models.py

"""Models for the builds app."""

import datetime
import logging
import os.path
import re
from shutil import rmtree

from django.conf import settings
from django.db import models
from django.db.models import F
from django.urls import reverse
from django.utils import timezone
from django.utils.translation import ugettext
from django.utils.translation import ugettext_lazy as _
from django_extensions.db.models import TimeStampedModel
from jsonfield import JSONField
from polymorphic.models import PolymorphicModel

import readthedocs.builds.automation_actions as actions
from readthedocs.builds.constants import (
    BRANCH,
    BUILD_STATE,
    BUILD_STATE_FINISHED,
    BUILD_STATE_TRIGGERED,
    BUILD_TYPES,
    EXTERNAL,
    GENERIC_EXTERNAL_VERSION_NAME,
    GITHUB_EXTERNAL_VERSION_NAME,
    GITLAB_EXTERNAL_VERSION_NAME,
    INTERNAL,
    LATEST,
    NON_REPOSITORY_VERSIONS,
    STABLE,
    TAG,
    VERSION_TYPES,
)
from readthedocs.builds.managers import (
    BuildManager,
    ExternalBuildManager,
    ExternalVersionManager,
    InternalBuildManager,
    InternalVersionManager,
    VersionAutomationRuleManager,
    VersionManager,
)
from readthedocs.builds.querysets import (
    BuildQuerySet,
    RelatedBuildQuerySet,
    VersionQuerySet,
)
from readthedocs.builds.utils import (
    get_bitbucket_username_repo,
    get_github_username_repo,
    get_gitlab_username_repo,
)
from readthedocs.builds.version_slug import VersionSlugField
from readthedocs.config import LATEST_CONFIGURATION_VERSION
from readthedocs.core.utils import broadcast
from readthedocs.projects.constants import (
    BITBUCKET_COMMIT_URL,
    BITBUCKET_URL,
    GITHUB_BRAND,
    GITHUB_COMMIT_URL,
    GITHUB_PULL_REQUEST_COMMIT_URL,
    GITHUB_PULL_REQUEST_URL,
    GITHUB_URL,
    GITLAB_BRAND,
    GITLAB_COMMIT_URL,
    GITLAB_MERGE_REQUEST_COMMIT_URL,
    GITLAB_MERGE_REQUEST_URL,
    GITLAB_URL,
    MEDIA_TYPES,
    PRIVACY_CHOICES,
    PRIVATE,
)
from readthedocs.projects.models import APIProject, Project
from readthedocs.projects.version_handling import determine_stable_version


log = logging.getLogger(__name__)


class Version(models.Model):

    """Version of a ``Project``."""

    project = models.ForeignKey(
        Project,
        verbose_name=_('Project'),
        related_name='versions',
    )
    type = models.CharField(
        _('Type'),
        max_length=20,
        choices=VERSION_TYPES,
        default='unknown',
    )
    # used by the vcs backend

    #: The identifier is the ID for the revision this is version is for. This
    #: might be the revision number (e.g. in SVN), or the commit hash (e.g. in
    #: Git). If the this version is pointing to a branch, then ``identifier``
    #: will contain the branch name.
    identifier = models.CharField(_('Identifier'), max_length=255)

    #: This is the actual name that we got for the commit stored in
    #: ``identifier``. This might be the tag or branch name like ``"v1.0.4"``.
    #: However this might also hold special version names like ``"latest"``
    #: and ``"stable"``.
    verbose_name = models.CharField(_('Verbose Name'), max_length=255)

