# Patchwork - automated patch tracking system
# Copyright (C) 2008 Jeremy Kerr <[email protected]>
# Copyright (C) 2015 Intel Corporation
#
# This file is part of the Patchwork package.
#
# Patchwork is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# Patchwork is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Patchwork; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

from collections import Counter, OrderedDict
import datetime
import jsonfield
import random
import re
import threadlocalrequest

from django.conf import settings
from django.contrib import auth
from django.contrib.auth.models import User
from django.contrib.sites.models import Site
from django.core.urlresolvers import reverse
from django.db import models
from django.db.models import Q
import django.dispatch
from django.utils.encoding import python_2_unicode_compatible
from django.utils.functional import cached_property
from django.utils.six.moves import filter

from patchwork.fields import HashField
from patchwork.parser import hash_patch, extract_tags


@python_2_unicode_compatible
class Person(models.Model):
    email = models.CharField(max_length=255, unique=True)
    name = models.CharField(max_length=255, null=True, blank=True)
    user = models.ForeignKey(User, null=True, blank=True,
                             on_delete=models.SET_NULL)

    def display_name(self):
        if self.name:
            return self.name
        else:
            return self.email

    def email_name(self):
        if (self.name):
            return "%s <%s>" % (self.name, self.email)
        else:
            return self.email

    def link_to_user(self, user):
        self.name = user.profile.name()
        self.user = user

    def __str__(self):
        return self.display_name()

    class Meta:
        verbose_name_plural = 'People'


def get_comma_separated_field(value):
    if not value:
        return []
    tags = [v.strip() for v in value.split(',')]
    tags = [tag for tag in tags if tag]
    return tags


@python_2_unicode_compatible
class Project(models.Model):
    linkname = models.CharField(max_length=255, unique=True)
    name = models.CharField(max_length=255, unique=True)
    description = models.TextField(blank=True, null=True)
    listid = models.CharField(max_length=255)
    listemail = models.CharField(max_length=200)
    web_url = models.CharField(max_length=2000, blank=True)
    scm_url = models.CharField(max_length=2000, blank=True)
    webscm_url = models.CharField(max_length=2000, blank=True)
    send_notifications = models.BooleanField(default=False)
    use_tags = models.BooleanField(default=True)
    git_send_email_only = models.BooleanField(default=False)
    subject_prefix_tags = models.CharField(max_length=255, blank=True,
               help_text='Comma separated list of tags')

    def is_editable(self, user):
        if not user.is_authenticated():
            return False
        return self in user.profile.maintainer_projects.all()

    @cached_property
    def tags(self):
        if not self.use_tags:
            return []
        return list(Tag.objects.all())

    def get_subject_prefix_tags(self):
        return get_comma_separated_field(self.subject_prefix_tags)

    def __str__(self):
        return self.name

    class Meta:
        ordering = ['linkname']


def user_name(user):
    if user.first_name or user.last_name:
        names = list(filter(bool, [user.first_name, user.last_name]))
        return u' '.join(names)
    return user.username

auth.models.User.add_to_class('name', user_name)


@python_2_unicode_compatible
class DelegationRule(models.Model):
    user = models.ForeignKey(User)
    path = models.CharField(max_length=255)
    project = models.ForeignKey(Project)
    priority = models.IntegerField(default=0)

    def __str__(self):
        return self.path

    class Meta:
        ordering = ['-priority', 'path']
        unique_together = (('path', 'project'))


@python_2_unicode_compatible
class UserProfile(models.Model):
    user = models.OneToOneField(User, unique=True, related_name='profile')
    primary_project = models.ForeignKey(Project, null=True, blank=True)
    maintainer_projects = models.ManyToManyField(Project,
             related_name='maintainer_project', blank=True)
    send_email = models.BooleanField(default=False,
             help_text='Selecting this option allows patchwork to send '
             'email on your behalf')
    patches_per_page = models.PositiveIntegerField(
            default=100, null=False, blank=False,
            help_text='Number of patches to display per page')

    def name(self):
        return user_name(self.user)

    def contributor_projects(self):
        submitters = Person.objects.filter(user=self.user)
        return Project.objects.filter(id__in=Patch.objects.filter(
            submitter__in=submitters)
            .values('project_id').query)

    def sync_person(self):
        pass

    def n_todo(self):
        return self.todo_patches().count() + self.todo_series().count()

    def todo_patches(self, project=None):

