changedetection.io/changedetectionio/fetch_site_status.py

import time
from changedetectionio import content_fetcher
from changedetectionio import html_tools
import hashlib
from inscriptis import get_text
import urllib3
from . import html_tools
import re

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)


# Some common stuff here that can be moved to a base class
class perform_site_check():

    def __init__(self, *args, datastore, **kwargs):
        super().__init__(*args, **kwargs)
        self.datastore = datastore

    def run(self, uuid):
        timestamp = int(time.time())  # used for storage etc too

        changed_detected = False
        stripped_text_from_html = ""

        watch = self.datastore.data['watching'][uuid]
        # Unset any existing notification error

        update_obj = {'last_notification_error': False, 'last_error': False}

        extra_headers = self.datastore.get_val(uuid, 'headers')

        # Tweak the base config with the per-watch ones
        request_headers = self.datastore.data['settings']['headers'].copy()
        request_headers.update(extra_headers)

        # https://github.com/psf/requests/issues/4525
        # Requests doesnt yet support brotli encoding, so don't put 'br' here, be totally sure that the user cannot
        # do this by accident.
        if 'Accept-Encoding' in request_headers and "br" in request_headers['Accept-Encoding']:
            request_headers['Accept-Encoding'] = request_headers['Accept-Encoding'].replace(', br', '')

        # @todo check the failures are really handled how we expect

        else:
            timeout = self.datastore.data['settings']['requests']['timeout']
            url = self.datastore.get_val(uuid, 'url')
            request_body = self.datastore.get_val(uuid, 'body')
            request_method = self.datastore.get_val(uuid, 'method')

            # Pluggable content fetcher
            prefer_backend = watch['fetch_backend']
            if hasattr(content_fetcher, prefer_backend):
                klass = getattr(content_fetcher, prefer_backend)
            else:
                # If the klass doesnt exist, just use a default
                klass = getattr(content_fetcher, "html_requests")


            fetcher = klass()
            fetcher.run(url, timeout, request_headers, request_body, request_method)
            # Fetching complete, now filters
            # @todo move to class / maybe inside of fetcher abstract base?

            # @note: I feel like the following should be in a more obvious chain system
            #  - Check filter text
            #  - Is the checksum different?
            #  - Do we convert to JSON?
            # https://stackoverflow.com/questions/41817578/basic-method-chaining ?
            # return content().textfilter().jsonextract().checksumcompare() ?

            is_json = 'application/json' in fetcher.headers.get('Content-Type', '')
            is_html = not is_json
            css_filter_rule = watch['css_filter']

            has_filter_rule = css_filter_rule and len(css_filter_rule.strip())
            if is_json and not has_filter_rule:
                css_filter_rule = "json:$"
                has_filter_rule = True

            if has_filter_rule:
                if 'json:' in css_filter_rule:
                    stripped_text_from_html = html_tools.extract_json_as_string(content=fetcher.content, jsonpath_filter=css_filter_rule)
                    is_html = False

            if is_html:
                # CSS Filter, extract the HTML that matches and feed that into the existing inscriptis::get_text
                html_content = fetcher.content
                if not fetcher.headers.get('Content-Type', '') == 'text/plain':

                    if has_filter_rule:
                        # For HTML/XML we offer xpath as an option, just start a regular xPath "/.."
                        if css_filter_rule[0] == '/':
                            html_content = html_tools.xpath_filter(xpath_filter=css_filter_rule, html_content=fetcher.content)
                        else:
                            # CSS Filter, extract the HTML that matches and feed that into the existing inscriptis::get_text
                            html_content = html_tools.css_filter(css_filter=css_filter_rule, html_content=fetcher.content)

                    # get_text() via inscriptis
                    stripped_text_from_html = get_text(html_content)
                else:
                    # Don't run get_text or xpath/css filters on plaintext
                    stripped_text_from_html = html_content

            # Re #340 - return the content before the 'ignore text' was applied
            text_content_before_ignored_filter = stripped_text_from_html.encode('utf-8')

            # We rely on the actual text in the html output.. many sites have random script vars etc,
            # in the future we'll implement other mechanisms.

            update_obj["last_check_status"] = fetcher.get_last_status_code()

            # If there's text to skip
            # @todo we could abstract out the get_text() to handle this cleaner
            text_to_ignore = watch.get('ignore_text', []) + self.datastore.data['settings']['application'].get('global_ignore_text', [])
            if len(text_to_ignore):
                stripped_text_from_html = html_tools.strip_ignore_text(stripped_text_from_html, text_to_ignore)
            else:
                stripped_text_from_html = stripped_text_from_html.encode('utf8')

            # Re #133 - if we should strip whitespaces from triggering the change detected comparison
            if self.datastore.data['settings']['application'].get('ignore_whitespace', False):
                fetched_md5 = hashlib.md5(stripped_text_from_html.translate(None, b'\r\n\t ')).hexdigest()
            else:
                fetched_md5 = hashlib.md5(stripped_text_from_html).hexdigest()

            # On the first run of a site, watch['previous_md5'] will be an empty string, set it the current one.
            if not len(watch['previous_md5']):
                watch['previous_md5'] = fetched_md5
                update_obj["previous_md5"] = fetched_md5

            blocked_by_not_found_trigger_text = False

            if len(watch['trigger_text']):
                # Yeah, lets block first until something matches
                blocked_by_not_found_trigger_text = True
                # Filter and trigger works the same, so reuse it
                result = html_tools.strip_ignore_text(content=str(stripped_text_from_html),
                                                      wordlist=watch['trigger_text'],
                                                      mode="line numbers")
                if result:
                    blocked_by_not_found_trigger_text = False


            if not blocked_by_not_found_trigger_text and watch['previous_md5'] != fetched_md5:
                changed_detected = True
                update_obj["previous_md5"] = fetched_md5
                update_obj["last_changed"] = timestamp


            # Extract title as title
            if is_html:
                if self.datastore.data['settings']['application']['extract_title_as_title'] or watch['extract_title_as_title']:
                    if not watch['title'] or not len(watch['title']):
                        update_obj['title'] = html_tools.extract_element(find='title', html_content=fetcher.content)


        return changed_detected, update_obj, text_content_before_ignored_filter