    #: The slug is the slugified version of ``verbose_name`` that can be used
    #: in the URL to identify this version in a project. It's also used in the
    #: filesystem to determine how the paths for this version are called. It
    #: must not be used for any other identifying purposes.
    slug = VersionSlugField(
        _('Slug'),
        max_length=255,
        populate_from='verbose_name',
    )

    supported = models.BooleanField(_('Supported'), default=True)
    active = models.BooleanField(_('Active'), default=False)
    built = models.BooleanField(_('Built'), default=False)
    uploaded = models.BooleanField(_('Uploaded'), default=False)
    privacy_level = models.CharField(
        _('Privacy Level'),
        max_length=20,
        choices=PRIVACY_CHOICES,
        default=settings.DEFAULT_VERSION_PRIVACY_LEVEL,
        help_text=_('Level of privacy for this Version.'),
    )
    machine = models.BooleanField(_('Machine Created'), default=False)

    objects = VersionManager.from_queryset(VersionQuerySet)()
    # Only include BRANCH, TAG, UNKNOWN type Versions.
    internal = InternalVersionManager.from_queryset(VersionQuerySet)()
    # Only include EXTERNAL type Versions.
    external = ExternalVersionManager.from_queryset(VersionQuerySet)()

    class Meta:
        unique_together = [('project', 'slug')]
        ordering = ['-verbose_name']
        permissions = (
            # Translators: Permission around whether a user can view the
            #              version
            ('view_version', _('View Version')),
        )

    def __str__(self):
        return ugettext(
            'Version {version} of {project} ({pk})'.format(
                version=self.verbose_name,
                project=self.project,
                pk=self.pk,
            ),
        )

    @property
    def ref(self):
        if self.slug == STABLE:
            stable = determine_stable_version(
                self.project.versions(manager=INTERNAL).all()
            )
            if stable:
                return stable.slug

    @property
    def vcs_url(self):
        """
        Generate VCS (github, gitlab, bitbucket) URL for this version.

        Example: https://github.com/rtfd/readthedocs.org/tree/3.4.2/.
        External Version Example: https://github.com/rtfd/readthedocs.org/pull/99/.
        """
        if self.type == EXTERNAL:
            if 'github' in self.project.repo:
                user, repo = get_github_username_repo(self.project.repo)
                return GITHUB_PULL_REQUEST_URL.format(
                    user=user,
                    repo=repo,
                    number=self.verbose_name,
                )
            if 'gitlab' in self.project.repo:
                user, repo = get_gitlab_username_repo(self.project.repo)
                return GITLAB_MERGE_REQUEST_URL.format(
                    user=user,
                    repo=repo,
                    number=self.verbose_name,
                )
            # TODO: Add VCS URL for BitBucket.
            return ''

        url = ''
        if self.slug == STABLE:
            slug_url = self.ref
        elif self.slug == LATEST:
            slug_url = self.project.default_branch or self.project.vcs_repo().fallback_branch
        else:
            slug_url = self.slug

        if ('github' in self.project.repo) or ('gitlab' in self.project.repo):
            url = f'/tree/{slug_url}/'

        if 'bitbucket' in self.project.repo:
            slug_url = self.identifier
            url = f'/src/{slug_url}'

        # TODO: improve this replacing
        return self.project.repo.replace('git://', 'https://').replace('.git', '') + url

    @property
    def last_build(self):
        return self.builds.order_by('-date').first()

    @property
    def config(self):
        """
        Proxy to the configuration of the build.

        :returns: The configuration used in the last successful build.
        :rtype: dict
        """
        last_build = (
            self.builds(manager=INTERNAL).filter(
                state=BUILD_STATE_FINISHED,
                success=True,
            ).order_by('-date')
            .only('_config')
            .first()
        )
        return last_build.config

    @property
    def commit_name(self):
        """
        Return the branch name, the tag name or the revision identifier.

