import textwrap
import os

from django.core.exceptions import ObjectDoesNotExist
from django.utils import timezone
from django.utils.translation import ugettext_lazy as _

from orchestra.apps.orchestration import ServiceController
from orchestra.apps.resources import ServiceMonitor

from . import settings
from .models import Address

# TODO http://wiki2.dovecot.org/HowTo/SimpleVirtualInstall
# TODO http://wiki2.dovecot.org/HowTo/VirtualUserFlatFilesPostfix
# TODO Set first/last_valid_uid/gid settings to contain only the range actually used by mail processes
# TODO Insert "/./" inside the returned home directory, eg.: home=/home/./user to chroot into /home, or home=/home/user/./ to chroot into /home/user.
# TODO mount the filesystem with "nosuid" option


class PasswdVirtualUserBackend(ServiceController):
    verbose_name = _("Mail virtual user (passwd-file)")
    model = 'mails.Mailbox'
    # TODO related_models = ('resources__content_type') ?? needed for updating disk usage from resource.data
    
    DEFAULT_GROUP = 'postfix'
    
    def set_user(self, context):
        self.append(textwrap.dedent("""
            if [[ $( grep "^%(username)s:" %(passwd_path)s ) ]]; then
               sed -i "s/^%(username)s:.*/%(passwd)s/" %(passwd_path)s
            else
               echo '%(passwd)s' >> %(passwd_path)s
            fi""" % context
        ))
        self.append("mkdir -p %(home)s" % context)
        self.append("chown %(uid)s.%(gid)s %(home)s" % context)
    
    def generate_filter(self, mailbox, context):
        now = timezone.now().strftime("%B %d, %Y, %H:%M")
        context['filtering'] = (
            "# Sieve Filter\n"
            "# Generated by Orchestra %s\n\n" % now
        )
        if mailbox.custom_filtering:
            context['filtering'] += mailbox.custom_filtering
        else:
            context['filtering'] += settings.MAILS_DEFAUL_FILTERING
        context['filter_path'] = os.path.join(context['home'], '.orchestra.sieve')
        self.append("echo '%(filtering)s' > %(filter_path)s" % context)
    
    def set_quota(self, mailbox, context):
        if not hasattr(mailbox, 'resources'):
            return
        context.update({
            'maildir_path': '~%(username)s/Maildir' % context,
            'maildirsize_path': '~%(username)s/Maildir/maildirsize' % context,
            'quota': mailbox.resources.disk.allocated*1000*1000,
        })
        self.append("mkdir -p %(maildir_path)s" % context)
        self.append(textwrap.dedent("""
            sed -i '1s/.*/%(quota)s,S/' %(maildirsize_path)s || {
               echo '%(quota)s,S' > %(maildirsize_path)s &&
               chown %(username)s %(maildirsize_path)s;
            }""" % context
        ))
    
    def save(self, mailbox):
        context = self.get_context(mailbox)
        self.set_user(context)
        self.generate_filter(mailbox, context)
    
    def delete(self, mailbox):
        context = self.get_context(mailbox)
        self.append("{ sleep 2 && killall -u %(uid)s -s KILL; } &" % context)
        self.append("killall -u %(uid)s" % context)
        self.append("sed -i '/^%(username)s:.*/d' %(passwd_path)s" % context)
        self.append("rm -fr %(home)s" % context)
    
    def get_extra_fields(self, mailbox, context):
        context['quota'] = self.get_quota(mailbox)
        return 'userdb_mail=maildir:~/Maildir {quota}'.format(**context)
    
    def get_quota(self, mailbox):
        try:
            quota = mailbox.resources.disk.allocated
        except (AttributeError, ObjectDoesNotExist):
            return ''
        unit = mailbox.resources.disk.unit[0].upper()
        return 'userdb_quota_rule=*:bytes=%i%s' % (quota, unit)
    
