~bac/charmworld/tag-constraints

__metaclass__ = type

from datetime import (
    datetime,
    timedelta,
)
from email.utils import parseaddr
from inspect import getargspec
from os.path import (
    join,
)
import re
from urllib import unquote

from gridfs.errors import NoFile
import pymongo
from pyramid.httpexceptions import (
    HTTPFound,
    HTTPNotFound,
)
from pyramid.view import view_config
from webob import Response


from charmworld.models import (
    Bundle,
    BundledCharmDescription,
    Charm,
    CharmFileSet,
    DatedMetricSource,
    FeaturedSource,
    getfs,
    QADataSource,
    resolve_charm_from_description,
)
from charmworld.search import (
    BUNDLE,
    CHARM,
    InvalidCharmType,
    NegativeLimit,
)
from charmworld.utils import (
    build_metric_key,
    quote_key,
    timestamp,
)
from charmworld.views.api.proof import proof_deployer_file
from charmworld.views.utils import (
    get_bundle_downloads,
    json_response,
)


@view_config(route_name="search-json-obsolete")
@view_config(route_name="api-obsolete-0")
@view_config(route_name="api-obsolete-1")
def obsolete(request):
    message = 'This API version is no longer supported.'
    return Response(
        message,
        headerlist=[
            ('Access-Control-Allow-Origin', '*'),
            ('Access-Control-Allow-Headers', 'X-Requested-With'),
            ('Content-Type', 'text/plain'),
            ('Cache-Control', 'max-age=86400, public')
        ],
        status_code=410)


class API3:
    """Implementation of API 3.

    This API is unstable. It is under development. Use API2 if you need
    stability.

    All methods whose names do not begin with an underscore are exposed.
    Methods may return a webob Response, which is returned directly, or a
    json-serializable value, which will be returned as a json HTTP response.
    """
    TEST_STATUSES = ('SUCCESS', 'FAILURE', 'UNSTABLE', 'ABORTED')
    ICON_PATH = '/static/img/'
    ICON_TRAILING = 'file/icon.svg'
    API_ROOT = 'api_3'

    def __init__(self, request):
        self.request = request

    def _handle(self, handler, args, kwargs):
        spec = getargspec(handler)
        if spec.keywords is None:
            for key in set(kwargs).difference(spec.args):
                return json_response(406, {
                    'type': 'parameter_not_supported',
                    'parameter': key})
        return handler(*args, **kwargs)

    def __call__(self):
        """Dispatch the request to the appropriate method.

        Find a method with the same name as 'endpoint'.  Raise HTTPNotFound if
        the method doesn't exist or starts with '_'.

        Return a 406 response if the query parameters are not supported by the
        method.
        """
        if self.request.method == 'OPTIONS':
            return json_response(200, None)
        endpoint = self.request.matchdict['endpoint']
        if endpoint.startswith('_'):
            raise HTTPNotFound(self.request.path)
        handler = getattr(self, endpoint, None)
        remainder = self.request.matchdict.get('remainder')
        if handler is None:
            raise HTTPNotFound(self.request.path)
        if remainder:
            args = (remainder,)
        else:
            args = ()
        kwargs = self.request.GET.dict_of_lists()
        try:
            kwargs['type_'] = kwargs.pop('type')
        except KeyError:
            pass
        result = self._handle(handler, args, kwargs)
        if isinstance(result, Response):
            return result
        return json_response(200, result)

    @staticmethod
    def _get_api_id(charm):
        """Return the API ID for a Mongo-formatted charm."""
        return re.sub('^cs:', '', charm.store_url)

    @staticmethod
    def _parsed_email(address):
        name, address = parseaddr(address)
        return {
            'name': name,
            'email': address,
        }

    @classmethod
    def _format_revision(cls, revision):
        created = datetime.utcfromtimestamp(round(revision['created']))
        authors = [cls._parsed_email(author)
                   for author in revision['authors']]
        return{
            'message': revision['message'],
            'revno': revision['revno'],
            'date': timestamp(created),
            'authors': authors,
        }

    @classmethod
    def _charm_result(cls, charm):
        return {
            'charm': cls._format_charm(charm),
            'metadata': {
                'doctype': CHARM,
            }
        }