        The result could be used as ref in a git repo, e.g. for linking to
        GitHub, Bitbucket or GitLab.
        """
        # LATEST is special as it is usually a branch but does not contain the
        # name in verbose_name.
        if self.slug == LATEST:
            if self.project.default_branch:
                return self.project.default_branch
            return self.project.vcs_repo().fallback_branch

        if self.slug == STABLE:
            if self.type == BRANCH:
                # Special case, as we do not store the original branch name
                # that the stable version works on. We can only interpolate the
                # name from the commit identifier, but it's hacky.
                # TODO: Refactor ``Version`` to store more actual info about
                # the underlying commits.
                if self.identifier.startswith('origin/'):
                    return self.identifier[len('origin/'):]
            return self.identifier

        # By now we must have handled all special versions.
        if self.slug in NON_REPOSITORY_VERSIONS:
            raise Exception('All special versions must be handled by now.')

        if self.type in (BRANCH, TAG):
            # If this version is a branch or a tag, the verbose_name will
            # contain the actual name. We cannot use identifier as this might
            # include the "origin/..." part in the case of a branch. A tag
            # would contain the hash in identifier, which is not as pretty as
            # the actual tag name.
            return self.verbose_name

        if self.type == EXTERNAL:
            # If this version is a EXTERNAL version, the identifier will
            # contain the actual commit hash. which we can use to
            # generate url for a given file name
            return self.identifier

        # If we came that far it's not a special version
        # nor a branch, tag or EXTERNAL version.
        # Therefore just return the identifier to make a safe guess.
        log.debug(
            'TODO: Raise an exception here. Testing what cases it happens',
        )
        return self.identifier

    def get_absolute_url(self):
        # Hack external versions for now.
        # TODO: We can integrate them into the resolver
        # but this is much simpler to handle since we only link them a couple places for now
        if self.type == EXTERNAL:
            # Django's static file serving doesn't automatically append index.html
            url = f'{settings.EXTERNAL_VERSION_URL}/html/' \
                f'{self.project.slug}/{self.slug}/index.html'
            return url

        if not self.built and not self.uploaded:
            return reverse(
                'project_version_detail',
                kwargs={
                    'project_slug': self.project.slug,
                    'version_slug': self.slug,
                },
            )
        private = self.privacy_level == PRIVATE
        return self.project.get_docs_url(
            version_slug=self.slug,
            private=private,
        )

    def save(self, *args, **kwargs):  # pylint: disable=arguments-differ
        """Add permissions to the Version for all owners on save."""
        from readthedocs.projects import tasks
        obj = super().save(*args, **kwargs)
        broadcast(
            type='app',
            task=tasks.symlink_project,
            args=[self.project.pk],
        )
        return obj

    def delete(self, *args, **kwargs):  # pylint: disable=arguments-differ
        from readthedocs.projects import tasks
        log.info('Removing files for version %s', self.slug)
        broadcast(
            type='app',
            task=tasks.remove_dirs,
            args=[self.get_artifact_paths()],
        )

        # Remove build artifacts from storage if the version is not external
        if self.type != EXTERNAL:
            storage_paths = self.get_storage_paths()
            tasks.remove_build_storage_paths.delay(storage_paths)

        project_pk = self.project.pk
        super().delete(*args, **kwargs)
        broadcast(
            type='app',
            task=tasks.symlink_project,
            args=[project_pk],
        )

    @property
    def identifier_friendly(self):
        """Return display friendly identifier."""
        if re.match(r'^[0-9a-f]{40}$', self.identifier, re.I):
            return self.identifier[:8]
        return self.identifier

    @property
    def is_editable(self):
        return self.type == BRANCH

    @property
    def supports_wipe(self):
        """Return True if version is not external."""
        return not self.type == EXTERNAL

    def get_subdomain_url(self):
        private = self.privacy_level == PRIVATE
        return self.project.get_docs_url(
            version_slug=self.slug,
            lang_slug=self.project.language,
            private=private,
        )

    def get_downloads(self, pretty=False):
        project = self.project
        data = {}

        def prettify(k):
            return k if pretty else k.lower()

        if project.has_pdf(self.slug, version_type=self.type):
            data[prettify('PDF')] = project.get_production_media_url(
                'pdf',
                self.slug,
            )
        if project.has_htmlzip(self.slug, version_type=self.type):
            data[prettify('HTML')] = project.get_production_media_url(
                'htmlzip',
                self.slug,
            )
        if project.has_epub(self.slug, version_type=self.type):
            data[prettify('Epub')] = project.get_production_media_url(
                'epub',
                self.slug,
            )
        return data

