122 lines
3.6 KiB
Python
122 lines
3.6 KiB
Python
# The core application of the Mia project.
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# by imacat <imacat@mail.imacat.idv.tw>, 2020/7/24
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# Copyright (c) 2020 imacat.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""The session-based POST data storage management of the Mia core application.
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"""
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import random
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from typing import Dict, Mapping, Any, Optional
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from django.http import HttpResponseRedirect, HttpRequest
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from django.shortcuts import redirect
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from .utils import UrlBuilder
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STORAGE_KEY: str = "stored_post"
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def error_redirect(request: HttpRequest, url: str,
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post: Dict[str, str]) -> HttpResponseRedirect:
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"""Redirects to a specific URL on error, with the POST data ID appended
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as the query parameter "s". The POST data can be loaded with the
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get_previous_post() utility.
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Args:
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request (HttpRequest): The request.
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url (str): The destination URL.
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post (dict[str]): The POST data.
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Returns:
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HttpResponseRedirect: The redirect response.
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"""
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post_id = _store(request, post)
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return redirect(str(UrlBuilder(url).query(s=post_id)))
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def get_previous_post(request: HttpRequest) -> Optional[Dict[str, str]]:
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"""Retrieves the previously-stored POST data.
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Args:
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request (HttpRequest): The request.
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Returns:
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dict: The previously-stored POST data.
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"""
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if "s" not in request.GET:
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return None
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return _retrieve(request, request.GET["s"])
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def _store(request: HttpRequest, post: Dict[str, str]) -> str:
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"""Stores the POST data into the session, and returns the POST data ID that
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can be used to retrieve it later with _retrieve().
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Args:
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request: The request.
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post: The POST data.
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Returns:
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The POST data ID
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"""
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if STORAGE_KEY not in request.session:
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request.session[STORAGE_KEY] = {}
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post_id = _new_post_id(request.session[STORAGE_KEY])
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request.session[STORAGE_KEY][post_id] = post
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return post_id
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def _retrieve(request: HttpRequest, post_id: str) -> Optional[Dict[str, str]]:
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"""Retrieves the POST data from the storage.
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Args:
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request: The request.
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post_id: The POST data ID.
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Returns:
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The POST data, or None if the corresponding data does not exist.
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"""
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if STORAGE_KEY not in request.session:
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return None
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if post_id not in request.session[STORAGE_KEY]:
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return None
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return request.session[STORAGE_KEY][post_id]
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def _new_post_id(post_store: Mapping[int, Any]) -> str:
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"""Generates and returns a new POST ID that does not exist yet.
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Args:
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post_store (dict): The POST storage.
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Returns:
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str: The newly-generated POST ID.
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"""
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while True:
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post_id = ""
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while len(post_id) < 16:
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n = random.randint(1, 64)
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if n < 26:
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post_id = post_id + chr(ord("a") + n)
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elif n < 52:
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post_id = post_id + chr(ord("a") + (n - 26))
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elif n < 62:
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post_id = post_id + chr(ord("0") + (n - 52))
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else:
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post_id = post_id + "-_."[n - 62]
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if post_id not in post_store:
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return post_id
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