    @classmethod
    def _bundle_result(cls, bundle, db, route_url):
        """Build standard metadata around a bundle search result."""
        bundle_obj = Bundle(bundle)
        bundle_metadata = cls._build_bundle_metadata(bundle_obj, db, route_url)
        return {
            'bundle': bundle_metadata,
            'metadata': {
                'doctype': BUNDLE,
            }
        }

    def _related_charms(self, charm_data):
        charm = Charm(charm_data)
        charms_provide = set(charm.i_provides)
        charms_require = set(charm.i_requires)
        # Swap provides and requires, so we get the charms which *require*
        # what these charms provide, and the charms that *provide* what these
        # charms require.
        r_requires, r_provides = self.request.index_client.related_charms(
            charms_provide, charms_require, series=charm.series,
            exclude_name=charm.name)
        f_requires = {}
        for key, value in r_requires.items():
            f_requires[key] = [
                self._format_related(payload['data'], payload['weight'])
                for payload in value]
        f_provides = {}
        for key, value in r_provides.items():
            f_provides[key] = [
                self._format_related(payload['data'], payload['weight'])
                for payload in value]
        return f_requires, f_provides

    @classmethod
    def _format_charm(cls, charm, annotations=None):
        """Format the charm for API consumers."""
        mapping = {
            'summary': 'summary',
            'name': 'name',
            'description': 'description',
            'owner': 'owner',
            'downloads': 'downloads',
            'downloads_in_past_30_days': 'downloads_in_past_30_days',
            'distro_series': 'series',
            'revision': 'revision',
            'url': 'store_url',
        }
        output = dict(
            (key, getattr(charm, value)) for key, value in mapping.items())
        tested_providers = {}
        for provider, result in charm.tests.items():
            if result not in cls.TEST_STATUSES:
                raise ValueError('Unsupported test status: %s' % result)
            tested_providers[provider] = result
        maintainers = charm.maintainers
        maintainer = maintainers[0] if maintainers else ''
        bugs_link = 'https://bugs.launchpad.net/charms/+source/%s' % charm.name
        revisions = [cls._format_revision(rev) for rev in charm.changes]
        output.update({
            'id': cls._get_api_id(charm),
            'categories': charm.categories,
            'rating_numerator': 0,
            'rating_denominator': 0,
            'date_created': charm.date_created,
            'code_source': {
                'type': 'bzr',
                'location': charm.bzr_branch,
                'revision': str(charm.last_change['revno']),
                'last_log': charm.last_change['message'],
                'bugs_link': bugs_link,
                'revisions': revisions,
            },
            'maintainer': cls._parsed_email(maintainer),
            'maintainers': [cls._parsed_email(m) for m in maintainers],
            'relations': {
                'provides': charm.provides,
                'requires': charm.requires,
            },
            'options': charm.options,
            'files': [join(entry['subdir'], entry['filename'])
                      for entry in charm.files.values()],
            'is_approved': charm.promulgated,
            'tested_providers': tested_providers,
            'is_subordinate': charm.subordinate
        })
        if annotations is not None:
            output.update({'annotations': annotations})
        return output

    @classmethod
    def _format_related(cls, charm_data, weight, _now=None):
        if _now is None:
            now = datetime.utcnow()
        else:
            now = _now
        since = now - timedelta(30)
        charm = Charm(charm_data)
        icon_key = quote_key('icon.svg')
        result = {
            'id': cls._get_api_id(charm),
            'name': charm.name,
            'code_source': {
                'type': 'bzr',
                'location': charm.bzr_branch,
                'revision': str(charm.last_change['revno']),
                'last_log': charm.last_change['message'],
            },
            'has_icon': icon_key in charm.files,
            'categories': charm.categories,
            'downloads': charm.downloads,
            'downloads_in_past_30_days': charm.downloads_in_past_30_days,
            'commits_in_past_30_days': len(charm.changes_since(since)),
            'weight': weight,
            'is_approved': charm.promulgated,
        }
        return result

    @staticmethod
    def _extract_charm_id(path):
        """Extract the charm API ID from a path.

        Charm API IDs beginning with a '~' are considered to include an owner.
        If the first element of the path appears to be an owner, then the
        charm API ID consists of the first three path elements, otherwise it
        consists of the first two.
        """
        # Determine if the path includes an owner and adjust the split point
        # appropriately.
        if unquote(path[0])[0] == '~':
            split_point = 3
        else:
            split_point = 2
        # Now that we have figured out which path elements constitute the
        # charm API ID we can join them together.
        charm_id = '/'.join(path[:split_point])
        # Any remaining path elements will also be interesting to the caller.
        if len(path) > split_point:
            trailing = '/'.join(path[split_point:])
        else:
            trailing = None
        return charm_id, trailing

    @staticmethod
    def _parse_bundle_id(path):
        """Extract the bundle API ID from a given URL path.

