changedetection.io/changedetectionio/store.py

from flask import (
    flash
)

from . model import App, Watch
from copy import deepcopy
from os import path, unlink
from threading import Lock
import json
import logging
import os
import re
import requests
import secrets
import threading
import time
import uuid as uuid_builder

# Is there an existing library to ensure some data store (JSON etc) is in sync with CRUD methods?
# Open a github issue if you know something :)
# https://stackoverflow.com/questions/6190468/how-to-trigger-function-on-value-change
class ChangeDetectionStore:
    lock = Lock()
    # For general updates/writes that can wait a few seconds
    needs_write = False

    # For when we edit, we should write to disk
    needs_write_urgent = False

    __version_check = True

    def __init__(self, datastore_path="/datastore", include_default_watches=True, version_tag="0.0.0"):
        # Should only be active for docker
        # logging.basicConfig(filename='/dev/stdout', level=logging.INFO)
        self.__data = App.model()
        self.datastore_path = datastore_path
        self.json_store_path = "{}/url-watches.json".format(self.datastore_path)
        self.needs_write = False
        self.start_time = time.time()
        self.stop_thread = False
        # Base definition for all watchers
        # deepcopy part of #569 - not sure why its needed exactly
        self.generic_definition = deepcopy(Watch.model(datastore_path = datastore_path, default={}))

        if path.isfile('changedetectionio/source.txt'):
            with open('changedetectionio/source.txt') as f:
                # Should be set in Dockerfile to look for /source.txt , this will give us the git commit #
                # So when someone gives us a backup file to examine, we know exactly what code they were running.
                self.__data['build_sha'] = f.read()

        try:
            # @todo retest with ", encoding='utf-8'"
            with open(self.json_store_path) as json_file:
                from_disk = json.load(json_file)

                # @todo isnt there a way todo this dict.update recursively?
                # Problem here is if the one on the disk is missing a sub-struct, it wont be present anymore.
                if 'watching' in from_disk:
                    self.__data['watching'].update(from_disk['watching'])

                if 'app_guid' in from_disk:
                    self.__data['app_guid'] = from_disk['app_guid']

                if 'settings' in from_disk:
                    if 'headers' in from_disk['settings']:
                        self.__data['settings']['headers'].update(from_disk['settings']['headers'])

                    if 'requests' in from_disk['settings']:
                        self.__data['settings']['requests'].update(from_disk['settings']['requests'])

                    if 'application' in from_disk['settings']:
                        self.__data['settings']['application'].update(from_disk['settings']['application'])

                # Convert each existing watch back to the Watch.model object
                for uuid, watch in self.__data['watching'].items():
                    watch['uuid']=uuid
                    self.__data['watching'][uuid] = Watch.model(datastore_path=self.datastore_path, default=watch)
                    print("Watching:", uuid, self.__data['watching'][uuid]['url'])

        # First time ran, Create the datastore.
        except (FileNotFoundError):
            if include_default_watches:
                print("No JSON DB found at {}, creating JSON store at {}".format(self.json_store_path, self.datastore_path))
                self.add_watch(url='https://news.ycombinator.com/',
                               tag='Tech news',
                               extras={'fetch_backend': 'html_requests'})

                self.add_watch(url='https://changedetection.io/CHANGELOG.txt',
                               tag='changedetection.io',
                               extras={'fetch_backend': 'html_requests'})
        self.__data['version_tag'] = version_tag

        # Just to test that proxies.json if it exists, doesnt throw a parsing error on startup
        test_list = self.proxy_list

        # Helper to remove password protection
        password_reset_lockfile = "{}/removepassword.lock".format(self.datastore_path)
        if path.isfile(password_reset_lockfile):
            self.__data['settings']['application']['password'] = False
            unlink(password_reset_lockfile)

        if not 'app_guid' in self.__data:
            import os
            import sys
            if "pytest" in sys.modules or "PYTEST_CURRENT_TEST" in os.environ:
                self.__data['app_guid'] = "test-" + str(uuid_builder.uuid4())
            else:
                self.__data['app_guid'] = str(uuid_builder.uuid4())

        # Generate the URL access token for RSS feeds
        if not 'rss_access_token' in self.__data['settings']['application']:
            secret = secrets.token_hex(16)
            self.__data['settings']['application']['rss_access_token'] = secret

        # Generate the API access token
        if not 'api_access_token' in self.__data['settings']['application']:
            secret = secrets.token_hex(16)
            self.__data['settings']['application']['api_access_token'] = secret