        # filter on project, if necessary
        if project:
            qs = Patch.objects.filter(project=project)
        else:
            qs = Patch.objects

        qs = qs.filter(archived=False) \
            .filter(delegate=self.user) \
            .filter(state__in=State.objects.filter(action_required=True)
                    .values('pk').query)
        return qs

    def todo_series(self, project=None):
        # filter on project, if necessary
        if project:
            qs = Series.objects.filter(project=project)
        else:
            qs = Series.objects

        qs = qs.filter(Q(reviewer=self.user),
                       ~Q(last_revision__state=RevisionState.DONE))
        return qs

    def __str__(self):
        return self.name()


def _user_saved_callback(sender, created, instance, **kwargs):
    try:
        profile = instance.profile
    except UserProfile.DoesNotExist:
        profile = UserProfile(user=instance)
    profile.save()

models.signals.post_save.connect(_user_saved_callback, sender=User)


@python_2_unicode_compatible
class State(models.Model):
    name = models.CharField(max_length=100)
    ordering = models.IntegerField(unique=True)
    action_required = models.BooleanField(default=True)

    @classmethod
    def from_string(cls, name):
        return State.objects.get(name__iexact=name)

    def __str__(self):
        return self.name

    class Meta:
        ordering = ['ordering']


@python_2_unicode_compatible
class Tag(models.Model):
    name = models.CharField(max_length=20)
    pattern = models.CharField(max_length=50,
            help_text='A simple regex to match the tag in the content of '
                      'a message. Will be used with MULTILINE and IGNORECASE '
                      'flags. eg. ^Acked-by:')
    abbrev = models.CharField(max_length=2, unique=True,
            help_text='Short (one-or-two letter) abbreviation for the tag, '
                       'used in table column headers')

    @property
    def attr_name(self):
        return 'tag_%d_count' % self.id

    def __str__(self):
        return self.name

    class Meta:
        ordering = ['abbrev']


class PatchTag(models.Model):
    patch = models.ForeignKey('Patch')
    tag = models.ForeignKey('Tag')
    count = models.IntegerField(default=1)

    class Meta:
        unique_together = [('patch', 'tag')]


def get_default_initial_patch_state():
    return State.objects.get(ordering=0)


class PatchQuerySet(models.query.QuerySet):

    def with_tag_counts(self, project):
        if not project.use_tags:
            return self

        # We need the project's use_tags field loaded for Project.tags().
        # Using prefetch_related means we'll share the one instance of
        # Project, and share the project.tags cache between all patch.project
        # references.
        qs = self.prefetch_related('project')
        select = OrderedDict()
        select_params = []
        for tag in project.tags:
            select[tag.attr_name] = (
                "coalesce("
                     "(SELECT count FROM patchwork_patchtag "
                     "WHERE patchwork_patchtag.patch_id=patchwork_patch.id "
                     "AND patchwork_patchtag.tag_id=%s), 0)")
            select_params.append(tag.id)

        return qs.extra(select=select, select_params=select_params)


class PatchManager(models.Manager):
    use_for_related_fields = True

    def get_queryset(self):
        return PatchQuerySet(self.model, using=self.db)

    def with_tag_counts(self, project):
        return self.get_queryset().with_tag_counts(project)


def filename(name, ext):
    fname_re = re.compile('[^-_A-Za-z0-9\.]+')
    str = fname_re.sub('-', name)
    return str.strip('-') + ext


