etiquette/frontends/etiquette_flask/backend/common.py

'''
Do not execute this file directly.
Use etiquette_flask_dev.py or etiquette_flask_prod.py.
'''
import flask; from flask import request
import mimetypes
import traceback

from voussoirkit import bytestring
from voussoirkit import flasktools
from voussoirkit import pathclass

import etiquette

from . import client_caching
from . import decorators
from . import jinja_filters
from . import sessions

# Flask init #######################################################################################

root_dir = pathclass.Path(__file__).parent.parent

TEMPLATE_DIR = root_dir.with_child('templates')
STATIC_DIR = root_dir.with_child('static')
FAVICON_PATH = STATIC_DIR.with_child('favicon.png')
BROWSER_CACHE_DURATION = 180

site = flask.Flask(
    __name__,
    template_folder=TEMPLATE_DIR.absolute_path,
    static_folder=STATIC_DIR.absolute_path,
)
site.config.update(
    SEND_FILE_MAX_AGE_DEFAULT=BROWSER_CACHE_DURATION,
    TEMPLATES_AUTO_RELOAD=True,
)
site.jinja_env.add_extension('jinja2.ext.do')
site.jinja_env.trim_blocks = True
site.jinja_env.lstrip_blocks = True
jinja_filters.register_all(site)
site.localhost_only = False

session_manager = sessions.SessionManager(maxlen=10000)
file_etag_manager = client_caching.FileEtagManager(
    maxlen=10000,
    max_filesize=5 * bytestring.MIBIBYTE,
    max_age=BROWSER_CACHE_DURATION,
)

# Response wrappers ################################################################################

# Flask provides decorators for before_request and after_request, but not for
# wrapping the whole request. The decorators I am using need to wrap the whole
# request, either to catch exceptions (which don't get passed through
# after_request) or to maintain some state before running the function and
# adding it to the response after.
# Instead of copy-pasting my decorators onto every single function and
# forgetting to keep up with them in the future, let's just hijack the
# decorator I know every endpoint will have: site.route.
_original_route = site.route
def decorate_and_route(*route_args, **route_kwargs):
    def wrapper(endpoint):
        # Since a function might have multiple routes, we may be seeing the
        # same one multiple times. The _fully_decorated will track that.
        if not hasattr(endpoint, '_fully_decorated'):
            endpoint = flasktools.ensure_response_type(endpoint)
            endpoint = flasktools.give_theme_cookie(
                endpoint,
                cookie_name='etiquette_theme',
                default_theme='slate',
            )
            endpoint = decorators.catch_etiquette_exception(endpoint)
            endpoint = session_manager.give_token(endpoint)

        endpoint = _original_route(*route_args, **route_kwargs)(endpoint)
        endpoint._fully_decorated = True
        return endpoint
    return wrapper
site.route = decorate_and_route

@site.before_request
def before_request():
    # Note for prod: If you see that remote_addr is always 127.0.0.1 for all
    # visitors, make sure your reverse proxy is properly setting X-Forwarded-For
    # so that werkzeug's proxyfix can set that as the remote_addr.
    # In NGINX: proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    request.is_localhost = (request.remote_addr == '127.0.0.1')
    if site.localhost_only and not request.is_localhost:
        flask.abort(403)

@site.after_request
def after_request(response):
    response = flasktools.gzip_response(request, response)
    return response

# P functions ######################################################################################

def P_wrapper(function):
    def P_wrapped(thingid, response_type):
        if response_type not in {'html', 'json'}:
            raise TypeError(f'response_type should be html or json, not {response_type}.')

        try:
            return function(thingid)

        except etiquette.exceptions.EtiquetteException as exc:
            if isinstance(exc, etiquette.exceptions.NoSuch):
                status = 404
            else:
                status = 400

            if response_type == 'html':
                flask.abort(status, exc.error_message)
            else:
                response = exc.jsonify()
                response = flasktools.json_response(response, status=status)
                flask.abort(response)

        except Exception as exc:
            traceback.print_exc()
            if response_type == 'html':
                flask.abort(500)
            else:
                flask.abort(flasktools.json_response({}, status=500))

    return P_wrapped

@P_wrapper
def P_album(album_id):
    return P.get_album(album_id)