        # Bump the update version by running updates
        self.run_updates()

        self.needs_write = True

        # Finally start the thread that will manage periodic data saves to JSON
        save_data_thread = threading.Thread(target=self.save_datastore).start()

    def set_last_viewed(self, uuid, timestamp):
        logging.debug("Setting watch UUID: {} last viewed to {}".format(uuid, int(timestamp)))
        self.data['watching'][uuid].update({'last_viewed': int(timestamp)})
        self.needs_write = True

    def remove_password(self):
        self.__data['settings']['application']['password'] = False
        self.needs_write = True

    def update_watch(self, uuid, update_obj):

        # It's possible that the watch could be deleted before update
        if not self.__data['watching'].get(uuid):
            return

        with self.lock:

            # In python 3.9 we have the |= dict operator, but that still will lose data on nested structures...
            for dict_key, d in self.generic_definition.items():
                if isinstance(d, dict):
                    if update_obj is not None and dict_key in update_obj:
                        self.__data['watching'][uuid][dict_key].update(update_obj[dict_key])
                        del (update_obj[dict_key])

            self.__data['watching'][uuid].update(update_obj)

        self.needs_write = True

    @property
    def threshold_seconds(self):
        seconds = 0
        for m, n in Watch.mtable.items():
            x = self.__data['settings']['requests']['time_between_check'].get(m)
            if x:
                seconds += x * n
        return seconds

    @property
    def has_unviewed(self):
        for uuid, watch in self.__data['watching'].items():
            if watch.viewed == False:
                return True
        return False

    @property
    def data(self):
        # Re #152, Return env base_url if not overriden, @todo also prefer the proxy pass url
        env_base_url = os.getenv('BASE_URL','')
        if not self.__data['settings']['application']['base_url']:
          self.__data['settings']['application']['base_url'] = env_base_url.strip('" ')

        return self.__data

    def get_all_tags(self):
        tags = []
        for uuid, watch in self.data['watching'].items():
            if watch['tag'] is None:
                continue
            # Support for comma separated list of tags.
            for tag in watch['tag'].split(','):
                tag = tag.strip()
                if tag not in tags:
                    tags.append(tag)

        tags.sort()
        return tags

    # Delete a single watch by UUID
    def delete(self, uuid):
        import pathlib
        import shutil

        with self.lock:
            if uuid == 'all':
                self.__data['watching'] = {}

                # GitHub #30 also delete history records
                for uuid in self.data['watching']:
                    path = pathlib.Path(os.path.join(self.datastore_path, uuid))
                    shutil.rmtree(path)
                    self.needs_write_urgent = True

            else:
                path = pathlib.Path(os.path.join(self.datastore_path, uuid))
                shutil.rmtree(path)
                del self.data['watching'][uuid]

            self.needs_write_urgent = True

    # Clone a watch by UUID
    def clone(self, uuid):
        url = self.data['watching'][uuid]['url']
        tag = self.data['watching'][uuid]['tag']
        extras = self.data['watching'][uuid]
        new_uuid = self.add_watch(url=url, tag=tag, extras=extras)
        return new_uuid

    def url_exists(self, url):

        # Probably their should be dict...
        for watch in self.data['watching'].values():
            if watch['url'] == url:
                return True

        return False

    # Remove a watchs data but keep the entry (URL etc)
    def clear_watch_history(self, uuid):
        import pathlib

        self.__data['watching'][uuid].update({
                'last_checked': 0,
                'has_ldjson_price_data': None,
                'last_error': False,
                'last_notification_error': False,
                'last_viewed': 0,
                'previous_md5': False,
                'track_ldjson_price_data': None,
            })

        # JSON Data, Screenshots, Textfiles (history index and snapshots), HTML in the future etc
        for item in pathlib.Path(os.path.join(self.datastore_path, uuid)).rglob("*.*"):
            unlink(item)

        # Force the attr to recalculate
        bump = self.__data['watching'][uuid].history

        self.needs_write_urgent = True

    def add_watch(self, url, tag="", extras=None, write_to_disk_now=True):

        if extras is None:
            extras = {}
        # should always be str
        if tag is None or not tag:
            tag = ''

        # Incase these are copied across, assume it's a reference and deepcopy()
        apply_extras = deepcopy(extras)

        # Was it a share link? try to fetch the data
        if (url.startswith("https://changedetection.io/share/")):
            try:
                r = requests.request(method="GET",
                                     url=url,
                                     # So we know to return the JSON instead of the human-friendly "help" page
                                     headers={'App-Guid': self.__data['app_guid']})
                res = r.json()