    def get_conf_py_path(self):
        conf_py_path = self.project.conf_dir(self.slug)
        checkout_prefix = self.project.checkout_path(self.slug)
        conf_py_path = os.path.relpath(conf_py_path, checkout_prefix)
        return conf_py_path

    def get_build_path(self):
        """Return version build path if path exists, otherwise `None`."""
        path = self.project.checkout_path(version=self.slug)
        if os.path.exists(path):
            return path
        return None

    def get_artifact_paths(self):
        """
        Return a list of all production artifacts/media path for this version.

        :rtype: list
        """
        paths = []

        for type_ in ('pdf', 'epub', 'htmlzip'):
            paths.append(
                self.project
                .get_production_media_path(type_=type_, version_slug=self.slug),
            )
        paths.append(self.project.rtd_build_path(version=self.slug))

        return paths

    def get_storage_paths(self):
        """
        Return a list of all build artifact storage paths for this version.

        :rtype: list
        """
        paths = []

        for type_ in MEDIA_TYPES:
            paths.append(
                self.project.get_storage_path(
                    type_=type_,
                    version_slug=self.slug,
                    include_file=False,
                    version_type=self.type,
                )
            )

        return paths

    def clean_build_path(self):
        """
        Clean build path for project version.

        Ensure build path is clean for project version. Used to ensure stale
        build checkouts for each project version are removed.
        """
        try:
            path = self.get_build_path()
            if path is not None:
                log.debug('Removing build path %s for %s', path, self)
                rmtree(path)
        except OSError:
            log.exception('Build path cleanup failed')

    def get_github_url(
            self,
            docroot,
            filename,
            source_suffix='.rst',
            action='view',
    ):
        """
        Return a GitHub URL for a given filename.

        :param docroot: Location of documentation in repository
        :param filename: Name of file
        :param source_suffix: File suffix of documentation format
        :param action: `view` (default) or `edit`
        """
        repo_url = self.project.repo
        if 'github' not in repo_url:
            return ''

        if not docroot:
            return ''

        # Normalize /docroot/
        docroot = '/' + docroot.strip('/') + '/'

        if action == 'view':
            action_string = 'blob'
        elif action == 'edit':
            action_string = 'edit'

        user, repo = get_github_username_repo(repo_url)
        if not user and not repo:
            return ''
        repo = repo.rstrip('/')

        if not filename:
            # If there isn't a filename, we don't need a suffix
            source_suffix = ''

        return GITHUB_URL.format(
            user=user,
            repo=repo,
            version=self.commit_name,
            docroot=docroot,
            path=filename,
            source_suffix=source_suffix,
            action=action_string,
        )

    def get_gitlab_url(
            self,
            docroot,
            filename,
            source_suffix='.rst',
            action='view',
    ):
        repo_url = self.project.repo
        if 'gitlab' not in repo_url:
            return ''

        if not docroot:
            return ''

        # Normalize /docroot/
        docroot = '/' + docroot.strip('/') + '/'

        if action == 'view':
            action_string = 'blob'
        elif action == 'edit':
            action_string = 'edit'

        user, repo = get_gitlab_username_repo(repo_url)
        if not user and not repo:
            return ''
        repo = repo.rstrip('/')

        if not filename:
            # If there isn't a filename, we don't need a suffix
            source_suffix = ''

        return GITLAB_URL.format(
            user=user,
            repo=repo,
            version=self.commit_name,
            docroot=docroot,
            path=filename,
            source_suffix=source_suffix,
            action=action_string,
        )

    def get_bitbucket_url(self, docroot, filename, source_suffix='.rst'):
        repo_url = self.project.repo
        if 'bitbucket' not in repo_url:
            return ''
        if not docroot:
            return ''

        # Normalize /docroot/
        docroot = '/' + docroot.strip('/') + '/'

        user, repo = get_bitbucket_username_repo(repo_url)
        if not user and not repo:
            return ''
        repo = repo.rstrip('/')

        if not filename:
            # If there isn't a filename, we don't need a suffix
            source_suffix = ''

        return BITBUCKET_URL.format(
            user=user,
            repo=repo,
            version=self.commit_name,
            docroot=docroot,
            path=filename,
            source_suffix=source_suffix,
        )


class APIVersion(Version):

    """
    Version proxy model for API data deserialization.