@python_2_unicode_compatible
class Patch(models.Model):
    project = models.ForeignKey(Project)
    msgid = models.CharField(max_length=255)
    name = models.CharField(max_length=255)
    date = models.DateTimeField(default=datetime.datetime.now)
    last_updated = models.DateTimeField(auto_now=True)
    submitter = models.ForeignKey(Person)
    delegate = models.ForeignKey(User, blank=True, null=True)
    state = models.ForeignKey(State, null=True)
    archived = models.BooleanField(default=False)
    headers = models.TextField(blank=True)
    content = models.TextField(null=True, blank=True)
    pull_url = models.CharField(max_length=255, null=True, blank=True)
    commit_ref = models.CharField(max_length=255, null=True, blank=True)
    hash = HashField(null=True, blank=True)
    tags = models.ManyToManyField(Tag, through=PatchTag)

    objects = PatchManager()

    def commit_message(self):
        """Retrieves the commit message"""
        return Comment.objects.filter(patch=self, msgid=self.msgid)

    def answers(self):
        """Retrieves the answers (ie all comments but the commit message)"""
        return Comment.objects.filter(Q(patch=self) & ~Q(msgid=self.msgid))

    def comments(self):
        """Retrieves all comments of this patch ie. the commit message and the
           answers"""
        return Comment.objects.filter(patch=self)

    def _set_tag(self, tag, count):
        if count == 0:
            self.patchtag_set.filter(tag=tag).delete()
            return
        (patchtag, _) = PatchTag.objects.get_or_create(patch=self, tag=tag)
        if patchtag.count != count:
            patchtag.count = count
            patchtag.save()

    def refresh_tag_counts(self):
        tags = self.project.tags
        counter = Counter()
        for comment in self.comment_set.all():
            counter = counter + extract_tags(comment.content, tags)

        for tag in tags:
            self._set_tag(tag, counter[tag])

    def save(self):
        if not hasattr(self, 'state') or not self.state:
            self.state = get_default_initial_patch_state()

        if self.hash is None and self.content is not None:
            self.hash = hash_patch(self.content).hexdigest()

        super(Patch, self).save()

    def is_editable(self, user):
        if not user.is_authenticated():
            return False

        if self.submitter.user == user or self.delegate == user:
            return True

        return self.project.is_editable(user)

    def filename(self):
        return filename(self.name, '.patch')

    def human_name(self):
        return self.name

    @models.permalink
    def get_absolute_url(self):
        return ('patchwork.views.patch.patch', (), {'patch_id': self.id})

    def __str__(self):
        return self.name

    class Meta:
        verbose_name_plural = 'Patches'
        ordering = ['date']
        unique_together = [('msgid', 'project')]


class Comment(models.Model):
    patch = models.ForeignKey(Patch)
    msgid = models.CharField(max_length=255)
    submitter = models.ForeignKey(Person)
    date = models.DateTimeField(default=datetime.datetime.now)
    headers = models.TextField(blank=True)
    content = models.TextField()

    response_re = re.compile(
        '^(Tested|Reviewed|Acked|Signed-off|Nacked|Reported)-by: .*$',
        re.M | re.I)

    def patch_responses(self):
        return ''.join([match.group(0) + '\n' for match in
                        self.response_re.finditer(self.content)])

    def save(self, *args, **kwargs):
        super(Comment, self).save(*args, **kwargs)
        self.patch.refresh_tag_counts()

    def delete(self, *args, **kwargs):
        super(Comment, self).delete(*args, **kwargs)
        self.patch.refresh_tag_counts()

    class Meta:
        ordering = ['date']
        unique_together = [('msgid', 'patch')]


class Bundle(models.Model):
    owner = models.ForeignKey(User)
    project = models.ForeignKey(Project)
    name = models.CharField(max_length=50, null=False, blank=False)
    patches = models.ManyToManyField(Patch, through='BundlePatch')
    public = models.BooleanField(default=False)

    def n_patches(self):
        return self.patches.all().count()

    def ordered_patches(self):
        return self.patches.order_by('bundlepatch__order')

    def append_patch(self, patch):
        # todo: use the aggregate queries in django 1.1
        orders = BundlePatch.objects.filter(bundle=self).order_by('-order') \
            .values('order')

        if len(orders) > 0:
            max_order = orders[0]['order']
        else:
            max_order = 0

        # see if the patch is already in this bundle
        if BundlePatch.objects.filter(bundle=self, patch=patch).count():
            raise Exception("patch is already in bundle")

        bp = BundlePatch.objects.create(bundle=self, patch=patch,
                                        order=max_order + 1)
        bp.save()

    def public_url(self):
        if not self.public:
            return None
        site = Site.objects.get_current()
        return 'http://%s%s' % (site.domain,
                                reverse('patchwork.views.bundle.bundle',
                                        kwargs={
                                            'username': self.owner.username,
                                            'bundlename': self.name
                                        }))

