calibre-web/cps/services/SyncToken.py

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
# Copyright (C) 2018-2019 shavitmichael, OzzieIsaacs
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import sys
from base64 import b64decode, b64encode
from jsonschema import validate, exceptions, __version__
from datetime import datetime
try:
from urllib import unquote
except ImportError:
from urllib.parse import unquote
from flask import json
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from .. import logger
log = logger.create()
def b64encode_json(json_data):
if sys.version_info < (3, 0):
return b64encode(json.dumps(json_data))
else:
return b64encode(json.dumps(json_data).encode())
# Python3 has a timestamp() method we could be calling, however it's not avaiable in python2.
def to_epoch_timestamp(datetime_object):
return (datetime_object - datetime(1970, 1, 1)).total_seconds()
def get_datetime_from_json(json_object, field_name):
try:
return datetime.utcfromtimestamp(json_object[field_name])
except (KeyError, OSError, OverflowError):
# OSError is thrown on Windows if timestamp is <1970 or >2038
return datetime.min
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class SyncToken:
""" The SyncToken is used to persist state accross requests.
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When serialized over the response headers, the Kobo device will propagate the token onto following
requests to the service. As an example use-case, the SyncToken is used to detect books that have been added
to the library since the last time the device synced to the server.
Attributes:
books_last_created: Datetime representing the newest book that the device knows about.
books_last_modified: Datetime representing the last modified book that the device knows about.
"""
SYNC_TOKEN_HEADER = "x-kobo-synctoken"
VERSION = "1-1-0"
LAST_MODIFIED_ADDED_VERSION = "1-1-0"
MIN_VERSION = "1-0-0"
token_schema = {
"type": "object",
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"properties": {"version": {"type": "string"}, "data": {"type": "object"}, },
}
# This Schema doesn't contain enough information to detect and propagate book deletions from Calibre to the device.
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# A potential solution might be to keep a list of all known book uuids in the token, and look for any missing
# from the db.
data_schema_v1 = {
"type": "object",
"properties": {
"raw_kobo_store_token": {"type": "string"},
"books_last_modified": {"type": "string"},
"books_last_created": {"type": "string"},
"archive_last_modified": {"type": "string"},
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"reading_state_last_modified": {"type": "string"},
"tags_last_modified": {"type": "string"},
},
}
def __init__(
self,
raw_kobo_store_token="",
books_last_created=datetime.min,
books_last_modified=datetime.min,
archive_last_modified=datetime.min,
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reading_state_last_modified=datetime.min,
tags_last_modified=datetime.min,
):
self.raw_kobo_store_token = raw_kobo_store_token
self.books_last_created = books_last_created
self.books_last_modified = books_last_modified
self.archive_last_modified = archive_last_modified
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self.reading_state_last_modified = reading_state_last_modified
self.tags_last_modified = tags_last_modified
@staticmethod
def from_headers(headers):
sync_token_header = headers.get(SyncToken.SYNC_TOKEN_HEADER, "")
if sync_token_header == "":
return SyncToken()
# On the first sync from a Kobo device, we may receive the SyncToken
# from the official Kobo store. Without digging too deep into it, that
# token is of the form [b64encoded blob].[b64encoded blob 2]
if "." in sync_token_header:
return SyncToken(raw_kobo_store_token=sync_token_header)
try:
sync_token_json = json.loads(
b64decode(sync_token_header + "=" * (-len(sync_token_header) % 4))
)
validate(sync_token_json, SyncToken.token_schema)
if sync_token_json["version"] < SyncToken.MIN_VERSION:
raise ValueError
data_json = sync_token_json["data"]
validate(sync_token_json, SyncToken.data_schema_v1)
except (exceptions.ValidationError, ValueError):
log.error("Sync token contents do not follow the expected json schema.")
return SyncToken()
raw_kobo_store_token = data_json["raw_kobo_store_token"]
try:
books_last_modified = get_datetime_from_json(data_json, "books_last_modified")
books_last_created = get_datetime_from_json(data_json, "books_last_created")
archive_last_modified = get_datetime_from_json(data_json, "archive_last_modified")
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reading_state_last_modified = get_datetime_from_json(data_json, "reading_state_last_modified")
tags_last_modified = get_datetime_from_json(data_json, "tags_last_modified")
except TypeError:
log.error("SyncToken timestamps don't parse to a datetime.")
return SyncToken(raw_kobo_store_token=raw_kobo_store_token)
return SyncToken(
raw_kobo_store_token=raw_kobo_store_token,
books_last_created=books_last_created,
books_last_modified=books_last_modified,
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archive_last_modified=archive_last_modified,
reading_state_last_modified=reading_state_last_modified,
tags_last_modified=tags_last_modified
)
def set_kobo_store_header(self, store_headers):
store_headers.set(SyncToken.SYNC_TOKEN_HEADER, self.raw_kobo_store_token)
def merge_from_store_response(self, store_response):
self.raw_kobo_store_token = store_response.headers.get(
SyncToken.SYNC_TOKEN_HEADER, ""
)
def to_headers(self, headers):
headers[SyncToken.SYNC_TOKEN_HEADER] = self.build_sync_token()
def build_sync_token(self):
token = {
"version": SyncToken.VERSION,
"data": {
"raw_kobo_store_token": self.raw_kobo_store_token,
"books_last_modified": to_epoch_timestamp(self.books_last_modified),
"books_last_created": to_epoch_timestamp(self.books_last_created),
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"archive_last_modified": to_epoch_timestamp(self.archive_last_modified),
"reading_state_last_modified": to_epoch_timestamp(self.reading_state_last_modified),
"tags_last_modified": to_epoch_timestamp(self.tags_last_modified)
},
}
return b64encode_json(token)