    This replaces the pattern where API data was deserialized into a mocked
    :py:class:`Version` object.
    This pattern was confusing, as it was not explicit
    as to what form of object you were working with -- API backed or database
    backed.

    This model preserves the Version model methods, allowing for overrides on
    model field differences. This model pattern will generally only be used on
    builder instances, where we are interacting solely with API data.
    """

    project = None

    class Meta:
        proxy = True

    def __init__(self, *args, **kwargs):
        self.project = APIProject(**kwargs.pop('project', {}))
        # These fields only exist on the API return, not on the model, so we'll
        # remove them to avoid throwing exceptions due to unexpected fields
        for key in ['resource_uri', 'absolute_url', 'downloads']:
            try:
                del kwargs[key]
            except KeyError:
                pass
        super().__init__(*args, **kwargs)

    def save(self, *args, **kwargs):
        return 0


class Build(models.Model):

    """Build data."""

    project = models.ForeignKey(
        Project,
        verbose_name=_('Project'),
        related_name='builds',
    )
    version = models.ForeignKey(
        Version,
        verbose_name=_('Version'),
        null=True,
        related_name='builds',
    )
    type = models.CharField(
        _('Type'),
        max_length=55,
        choices=BUILD_TYPES,
        default='html',
    )
    state = models.CharField(
        _('State'),
        max_length=55,
        choices=BUILD_STATE,
        default='finished',
    )
    date = models.DateTimeField(_('Date'), auto_now_add=True)
    success = models.BooleanField(_('Success'), default=True)

    setup = models.TextField(_('Setup'), null=True, blank=True)
    setup_error = models.TextField(_('Setup error'), null=True, blank=True)
    output = models.TextField(_('Output'), default='', blank=True)
    error = models.TextField(_('Error'), default='', blank=True)
    exit_code = models.IntegerField(_('Exit code'), null=True, blank=True)
    commit = models.CharField(
        _('Commit'),
        max_length=255,
        null=True,
        blank=True,
    )
    _config = JSONField(_('Configuration used in the build'), default=dict)

    length = models.IntegerField(_('Build Length'), null=True, blank=True)

    builder = models.CharField(
        _('Builder'),
        max_length=255,
        null=True,
        blank=True,
    )

    cold_storage = models.NullBooleanField(
        _('Cold Storage'),
        help_text='Build steps stored outside the database.',
    )

    # Managers
    objects = BuildManager.from_queryset(BuildQuerySet)()
    # Only include BRANCH, TAG, UNKNOWN type Version builds.
    internal = InternalBuildManager.from_queryset(BuildQuerySet)()
    # Only include EXTERNAL type Version builds.
    external = ExternalBuildManager.from_queryset(BuildQuerySet)()

    CONFIG_KEY = '__config'

    class Meta:
        ordering = ['-date']
        get_latest_by = 'date'
        index_together = [['version', 'state', 'type']]

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._config_changed = False

    @property
    def previous(self):
        """
        Returns the previous build to the current one.

        Matching the project and version.
        """
        date = self.date or timezone.now()
        if self.project is not None and self.version is not None:
            return (
                Build.objects.filter(
                    project=self.project,
                    version=self.version,
                    date__lt=date,
                ).order_by('-date').first()
            )
        return None

    @property
    def config(self):
        """
        Get the config used for this build.