    @models.permalink
    def get_absolute_url(self):
        return ('patchwork.views.bundle.bundle', (), {
            'username': self.owner.username,
            'bundlename': self.name,
        })

    class Meta:
        unique_together = [('owner', 'name')]


class BundlePatch(models.Model):
    patch = models.ForeignKey(Patch)
    bundle = models.ForeignKey(Bundle)
    order = models.IntegerField()

    class Meta:
        unique_together = [('bundle', 'patch')]
        ordering = ['order']

SERIES_DEFAULT_NAME = "Series without cover letter"


class TestState:
    STATE_PENDING = 0
    STATE_INFO = 1
    STATE_SUCCESS = 2
    STATE_WARNING = 3
    STATE_FAILURE = 4
    STATE_CHOICES = (
        (STATE_PENDING, 'pending'),
        (STATE_INFO, 'info'),
        (STATE_SUCCESS, 'success'),
        (STATE_WARNING, 'warning'),
        (STATE_FAILURE, 'failure'),
    )

    @classmethod
    def from_string(cls, s):
        s2i = {s: i for i, s in cls.STATE_CHOICES}
        return s2i[s]


# This Model represents the "top level" Series, an object that doesn't change
# with the various versions of patches sent to the mailing list.
@python_2_unicode_compatible
class Series(models.Model):
    project = models.ForeignKey(Project)
    name = models.CharField(max_length=200, default=SERIES_DEFAULT_NAME)
    submitter = models.ForeignKey(Person, related_name='submitters')
    reviewer = models.ForeignKey(User, related_name='reviewers', null=True,
                                 blank=True)
    submitted = models.DateTimeField(default=datetime.datetime.now)
    last_updated = models.DateTimeField(auto_now=True)
    # direct access to the latest revision so we can get the latest revision
    # information with a JOIN
    last_revision = models.OneToOneField('SeriesRevision', null=True,
                                         related_name='+')

    def revisions(self):
        return SeriesRevision.objects.filter(series=self)

    def latest_revision(self):
        return self.revisions().reverse()[0]

    def get_absolute_url(self):
        return reverse('series', kwargs={'series': self.pk})

    def dump(self):
        print('')
        print('===')
        print('Series: %s' % self)
        print('    version: %d' % self.version)
        print('    n_patches: %d' % self.n_patches)
        for rev in self.revisions():
            print('    rev %d:' % rev.version)
            i = 1
            for patch in rev.ordered_patches():
                print('        patch %d:' % i)
                print('            subject: %s' % patch.name)
                print('            msgid  : %s' % patch.msgid)
                i += 1

    def filename(self):
        return filename(self.name, '.mbox')

    def human_name(self):
        name = self.name
        if name == SERIES_DEFAULT_NAME:
            name = "series starting with " + \
                    self.last_revision.ordered_patches()[0].name
        return name

    def __str__(self):
        return self.name

    class Meta:
        verbose_name_plural = 'Series'

# Signal one can listen to to know when a revision is complete (ie. has all of
# its patches)
series_revision_complete = django.dispatch.Signal(providing_args=["revision"])


class RevisionState:
    INCOMPLETE = 0
    INITIAL = 1
    IN_PROGRESS = 2
    DONE = 3
    CHOICES = (
        (INCOMPLETE, 'incomplete'),
        (INITIAL, 'initial'),
        (IN_PROGRESS, 'in progress'),
        (DONE, 'done'),
    )

    i2s = dict(CHOICES)

    @classmethod
    def to_string(cls, i):
        return cls.i2s[i]

    @classmethod
    def from_string(cls, s):
        s2i = {s: i for i, s in cls.CHOICES}
        return s2i[s]

# A 'revision' of a series. Resending a new version of a patch or a full new
# iteration of a series will create a new revision.


