models.py

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

import datetime
import os.path
import re
from functools import partial

import regex
import structlog
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 gettext
from django.utils.translation import gettext_lazy as _
from django_extensions.db.fields import (
    CreationDateTimeField,
    ModificationDateTimeField,
)
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_STATUS_CHOICES,
    BUILD_TYPES,
    EXTERNAL,
    GENERIC_EXTERNAL_VERSION_NAME,
    GITHUB_EXTERNAL_VERSION_NAME,
    GITLAB_EXTERNAL_VERSION_NAME,
    INTERNAL,
    LATEST,
    NON_REPOSITORY_VERSIONS,
    PREDEFINED_MATCH_ARGS,
    PREDEFINED_MATCH_ARGS_VALUES,
    STABLE,
    TAG,
    VERSION_TYPES,
)
from readthedocs.builds.managers import (
    AutomationRuleMatchManager,
    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,
    get_vcs_url,
)
from readthedocs.builds.version_slug import VersionSlugField
from readthedocs.config import LATEST_CONFIGURATION_VERSION
from readthedocs.projects.constants import (
    BITBUCKET_COMMIT_URL,
    BITBUCKET_URL,
    DOCTYPE_CHOICES,
    GITHUB_BRAND,
    GITHUB_COMMIT_URL,
    GITHUB_PULL_REQUEST_COMMIT_URL,
    GITHUB_URL,
    GITLAB_BRAND,
    GITLAB_COMMIT_URL,
    GITLAB_MERGE_REQUEST_COMMIT_URL,
    GITLAB_URL,
    MEDIA_TYPES,
    PRIVACY_CHOICES,
    PRIVATE,
    SPHINX,
    SPHINX_HTMLDIR,
    SPHINX_SINGLEHTML,
)
from readthedocs.projects.models import APIProject, Project
from readthedocs.projects.version_handling import determine_stable_version
from readthedocs.storage import build_environment_storage

log = structlog.get_logger(__name__)


class Version(TimeStampedModel):

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

    # Overridden from TimeStampedModel just to allow null values.
    # TODO: remove after deploy.
    created = CreationDateTimeField(
        _('created'),
        null=True,
        blank=True,
    )
    modified = ModificationDateTimeField(
        _('modified'),
        null=True,
        blank=True,
    )

    project = models.ForeignKey(
        Project,
        verbose_name=_('Project'),
        related_name='versions',
        on_delete=models.CASCADE,
    )
    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.'),
    )
    hidden = models.BooleanField(
        _('Hidden'),
        default=False,
        help_text=_('Hide this version from the version (flyout) menu and search results?')
    )
    machine = models.BooleanField(_('Machine Created'), default=False)

    # Whether the latest successful build for this version contains certain media types
    has_pdf = models.BooleanField(_('Has PDF'), default=False)
    has_epub = models.BooleanField(_('Has ePub'), default=False)
    has_htmlzip = models.BooleanField(_('Has HTML Zip'), default=False)

    documentation_type = models.CharField(
        _('Documentation type'),
        max_length=20,
        choices=DOCTYPE_CHOICES,
        default=SPHINX,
        help_text=_(
            'Type of documentation the version was built with.'
        ),
    )

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

    class Meta:
        unique_together = [('project', 'slug')]
        ordering = ['-verbose_name']

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

    @property
    def is_private(self):
        """
        Check if the version is private (taking external versions into consideration).

        The privacy level of an external version is given by
        the value of ``project.external_builds_privacy_level``.
        """
        if self.is_external:
            return self.project.external_builds_privacy_level == PRIVATE
        return self.privacy_level == PRIVATE

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

    @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):
        version_name = self.verbose_name
        if not self.is_external:
            if self.slug == STABLE:
                version_name = self.ref
            elif self.slug == LATEST:
                version_name = self.project.get_default_branch()
            else:
                version_name = self.slug
            if 'bitbucket' in self.project.repo:
                version_name = self.identifier

        return get_vcs_url(
            project=self.project,
            version_type=self.type,
            version_name=version_name,
        )

    @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:
            return self.project.get_default_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):
        """Get absolute url to the docs of the version."""
        if not self.built and not self.uploaded:
            return reverse(
                'project_version_detail',
                kwargs={
                    'project_slug': self.project.slug,
                    'version_slug': self.slug,
                },
            )
        external = self.type == EXTERNAL
        return self.project.get_docs_url(
            version_slug=self.slug,
            external=external,
        )

    def delete(self, *args, **kwargs):  # pylint: disable=arguments-differ
        from readthedocs.projects.tasks.utils import clean_project_resources
        log.info('Removing files for version.', version_slug=self.slug)
        clean_project_resources(self.project, self)
        super().delete(*args, **kwargs)

    @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 self.type != EXTERNAL

    @property
    def is_sphinx_type(self):
        return self.documentation_type in {SPHINX, SPHINX_HTMLDIR, SPHINX_SINGLEHTML}

    def get_subdomain_url(self):
        external = self.type == EXTERNAL
        return self.project.get_docs_url(
            version_slug=self.slug,
            lang_slug=self.project.language,
            external=external,
        )