                # List of permissible attributes we accept from the wild internet
                for k in [
                    'body',
                    'browser_steps',
                    'css_filter',
                    'extract_text',
                    'extract_title_as_title',
                    'headers',
                    'ignore_text',
                    'include_filters',
                    'method',
                    'paused',
                    'previous_md5',
                    'processor',
                    'subtractive_selectors',
                    'tag',
                    'text_should_not_be_present',
                    'title',
                    'trigger_text',
                    'url',
                    'webdriver_js_execute_code',
                ]:
                    if res.get(k):
                        if k != 'css_filter':
                            apply_extras[k] = res[k]
                        else:
                            # We renamed the field and made it a list
                            apply_extras['include_filters'] = [res['css_filter']]

            except Exception as e:
                logging.error("Error fetching metadata for shared watch link", url, str(e))
                flash("Error fetching metadata for {}".format(url), 'error')
                return False
        from .model.Watch import is_safe_url
        if not is_safe_url(url):
            flash('Watch protocol is not permitted by SAFE_PROTOCOL_REGEX', 'error')
            return None

        with self.lock:
            # #Re 569
            new_watch = Watch.model(datastore_path=self.datastore_path, default={
                'url': url,
                'tag': tag
            })

            new_uuid = new_watch['uuid']
            logging.debug("Added URL {} - {}".format(url, new_uuid))

            for k in ['uuid', 'history', 'last_checked', 'last_changed', 'newest_history_key', 'previous_md5', 'viewed']:
                if k in apply_extras:
                    del apply_extras[k]

            new_watch.update(apply_extras)
            self.__data['watching'][new_uuid] = new_watch

        self.__data['watching'][new_uuid].ensure_data_dir_exists()

        if write_to_disk_now:
            self.sync_to_json()

        return new_uuid

    def visualselector_data_is_ready(self, watch_uuid):
        output_path = "{}/{}".format(self.datastore_path, watch_uuid)
        screenshot_filename = "{}/last-screenshot.png".format(output_path)
        elements_index_filename = "{}/elements.json".format(output_path)
        if path.isfile(screenshot_filename) and  path.isfile(elements_index_filename) :
            return True

        return False

    # Save as PNG, PNG is larger but better for doing visual diff in the future
    def save_screenshot(self, watch_uuid, screenshot: bytes, as_error=False):
        if not self.data['watching'].get(watch_uuid):
            return

        if as_error:
            target_path = os.path.join(self.datastore_path, watch_uuid, "last-error-screenshot.png")
        else:
            target_path = os.path.join(self.datastore_path, watch_uuid, "last-screenshot.png")

        self.data['watching'][watch_uuid].ensure_data_dir_exists()

        with open(target_path, 'wb') as f:
            f.write(screenshot)
            f.close()


    def save_error_text(self, watch_uuid, contents):
        if not self.data['watching'].get(watch_uuid):
            return
        target_path = os.path.join(self.datastore_path, watch_uuid, "last-error.txt")

        with open(target_path, 'w') as f:
            f.write(contents)

    def save_xpath_data(self, watch_uuid, data, as_error=False):
        if not self.data['watching'].get(watch_uuid):
            return
        if as_error:
            target_path = os.path.join(self.datastore_path, watch_uuid, "elements-error.json")
        else:
            target_path = os.path.join(self.datastore_path, watch_uuid, "elements.json")

        with open(target_path, 'w') as f:
            f.write(json.dumps(data))
            f.close()


    def sync_to_json(self):
        logging.info("Saving JSON..")
        print("Saving JSON..")
        try:
            data = deepcopy(self.__data)
        except RuntimeError as e:
            # Try again in 15 seconds
            time.sleep(15)
            logging.error ("! Data changed when writing to JSON, trying again.. %s", str(e))
            self.sync_to_json()
            return
        else:

            try:
                # Re #286  - First write to a temp file, then confirm it looks OK and rename it
                # This is a fairly basic strategy to deal with the case that the file is corrupted,
                # system was out of memory, out of RAM etc
                with open(self.json_store_path+".tmp", 'w') as json_file:
                    json.dump(data, json_file, indent=4)
                os.replace(self.json_store_path+".tmp", self.json_store_path)
            except Exception as e:
                logging.error("Error writing JSON!! (Main JSON file save was skipped) : %s", str(e))

            self.needs_write = False
            self.needs_write_urgent = False

    # Thread runner, this helps with thread/write issues when there are many operations that want to update the JSON
    # by just running periodically in one thread, according to python, dict updates are threadsafe.
    def save_datastore(self):

        while True:
            if self.stop_thread:
                print("Shutting down datastore thread")
                return

            if self.needs_write or self.needs_write_urgent:
                self.sync_to_json()

