import hashlib
import os
import os.path
import tempfile

import batou.component
import batou.lib.cron
import batou.lib.download
import batou.lib.file
import batou.lib.nagios
import pkg_resources
import six


class Certificate(batou.component.Component):
    """SSL certificate management using let's encrypt -- or not

    Usage::

        # Add certificate component. After this step, a key and certificate
        # is available. In case of Let's Encrypt it's a self-signed one.
        self.cert = Certificate(
            self.public_name,
            docroot=self.docroot,
            key_content=self.key_content,
            crt_content=self.crt_content,
            use_letsencrypt=self.letsencrypt,
            extracommand='sudo systemctl reload nginx',
        )
        self += self.cert

        # Configure web server. Use `key` and `fullchain` attributes to get
        # the paths to the key and the certificate:
        self += batou.lib.file.File(
            '/etc/local/nginx/myconfig.conf')

        # Activate the configuration.
        self += batou_ext.nix.Rebuild()

        # Actually get a proper Let's Encrypt certificate. This step does
        # nothing, if you don't use LE.
        self += self.cert.activate_letsencrypt()


    If you need to run some command after executing dehydrated, e.g.
    restarting a service, you can use the extracommand argument
    to configure it. It will be called everytime the script is invoked.

    The component is setting up a cronjob (in case of you are using
    Let's encrypt). So you need to add the CronTab-component to your
    deployment. Import::

        from batou.lib.cron import CronTab

    ... and add the crontab component to the nginx host in your environment.

    """

    _required_params_ = {
        "wellknown": "hello",
    }

    # Let's Encrypt, dehydrated v0.7.0
    dehydrated_url = (
        "https://raw.githubusercontent.com/dehydrated-io/dehydrated"
        "/082da2527cb4aaa3a4740ba03e550205b076f822/dehydrated"
    )
    dehydrated_checksum = "md5:95a90950d3b9c01174e4f4f98cf3bd53"
    dehydrated_publickey_algo = batou.component.Attribute(
        str, default="secp384r1"
    )

    extracommand = None

    namevar = "domain"
    domain = None
    alternative_names = ()

    wellknown = None
    docroot = None

    refresh_timing = None

    # Optinal if you are having a valid certificate and don't want to
    # make usage of letsencrypt
    key_content = None
    crt_content = None

    # OSCP stapling
    trusted_crt_content = None

    use_letsencrypt = batou.component.Attribute("literal", default=True)

    letsencrypt_ca = "https://acme-v02.api.letsencrypt.org/directory"
    letsencrypt_challenge = "http-01"
    letsencrypt_hook = ""
    # Allow selecting an alternative root chain,
    # e.g. "ISRG Root X1" for the short chain after the X3 expiry.
    letsencrypt_alternative_chain = None

    # Whether a certificate check should be deployed, too
    # You will need something like nrpehost or sensuchecks on the host
    enable_check = batou.component.Attribute("literal", default=True)

    granted_user = batou.component.Attribute(str, default="nginx")

    _may_need_to_generate_certificates = False

    def configure(self):
        if not isinstance(self.alternative_names, (tuple, list)):
            raise ValueError(
                '"alternative_names" needs to be a tuple of string.'
            )
        if not self.refresh_timing:
            h = int(
                hashlib.md5(
                    six.ensure_binary(self.domain, "UTF-8")
                ).hexdigest(),
                16,
            )
            self.refresh_timing = "{} {} * * *".format(h % 60, h % 24)
        if self.key_content and not self.use_letsencrypt:
            self.crt_file = batou.lib.file.File(
                os.path.join("{}/{}.crt".format(self.workdir, self.domain)),
                content=self.crt_content,
            )
            self += self.crt_file
            self.key_file = batou.lib.file.File(
                os.path.join("{}/{}.key".format(self.workdir, self.domain)),
                content=self.key_content,
                mode=0o600,
                sensitive_data=True,
            )
            self += self.key_file

            if self.trusted_crt_content:
                self.trusted_file = batou.lib.file.File(
                    "{}/{}.trust.crt".format(self.workdir, self.domain),
                    content=self.trusted_crt_content,
                    mode=0o600,
                )
                self += self.trusted_file
                self.trusted = self.trusted_file.path

            self.key = self.key_file.path
            self.fullchain = self.crt_file.path

        else:
            self._may_need_to_generate_certificates = True
            self.key_dir = os.path.join(self.workdir, self.domain)
            self.key = os.path.join(self.key_dir, "privkey.pem")
            self.fullchain = os.path.join(self.key_dir, "fullchain.pem")

        if self.use_letsencrypt:
            # Okay, let's encrypt it is. There are two situations:
            # 1. bootstrap -- there is nothing.
            # 2. there already is a cert, either replace it with
            #    LE or refresh existing LE.

