# SPDX-License-Identifier: AGPL-3.0-or-later
"""FreedomBox app to manage an email server."""

import logging

from django.urls import reverse_lazy
from django.utils.translation import gettext_lazy as _

import plinth.app
from plinth import cfg, frontpage, menu
from plinth.daemon import Daemon
from plinth.modules.apache.components import Webserver
from plinth.modules.backups.components import BackupRestore
from plinth.modules.config import get_domainname
from plinth.modules.firewall.components import Firewall
from plinth.modules.letsencrypt.components import LetsEncrypt
from plinth.package import Packages, uninstall
from plinth.privileged import service as service_privileged
from plinth.signals import domain_added, domain_removed
from plinth.utils import format_lazy

from . import aliases, manifest, privileged

_description = [
    _('This is a complete email server solution using Postfix, Dovecot, '
      'and Rspamd. Postfix sends and receives emails. Dovecot allows '
      'email clients to access your mailbox using IMAP and POP3. Rspamd deals '
      'with spam.'),
    _('Email server currently does not work with many free domain services '
      'including those provided by the FreedomBox Foundation. Many ISPs '
      'also restrict outgoing email. Some lift the restriction after an '
      'explicit request. See manual page for more information.'),
    format_lazy(
        _('Each user on {box_name} gets an email address like '
          'user@mydomain.example. They will also receive mail from all '
          'addresses that look like user+foo@mydomain.example. Further, '
          'they can add aliases to their email address. Necessary aliases '
          'such as "postmaster" are automatically created pointing to the '
          'first admin user.'), box_name=_(cfg.box_name)),
    _('<a href="/plinth/apps/roundcube/">Roundcube app</a> provides web '
      'interface for users to access email.'),
    _('During installation, any other email servers in the system will be '
      'uninstalled.')
]

logger = logging.getLogger(__name__)


class EmailApp(plinth.app.App):
    """FreedomBox app for an email server."""

    app_id = 'email'

    _version = 1

    def __init__(self):
        """Initialize the email app."""
        super().__init__()

        info = plinth.app.Info(app_id=self.app_id, version=self._version,
                               name=_('Postfix/Dovecot'),
                               icon_filename='email',
                               short_description=_('Email Server'),
                               description=_description, manual_page='Email',
                               clients=manifest.clients,
                               donation_url='https://rspamd.com/support.html')
        self.add(info)

        menu_item = menu.Menu('menu-email', info.name, info.short_description,
                              info.icon_filename, 'email:index',
                              parent_url_name='apps')
        self.add(menu_item)

        shortcut = frontpage.Shortcut(
            'shortcut-email', info.name,
            short_description=info.short_description, icon=info.icon_filename,
            description=info.description, manual_page=info.manual_page,
            configure_url=reverse_lazy('email:index'), clients=info.clients,
            login_required=True)
        self.add(shortcut)

        shortcut = frontpage.Shortcut(
            'shortcut-email-aliases', _('My Email Aliases'),
            short_description=_('Manage Aliases for Mailbox'),
            icon=info.icon_filename, url=reverse_lazy('email:aliases'),
            login_required=True)
        self.add(shortcut)

        # Other likely install conflicts have been discarded:
        # - msmtp, nullmailer, sendmail don't cause install faults.
        # - qmail and smail are missing in Bullseye (Not tested,
        #   but less likely due to that).
        packages = Packages(
            'packages-email', [
                'postfix', 'postfix-sqlite', 'dovecot-pop3d', 'dovecot-imapd',
                'dovecot-lmtpd', 'dovecot-managesieved', 'dovecot-ldap',
                'rspamd', 'redis-server', 'openssl'
            ], conflicts=['exim4-base', 'exim4-config', 'exim4-daemon-light'],
            conflicts_action=Packages.ConflictsAction.IGNORE)
        self.add(packages)

        listen_ports = [(25, 'tcp4'), (25, 'tcp6'), (465, 'tcp4'),
                        (465, 'tcp6'), (587, 'tcp4'), (587, 'tcp6')]
        daemon = Daemon('daemon-email-postfix', 'postfix',
                        listen_ports=listen_ports)
        self.add(daemon)

