content.py

# -*- coding: utf-8 -*-

from __future__ import division

__copyright__ = "Copyright (C) 2014 Andreas Kloeckner"

__license__ = """
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""

from django.conf import settings
from django.utils.translation import ugettext as _

import re
import datetime
import six

from django.utils.timezone import now
from django.core.exceptions import ObjectDoesNotExist, ImproperlyConfigured
from django.core.urlresolvers import NoReverseMatch

from markdown.extensions import Extension
from markdown.treeprocessors import Treeprocessor

from six.moves import html_parser

from jinja2 import BaseLoader as BaseTemplateLoader, TemplateNotFound

from relate.utils import dict_to_struct

from yaml import load as load_yaml


# {{{ repo interaction

class SubdirRepoWrapper(object):
    def __init__(self, repo, subdir):
        self.repo = repo

        # This wrapper should only get used if there is a subdir to be had.
        assert subdir
        self.subdir = subdir

    def controldir(self):
        return self.repo.controldir()


def get_course_repo_path(course):
    from os.path import join
    return join(settings.GIT_ROOT, course.identifier)


def get_course_repo(course):
    from dulwich.repo import Repo
    repo = Repo(get_course_repo_path(course))

    if course.course_root_path:
        return SubdirRepoWrapper(repo, course.course_root_path)
    else:
        return repo


def get_repo_blob(repo, full_name, commit_sha):
    """
    :arg full_name: A Unicode string indicating the file name.
    :arg commit_sha: A byte string containing the commit hash
    """

    if isinstance(repo, SubdirRepoWrapper):
        # full_name must be non-empty
        full_name = repo.subdir + "/" + full_name
        repo = repo.repo

    names = full_name.split("/")

    # Allow non-ASCII file name
    full_name = full_name.encode('utf-8')

    tree_sha = repo[commit_sha].tree
    tree = repo[tree_sha]

    if not full_name:
        return tree

    try:
        for name in names[:-1]:
            if not name:
                # tolerate empty path components (begrudgingly)
                continue

            mode, blob_sha = tree[name.encode()]
            tree = repo[blob_sha]

        mode, blob_sha = tree[names[-1].encode()]
        return repo[blob_sha]
    except KeyError:
        raise ObjectDoesNotExist(_("resource '%s' not found") % full_name)


def get_repo_blob_data_cached(repo, full_name, commit_sha):
    """
    :arg commit_sha: A byte string containing the commit hash
    """

    if isinstance(commit_sha, six.binary_type):
        from six.moves.urllib.parse import quote_plus
        cache_key = "%%%1".join((
            quote_plus(repo.controldir()),
            quote_plus(full_name),
            commit_sha.decode()))
    else:
        cache_key = None

    try:
        import django.core.cache as cache
    except ImproperlyConfigured:
        cache_key = None

    if cache_key is None:
        return get_repo_blob(repo, full_name, commit_sha).data

    def_cache = cache.caches["default"]

    result = None
    # Memcache is apparently limited to 250 characters.
    if len(cache_key) < 240:
        result = def_cache.get(cache_key)
    if result is not None:
        return result

    result = get_repo_blob(repo, full_name, commit_sha).data

    if len(result) <= getattr(settings, "RELATE_CACHE_MAX_BYTES", 0):
        def_cache.add(cache_key, result, None)

    return result


JINJA_YAML_RE = re.compile(
    r"^\[JINJA\]\s*$(.*?)^\[\/JINJA\]\s*$",
    re.MULTILINE | re.DOTALL)
YAML_BLOCK_START_SCALAR_RE = re.compile(
    r":\s*[|>](?:[0-9][-+]?|[-+][0-9]?)?(?:\s*\#.*)?$")
GROUP_COMMENT_START = re.compile(r"^\s*#\s*\{\{\{")
LEADING_SPACES_RE = re.compile(r"^( *)")


def expand_yaml_macros(repo, commit_sha, yaml_str):
    if isinstance(yaml_str, six.binary_type):
        yaml_str = yaml_str.decode("utf-8")

    from jinja2 import Environment, StrictUndefined
    jinja_env = Environment(
            loader=GitTemplateLoader(repo, commit_sha),
            undefined=StrictUndefined)

    def compute_replacement(match):
        template = jinja_env.from_string(match.group(1))
        return template.render()

    yaml_str, count = JINJA_YAML_RE.subn(compute_replacement, yaml_str)

    if count:
        # The file uses explicit YAML tags. Assume that it doesn't
        # want anything else processed through YAML.
        return yaml_str

    # {{{ process non-block-scalar YAML lines through Jinja

    block_var_num = [0]
    block_vars = {}
    block_name_template = "_RELATE_JINJA_BLOCK_SUB_%d"

    lines = yaml_str.split("\n")
    jinja_lines = []

    def add_unprocessed_block(s):
        my_block_num = block_var_num[0]
        block_var_num[0] += 1

        my_block_name = block_name_template % my_block_num
        block_vars[my_block_name] = s
        jinja_lines.append("{{ %s }}" % my_block_name)