#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# Copyright (c) 2016, CESNET, z. s. p. o.
# Use of this source is governed by an ISC license, see LICENSE file.

import sys
import os
import string
import random
import struct
import argparse
import subprocess
import json
import logging
# *ph* server vulnerable to logjam, local openssl too new, use hammer to disable Diffie-Helmann
import ssl
ssl._DEFAULT_CIPHERS += ":!DH"

import ejbcaws

# usual path to warden server
sys.path.append(os.path.join(os.path.dirname(__file__), "..", "..", "warden_server"))
from warden_server import Request, ObjectReq, StreamLogger, FileLogger, Server, expose


class EjbcaClient(object):

    def __init__(self, registry, ejbca_data=None):
        self.registry = registry
        self.ejbca_data = ejbca_data or {}

    @property
    def admins(self):
        return [u if not u.startswith("RFC822NAME") else u[11:] for u in self.ejbca_data["subjectAltName"].split(",")]

    @admins.setter
    def admins(self, emails):
        self.ejbca_data["subjectAltName"] = ",".join(("RFC822NAME=%s" % e for e in emails))

    @property
    def name(self):
        username = self.ejbca_data["username"]
        if not username.endswith(self.registry.username_suffix):
            raise ValueError(("Ejbca user username does not conform to config", self.ejbca_data))
        return username[:-len(self.registry.username_suffix)]

    @name.setter
    def name(self, new):
        self.ejbca_data["username"] = new + self.registry.username_suffix
        self.ejbca_data["subjectDN"] = self.registry.subjectDN_template % new

    @property
    def status(self):
        s = self.ejbca_data["status"]
        if s == ejbcaws.STATUS_NEW:
            return "Issuable"
        elif s == ejbcaws.STATUS_GENERATED:
            return "Passive"
        elif s == ejbcaws.STATUS_INITIALIZED:
            return "New"
        else:
            return "EJBCA status %d" % s

    def get_certs(self):
        return self.registry.ejbca.find_certs(self.ejbca_data["username"], validOnly=False)

    def allow_new_cert(self, pwd=None):
        self.ejbca_data["status"] = ejbcaws.STATUS_NEW
        if pwd is not None:
            self.ejbca_data["password"] = pwd
            self.ejbca_data["clearPwd"] = True

    def new_cert(self, csr, pwd):
        cert = self.registry.ejbca.pkcs10_request(
            self.ejbca_data["username"],
            pwd, csr, 0, ejbcaws.RESPONSETYPE_CERTIFICATE)
        return cert

    def __str__(self):
        return (
            "Client:   %s (%s)\n"
            "Admins:   %s\n"
            "Status:   %s\n"
        ) % (
            self.name,
            self.ejbca_data["subjectDN"],
            ", ".join(self.admins),
            self.status
        )

    def verbose_str(self):
        return "%s\n" % self.ejbca_data

    def save(self):
        self.registry.ejbca.edit_user(self.ejbca_data)


class EjbcaRegistry(object):

    def __init__(self, url, cert=None, key=None,
                 caName="", certificateProfileName="", endEntityProfileName="",
                 subjectDN_template="%s", username_suffix=""):
        self.ejbca = ejbcaws.Ejbca(url, cert, key)
        self.caName = caName
        self.certificateProfileName = certificateProfileName
        self.endEntityProfileName = endEntityProfileName
        self.subjectDN_template = subjectDN_template
        self.username_suffix = username_suffix

    def get_clients(self):
        return (EjbcaClient(registry=self, ejbca_data=data) for data in self.ejbca.get_users())

    def get_client(self, name):
        users = self.ejbca.find_user(ejbcaws.MATCH_WITH_USERNAME, ejbcaws.MATCH_TYPE_EQUALS, name + self.username_suffix)
        if len(users) > 1:
            raise LookupError("%d users %s found (more than one?!)" % (len(users), name))
        if not users:
            return None
        return EjbcaClient(registry=self, ejbca_data=users[0])