        listen_ports = [(143, 'tcp4'), (143, 'tcp6'), (993, 'tcp4'),
                        (993, 'tcp6'), (110, 'tcp4'), (110, 'tcp6'),
                        (995, 'tcp4'), (995, 'tcp6'), (4190, 'tcp4'),
                        (4190, 'tcp6')]
        daemon = Daemon('daemon-email-dovecot', 'dovecot',
                        listen_ports=listen_ports)
        self.add(daemon)

        listen_ports = [(11332, 'tcp4'), (11332, 'tcp6'), (11333, 'tcp4'),
                        (11333, 'tcp6'), (11334, 'tcp4'), (11334, 'tcp6')]
        daemon = Daemon('daemon-email-rspamd', 'rspamd',
                        listen_ports=listen_ports)
        self.add(daemon)

        daemon = Daemon('daemon-email-redis', 'redis-server',
                        listen_ports=[(6379, 'tcp4'), (6379, 'tcp6')])
        self.add(daemon)

        port_names = [
            'smtp', 'smtps', 'smtp-submission', 'imaps', 'pop3s', 'managesieve'
        ]
        firewall = Firewall('firewall-email', info.name, ports=port_names,
                            is_external=True)
        self.add(firewall)

        # /rspamd location
        webserver = Webserver(
            'webserver-email',  # unique id
            'email-freedombox',  # config file name
            urls=['https://{host}/rspamd'])
        self.add(webserver)

        # Let's Encrypt event hook
        letsencrypt = LetsEncrypt(
            'letsencrypt-email-postfix', domains='*', daemons=['postfix'],
            should_copy_certificates=True,
            private_key_path='/etc/postfix/letsencrypt/{domain}/chain.pem',
            certificate_path='/etc/postfix/letsencrypt/{domain}/chain.pem',
            user_owner='root', group_owner='root', managing_app='email')
        self.add(letsencrypt)

        letsencrypt = LetsEncrypt(
            'letsencrypt-email-dovecot', domains='*', daemons=['dovecot'],
            should_copy_certificates=True,
            private_key_path='/etc/dovecot/letsencrypt/{domain}/privkey.pem',
            certificate_path='/etc/dovecot/letsencrypt/{domain}/cert.pem',
            user_owner='root', group_owner='root', managing_app='email')
        self.add(letsencrypt)

        backup_restore = BackupRestore('backup-restore-email',
                                       **manifest.backup)
        self.add(backup_restore)

    @staticmethod
    def post_init():
        """Perform post initialization operations."""
        domain_added.connect(on_domain_added)
        domain_removed.connect(on_domain_removed)

    def setup(self, old_version):
        """Install and configure the app."""

        def _clear_conflicts():
            component = self.get_component('packages-email')
            packages_to_remove = component.find_conflicts()
            if packages_to_remove:
                logger.info('Removing conflicting packages: %s',
                            packages_to_remove)
                uninstall(packages_to_remove)

        # Install
        _clear_conflicts()
        super().setup(old_version)

        # Setup
        privileged.setup_home()
        self.get_component('letsencrypt-email-postfix').setup_certificates()
        self.get_component('letsencrypt-email-dovecot').setup_certificates()
        privileged.domain.set_all_domains()
        aliases.first_setup()
        privileged.setup_postfix()
        aliases.setup_common_aliases(_get_first_admin())
        privileged.setup_spam()

        # Restart daemons
        service_privileged.try_restart('postfix')
        service_privileged.try_restart('dovecot')
        service_privileged.try_restart('rspamd')

        # Expose to public internet
        if old_version == 0:
            self.enable()


def get_domains():
    """Return the list of domains configured."""
    default_domain = get_domainname()
    return [default_domain] if default_domain else []


def _get_first_admin():
    """Return an admin user in the system or None if non exist."""
    from django.contrib.auth.models import User
    users = User.objects.filter(groups__name='admin')
    return users[0].username if users else None


def on_domain_added(sender, domain_type, name, description='', services=None,
                    **kwargs):
    """Handle addition of a new domain."""
    app = plinth.app.App.get('email')
    if app.needs_setup():
        return

    privileged.domain.set_all_domains()


def on_domain_removed(sender, domain_type, name='', **kwargs):
    """Handle removal of a domain."""
    app = plinth.app.App.get('email')
    if app.needs_setup():
        return

    privileged.domain.set_all_domains()