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

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

        if self.has_pdf:
            data[prettify('PDF')] = project.get_production_media_url(
                'pdf',
                self.slug,
            )

        if self.has_htmlzip:
            data[prettify('HTML')] = project.get_production_media_url(
                'htmlzip',
                self.slug,
            )
        if self.has_epub:
            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_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 get_storage_environment_cache_path(self):
        """Return the path of the cached environment tar file."""
        return build_environment_storage.join(self.project.slug, f'{self.slug}.tar')

    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 ''

        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 ''

        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 ''

        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):  # pylint: disable=arguments-differ
        return 0


class Build(models.Model):

    """Build data."""

    project = models.ForeignKey(
        Project,
        verbose_name=_('Project'),
        related_name='builds',
        on_delete=models.CASCADE,
    )
    version = models.ForeignKey(
        Version,
        verbose_name=_('Version'),
        null=True,
        related_name='builds',
        on_delete=models.SET_NULL,
    )
    type = models.CharField(
        _('Type'),
        max_length=55,
        choices=BUILD_TYPES,
        default='html',
    )

    # Describe build state as where in the build process the build is. This
    # allows us to show progression to the user in the form of a progress bar
    # or in the build listing
    state = models.CharField(
        _('State'),
        max_length=55,
        choices=BUILD_STATE,
        default='finished',
        db_index=True,
    )

    # Describe status as *why* the build is in a particular state. It is
    # helpful for communicating more details about state to the user, but it
    # doesn't help describe progression
    # https://github.com/readthedocs/readthedocs.org/pull/7123#issuecomment-635065807
    status = models.CharField(
        _('Status'),
        choices=BUILD_STATUS_CHOICES,
        max_length=32,
        null=True,
        default=None,
        blank=True,
    )
    date = models.DateTimeField(_('Date'), auto_now_add=True, db_index=True)
    success = models.BooleanField(_('Success'), default=True)

    # TODO: remove these fields (setup, setup_error, output, error, exit_code)
    # since they are not used anymore in the new implementation and only really
    # old builds (>5 years ago) only were using these fields.
    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)

    # Metadata from were the build happened.
    # This is also used after the version is deleted.
    commit = models.CharField(
        _('Commit'),
        max_length=255,
        null=True,
        blank=True,
    )
    version_slug = models.CharField(
        _('Version slug'),
        max_length=255,
        null=True,
        blank=True,
    )
    version_name = models.CharField(
        _('Version name'),
        max_length=255,
        null=True,
        blank=True,
    )
    version_type = models.CharField(
        _('Version type'),
        max_length=32,
        choices=VERSION_TYPES,
        null=True,
        blank=True,
    )
    _config = JSONField(_('Configuration used in the build'), default=dict)
    _config_json = models.JSONField(
        _('Configuration used in the build'),
        null=True,
        blank=True,
    )

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

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

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

    # Managers
    objects = BuildQuerySet.as_manager()
    # 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'],
            ['date', 'id'],
        ]
        indexes = [
            models.Index(fields=['project', 'date']),
        ]

    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).
        """
        # TODO: now that we are using a proper JSONField here, we could
        # probably change this field to be a ForeignKey to avoid repeating the
        # config file over and over again and re-use them to save db data as
        # well
        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
            if (
                previous is not None
                and self._config
                and self._config == previous.config
            ):
                previous_pk = previous._config.get(self.CONFIG_KEY, previous.pk)
                self._config = {self.CONFIG_KEY: previous_pk}

        if self.version:
            self.version_name = self.version.verbose_name
            self.version_slug = self.version.slug
            self.version_type = self.version.type

        # TODO: delete copying config after deploy
        # Copy `_config` into the new `_config_json` JSONField
        self._config_json = self._config

        super().save(*args, **kwargs)
        self._config_changed = False

    def __str__(self):
        return gettext(
            '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_version_name(self):
        if self.version:
            return self.version.verbose_name
        return self.version_name

    def get_version_slug(self):
        if self.version:
            return self.version.verbose_name
        return self.version_name

    def get_version_type(self):
        if self.version:
            return self.version.type
        return self.version_type

    @property
    def vcs_url(self):
        if self.version:
            return self.version.vcs_url
        return get_vcs_url(
            project=self.project,
            version_type=self.get_version_type(),
            version_name=self.get_version_name(),
        )

    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 ''

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

                return GITLAB_MERGE_REQUEST_COMMIT_URL.format(
                    user=user,
                    repo=repo,
                    number=self.get_version_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 ''

                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 ''

                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 ''

                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):
        type = self.version_type
        if self.version:
            type = self.version.type
        return type == EXTERNAL

    @property
    def can_rebuild(self):
        """
        Check if external build can be rebuilt.