        Since we are saving the config into the JSON field only when it differs
        from the previous one, this helper returns the correct JSON used in this
        Build object (it could be stored in this object or one of the previous
        ones).
        """
        if self.CONFIG_KEY in self._config:
            return (
                Build.objects
                .only('_config')
                .get(pk=self._config[self.CONFIG_KEY])
                ._config
            )
        return self._config

    @config.setter
    def config(self, value):
        """
        Set `_config` to value.

        `_config` should never be set directly from outside the class.
        """
        self._config = value
        self._config_changed = True

    def save(self, *args, **kwargs):  # noqa
        """
        Save object.

        To save space on the db we only save the config if it's different
        from the previous one.

        If the config is the same, we save the pk of the object
        that has the **real** config under the `CONFIG_KEY` key.
        """
        if self.pk is None or self._config_changed:
            previous = self.previous
            # yapf: disable
            if (
                previous is not None and self._config and
                self._config == previous.config
            ):
                # yapf: enable
                previous_pk = previous._config.get(self.CONFIG_KEY, previous.pk)
                self._config = {self.CONFIG_KEY: previous_pk}
        super().save(*args, **kwargs)
        self._config_changed = False

    def __str__(self):
        return ugettext(
            'Build {project} for {usernames} ({pk})'.format(
                project=self.project,
                usernames=' '.join(
                    self.project.users.all().values_list('username', flat=True),
                ),
                pk=self.pk,
            ),
        )

    def get_absolute_url(self):
        return reverse('builds_detail', args=[self.project.slug, self.pk])

    def get_full_url(self):
        """
        Get full url of the build including domain.

        Example: https://readthedocs.org/projects/pip/builds/99999999/
        """
        scheme = 'http' if settings.DEBUG else 'https'
        full_url = '{scheme}://{domain}{absolute_url}'.format(
            scheme=scheme,
            domain=settings.PRODUCTION_DOMAIN,
            absolute_url=self.get_absolute_url()
        )
        return full_url

    def get_commit_url(self):
        """Return the commit URL."""
        repo_url = self.project.repo
        if self.is_external:
            if 'github' in repo_url:
                user, repo = get_github_username_repo(repo_url)
                if not user and not repo:
                    return ''

                repo = repo.rstrip('/')
                return GITHUB_PULL_REQUEST_COMMIT_URL.format(
                    user=user,
                    repo=repo,
                    number=self.version.verbose_name,
                    commit=self.commit
                )
            if 'gitlab' in repo_url:
                user, repo = get_gitlab_username_repo(repo_url)
                if not user and not repo:
                    return ''

                repo = repo.rstrip('/')
                return GITLAB_MERGE_REQUEST_COMMIT_URL.format(
                    user=user,
                    repo=repo,
                    number=self.version.verbose_name,
                    commit=self.commit
                )
            # TODO: Add External Version Commit URL for BitBucket.
        else:
            if 'github' in repo_url:
                user, repo = get_github_username_repo(repo_url)
                if not user and not repo:
                    return ''

                repo = repo.rstrip('/')
                return GITHUB_COMMIT_URL.format(
                    user=user,
                    repo=repo,
                    commit=self.commit
                )
            if 'gitlab' in repo_url:
                user, repo = get_gitlab_username_repo(repo_url)
                if not user and not repo:
                    return ''

                repo = repo.rstrip('/')
                return GITLAB_COMMIT_URL.format(
                    user=user,
                    repo=repo,
                    commit=self.commit
                )
            if 'bitbucket' in repo_url:
                user, repo = get_bitbucket_username_repo(repo_url)
                if not user and not repo:
                    return ''

                repo = repo.rstrip('/')
                return BITBUCKET_COMMIT_URL.format(
                    user=user,
                    repo=repo,
                    commit=self.commit
                )

        return None

    @property
    def finished(self):
        """Return if build has a finished state."""
        return self.state == BUILD_STATE_FINISHED