        Bundle API IDs beginning with a '~' are considered to include an owner.
        Bundle IDs can consist of up to 4 parts.

        - owner (optional)
        - basket (required)
        - version (optional)
        - bundle (required)

        """
        if len(path) < 2:
            raise ValueError('The bundle ID does not contain enough elements')

        # Determine if the path includes an owner and adjust the backet index
        # appropriately.
        owner = None
        if unquote(path[0])[0] == '~':
            owner = path[0]
            basket = path[1]
        else:
            basket = path[0]

        # Now check if there's an optional revision section in there after the
        # basket name.
        version_index = 2 if owner else 1
        try:
            version = int(path[version_index])
        except (IndexError, ValueError):
            # If the url isn't long enough to have a version value, or the
            # value in that slot is not an integer, then no version was
            # provided.
            version = None

        if version is not None:
            if owner:
                # URL includes an owner, a basket, and a version.
                bundle = path[3]
            else:
                # URL does not include an owner and only has a basket,
                # version, and bundle name.
                bundle = path[2]
        else:
            if owner:
                # URL includes an owner, a basket, and a bundle name.
                bundle = path[2]
            else:
                # URL only includes a basket name and a bundle name.
                bundle = path[1]

        # So now we can pull out the parts that are the ID and the rest will
        # be the trailing.
        id_length = 2
        if owner:
            id_length = id_length + 1
        if version:
            id_length = id_length + 1
        parsedId = '/'.join(path[0:id_length])
        trailing = path[id_length:]

        return parsedId, trailing, {
            'owner': owner,
            'basket': basket,
            'version': version,
            'bundle': bundle
        }

    @staticmethod
    def _parse_charm_id(charm_id):
        """Split a charm ID into its component parts.

        Returns a tuple of (owner, series, name, revision).
        """
        elements = [unquote(element) for element in charm_id.split('/')]
        if len(elements) < 2:
            raise ValueError('charm ID does not contain enough elements')
        # If the charm ID includes a revision number, parse it out.
        if re.search('-\d+$', elements[-1]):
            name, revision = elements[-1].rsplit('-', 1)
        else:
            name = elements[-1]
            revision = None
        # If the charm ID includes an owner, parse it out.
        if len(elements) == 3:
            owner = elements[0]
            if not owner.startswith('~'):
                raise ValueError('Owner should begin with a "~".')
            else:
                owner = owner[1:]
        else:
            owner = None
        series = elements[-2]
        return owner, series, name, revision

    def _find_charm(self, path):
        charm_id, trailing = self._extract_charm_id(path)
        try:
            owner, series, name, revision = self._parse_charm_id(charm_id)
        except ValueError:
            charm = None
        else:
            query = {
                'series': series,
                'name': name,
            }
            if revision is not None:
                query['store_data.revision'] = int(revision)
            # If no owner is given, this must be a promulgated charm.
            if owner is None:
                query['promulgated'] = True
            else:
                query['promulgated'] = False
                query['owner'] = owner
            charm = self.request.db.charms.find_one(
                query, sort=[('store_data.revision', pymongo.DESCENDING)])
        return charm_id, trailing, charm

    @classmethod
    def _build_bundle_metadata(cls, bundle, db, route_url):
        bundle_dict = dict(bundle)
        # Add the list of files in the bundle.
        bundle_dict['files'] = bundle.get_file_list(db)
        bundle_dict['charm_metadata'] = {}
        bundle_dict['deployer_file_url'] = route_url(
            'personal-bundle-json-revision',
            basket=bundle_dict['basket_name'],
            bundle=bundle_dict['name'],
            owner=bundle_dict['owner'],
            rev=bundle_dict['basket_revision'],
        )

        # Add in download data.
        downloads = get_bundle_downloads(db, bundle.id)
        bundle_dict['downloads'] = downloads.total
        bundle_dict['downloads_in_past_30_days'] = downloads.past_30_days

        mongo_bundle = db.bundles.find_one({'_id': bundle.id})
        mongo_services = mongo_bundle['data']['services']
        service_data = bundle_dict.get('data')
        # Now load the charm information we require for the services in the
        # bundle.
        for service, data in bundle.data['services'].iteritems():
            description = BundledCharmDescription(
                service, data, service_data.get('series'))
            charm = resolve_charm_from_description(db, description)
            if charm:
                annotations = mongo_services[service].get('annotations')
                formatted = cls._format_charm(
                    Charm(charm), annotations=annotations)
                bundle_dict['charm_metadata'][service] = formatted
                if 'annotations' not in data:
                    data['annotations'] = annotations
        return bundle_dict