            self += batou.lib.download.Download(
                self.dehydrated_url,
                checksum=self.dehydrated_checksum,
                target="dehydrated",
            )
            self += batou.lib.file.Mode("dehydrated", mode=0o755)

            if not self.wellknown and self.docroot:
                self.wellknown = "{}/.well-known/acme-challenge".format(
                    self.docroot
                )
            self += batou.lib.file.File(
                self.wellknown, ensure="directory", leading=True
            )

            self += batou.lib.file.File(
                self.expand("domains-{{component.domain}}.txt"),
                content=self.expand(
                    "{{component.domain}} {{alternative}}",
                    alternative=" ".join(self.alternative_names),
                ),
            )
            self.domains_txt = self._

            self += batou.lib.file.File(
                "cert-{}.conf".format(self.domain),
                content=self.expand(
                    """
WELLKNOWN={{component.wellknown}}
CA={{component.letsencrypt_ca}}
CHALLENGETYPE={{component.letsencrypt_challenge}}
HOOK={{component.letsencrypt_hook}}
DOMAINS_TXT={{component.domains_txt.path}}
KEY_ALGO={{component.dehydrated_publickey_algo}}
"""
                ),
            )
            self.config = self._

            self += batou.lib.file.File(
                self.expand("cert-{{component.domain}}.sh"),
                content=pkg_resources.resource_string(
                    "batou_ext", "resources/cert.sh"
                ),
                mode=0o700,
            )
            self.cert_sh = self._

            self += batou.lib.cron.CronJob(
                self.cert_sh.path,
                timing=self.refresh_timing,
                logger="cert-update",
            )

        if self.enable_check:
            self += CertificateCheck(self.domain)

    def activate_letsencrypt(self):
        """Return a component which really activates LE"""
        return ActivateLetsEncrypt(cert=self)

    def verify(self):
        if not self._may_need_to_generate_certificates:
            return
        if os.path.exists(self.key) and os.path.exists(self.fullchain):
            # So there are certificates. All done.
            return
        raise batou.UpdateNeeded()

    def update(self):
        # Create a temporary, self-signed certificate, to let the web server
        # start up, so let's encrypt can do what it needs.
        if not os.path.isdir(self.key_dir):
            os.makedirs(self.key_dir)
        self.csr_file = tempfile.NamedTemporaryFile()
        self.cmd("openssl genrsa -out {{component.key}} 2048")
        self.cmd(
            """\
openssl req -new \
    -key {{component.key}} \
    -out {{component.csr_file.name}} \
    -batch \
    -subj "/CN={{component.domain}}/emailAddress=admin@{{component.domain}}/C=DE"
"""
        )  # noqa
        self.cmd(
            """
openssl x509 -req -days 3650 \
    -in {{component.csr_file.name}} \
    -signkey {{component.key}} \
    -out {{component.fullchain}}
"""
        )
        self.cert_dir = os.path.join(self.workdir, self.domain)
        self.cmd(f"setfacl -Rm u:{self.granted_user}:rX {self.cert_dir}")
        self.csr_file.close()
        del self.csr_file


class ActivateLetsEncrypt(batou.component.Component):

    cert: Certificate = None

    def verify(self):
        if self.cert.use_letsencrypt:
            self.cert.assert_no_subcomponent_changes()

    def update(self):
        # If batou thinks we need to run for a new certificate because
        # we changed settings etc. we need to speed up certificate renewal.
        self.cmd(self.cert.cert_sh.path + " -x")

    @property
    def namevar_for_breadcrumb(self):
        return self.cert.namevar_for_breadcrumb


class CertificateCheck(batou.component.Component):

    namevar = "public_name"
    warning_days = 25
    critical_days = 14

    # If HTTPS is not running on 443
    port = batou.component.Attribute(int, default=443)

    def configure(self):
        self += batou.lib.nagios.ServiceCheck(
            self.expand("https://{{component.public_name}} certificate valid?"),
            name=self.expand("ssl_cert_{{component.public_name}}"),
            command="check_http",
            args=self.expand(
                "-H {{component.public_name}} "
                "-p {{component.port}} "
                "-S --sni "
                "-C {{component.warning_days}},{{component.critical_days}}"
            ),
        )


class CertificateCheckLocal(batou.component.Component):
    """
    This component helps to check whether a local certificate has expired
    or will expire soon. Useful in e.g. combination with
    client-certificates.

    Usage:

    self += batou_ext.ssl.CertificateCheckLocal(
        'path/to/your/certificate',
        name='My client certificate',
        warning_days=30,
        critical_days=10)

    """

    _required_params_ = {
        "name": "cert",
    }
    namevar = "certificate_path"
    name = None
    warning_days = 25
    critical_days = 14

    def configure(self):
        self.critical = self.critical_days * 24 * 3600
        self.warning = self.warning_days * 24 * 3600

        if self.name is None:
            raise ValueError("Required name is missing from certificate check")

        self += batou.lib.file.File(
            "cert_check_{}.sh".format(self.name),
            content=pkg_resources.resource_string(
                __name__, "resources/ssl/local_certificate_check.sh"
            ),
            mode=0o755,
        )
        self.script = self._.path
        self += batou.lib.nagios.ServiceCheck(
            self.expand("{{component.certificate_path}} certificate valid?"),
            name=self.name,
            command=self.script,
        )