    def get_context(self, mailbox):
        context = {
            'name': mailbox.name,
            'username': mailbox.name,
            'password': mailbox.password if mailbox.active else '*%s' % mailbox.password,
            'uid': 10000 + mailbox.pk,
            'gid': 10000 + mailbox.pk,
            'group': self.DEFAULT_GROUP,
            'quota': self.get_quota(mailbox),
            'passwd_path': settings.MAILS_PASSWD_PATH,
            'home': mailbox.get_home(),
        }
        context['extra_fields'] = self.get_extra_fields(mailbox, context)
        context['passwd'] = '{username}:{password}:{uid}:{gid}:,,,:{home}:{extra_fields}'.format(**context)
        return context


class PostfixAddressBackend(ServiceController):
    verbose_name = _("Postfix address")
    model = 'mails.Address'
    
    def include_virtdomain(self, context):
        self.append(
            '[[ $(grep "^\s*%(domain)s\s*$" %(virtdomains)s) ]]'
            '   || { echo "%(domain)s" >> %(virtdomains)s; UPDATED_VIRTDOMAINS=1; }' % context
        )
    
    def exclude_virtdomain(self, context):
        domain = context['domain']
        if not Address.objects.filter(domain=domain).exists():
            self.append('sed -i "s/^%(domain)s//" %(virtdomains)s' % context)
    
    def update_virtusertable(self, context):
        self.append(textwrap.dedent("""
            LINE="%(email)s\t%(destination)s"
            if [[ ! $(grep "^%(email)s\s" %(virtusertable)s) ]]; then
               echo "${LINE}" >> %(virtusertable)s
               UPDATED_VIRTUSERTABLE=1
            else
               if [[ ! $(grep "^${LINE}$" %(virtusertable)s) ]]; then
                   sed -i "s/^%(email)s\s.*$/${LINE}/" %(virtusertable)s
                   UPDATED_VIRTUSERTABLE=1
               fi
            fi""" % context
        ))
    
    def exclude_virtusertable(self, context):
        self.append(textwrap.dedent("""
            if [[ $(grep "^%(email)s\s") ]]; then
               sed -i "s/^%(email)s\s.*$//" %(virtusertable)s
               UPDATED=1
            fi"""
        ))
    
    def save(self, address):
        context = self.get_context(address)
        self.include_virtdomain(context)
        self.update_virtusertable(context)
    
    def delete(self, address):
        context = self.get_context(address)
        self.exclude_virtdomain(context)
        self.exclude_virtusertable(context)
    
    def commit(self):
        context = self.get_context_files()
        self.append(textwrap.dedent("""
            [[ $UPDATED_VIRTUSERTABLE == 1 ]] && { postmap %(virtusertable)s; }
            # TODO not sure if always needed
            [[ $UPDATED_VIRTDOMAINS == 1 ]] && { /etc/init.d/postfix reload; }
            """ % context
        ))
    
    def get_context_files(self):
        return {
            'virtdomains': settings.MAILS_VIRTDOMAINS_PATH,
            'virtusertable': settings.MAILS_VIRTUSERTABLE_PATH,
        }
    
    def get_context(self, address):
        context = self.get_context_files()
        context.update({
            'domain': address.domain,
            'email': address.email,
            'destination': address.destination,
        })
        return context


class AutoresponseBackend(ServiceController):
    verbose_name = _("Mail autoresponse")
    model = 'mail.Autoresponse'


class MaildirDisk(ServiceMonitor):
    model = 'mails.Mailbox'
    resource = ServiceMonitor.DISK
    verbose_name = _("Maildir disk usage")
    
    def monitor(self, mailbox):
        context = self.get_context(mailbox)
        self.append(
            "SIZE=$(sed -n '2p' %(maildir_path)s | cut -d' ' -f1)\n"
            "echo %(object_id)s ${SIZE:-0}" % context
        )
    
    def get_context(self, mailbox):
        context = MailSystemUserBackend().get_context(mailbox)
        context.update({
            'rr_path': os.path.join(context['home'], 'Maildir/maildirsize'),
            'object_id': mailbox.pk
        })
        return context