    def _find_bundle(self, path):
        try:
            bundle_id, trailing, bundle_bits = self._parse_bundle_id(path)
        except ValueError:
            bundle = bundle_id = trailing = bundle_bits = None
        else:
            if bundle_bits['owner'] and bundle_bits['version']:
                # We have all 4 parts needed, just use the ID.
                query = {'_id': bundle_id}
            elif bundle_bits['owner']:
                # This URL includes the owner, basket name, and bundle name.
                # The specified bundle may be promulgated or not.
                owner = bundle_bits['owner'][1:]  # Strip the tilde.
                query = {
                    'owner': owner,
                    'basket_name': bundle_bits['basket'],
                    'name': bundle_bits['bundle'],
                }
            else:
                query = {
                    'basket_name': bundle_bits['basket'],
                    'name': bundle_bits['bundle'],
                    'promulgated': True,
                }

            bundle = Bundle.from_query(query, self.request.db)
        return bundle_id, trailing, bundle

    def charm(self, path=None, **kwargs):
        """Retrieve a charm according to its API ID (the path prefix)."""
        if path is None:
            raise HTTPNotFound(self.request.path)
        charm_id, trailing, charm_data = self._find_charm(path)

        if path[0] == 'resolve-icon':
            return self._resolve_charm_icon_url(path[1:])

        if charm_data is None:
            return json_response(
                404, {'type': 'no_such_charm', 'charm_id': charm_id})

        charm = Charm(charm_data)
        if trailing is None:
            return self._charm_details(charm_data)
        elif trailing == self.ICON_TRAILING:
            return self._charm_icon(charm, kwargs.get('debug', False))
        elif trailing.startswith('file/'):
            return self._charm_file(charm, trailing)
        elif trailing == 'qa':
            return self._charm_qa(charm)
        elif trailing == 'related':
            return self._charm_related(charm_data)
        else:
            raise HTTPNotFound(self.request.path)

    def _bundle_file(self, bundle, filename):
        file_handle = bundle.get_file(self.request.db, filename)
        if file_handle is None:
            return json_response(
                404, {'type': 'no_such_file', 'file': filename})
        headerlist = self._get_file_headers(
            file_handle.md5, file_handle.content_type)
        return Response(
            file_handle.read(),
            headerlist=headerlist,
            status_code=200)

    bundle_metric_types = ('deployments',)

    def _bundle_metric(self, bundle_id, metric_name, operation):
        """Handle a request for a bundle metric.

        The metric_name will be something like "deployments" and the operation
        can be "total" (retrieve the current total) or "increment" (add one
        to the count).
        """
        # The metric names are a controlled vocabulary.
        if metric_name not in self.bundle_metric_types:
            raise HTTPNotFound
        # Define the key that corresponds to the desired metric.
        metric_key = build_metric_key(metric_name, bundle_id)
        # Create a metric source and look up (or create) the metric.
        source = DatedMetricSource.from_db(self.request.db)
        metric = source.retrieve(metric_key, create=True)
        # Do the thing we were asked to do.
        if operation == 'total':
            return metric.get_total()
        elif operation == 'increment':
            metric.increment()
            # Save the newly updated metric to the database.
            source.store(metric, metric_key)
            return
        else:
            raise HTTPNotFound('unexpected operation: %r' % operation)

    def bundle(self, path=None):
        """Retrieve a bundle based on ID."""
        if path is None:
            raise HTTPNotFound(self.request.path)
        path = list(path)

        if path[0] == 'proof':
            return proof_deployer_file(self.request)

        bundle_id, trailing, bundle = self._find_bundle(path)

        if bundle is None:
            status = 404
            result = {'type': 'no_such_bundle', 'bundle_id': '/'.join(path)}
            return json_response(status, result)
        if not trailing:
            bundle = self._build_bundle_metadata(
                bundle, self.request.db, self.request.route_url)
            return json_response(200, bundle)
        elif trailing and '/'.join(trailing) == self.ICON_TRAILING:
            return self._bundle_icon(bundle)
        elif trailing and trailing[0] == 'file':
            return self._bundle_file(bundle, '/'.join(trailing[1:]))
        elif trailing and trailing[0] == 'metric' and len(trailing) == 3:
            return json_response(
                200, self._bundle_metric(bundle_id, *trailing[1:]))
        else:
            raise HTTPNotFound('/'.join(path))

