postgres-web/pgweb/util/signals.py

from django.db.models.signals import pre_save, post_save, pre_delete, m2m_changed
from django.db import models
from django.conf import settings

import difflib

from pgweb.util.middleware import get_current_user
from pgweb.util.misc import varnish_purge
from pgweb.mailqueue.util import send_simple_mail


def _build_url(obj):
    if obj.id:
        return "%s/admin/%s/%s/%s/" % (
            settings.SITE_ROOT,
            obj._meta.app_label,
            obj._meta.model_name,
            obj.id,
        )
    else:
        return "%s/admin/%s/%s/" % (
            settings.SITE_ROOT,
            obj._meta.app_label,
            obj._meta.model_name,
        )


def _get_full_text_diff(obj, oldobj):
    fieldlist = _get_all_notification_fields(obj)
    if not fieldlist:
        return "This object does not know how to express ifself."

    s = "\n\n".join(["\n".join(
        filter(
            lambda x: not x.startswith('@@'),
            difflib.unified_diff(
                _get_attr_value(oldobj, n).splitlines(),
                _get_attr_value(obj, n).splitlines(),
                n=1,
                lineterm='',
                fromfile=n,
                tofile=n,
            )
        )
    ) for n in fieldlist if _get_attr_value(oldobj, n) != _get_attr_value(obj, n)])
    if not s:
        return None
    return s


def _get_all_notification_fields(obj):
    if hasattr(obj, 'notify_fields'):
        return obj.notify_fields
    else:
        # Include all field names except specified ones,
        # that are local to this model (not auto created)
        return [f.name for f in obj._meta.get_fields() if not f.name in ('approved', 'submitter', 'id', ) and not f.auto_created]


def _get_attr_value(obj, fieldname):
    # see if this is a Many-to-many field. If yes, we want to print
    # it out as a pretty list
    if isinstance(obj._meta.get_field(fieldname), models.ManyToManyField):
        # XXX: Changes to ManyToMany fields can't be tracked here :(
        #      For now, we have no good way to deal with it so, well, don't.
        #      (trying to get the value will return None for it)
        return ''

    # Return the value, or an empty tring if it's NULL (migrated records)
    return unicode(getattr(obj, fieldname)) or ''


def _get_full_text_representation(obj):
    fieldlist = _get_all_notification_fields(obj)
    if not fieldlist:
        return "This object does not know how to express itself."

    return "\n".join([u'%s: %s' % (n, _get_attr_value(obj, n)) for n in fieldlist])


def _get_notification_text(obj):
    try:
        oldobj = obj.__class__.objects.get(pk=obj.pk)
    except obj.DoesNotExist:
        return ('A new {0} has been added'.format(obj._meta.verbose_name),
                _get_full_text_representation(obj))

    if hasattr(obj, 'approved'):
            # This object has the capability to do approving. Apply the following logic:
            # 1. If object was unapproved, and is still unapproved, don't send notification
            # 2. If object was unapproved, and is now approved, send "object approved" notification
            # 3. If object was approved, and is no longer approved, send "object unapproved" notification
            # 4. (FIXME: configurable?) If object was approved and is still approved, send changes notification
        if not obj.approved:
            if not oldobj.approved:
                # Was approved, still approved -> no notification
                return (None, None)
            # From approved to unapproved
            return ('{0} id {1} has been unapproved'.format(obj._meta.verbose_name, obj.id),
                    _get_full_text_representation(obj))
        else:
            if not oldobj.approved:
                # Object went from unapproved to approved
                return ('{0} id {1} has been approved'.format(obj._meta.verbose_name, obj.id),
                        _get_full_text_representation(obj))
            # Object contents have changed. Generate a diff!
        diff = _get_full_text_diff(obj, oldobj)
        if not diff:
            return (None, None)
        return ('{0} id {1} has been modified'.format(obj._meta.verbose_name, obj.id),
                'The following fields have been modified:\n\n%s' % diff)
    else:
        # If there is no approved field, but send_notifications was set
        # to True, we notify on all changes.
        diff = _get_full_text_diff(obj, oldobj)
        if not diff:
            return (None, None)
        return ('{0} id {1} has been modified'.format(obj._meta.verbose_name, obj.id),
                'The following fields have been modified:\n\n%s' % diff)


def my_pre_save_handler(sender, **kwargs):
    instance = kwargs['instance']
    if getattr(instance, 'send_notification', False) and get_current_user():
        (subj, cont) = _get_notification_text(instance)
        if cont:
            cont = _build_url(instance) + "\n\n" + cont
            send_simple_mail(settings.NOTIFICATION_FROM,
                             settings.NOTIFICATION_EMAIL,
                             "%s by %s" % (subj, get_current_user()),
                             cont)


def my_m2m_changed_handler(sender, **kwargs):
    instance = kwargs['instance']
    if getattr(instance, 'send_m2m_notification', False) and get_current_user():
        (cl, f) = sender.__name__.split('_')
        if not hasattr(instance, '_stored_m2m'):
            instance._stored_m2m = {}
        if kwargs['action'] == 'pre_clear':
            instance._stored_m2m[f] = set([unicode(t) for t in getattr(instance, f).all()])
        elif kwargs['action'] == 'post_add':
            newset = set([unicode(t) for t in getattr(instance, f).all()])
            added = newset.difference(instance._stored_m2m.get(f, set()))
            removed = instance._stored_m2m.get(f, set()).difference(newset)
            subj = '{0} id {1} has been modified'.format(instance._meta.verbose_name, instance.id)
            if added or removed:
                send_simple_mail(settings.NOTIFICATION_FROM,
                                 settings.NOTIFICATION_EMAIL,
                                 "%s by %s" % (subj, get_current_user()),
                                 "The following values for {0} were changed:\n\n{1}\n{2}\n\n".format(
                                     instance._meta.get_field(f).verbose_name,
                                     "\n".join([u"Added: %s" % a for a in added]),
                                     "\n".join([u"Removed: %s" % r for r in removed]),
                                 ))


def my_pre_delete_handler(sender, **kwargs):
    instance = kwargs['instance']
    if getattr(instance, 'send_notification', False) and get_current_user():
        send_simple_mail(settings.NOTIFICATION_FROM,
                         settings.NOTIFICATION_EMAIL,
                         "%s id %s has been deleted by %s" % (
                             instance._meta.verbose_name,
                             instance.id,
                             get_current_user()),
                         _get_full_text_representation(instance))


def my_post_save_handler(sender, **kwargs):
    instance = kwargs['instance']
    if hasattr(instance, 'purge_urls'):
        if callable(instance.purge_urls):
            purgelist = instance.purge_urls()
        else:
            purgelist = instance.purge_urls
        map(varnish_purge, purgelist)


def register_basic_signal_handlers():
    pre_save.connect(my_pre_save_handler)
    pre_delete.connect(my_pre_delete_handler)
    post_save.connect(my_post_save_handler)
    m2m_changed.connect(my_m2m_changed_handler)