@P_wrapper
def P_albums(album_ids):
    return P.get_albums_by_id(album_ids)

@P_wrapper
def P_bookmark(bookmark_id):
    return P.get_bookmark(bookmark_id)

@P_wrapper
def P_photo(photo_id):
    return P.get_photo(photo_id)

@P_wrapper
def P_photos(photo_ids):
    return P.get_photos_by_id(photo_ids)

@P_wrapper
def P_tag(tagname):
    return P.get_tag(name=tagname)

@P_wrapper
def P_tag_id(tag_id):
    return P.get_tag(id=tag_id)

@P_wrapper
def P_user(username):
    return P.get_user(username=username)

@P_wrapper
def P_user_id(user_id):
    return P.get_user(id=user_id)

# Other functions ##################################################################################

def back_url():
    return request.args.get('goto') or request.referrer or '/'

def render_template(request, template_name, **kwargs):
    session = session_manager.get(request)
    theme = request.cookies.get('etiquette_theme', None)

    response = flask.render_template(
        template_name,
        request=request,
        session=session,
        theme=theme,
        **kwargs,
    )
    return response

def send_file(filepath, override_mimetype=None):
    '''
    Range-enabled file sending.
    '''
    filepath = pathclass.Path(filepath)

    if not filepath.is_file:
        flask.abort(404)

    file_size = filepath.size

    headers = file_etag_manager.get_304_headers(request=request, filepath=filepath)
    if headers:
        response = flask.Response(status=304, headers=headers)
        return response

    outgoing_headers = {}
    if override_mimetype is not None:
        mimetype = override_mimetype
    else:
        mimetype = mimetypes.guess_type(filepath.absolute_path)[0]

    if mimetype is not None:
        if 'text/' in mimetype:
            mimetype += '; charset=utf-8'
        outgoing_headers['Content-Type'] = mimetype

    if 'range' in request.headers:
        desired_range = request.headers['range'].lower()
        desired_range = desired_range.split('bytes=')[-1]

        int_helper = lambda x: int(x) if x.isdigit() else None
        if '-' in desired_range:
            (desired_min, desired_max) = desired_range.split('-')
            range_min = int_helper(desired_min)
            range_max = int_helper(desired_max)
        else:
            range_min = int_helper(desired_range)
            range_max = None

        if range_min is None:
            range_min = 0
        if range_max is None:
            range_max = file_size

        # because ranges are 0-indexed
        range_max = min(range_max, file_size - 1)
        range_min = max(range_min, 0)

        range_header = 'bytes {min}-{max}/{outof}'.format(
            min=range_min,
            max=range_max,
            outof=file_size,
        )
        outgoing_headers['Content-Range'] = range_header
        status = 206
    else:
        range_max = file_size - 1
        range_min = 0
        status = 200

    outgoing_headers['Accept-Ranges'] = 'bytes'
    outgoing_headers['Content-Length'] = (range_max - range_min) + 1

    file_etag = file_etag_manager.get_file(filepath)
    if file_etag is not None:
        outgoing_headers.update(file_etag.get_headers())

    if request.method == 'HEAD':
        outgoing_data = bytes()
    else:
        outgoing_data = etiquette.helpers.read_filebytes(
            filepath.absolute_path,
            range_min=range_min,
            range_max=range_max,
            chunk_size=P.config['file_read_chunk'],
        )

    response = flask.Response(
        outgoing_data,
        status=status,
        headers=outgoing_headers,
    )
    return response

####################################################################################################

# These functions will be called by the launcher, flask_dev, flask_prod.

def init_photodb(*args, **kwargs):
    global P
    P = etiquette.photodb.PhotoDB.closest_photodb(*args, **kwargs)