    @staticmethod
    def _get_file_headers(md5sum, content_type=None):
        headerlist = [
            ("Access-Control-Allow-Origin", "*"),
            ("Access-Control-Allow-Headers", "X-Requested-With"),
            ("Cache-Control", "max-age=86400, public"),
            ("Etag", '"%s"' % md5sum),
        ]
        if content_type is not None:
            headerlist.append(('Content-Type', content_type))
        return headerlist

    def _charm_details(self, charm_data):
        h = charm_data.get('hash')
        if h is not None:
            if_none_match = getattr(self.request, 'if_none_match', None)
            if if_none_match is not None and h in if_none_match:
                return Response('', status_code=304)
            result = self._charm_result(Charm(charm_data))
            return json_response(200, result, [('Etag', h)])
        return self._charm_result(Charm(charm_data))

    def _charm_file(self, charm, trailing):
        path = trailing.split('/', 1)[1]
        file_data = charm.files.get(quote_key(path.split('/')[-1]))
        if file_data is not None:
            if_none_match = getattr(self.request, 'if_none_match', None)
            if if_none_match is not None and file_data['md5'] in if_none_match:
                headerlist = self._get_file_headers(
                    file_data['md5'], file_data.get('contentType'))
                return Response('', headerlist=headerlist, status_code=304)
        fs = getfs(self.request.db)
        file_id = CharmFileSet.gen_fileid(charm._representation, path)
        try:
            charm_file = CharmFileSet.get_by_id(fs, file_id)
        except NoFile:
            return json_response(404, {'type': 'no_such_file', 'path': path})
        headerlist = self._get_file_headers(
            charm_file.md5, charm_file.contentType)
        return Response(
            charm_file.read(),
            headerlist=headerlist,
            status_code=200)

    def _charm_icon(self, charm, debug=False):
        if (charm.files and
                charm.files.get(quote_key('icon.svg')) and
                (debug or charm.promulgated)):
            return self._charm_file(charm, '/icon.svg')
        elif charm.categories:
            main_category = charm.categories[0]
            icon_url = "{0}charm-{1}.svg".format(self.ICON_PATH, main_category)
        else:
            icon_url = self.ICON_PATH + 'charm_160.svg'
        return HTTPFound(icon_url)

    def _resolve_charm_icon_url(self, identifiers):
        identifier = '/'.join(identifiers)
        charm_identification = {}
        series = None

        # Build the data the bundle to resolve it.
        if 'cs:' in identifier:
            # We have a charm: cs:....... to find the charm
            charm_identification['charm'] = identifier
        elif 'lp:' in identifier:
            # We have a branch: lp:.... to find the charm
            charm_identification['branch'] = identifier
        else:
            # See if we have a /series/name.
            bits = identifier.split('/')
            if len(bits) == 2:
                charm_identification['charm'] = bits[1]
                series = bits[0]

        # Find the charm
        charm_description = BundledCharmDescription(
            'skip_is_icon', charm_identification, series=series)
        charm = resolve_charm_from_description(
            self.request.db,
            charm_description)

        if charm:
            # Get the id
            charm = Charm(charm)
            icon_path = API3._get_api_id(charm) + '/file/icon.svg'
            icon_root = self.request.route_path(
                self.API_ROOT,
                endpoint='charm'
            )
            icon_url = icon_root + '/' + icon_path
        else:
            # If the charm is not found, use the default icon
            icon_url = self.ICON_PATH + 'charm_160.svg'

        # Redirect to the proper charm icon url for this charm
        return HTTPFound(icon_url)

    def _bundle_icon(self, bundle):
        # The bundle is currently hard coded to only ever have the one generic
        # icon file.
        icon_url = self.ICON_PATH + 'bundle.svg'
        return HTTPFound(icon_url)

    def _charm_related(self, charm_data):
        requires, provides = self._related_charms(charm_data)
        return {'result': {'requires': requires, 'provides': provides}}

    @staticmethod
    def _format_category(category):
        return dict((key, value) for key, value in category.items()
                    if key != '_id')

    def _charm_qa(self, charm):
        qa_data_source = QADataSource.from_db(self.request.db)
        qa_data = qa_data_source.get_qa_data(charm)
        categories = [self._format_category(category) for category
                      in qa_data.qa_categories.values()]
        scores = qa_data.filtered_scores()
        return {'result': {'questions': categories}, 'scores': scores}

    def search(self, path=None, *args, **kwargs):
        if path is None or path == ['']:
            handler = self._search
        elif path[0] == 'interesting':
            handler = self._interesting_charms_and_bundles
        else:
            raise HTTPNotFound(self.request.path)
        return self._handle(handler, args, kwargs)

    def _search(self, limit=None, name=None, series=None, owner=None,
                provides=None, requires=None, type_=None, provider=None,
                scope=None, categories=None, text=None, autocomplete=False,
                doctype=None, min_score=None):
        """Search for charms and bundles matching parameters.