    @property
    def is_stale(self):
        """Return if build state is triggered & date more than 5m ago."""
        mins_ago = timezone.now() - datetime.timedelta(minutes=5)
        return self.state == BUILD_STATE_TRIGGERED and self.date < mins_ago

    @property
    def is_external(self):
        return self.version.type == EXTERNAL

    @property
    def external_version_name(self):
        if self.is_external:
            if self.project.git_provider_name == GITHUB_BRAND:
                return GITHUB_EXTERNAL_VERSION_NAME

            if self.project.git_provider_name == GITLAB_BRAND:
                return GITLAB_EXTERNAL_VERSION_NAME

            # TODO: Add External Version Name for BitBucket.
            return GENERIC_EXTERNAL_VERSION_NAME
        return None

    def using_latest_config(self):
        return int(self.config.get('version', '1')) == LATEST_CONFIGURATION_VERSION


class BuildCommandResultMixin:

    """
    Mixin for common command result methods/properties.

    Shared methods between the database model :py:class:`BuildCommandResult` and
    non-model respresentations of build command results from the API
    """

    @property
    def successful(self):
        """Did the command exit with a successful exit code."""
        return self.exit_code == 0

    @property
    def failed(self):
        """
        Did the command exit with a failing exit code.

        Helper for inverse of :py:meth:`successful`
        """
        return not self.successful


class BuildCommandResult(BuildCommandResultMixin, models.Model):

    """Build command for a ``Build``."""

    build = models.ForeignKey(
        Build,
        verbose_name=_('Build'),
        related_name='commands',
    )

    command = models.TextField(_('Command'))
    description = models.TextField(_('Description'), blank=True)
    output = models.TextField(_('Command output'), blank=True)
    exit_code = models.IntegerField(_('Command exit code'))

    start_time = models.DateTimeField(_('Start time'))
    end_time = models.DateTimeField(_('End time'))

    class Meta:
        ordering = ['start_time']
        get_latest_by = 'start_time'

    objects = RelatedBuildQuerySet.as_manager()

    def __str__(self):
        return (
            ugettext('Build command {pk} for build {build}')
            .format(pk=self.pk, build=self.build)
        )

    @property
    def run_time(self):
        """Total command runtime in seconds."""
        if self.start_time is not None and self.end_time is not None:
            diff = self.end_time - self.start_time
            return diff.seconds


class VersionAutomationRule(PolymorphicModel, TimeStampedModel):

    """Versions automation rules for projects."""

    ACTIVATE_VERSION_ACTION = 'activate-version'
    SET_DEFAULT_VERSION_ACTION = 'set-default-version'
    ACTIONS = (
        (ACTIVATE_VERSION_ACTION, _('Activate version on match')),
        (SET_DEFAULT_VERSION_ACTION, _('Set as default version on match')),
    )

    project = models.ForeignKey(
        Project,
        related_name='automation_rules',
        on_delete=models.CASCADE,
    )
    priority = models.IntegerField(
        _('Rule priority'),
        help_text=_('A lower number (0) means a higher priority'),
    )
    description = models.CharField(
        _('Description'),
        max_length=255,
        null=True,
        blank=True,
    )
    match_arg = models.CharField(
        _('Match argument'),
        help_text=_('Value used for the rule to match the version'),
        max_length=255,
    )
    action = models.CharField(
        _('Action'),
        max_length=32,
        choices=ACTIONS,
    )
    action_arg = models.CharField(
        _('Action argument'),
        help_text=_('Value used for the action to perfom an operation'),
        max_length=255,
        null=True,
        blank=True,
    )
    version_type = models.CharField(
        _('Version type'),
        max_length=32,
        choices=VERSION_TYPES,
    )

    objects = VersionAutomationRuleManager()

    class Meta:
        unique_together = (('project', 'priority'),)
        ordering = ('priority', '-modified', '-created')

    def run(self, version, *args, **kwargs):
        """
        Run an action if `version` matches the rule.