    def new_client(self, name, admins):
        user = self.get_client(name)
        if user:
            raise LookupError("Client %s already exists" % name)
        new_ejbca_data = dict(
            caName=self.caName,
            certificateProfileName=self.certificateProfileName,
            endEntityProfileName=self.endEntityProfileName,
            keyRecoverable=False,
            sendNotification=False,
            status=ejbcaws.STATUS_INITIALIZED,
            subjectAltName="",
            subjectDN="",
            tokenType=ejbcaws.TOKEN_TYPE_USERGENERATED,
            username="",
            password = "".join((random.choice(string.ascii_letters + string.digits) for dummy in range(16))),
            clearPwd = True
        )
        client = EjbcaClient(registry=self, ejbca_data=new_ejbca_data)
        client.name = name
        client.admins = admins
        return client

    def verbose_str(self):
        return self.ejbca.get_version()


def format_cert(cert):
    return (
        "Subject:     %s\n"
        "Validity:    %s - %s\n"
        "Serial:      %s\n"
        "Fingerprint: md5:%s, sha1:%s\n"
        "Issuer:      %s\n"
    ) % (
        cert.get_subject().as_text(),
        cert.get_not_before().get_datetime().isoformat(),
        cert.get_not_after().get_datetime().isoformat(),
        ":".join(["%02x" % ord(c) for c in struct.pack('!Q', cert.get_serial_number())]),
        cert.get_fingerprint("md5"),
        cert.get_fingerprint("sha1"),
        cert.get_issuer().as_text()
    )

# Server side

class NullAuthenticator(ObjectReq):

    def __init__(self, req):
        ObjectReq.__init__(self, req)


    def __str__(self):
        return "%s(req=%s)" % (type(self).__name__, type(self.req).__name__)


    def authenticate(self, env, args):
        return True


    def authorize(self, env, client, path, method):
        return True


class CertHandler(ObjectReq):

    def __init__(self, req, registry):
        ObjectReq.__init__(self, req)
        self.registry = registry

    @expose(read=1, debug=1)
    def getCert(self, csr_data=None, name=None, password=None):
        if not (name and password and csr_data):
            raise self.req.error(message="Wrong or missing arguments", error=400)
        client = self.registry.get_client(name[0])
        if not client:
            raise self.req.error(message="Unknown client", error=403)
        try:
            newcert = client.new_cert(csr_data, password)
        except Exception as e:
            raise self.req.error(message="Processing error", error=403, cause=e)
        return [("Content-Type", "application/x-x509-user-cert")], newcert.as_pem()


def build_server(conf):
    StreamLogger()
    req = Request()
    log = FileLogger(
        req,
        filename=os.path.join(os.path.dirname(__file__), os.path.splitext(os.path.split(__file__)[1])[0] + ".log"),
        level=logging.DEBUG)
    auth = NullAuthenticator(req)
    registry = EjbcaRegistry(**conf)
    handler = CertHandler(req, registry)
    server = Server(req, auth, handler)
    return server


# Command line

def list_clients(registry, name=None, verbose=False):
    if name is not None:
        client = registry.get_client(name)
        if client is None:
            print "No such client."
            return
        else:
            clients = [client]
    else:
        clients = registry.get_clients()
    for client in clients:
        print(client)
        if verbose:
            print(client.verbose_str())
        for cert in sorted(client.get_certs(), key=lambda c: c.get_not_after().get_datetime()):
            print(format_cert(cert))
            if verbose:
                print(cert.as_text())


def register_client(registry, name, admins=None, verbose=False):
    try:
        client = registry.new_client(name, admins or [])
    except LookupError as e:
        print(e)
        return
    client.save()
    list_clients(registry, name, verbose)


def applicant(registry, name, password=None, verbose=False):
    client = registry.get_client(name)
    if password is None:
        password = "".join((random.choice(string.ascii_letters + string.digits) for dummy in range(16)))
        print("Application password is: %s\n" % password)
    client.allow_new_cert(pwd=password)
    client.save()
    list_clients(registry, name, verbose)


