base64url(json.dumps(protected).encode('utf8'))
        out = tools.signature_of_str(self.key, '.'.join([protected64, payload64]))
        data = json.dumps({
            "protected": protected64,
            "payload": payload64,
            "signature": tools.bytes_to_base64url(out),
        })
        return self._request_url(url, data, raw_result)

    # @brief send a signed request to authority
    def _request_acme_endpoint(self, request, payload=None, protected=None, raw_result=False):
        return self._request_acme_url(self.directory[request], payload, protected, raw_result)

    # @brief register an account over ACME
    def register_account(self):
        if self.account_id:
            # We already have registered with this authority, just return
            return

        protected = copy.deepcopy(self.account_protected)
        payload = {
            "termsOfServiceAgreed": self.tos_agreed,
            "onlyReturnExisting": False,
        }
        if self.contact:
            payload["contact"] = self.contact
        code, result, headers = self._request_acme_endpoint("newAccount", payload, protected)
        if code < 400 and result['status'] == 'valid':
            self.account_id = headers['Location']
            if 'meta' in self.directory and 'termsOfService' in self.directory['meta']:
                log("ToS at {} have been accepted.".format(self.directory['meta']['termsOfService']))
            log("Account registered and valid on {}.".format(self.ca))
        else:
            raise ValueError("Error registering account: {0} {1}".format(code, result))

    # @brief function to fetch certificate using ACME
    # @param csr the certificate signing request in pyopenssl format
    # @param domains list of domains in the certificate, first is CN
    # @param challenge_handlers a dict containing challenge for all given domains
    # @return the certificate and corresponding ca as a tuple
    # @note algorithm and parts of the code are from acme-tiny
    def get_crt_from_csr(self, csr, domains, challenge_handlers):
        account_thumbprint = tools.bytes_to_base64url(
            tools.hash_of_str(json.dumps(self.account_protected['jwk'], sort_keys=True, separators=(',', ':'))))

        log("Ordering certificate for {}".format(domains))
        identifiers = [{'type': 'dns', 'value': domain} for domain in domains]
        code, order, headers = self._request_acme_endpoint('newOrder', {'identifiers': identifiers})
        if code >= 400:
            raise ValueError("Error with certificate order: {0} {1}".format(code, order))

        order_url = headers['Location']
        authorizations = list()
        # verify each domain
        try:
            for authorizationUrl in order['authorizations']:
                # get new challenge
                code, authorization, _ = self._request_acme_url(authorizationUrl)
                if code >= 400:
                    raise ValueError("Error requesting authorization: {0} {1}".format(code, authorization))

                authorization['_domain'] = "*.{}".format(authorization['identifier']['value']) if \
                    'wildcard' in authorization and authorization['wildcard'] else authorization['identifier']['value']

                if authorization.get('status', 'no-status-found') == 'valid':
                    log("{} has already been authorized".format(authorization['_domain']))
                    continue
                if authorization['_domain'] not in challenge_handlers:
                    raise ValueError("No challenge handler given for domain: {0}".format(authorization['_domain']))
                log("Authorizing {0}".format(authorization['_domain']))

                # create the challenge
                ctype = challenge_handlers[authorization['_domain']].get_challenge_type()
                matching_challenges = [c for c in authorization['challenges'] if c['type'] == ctype]
                if len(matching_challenges) == 0:
                    raise ValueError("Error no challenge matching {0} found: {1}".format(ctype, authorization))

                authorization['_challenge'] = matching_challenges[0]
                if authorization['_challenge'].get('status', 'no-status-found') == 'valid':
                    log("{} has already been authorized using {}".format(authorization['_domain'], ctype))
                    continue

                authorization['_token'] = re.sub(r"[^A-Za-z0-9_\-]", "_", authorization['_challenge']['token'])
                challenge_handlers[authorization['_domain']].create_challenge(authorization['identifier']['value'],
                                                                              account_thumbprint,
                                                                              authorization['_token'])
                authorizations.append(authorization)