@python_2_unicode_compatible
class SeriesRevision(models.Model):
    series = models.ForeignKey(Series)
    version = models.IntegerField(default=1)
    root_msgid = models.CharField(max_length=255)
    cover_letter = models.TextField(null=True, blank=True)
    n_patches = models.IntegerField(default=0)
    patches = models.ManyToManyField(Patch, through='SeriesRevisionPatch')
    state = models.SmallIntegerField(choices=RevisionState.CHOICES,
                                     default=RevisionState.INCOMPLETE)
    state_summary = jsonfield.JSONField(null=True)
    test_state = models.SmallIntegerField(choices=TestState.STATE_CHOICES,
                                          null=True, blank=True)

    class Meta:
        unique_together = [('series', 'version')]
        ordering = ['version']

    def ordered_patches(self):
        return self.patches.order_by('seriesrevisionpatch__order')

    def add_patch(self, patch, order):
        # see if the patch is already in this revision
        if SeriesRevisionPatch.objects.filter(revision=self,
                                              patch=patch).count():
            raise Exception("patch is already in revision")

        sp = SeriesRevisionPatch.objects.create(revision=self, patch=patch,
                                                order=order)
        sp.save()

        revision_complete = self.patches.count() == self.n_patches
        if revision_complete:
            series_revision_complete.send(sender=self.__class__, revision=self)

    def duplicate_meta(self):
        new = SeriesRevision.objects.get(pk=self.pk)
        new.pk = None
        new.cover_letter = None
        new.version = self.version + 1
        new.test_state = None
        new.save()

        return new

    def duplicate(self, exclude_patches=()):
        """Create a new revision based on 'self', incrementing the version
           and populating the new revision with all 'self' patches.
           exclude_patch (a list of 'order's) can be used to exclude
           patches from the operation"""
        new = self.duplicate_meta()
        order = 0
        for p in self.ordered_patches():
            order += 1
            if order in exclude_patches:
                continue
            new.add_patch(p, order)
        return new

    def refresh_test_state(self):
        results = TestResult.objects.filter(revision=self)
        if results.count() > 0:
            self.test_state = max([r.state for r in results])
        else:
            self.test_state = None
        self.save()
        self.series.save()

    def human_name(self):
        name = self.series.name
        if name == SERIES_DEFAULT_NAME:
            name = "series starting with " + self.ordered_patches()[0].name
        if self.version > 1:
            name += " (rev%d)" % self.version
        return name

    def __str__(self):
        return "Revision " + str(self.version)


class SeriesRevisionPatch(models.Model):
    patch = models.ForeignKey(Patch)
    revision = models.ForeignKey(SeriesRevision)
    order = models.IntegerField()

    class Meta:
        unique_together = [('revision', 'patch'), ('revision', 'order')]
        ordering = ['order']


class Event(models.Model):
    name = models.CharField(max_length=20)


class EventLog(models.Model):
    event = models.ForeignKey(Event)
    event_time = models.DateTimeField(auto_now=True)
    series = models.ForeignKey(Series)
    user = models.ForeignKey(User, null=True)
    parameters = jsonfield.JSONField(null=True)
    patch = models.ForeignKey(Patch, null=True)

    class Meta:
        ordering = ['-event_time']


@python_2_unicode_compatible
class Test(models.Model):
    # no mail, default so test systems/scripts can have a grace period to
    # settle down and give useful results
    RECIPIENT_NONE = 0
    # send mail only to submitter
    RECIPIENT_SUBMITTER = 1
    # send mail to submitter and mailing-list in Cc
    RECIPIENT_MAILING_LIST = 2
    # send mail to the addresses listed in the mail_to_list field only
    RECIPIENT_TO_LIST = 3
    RECIPIENT_CHOICES = (
        (RECIPIENT_NONE, 'none'),
        (RECIPIENT_SUBMITTER, 'submitter'),
        (RECIPIENT_MAILING_LIST, 'mailing list'),
        (RECIPIENT_TO_LIST, 'recipient list'),
    )