def request(registry, key, csr, verbose=False):
    openssl = subprocess.Popen(
        [
            "openssl", "req", "-new", "-nodes", "-batch",
            "-keyout", key,
            "-out", csr,
            "-config", "/dev/stdin"
        ], stdin=subprocess.PIPE
    )
    openssl.stdin.write(
        "distinguished_name=req_distinguished_name\n"
        "prompt=no\n"
        "\n"
        "[req_distinguished_name]\n"
        "commonName=dummy"
    )
    openssl.stdin.close()
    openssl.wait()
    if verbose:
        with open(csr, "r") as f:
            print(f.read())


def gen_cert(registry, name, csr, cert, password, verbose=False):
    with open(csr, "r") as f:
        csr_data = f.read()
    client = registry.get_client(name)
    newcert = client.new_cert(csr_data, password)
    print(format_cert(newcert))
    if verbose:
        print(newcert.as_text())
        print(newcert.as_pem())
    with open(cert, "w") as f:
        f.write(newcert.as_text())
        f.write(newcert.as_pem())


def get_args():
    argp = argparse.ArgumentParser(
        description="Warden server certificate registry", add_help=False)
    argp.add_argument("--help", action="help",
        help="show this help message and exit")
    argp.add_argument("-c", "--config",
        help="path to configuration file")
    argp.add_argument("-v", "--verbose", action="store_true", default=False,
        help="be more chatty")
    subargp = argp.add_subparsers(title="commands")

    subargp_list = subargp.add_parser("list", add_help=False,
        description="List registered clients.",
        help="list clients")
    subargp_list.set_defaults(command=list_clients)
    subargp_list.add_argument("--help", action="help",
        help="show this help message and exit")
    subargp_list.add_argument("--name", action="store", type=str,
        help="client name")

    subargp_reg = subargp.add_parser("register", add_help=False,
        description="Add client registration entry.",
        help="register client")
    subargp_reg.set_defaults(command=register_client)
    subargp_reg.add_argument("--help", action="help",
        help="show this help message and exit")
    subargp_reg.add_argument("--name", action="store", type=str,
        required=True, help="client name")
    subargp_reg.add_argument("--admins", action="store", type=str,
        nargs="*", help="administrator list")

    subargp_apply = subargp.add_parser("applicant", add_help=False,
        description="Set client into certificate application mode and set its password",
        help="allow for certificate application")
    subargp_apply.set_defaults(command=applicant)
    subargp_apply.add_argument("--help", action="help",
        help="show this help message and exit")
    subargp_apply.add_argument("--name", action="store", type=str,
        required=True, help="client name")
    subargp_apply.add_argument("--password", action="store", type=str,
        help="password for application (will be autogenerated if not set)")

    subargp_req = subargp.add_parser("request", add_help=False,
        description="Generate certificate request",
        help="generate CSR")
    subargp_req.set_defaults(command=request)
    subargp_req.add_argument("--help", action="help",
        help="show this help message and exit")
    subargp_req.add_argument("--key", action="store", type=str,
        required=True, help="file for saving the key")
    subargp_req.add_argument("--csr", action="store", type=str,
        required=True, help="file for saving the request")

    subargp_cert = subargp.add_parser("gencert", add_help=False,
        description="Request new certificate from registry",
        help="get new certificate")
    subargp_cert.set_defaults(command=gen_cert)
    subargp_cert.add_argument("--help", action="help",
        help="show this help message and exit")
    subargp_cert.add_argument("--name", action="store", type=str,
        required=True, help="client name")
    subargp_cert.add_argument("--csr", action="store", type=str,
        required=True, help="file for saving the request")
    subargp_cert.add_argument("--cert", action="store", type=str,
        required=True, help="file for saving the new certificate")
    subargp_cert.add_argument("--password", action="store", type=str,
        required=True, help="password for application")

    return argp.parse_args()


def read_cfg(path):
    with open(path, "r") as f:
        stripcomments = "\n".join((l for l in f if not l.lstrip().startswith(("#", "//"))))
        conf = json.loads(stripcomments)
    return conf


if __name__ == "__main__":
    args = get_args()
    config = read_cfg(os.path.join(os.path.dirname(__file__), args.config or "warden_ra.cfg"))
    registry = EjbcaRegistry(**config)
    if args.verbose:
        print(registry)
    command = args.command
    subargs = vars(args)
    del subargs["command"]
    del subargs["config"]
    sys.exit(command(registry, **subargs))