        :type version: readthedocs.builds.models.Version
        :returns: True if the action was performed
        """
        if version.type == self.version_type:
            match, result = self.match(version, self.match_arg)
            if match:
                self.apply_action(version, result)
                return True
        return False

    def match(self, version, match_arg):
        """
        Returns True and the match result if the version matches the rule.

        :type version: readthedocs.builds.models.Version
        :param str match_arg: Additional argument to perform the match
        :returns: A tuple of (boolean, match_resul).
                  The result will be passed to `apply_action`.
        """
        return False, None

    def apply_action(self, version, match_result):
        """
        Apply the action from allowed_actions.

        :type version: readthedocs.builds.models.Version
        :param any match_result: Additional context from the match operation
        :raises: NotImplementedError if the action
                 isn't implemented or supported for this rule.
        """
        action = self.allowed_actions.get(self.action)
        if action is None:
            raise NotImplementedError
        action(version, match_result, self.action_arg)

    def move(self, steps):
        """
        Change the priority of this Automation Rule.

        This is done by moving it ``n`` steps,
        relative to the other priority rules.
        The priority from the other rules are updated too.

        :param steps: Number of steps to be moved
                      (it can be negative)
        :returns: True if the priority was changed
        """
        total = self.project.automation_rules.count()
        current_priority = self.priority
        new_priority = (current_priority + steps) % total

        if current_priority == new_priority:
            return False

        # Move other's priority
        if new_priority > current_priority:
            # It was moved down
            rules = (
                self.project.automation_rules
                .filter(priority__gt=current_priority, priority__lte=new_priority)
                # We sort the queryset in asc order
                # to be updated in that order
                # to avoid hitting the unique constraint (project, priority).
                .order_by('priority')
            )
            expression = F('priority') - 1
        else:
            # It was moved up
            rules = (
                self.project.automation_rules
                .filter(priority__lt=current_priority, priority__gte=new_priority)
                .exclude(pk=self.pk)
                # We sort the queryset in desc order
                # to be updated in that order
                # to avoid hitting the unique constraint (project, priority).
                .order_by('-priority')
            )
            expression = F('priority') + 1

        # Put an imposible priority to avoid
        # the unique constraint (project, priority)
        # while updating.
        self.priority = total + 99
        self.save()

        # We update each object one by one to
        # avoid hitting the unique constraint (project, priority).
        for rule in rules:
            rule.priority = expression
            rule.save()

        # Put back new priority
        self.priority = new_priority
        self.save()
        return True

    def delete(self, *args, **kwargs):  # pylint: disable=arguments-differ
        """Override method to update the other priorities after delete."""
        current_priority = self.priority
        project = self.project
        super().delete(*args, **kwargs)

        rules = (
            project.automation_rules
            .filter(priority__gte=current_priority)
            # We sort the queryset in asc order
            # to be updated in that order
            # to avoid hitting the unique constraint (project, priority).
            .order_by('priority')
        )
        # We update each object one by one to
        # avoid hitting the unique constraint (project, priority).
        for rule in rules:
            rule.priority = F('priority') - 1
            rule.save()

    def get_description(self):
        if self.description:
            return self.description
        return f'{self.get_action_display()}'

    def __str__(self):
        class_name = self.__class__.__name__
        return (
            f'({self.priority}) '
            f'{class_name}/{self.get_action_display()} '
            f'for {self.project.slug}:{self.get_version_type_display()}'
        )


class RegexAutomationRule(VersionAutomationRule):

    allowed_actions = {
        VersionAutomationRule.ACTIVATE_VERSION_ACTION: actions.activate_version,
        VersionAutomationRule.SET_DEFAULT_VERSION_ACTION: actions.set_default_version,
    }

    class Meta:
        proxy = True

    def match(self, version, match_arg):
        try:
            match = re.search(
                match_arg, version.verbose_name
            )
            return bool(match), match
        except Exception as e:
            log.info('Error parsing regex: %s', e)
            return False, None