    # send result mail on any state (but pending)
    CONDITION_ALWAYS = 0
    # send result mail on warning or failure
    CONDITION_ON_WARNING = 1
    # send result mail on error
    CONDITION_ON_FAILURE = 2
    CONDITION_CHOICES = (
        (CONDITION_ALWAYS, 'always'),
        (CONDITION_ON_WARNING, 'on warning/failure'),
        (CONDITION_ON_FAILURE, 'on failure'),
    )

    project = models.ForeignKey(Project)
    name = models.CharField(max_length=255)
    mail_recipient = models.SmallIntegerField(choices=RECIPIENT_CHOICES,
                                              default=RECIPIENT_NONE)
    # email addresses in these lists are always added to the To: and Cc:fields,
    # unless we don't want to send any email at all.
    mail_to_list = models.CharField(max_length=255, blank=True, null=True,
                                    help_text='Comma separated list of emails')
    mail_cc_list = models.CharField(max_length=255, blank=True, null=True,
                                    help_text='Comma separated list of emails')
    mail_condition = models.SmallIntegerField(choices=CONDITION_CHOICES,
                                              default=CONDITION_ALWAYS)

    class Meta:
        unique_together = [('project', 'name')]

    def get_to_list(self):
        return get_comma_separated_field(self.mail_to_list)

    def get_cc_list(self):
        return get_comma_separated_field(self.mail_cc_list)

    def __str__(self):
        return self.name


@python_2_unicode_compatible
class TestResult(models.Model):

    test = models.ForeignKey(Test)
    revision = models.ForeignKey(SeriesRevision, blank=True, null=True)
    patch = models.ForeignKey(Patch, blank=True, null=True)
    user = models.ForeignKey(User)
    date = models.DateTimeField(auto_now=True)
    state = models.SmallIntegerField(choices=TestState.STATE_CHOICES)
    url = models.URLField(blank=True, null=True)
    summary = models.TextField(blank=True, null=True)

    def __str__(self):
        return self.get_state_display()

    class Meta:
        unique_together = [('test', 'revision'), ('test', 'patch')]


class EmailConfirmation(models.Model):
    validity = datetime.timedelta(days=settings.CONFIRMATION_VALIDITY_DAYS)
    type = models.CharField(max_length=20, choices=[
        ('userperson', 'User-Person association'),
        ('registration', 'Registration'),
        ('optout', 'Email opt-out'),
    ])
    email = models.CharField(max_length=200)
    user = models.ForeignKey(User, null=True)
    key = HashField()
    date = models.DateTimeField(default=datetime.datetime.now)
    active = models.BooleanField(default=True)

    def deactivate(self):
        self.active = False
        self.save()

    def is_valid(self):
        return self.date + self.validity > datetime.datetime.now()

    def save(self):
        max = 1 << 32
        if self.key == '':
            str = '%s%s%d' % (self.user, self.email, random.randint(0, max))
            self.key = self._meta.get_field('key').construct(str).hexdigest()
        super(EmailConfirmation, self).save()


@python_2_unicode_compatible
class EmailOptout(models.Model):
    email = models.CharField(max_length=200, primary_key=True)

    @classmethod
    def is_optout(cls, email):
        email = email.lower().strip()
        return cls.objects.filter(email=email).count() > 0

    def __str__(self):
        return self.email


class PatchChangeNotification(models.Model):
    patch = models.OneToOneField(Patch, primary_key=True)
    last_modified = models.DateTimeField(default=datetime.datetime.now)
    orig_state = models.ForeignKey(State)


def find_series_for_patch(patch):
    try:
        revision = SeriesRevisionPatch.objects.filter(patch=patch)[0].revision
        return revision.series
    except:
        return None


def _patch_change_log_event(old_patch, new_patch):
    # If state changed, log the event
    event_state_change = Event.objects.get(name='patch-state-change')
    curr_user = threadlocalrequest.get_current_user()
    previous_state = str(old_patch.state)
    new_state = str(new_patch.state)