            # after all challenges are created, start processing authorizations
            for authorization in authorizations:
                try:
                    log("Starting verification of {}".format(authorization['_domain']))
                    challenge_handlers[authorization['_domain']].start_challenge(authorization['identifier']['value'],
                                                                                 account_thumbprint,
                                                                                 authorization['_token'])
                    # notify challenge is met
                    code, challenge_status, _ = self._request_acme_url(authorization['_challenge']['url'], {
                        "keyAuthorization": "{0}.{1}".format(authorization['_token'], account_thumbprint),
                    })
                    # wait for challenge to be verified
                    while code < 400 and challenge_status.get('status') == "pending":
                        time.sleep(5)
                        code, challenge_status, _ = self._request_acme_url(authorization['_challenge']['url'])

                    if code < 400 and challenge_status.get('status') == "valid":
                        log("{0} verified".format(authorization['_domain']))
                    else:
                        raise ValueError("{0} challenge did not pass ({1}): {2}".format(
                            authorization['_domain'], code, challenge_status))
                finally:
                    challenge_handlers[authorization['_domain']].stop_challenge(authorization['identifier']['value'],
                                                                                account_thumbprint,
                                                                                authorization['_token'])
        finally:
            # Destroy challenge handlers in reverse order to replay
            # any saved state information in the handlers correctly
            for authorization in reversed(authorizations):
                try:
                    challenge_handlers[authorization['_domain']].destroy_challenge(
                        authorization['identifier']['value'], account_thumbprint, authorization['_token'])
                except Exception as e:
                    log('Challenge destruction failed: {}'.format(e), error=True)

        # check order status and retry once
        code, order, _ = self._request_acme_url(order_url)
        if code < 400 and order.get('status') == 'pending':
            time.sleep(5)
            code, order, _ = self._request_acme_url(order_url)
        if code >= 400:
            raise ValueError("Order is still not ready to be finalized: {0} {1}".format(code, order))

        # get the new certificate
        log("Finalizing certificate")
        code, finalize, _ = self._request_acme_url(order['finalize'], {
            "csr": tools.bytes_to_base64url(tools.convert_cert_to_der_bytes(csr)),
        })
        while code < 400 and (finalize.get('status') == 'pending' or finalize.get('status') == 'processing'):
            time.sleep(5)
            code, finalize, _ = self._request_acme_url(order_url)
        if code >= 400:
            raise ValueError("Error finalizing certificate: {0} {1}".format(code, finalize))
        log("Certificate ready!")

        # return certificate
        code, certificate, _ = self._request_acme_url(finalize['certificate'], raw_result=True)
        if code >= 400:
            raise ValueError("Error downloading certificate chain: {0} {1}".format(code, certificate))

        cert_dict = re.match((r'(?P<cert>^-----BEGIN CERTIFICATE-----\n[^\-]+\n-----END CERTIFICATE-----)\n*'
                              r'(?P<ca>-----BEGIN CERTIFICATE-----\n.+\n-----END CERTIFICATE-----)?$'),
                             certificate, re.DOTALL).groupdict()
        cert = tools.convert_pem_str_to_cert(cert_dict['cert'])
        if cert_dict['ca'] is None:
            ca = tools.download_issuer_ca(cert)
        else:
            ca = tools.convert_pem_str_to_cert(cert_dict['ca'])

        return cert, ca

    # @brief function to revoke a certificate using ACME
    # @param crt certificate to revoke
    # @param reason (int) optional certificate revoke reason (see https://tools.ietf.org/html/rfc5280#section-5.3.1)
    def revoke_crt(self, crt, reason=None):
        payload = {'certificate': tools.bytes_to_base64url(tools.convert_cert_to_der_bytes(crt))}
        if reason:
            payload['reason'] = int(reason)
        code, result, _ = self._request_acme_endpoint("revokeCert", payload)
        if code < 400:
            log("Revocation successful")
        else:
            raise ValueError("Revocation failed: {}".format(result))