"""

Wrapper for loading templates from the filesystem.

"""

from django.conf import settings

from django.template import TemplateDoesNotExist

from django.utils._os import safe_join

def get_template_sources(template_name, template_dirs=None):

    """

    Returns the absolute paths to "template_name", when appended to each

    directory in "template_dirs". Any paths that don't lie inside one of the

    template dirs are excluded from the result set, for security reasons.

    """

    if not template_dirs:

        template_dirs = settings.TEMPLATE_DIRS

    for template_dir in template_dirs:

        try:

            yield safe_join(template_dir, template_name)

        except UnicodeDecodeError:

            # The template dir name was a bytestring that wasn't valid UTF-8.

            raise

        except ValueError:

            # The joined path was located outside of this particular

            # template_dir (it might be inside another one, so this isn't

            # fatal).

            pass

def load_template_source(template_name, template_dirs=None):

    tried = []

    for filepath in get_template_sources(template_name, template_dirs):

        try:

            return (open(filepath).read().decode(settings.FILE_CHARSET), filepath)

        except IOError:

            tried.append(filepath)

    if tried:

        error_msg = "Tried %s" % tried

    else:

        error_msg = "Your TEMPLATE_DIRS setting is empty. Change it to point to at least one template directory."

    raise TemplateDoesNotExist, error_msg

load_template_source.is_usable = True