    # Do not log patch-state-change events for Patches that are not part of a
    # Series (ie patches older than the introduction of Series)
    series = find_series_for_patch(old_patch)
    if series:
        log = EventLog(event=event_state_change,
                       user=curr_user,
                       series_id=series.id,
                       patch=old_patch,
                       parameters={'previous_state': previous_state,
                                   'new_state': new_state,
                                  })
        log.save()


def _patch_change_send_notification(old_patch, new_patch):
    if not new_patch.project.send_notifications:
        return

    notification = None
    try:
        notification = PatchChangeNotification.objects.get(patch=new_patch)
    except PatchChangeNotification.DoesNotExist:
        pass

    if notification is None:
        notification = PatchChangeNotification(patch=new_patch,
                                               orig_state=old_patch.state)

    elif notification.orig_state == new_patch.state:
        # If we're back at the original state, there is no need to notify
        notification.delete()
        return

    notification.last_modified = datetime.datetime.now()
    notification.save()


def _revision_is_done(revision, summary):
    for entry in summary:
        if entry[2]:  # state__action_required
            return False
    return True


def _revision_update_state(revision):
    # the order_by() clears the default ordering (from the Meta class) which
    # would be used in the GROUP BY clause otherwise. See:
    # https://docs.djangoproject.com/en/1.8/topics/db/aggregation/#interaction-with-default-ordering-or-order-by
    summary = revision.patches.values_list('state', 'state__name',
                                           'state__action_required',
                                           'state__ordering') \
                              .annotate(count=models.Count('state')) \
                              .order_by()
    summary = list(summary)
    summary.sort(key=lambda e: e[3])
    revision.state_summary = [{
        'name': s[1],
        'final': not s[2],
        'count': s[4],
    } for s in summary]

    # revision not yet complete
    revision_complete = revision.patches.count() == revision.n_patches
    if not revision_complete:
        revision.state = RevisionState.INCOMPLETE

    # initial state
    elif len(summary) == 1 and \
       summary[0][0] == get_default_initial_patch_state().pk:
        revision.state = RevisionState.INITIAL

    # done: all patches are in a 'final' state, ie. a state that doesn't
    # require any more action
    elif _revision_is_done(revision, summary):
        revision.state = RevisionState.DONE

    # in progress
    else:
        revision.state = RevisionState.IN_PROGRESS

    revision.save()


def _patch_change_update_revision_state(new_patch):
    # gather all the revisions we need to update (a patch can be part of more
    # than one revision)
    revisions = new_patch.seriesrevision_set.all()

    # we shouldn't hit this since we're careful to not call this function on
    # brand new patches that haven't been linked to a revision yet
    if len(revisions) == 0:
        return

    for rev in revisions:
        _revision_update_state(rev)


def _patch_pre_change_callback(sender, instance, **kwargs):
    # we only want notification of modified patches
    if instance.pk is None:
        return

    if instance.project is None:
        return

    try:
        orig_patch = Patch.objects.get(pk=instance.pk)
    except Patch.DoesNotExist:
        return

    # If there's no interesting changes, abort without creating the
    # notification or log
    if orig_patch.state == instance.state:
        return

    _patch_change_log_event(orig_patch, instance)
    _patch_change_send_notification(orig_patch, instance)


def _patch_post_change_callback(sender, instance, created, **kwargs):
    # We filter out brand new patches because the SeriesRevisionPatch m2m table
    # isn't populated at that point and so we can't query for the
    # SeriesRevision <-> Patch relationship.
    if created:
        return

    _patch_change_update_revision_state(instance)


def _series_revision_patch_post_change_callback(sender, instance, created,
                                                **kwargs):
    # We only hook into that many to many table to cover the case when the
    # patches are first inserted and the SeriesRevision <-> Patch link wasn't
    # established until now.
    if not created:
        return

    _revision_update_state(instance.revision)


models.signals.pre_save.connect(_patch_pre_change_callback, sender=Patch)
models.signals.post_save.connect(_patch_post_change_callback, sender=Patch)
models.signals.post_save.connect(_series_revision_patch_post_change_callback,
                                 sender=SeriesRevisionPatch)


def _on_revision_complete(sender, revision, **kwargs):
    series = revision.series

    # update series.last_revision
    series.last_revision = series.latest_revision()
    series.save()

    # log event
    new_revision = Event.objects.get(name='series-new-revision')
    log = EventLog(event=new_revision, series=series,
                   user=series.submitter.user,
                   parameters={'revision': revision.version})
    log.save()

series_revision_complete.connect(_on_revision_complete)