            # Once per minute is enough, more and it can cause high CPU usage
            # better here is to use something like self.app.config.exit.wait(1), but we cant get to 'app' from here
            for i in range(120):
                time.sleep(0.5)
                if self.stop_thread or self.needs_write_urgent:
                    break

    # Go through the datastore path and remove any snapshots that are not mentioned in the index
    # This usually is not used, but can be handy.
    def remove_unused_snapshots(self):
        print ("Removing snapshots from datastore that are not in the index..")

        index=[]
        for uuid in self.data['watching']:
            for id in self.data['watching'][uuid].history:
                index.append(self.data['watching'][uuid].history[str(id)])

        import pathlib

        # Only in the sub-directories
        for uuid in self.data['watching']:
            for item in pathlib.Path(self.datastore_path).rglob(uuid+"/*.txt"):
                if not str(item) in index:
                    print ("Removing",item)
                    unlink(item)

    @property
    def proxy_list(self):
        proxy_list = {}
        proxy_list_file = os.path.join(self.datastore_path, 'proxies.json')

        # Load from external config file
        if path.isfile(proxy_list_file):
            with open("{}/proxies.json".format(self.datastore_path)) as f:
                proxy_list = json.load(f)

        # Mapping from UI config if available
        extras = self.data['settings']['requests'].get('extra_proxies')
        if extras:
            i=0
            for proxy in extras:
                i += 0
                if proxy.get('proxy_name') and proxy.get('proxy_url'):
                    k = "ui-" + str(i) + proxy.get('proxy_name')
                    proxy_list[k] = {'label': proxy.get('proxy_name'), 'url': proxy.get('proxy_url')}


        return proxy_list if len(proxy_list) else None




    def get_preferred_proxy_for_watch(self, uuid):
        """
        Returns the preferred proxy by ID key
        :param uuid: UUID
        :return: proxy "key" id
        """

        if self.proxy_list is None:
            return None

        # If it's a valid one
        watch = self.data['watching'].get(uuid)

        if watch.get('proxy') and watch.get('proxy') in list(self.proxy_list.keys()):
            return watch.get('proxy')

        # not valid (including None), try the system one
        else:
            system_proxy_id = self.data['settings']['requests'].get('proxy')
            # Is not None and exists
            if self.proxy_list.get(system_proxy_id):
                return system_proxy_id


        # Fallback - Did not resolve anything, or doesnt exist, use the first available
        if system_proxy_id is None or not self.proxy_list.get(system_proxy_id):
            first_default = list(self.proxy_list)[0]
            return first_default

        return None

    # Run all updates
    # IMPORTANT - Each update could be run even when they have a new install and the schema is correct
    #             So therefor - each `update_n` should be very careful about checking if it needs to actually run
    #             Probably we should bump the current update schema version with each tag release version?
    def run_updates(self):
        import inspect
        import shutil

        updates_available = []
        for i, o in inspect.getmembers(self, predicate=inspect.ismethod):
            m = re.search(r'update_(\d+)$', i)
            if m:
                updates_available.append(int(m.group(1)))
        updates_available.sort()

        for update_n in updates_available:
            if update_n > self.__data['settings']['application']['schema_version']:
                print ("Applying update_{}".format((update_n)))
                # Wont exist on fresh installs
                if os.path.exists(self.json_store_path):
                    shutil.copyfile(self.json_store_path, self.datastore_path+"/url-watches-before-{}.json".format(update_n))

                try:
                    update_method = getattr(self, "update_{}".format(update_n))()
                except Exception as e:
                    print("Error while trying update_{}".format((update_n)))
                    print(e)
                    # Don't run any more updates
                    return
                else:
                    # Bump the version, important
                    self.__data['settings']['application']['schema_version'] = update_n

    # Convert minutes to seconds on settings and each watch
    def update_1(self):
        if self.data['settings']['requests'].get('minutes_between_check'):
            self.data['settings']['requests']['time_between_check']['minutes'] = self.data['settings']['requests']['minutes_between_check']
            # Remove the default 'hours' that is set from the model
            self.data['settings']['requests']['time_between_check']['hours'] = None

        for uuid, watch in self.data['watching'].items():
            if 'minutes_between_check' in watch:
                # Only upgrade individual watch time if it was set
                if watch.get('minutes_between_check', False):
                    self.data['watching'][uuid]['time_between_check']['minutes'] = watch['minutes_between_check']