        Rebuild can be done only if the build is external,
        build version is active and
        it's the latest build for the version.
        see https://github.com/readthedocs/readthedocs.org/pull/6995#issuecomment-852918969
        """
        if self.is_external:
            is_latest_build = (
                self == Build.objects.filter(
                    project=self.project,
                    version=self.version
                ).only('id').first()
            )
            return self.version and self.version.active and is_latest_build
        return False

    @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

    def reset(self):
        """
        Reset the build so it can be re-used when re-trying.

        Dates and states are usually overridden by the build,
        we care more about deleting the commands.
        """
        self.state = BUILD_STATE_TRIGGERED
        self.status = ''
        self.success = True
        self.output = ''
        self.error = ''
        self.exit_code = None
        self.builder = ''
        self.cold_storage = False
        self.commands.all().delete()
        self.save()


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',
        on_delete=models.CASCADE,
    )

    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 (
            gettext('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'
    DELETE_VERSION_ACTION = 'delete-version'
    HIDE_VERSION_ACTION = 'hide-version'
    MAKE_VERSION_PUBLIC_ACTION = 'make-version-public'
    MAKE_VERSION_PRIVATE_ACTION = 'make-version-private'
    SET_DEFAULT_VERSION_ACTION = 'set-default-version'

    ACTIONS = (
        (ACTIVATE_VERSION_ACTION, _('Activate version')),
        (HIDE_VERSION_ACTION, _('Hide version')),
        (MAKE_VERSION_PUBLIC_ACTION, _('Make version public')),
        (MAKE_VERSION_PRIVATE_ACTION, _('Make version private')),
        (SET_DEFAULT_VERSION_ACTION, _('Set version as default')),
        (DELETE_VERSION_ACTION, _('Delete version (on branch/tag deletion)')),
    )

    allowed_actions_on_create = {}
    allowed_actions_on_delete = {}

    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,
    )
    predefined_match_arg = models.CharField(
        _('Predefined match argument'),
        help_text=_(
            'Match argument defined by us, it is used if is not None, '
            'otherwise match_arg will be used.'
        ),
        max_length=255,
        choices=PREDEFINED_MATCH_ARGS,
        null=True,
        blank=True,
        default=None,
    )
    action = models.CharField(
        _('Action'),
        help_text=_('Action to apply to matching versions'),
        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'),
        help_text=_('Type of version the rule should be applied to'),
        max_length=32,
        choices=VERSION_TYPES,
    )

    objects = VersionAutomationRuleManager()

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

    def get_match_arg(self):
        """Get the match arg defined for `predefined_match_arg` or the match from user."""
        match_arg = PREDEFINED_MATCH_ARGS_VALUES.get(
            self.predefined_match_arg,
        )
        return match_arg or self.match_arg

    def run(self, version, **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:
            return False

        match, result = self.match(version, self.get_match_arg())
        if match:
            self.apply_action(version, result)
            AutomationRuleMatch.objects.register_match(
                rule=self,
                version=version,
            )
            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_on_*.

        :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_on_create.get(self.action)
            or self.allowed_actions_on_delete.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 impossible 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 get_edit_url(self):
        raise NotImplementedError

    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):

    TIMEOUT = 1  # timeout in seconds

    allowed_actions_on_create = {
        VersionAutomationRule.ACTIVATE_VERSION_ACTION: actions.activate_version,
        VersionAutomationRule.HIDE_VERSION_ACTION: actions.hide_version,
        VersionAutomationRule.MAKE_VERSION_PUBLIC_ACTION: actions.set_public_privacy_level,
        VersionAutomationRule.MAKE_VERSION_PRIVATE_ACTION: actions.set_private_privacy_level,
        VersionAutomationRule.SET_DEFAULT_VERSION_ACTION: actions.set_default_version,
    }

    allowed_actions_on_delete = {
        VersionAutomationRule.DELETE_VERSION_ACTION: actions.delete_version,
    }

    class Meta:
        proxy = True

    def match(self, version, match_arg):
        """
        Find a match using regex.search.

        .. note::

           We use the regex module with the timeout
           arg to avoid ReDoS.

           We could use a finite state machine type of regex too,
           but there isn't a stable library at the time of writing this code.
        """
        try:
            match = regex.search(
                match_arg,
                version.verbose_name,
                # Compatible with the re module
                flags=regex.VERSION0,
                timeout=self.TIMEOUT,
            )
            return bool(match), match
        except TimeoutError:
            log.warning(
                'Timeout while parsing regex.',
                pattern=match_arg,
                version_slug=version.slug,
            )
        except Exception as e:
            log.exception('Error parsing regex.', exc_info=True)
        return False, None

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


class AutomationRuleMatch(TimeStampedModel):
    rule = models.ForeignKey(
        VersionAutomationRule,
        verbose_name=_('Matched rule'),
        related_name='matches',
        on_delete=models.CASCADE,
    )

    # Metadata from when the match happened.
    version_name = models.CharField(max_length=255)
    match_arg = models.CharField(max_length=255)
    action = models.CharField(
        max_length=255,
        choices=VersionAutomationRule.ACTIONS,
    )
    version_type = models.CharField(
        max_length=32,
        choices=VERSION_TYPES,
    )

    objects = AutomationRuleMatchManager()

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