base.py

# encoding: utf-8

"""The base Controller API

Provides the BaseController class for subclassing.
"""
import logging
import time
import inspect
import sys

from pylons import cache
from pylons.controllers import WSGIController
from pylons.controllers.util import abort as _abort
from pylons.decorators import jsonify
from pylons.templating import cached_template, pylons_globals
from jinja2.exceptions import TemplateNotFound

from flask import (
    render_template as flask_render_template,
    abort as flask_abort
)
import ckan.exceptions
import ckan
import ckan.lib.i18n as i18n
import ckan.lib.render as render_
import ckan.lib.helpers as h
import ckan.lib.app_globals as app_globals
import ckan.plugins as p
import ckan.model as model

from ckan.views import (identify_user,
                        set_cors_headers_for_response,
                        check_session_cookie,
                        )

# These imports are for legacy usages and will be removed soon these should
# be imported directly from ckan.common for internal ckan code and via the
# plugins.toolkit for extensions.
from ckan.common import (json, _, ungettext, c, request, response, config,
                         session, is_flask_request)

log = logging.getLogger(__name__)

APIKEY_HEADER_NAME_KEY = 'apikey_header_name'
APIKEY_HEADER_NAME_DEFAULT = 'X-CKAN-API-Key'


def abort(status_code=None, detail='', headers=None, comment=None):
    '''Abort the current request immediately by returning an HTTP exception.

    This is a wrapper for :py:func:`pylons.controllers.util.abort` that adds
    some CKAN custom behavior, including allowing
    :py:class:`~ckan.plugins.interfaces.IAuthenticator` plugins to alter the
    abort response, and showing flash messages in the web interface.

    '''
    if status_code == 403:
        # Allow IAuthenticator plugins to alter the abort
        for item in p.PluginImplementations(p.IAuthenticator):
            result = item.abort(status_code, detail, headers, comment)
            (status_code, detail, headers, comment) = result

    if detail and status_code != 503:
        h.flash_error(detail)

    if is_flask_request():
        flask_abort(status_code, detail)

    # #1267 Convert detail to plain text, since WebOb 0.9.7.1 (which comes
    # with Lucid) causes an exception when unicode is received.
    detail = detail.encode('utf8')

    return _abort(status_code=status_code,
                  detail=detail,
                  headers=headers,
                  comment=comment)


def render_snippet(*template_names, **kw):
    ''' Helper function for rendering snippets. Rendered html has
    comment tags added to show the template used. NOTE: unlike other
    render functions this takes a list of keywords instead of a dict for
    the extra template variables.

    :param template_names: the template to render, optionally with fallback
        values, for when the template can't be found. For each, specify the
        relative path to the template inside the registered tpl_dir.
    :type template_names: str
    :param kw: extra template variables to supply to the template
    :type kw: named arguments of any type that are supported by the template
    '''

    exc = None
    for template_name in template_names:
        try:
            output = render(template_name, extra_vars=kw)
            if config.get('debug'):
                output = (
                    '\n<!-- Snippet %s start -->\n%s\n<!-- Snippet %s end -->'
                    '\n' % (template_name, output, template_name))
            return h.literal(output)
        except TemplateNotFound as exc:
            if exc.name == template_name:
                # the specified template doesn't exist - try the next fallback
                continue
            # a nested template doesn't exist - don't fallback
            raise exc
    else:
        raise exc or TemplateNotFound


def render_jinja2(template_name, extra_vars):
    env = config['pylons.app_globals'].jinja_env
    template = env.get_template(template_name)
    return template.render(**extra_vars)


def render(template_name, extra_vars=None, *pargs, **kwargs):
    '''Render a template and return the output.

    This is CKAN's main template rendering function.