    # Move the history list to a flat text file index
    # Better than SQLite because this list is only appended to, and works across NAS / NFS type setups
    def update_2(self):
        # @todo test running this on a newly updated one (when this already ran)
        for uuid, watch in self.data['watching'].items():
            history = []

            if watch.get('history', False):
                for d, p in watch['history'].items():
                    d = int(d)  # Used to be keyed as str, we'll fix this now too
                    history.append("{},{}\n".format(d,p))

                if len(history):
                    target_path = os.path.join(self.datastore_path, uuid)
                    if os.path.exists(target_path):
                        with open(os.path.join(target_path, "history.txt"), "w") as f:
                            f.writelines(history)
                    else:
                        logging.warning("Datastore history directory {} does not exist, skipping history import.".format(target_path))

                # No longer needed, dynamically pulled from the disk when needed.
                # But we should set it back to a empty dict so we don't break if this schema runs on an earlier version.
                # In the distant future we can remove this entirely
                self.data['watching'][uuid]['history'] = {}

    # We incorrectly stored last_changed when there was not a change, and then confused the output list table
    def update_3(self):
        # see https://github.com/dgtlmoon/changedetection.io/pull/835
        return

    # `last_changed` not needed, we pull that information from the history.txt index
    def update_4(self):
        for uuid, watch in self.data['watching'].items():
            try:
                # Remove it from the struct
                del(watch['last_changed'])
            except:
                continue
        return

    def update_5(self):
        # If the watch notification body, title look the same as the global one, unset it, so the watch defaults back to using the main settings
        # In other words - the watch notification_title and notification_body are not needed if they are the same as the default one
        current_system_body = self.data['settings']['application']['notification_body'].translate(str.maketrans('', '', "\r\n "))
        current_system_title = self.data['settings']['application']['notification_body'].translate(str.maketrans('', '', "\r\n "))
        for uuid, watch in self.data['watching'].items():
            try:
                watch_body = watch.get('notification_body', '')
                if watch_body and watch_body.translate(str.maketrans('', '', "\r\n ")) == current_system_body:
                    # Looks the same as the default one, so unset it
                    watch['notification_body'] = None

                watch_title = watch.get('notification_title', '')
                if watch_title and watch_title.translate(str.maketrans('', '', "\r\n ")) == current_system_title:
                    # Looks the same as the default one, so unset it
                    watch['notification_title'] = None
            except Exception as e:
                continue
        return


    # We incorrectly used common header overrides that should only apply to Requests
    # These are now handled in content_fetcher::html_requests and shouldnt be passed to Playwright/Selenium
    def update_7(self):
        # These were hard-coded in early versions
        for v in ['User-Agent', 'Accept', 'Accept-Encoding', 'Accept-Language']:
            if self.data['settings']['headers'].get(v):
                del self.data['settings']['headers'][v]

    # Convert filters to a list of filters css_filter -> include_filters
    def update_8(self):
        for uuid, watch in self.data['watching'].items():
            try:
                existing_filter = watch.get('css_filter', '')
                if existing_filter:
                    watch['include_filters'] = [existing_filter]
            except:
                continue
        return

    # Convert old static notification tokens to jinja2 tokens
    def update_9(self):
        # Each watch
        import re
        # only { } not {{ or }}
        r = r'(?<!{){(?!{)(\w+)(?<!})}(?!})'
        for uuid, watch in self.data['watching'].items():
            try:
                n_body = watch.get('notification_body', '')
                if n_body:
                    watch['notification_body'] = re.sub(r, r'{{\1}}', n_body)

                n_title = watch.get('notification_title')
                if n_title:
                    watch['notification_title'] = re.sub(r, r'{{\1}}', n_title)

                n_urls = watch.get('notification_urls')
                if n_urls:
                    for i, url in enumerate(n_urls):
                        watch['notification_urls'][i] = re.sub(r, r'{{\1}}', url)

            except:
                continue

        # System wide
        n_body = self.data['settings']['application'].get('notification_body')
        if n_body:
            self.data['settings']['application']['notification_body'] = re.sub(r, r'{{\1}}', n_body)

        n_title = self.data['settings']['application'].get('notification_title')
        if n_body:
            self.data['settings']['application']['notification_title'] = re.sub(r, r'{{\1}}', n_title)

        n_urls =  self.data['settings']['application'].get('notification_urls')
        if n_urls:
            for i, url in enumerate(n_urls):
                self.data['settings']['application']['notification_urls'][i] = re.sub(r, r'{{\1}}', url)

        return

    # Some setups may have missed the correct default, so it shows the wrong config in the UI, although it will default to system-wide
    def update_10(self):
        for uuid, watch in self.data['watching'].items():
            try:
                if not watch.get('fetch_backend', ''):
                    watch['fetch_backend'] = 'system'
            except:
                continue
        return