        :limit: A query limit.  (The max number of results.)  Dispatched as a
           list of numeric characters representing an int, e.g. ['4'].
        :min_score: The minimum score for filtering.  Dispatched as a
           list of numeric characters representing a float, e.g. ['1.1'].
        """
        autocomplete = autocomplete == ['true']
        params = dict((key, value) for key, value in locals().items()
                      if key in ('series', 'owner', 'name', 'categories'))
        if text is None:
            text = ['']
        if min_score is not None:
            min_score = float(min_score[0])
        params['i_provides'] = provides
        params['i_requires'] = requires
        filters = dict(item for item in params.items() if item[1] is not None)
        if limit is not None:
            if len(limit) > 1:
                return json_response(406, {
                                     'type': 'multiple_values',
                                     'parameter': 'limit'})
            limit = int(limit[0])
        try:
            results = self.request.index_client.api_search(
                text[0], filters, type_, limit, autocomplete=autocomplete,
                doctype=doctype, min_score=min_score)
        except InvalidCharmType as e:
            return json_response(406, {
                                 'type': 'unsupported_value',
                                 'parameter': 'type',
                                 'value': e[0]})
        except NegativeLimit:
            return json_response(406, {
                                 'type': 'negative_value',
                                 'parameter': 'limit'})
        return {'result': self._item_results(results)}

    def _item_results(self, items):
        results = []
        for item in items:
            if item['doctype'] == BUNDLE:
                result = self._bundle_result(
                    Bundle(item['data'])._representation,
                    self.request.db,
                    self.request.route_url)
            else:
                result = self._charm_result(Charm(item['data']))
            results.append(result)
        return results

    def _interesting_charms_and_bundles(self, doctype=None):
        """Generate a JSON structure of interesting charms.

        Includes featured, new and popular charms.
        """
        db = self.request.db
        popular = self.request.index_client.api_search(
            sort='downloaded', doctype=doctype, limit=10)
        new = self.request.index_client.api_search(
            sort='new', doctype=doctype, limit=10)
        typed_ids = FeaturedSource.from_db(db).get_featured_typed_ids(doctype)
        featured = self.request.index_client.get_items(typed_ids)
        return {
            'result': {
                'new': self._item_results(new),
                'featured': self._item_results(featured),
                'popular': self._item_results(popular),
            }
        }


class API2(API3):
    """Implementation of API 2.

    This API is stable.

    All methods whose names do not begin with an underscore are exposed.
    Methods may return a webob Response, which is returned directly, or a
    json-serializable value, which will be returned as a json HTTP response.
    """
    ICON_TRAILING = 'icon.svg'
    API_ROOT = 'api_2_single'

    def charms(self, path=None, *args, **kwargs):
        kwargs['doctype'] = CHARM
        if path is None or path == ['']:
            handler = self._search
        elif path[0] == 'interesting':
            handler = self._interesting_charms_and_bundles
        else:
            raise HTTPNotFound(self.request.path)
        return self._handle(handler, args, kwargs)

    def _find_charm(self, path):
        charm_id, trailing = self._extract_charm_id(path)
        try:
            owner, series, name, _ = self._parse_charm_id(charm_id)
        except ValueError:
            charm = None
        else:
            if name.endswith('-HEAD'):
                name = name[:-5]
            if owner is None:
                charm = self.request.db.charms.find_one({
                    'promulgated': True,
                    'series': series,
                    'name': name,
                }, sort=[('store_data.revision', pymongo.DESCENDING)])
            else:
                charm = self.request.db.charms.find_one({
                    'owner': owner,
                    'series': series,
                    'name': name,
                }, sort=[('store_data.revision', pymongo.DESCENDING)])
        if charm is not None:
            api_id = self._get_api_id(Charm(charm))
            # Charm ID should match up to, but not including the revision.
            revisionless_charm_id = charm_id.split('-', 1)[0]
            if not api_id.startswith(revisionless_charm_id):
                charm = None
        return charm_id, trailing, charm