    :params template_name: relative path to template inside registered tpl_dir
    :type template_name: str
    :params extra_vars: additional variables available in template
    :type extra_vars: dict
    :params pargs: DEPRECATED
    :type pargs: tuple
    :params kwargs: DEPRECATED
    :type kwargs: dict

    '''
    if pargs or kwargs:
        tb = inspect.getframeinfo(sys._getframe(1))
        log.warning(
            'Extra arguments to `base.render` are deprecated: ' +
            '<{0.filename}:{0.lineno}>'.format(tb)
        )

    if extra_vars is None:
        extra_vars = {}

    if not is_flask_request():
        renderer = _pylons_prepare_renderer(template_name, extra_vars,
                                            *pargs, **kwargs)
        return cached_template(template_name, renderer)

    return flask_render_template(template_name, **extra_vars)


def _pylons_prepare_renderer(template_name, extra_vars, cache_key=None,
                             cache_type=None, cache_expire=None,
                             cache_force=None, renderer=None):
    def render_template():
        globs = extra_vars or {}
        globs.update(pylons_globals())

        # Using pylons.url() directly destroys the localisation stuff so
        # we remove it so any bad templates crash and burn
        del globs['url']

        try:
            template_path, template_type = render_.template_info(template_name)
        except render_.TemplateNotFound:
            raise

        log.debug('rendering %s [%s]' % (template_path, template_type))
        if config.get('debug'):
            context_vars = globs.get('c')
            if context_vars:
                context_vars = dir(context_vars)
            debug_info = {'template_name': template_name,
                          'template_path': template_path,
                          'template_type': template_type,
                          'vars': globs,
                          'c_vars': context_vars,
                          'renderer': renderer}
            if 'CKAN_DEBUG_INFO' not in request.environ:
                request.environ['CKAN_DEBUG_INFO'] = []
            request.environ['CKAN_DEBUG_INFO'].append(debug_info)

        del globs['config']
        return render_jinja2(template_name, globs)

    def set_pylons_response_headers(allow_cache):
        if 'Pragma' in response.headers:
            del response.headers["Pragma"]
        if allow_cache:
            response.headers["Cache-Control"] = "public"
            try:
                cache_expire = int(config.get('ckan.cache_expires', 0))
                response.headers["Cache-Control"] += \
                    ", max-age=%s, must-revalidate" % cache_expire
            except ValueError:
                pass
        else:
            # We do not want caching.
            response.headers["Cache-Control"] = "private"

    # Caching Logic

    allow_cache = True
    # Force cache or not if explicit.
    if cache_force is not None:
        allow_cache = cache_force
    # Do not allow caching of pages for logged in users/flash messages etc.
    elif session.last_accessed:
        allow_cache = False
    # Tests etc.
    elif 'REMOTE_USER' in request.environ:
        allow_cache = False
    # Don't cache if based on a non-cachable template used in this.
    elif request.environ.get('__no_cache__'):
        allow_cache = False
    # Don't cache if we have set the __no_cache__ param in the query string.
    elif request.params.get('__no_cache__'):
        allow_cache = False
    # Don't cache if we have extra vars containing data.
    elif extra_vars:
        for k, v in extra_vars.iteritems():
            allow_cache = False
            break

    # TODO: replicate this logic in Flask once we start looking at the
    # rendering for the frontend controllers
    set_pylons_response_headers(allow_cache)

    if not allow_cache:
        # Prevent any further rendering from being cached.
        request.environ['__no_cache__'] = True

    return render_template


class ValidationException(Exception):
    pass


class BaseController(WSGIController):
    '''Base class for CKAN controller classes to inherit from.

    '''
    repo = model.repo
    log = logging.getLogger(__name__)

    def __before__(self, action, **params):
        c.__timer = time.time()
        app_globals.app_globals._check_uptodate()

        identify_user()

        i18n.handle_request(request, c)

    def __call__(self, environ, start_response):
        """Invoke the Controller"""
        # WSGIController.__call__ dispatches to the Controller method
        # the request is routed to. This routing information is
        # available in environ['pylons.routes_dict']

        try:
            res = WSGIController.__call__(self, environ, start_response)
        finally:
            model.Session.remove()

        check_session_cookie(response)

        return res

    def __after__(self, action, **params):

        set_cors_headers_for_response(response)

        r_time = time.time() - c.__timer
        url = request.environ['CKAN_CURRENT_URL'].split('?')[0]
        log.info(' %s render time %.3f seconds' % (url, r_time))


# Include the '_' function in the public names
__all__ = [__name for __name in locals().keys() if not __name.startswith('_')
           or __name == '_']