__init__.py

from abc import abstractmethod
from changedetectionio.content_fetchers.base import Fetcher
from changedetectionio.strtobool import strtobool
from copy import deepcopy
from loguru import logger
import hashlib
import importlib
import inspect
import os
import pkgutil
import re

class difference_detection_processor():

    browser_steps = None
    datastore = None
    fetcher = None
    screenshot = None
    watch = None
    xpath_data = None
    preferred_proxy = None

    def __init__(self, *args, datastore, watch_uuid, **kwargs):
        super().__init__(*args, **kwargs)
        self.datastore = datastore
        self.watch = deepcopy(self.datastore.data['watching'].get(watch_uuid))
        # Generic fetcher that should be extended (requests, playwright etc)
        self.fetcher = Fetcher()

    def call_browser(self, preferred_proxy_id=None):

        from requests.structures import CaseInsensitiveDict

        url = self.watch.link

        # Protect against file:// access, check the real "link" without any meta "source:" etc prepended.
        if re.search(r'^file://', url, re.IGNORECASE):
            if not strtobool(os.getenv('ALLOW_FILE_URI', 'false')):
                raise Exception(
                    "file:// type access is denied for security reasons."
                )

        # Requests, playwright, other browser via wss:// etc, fetch_extra_something
        prefer_fetch_backend = self.watch.get('fetch_backend', 'system')

        # Proxy ID "key"
        preferred_proxy_id = preferred_proxy_id if preferred_proxy_id else self.datastore.get_preferred_proxy_for_watch(uuid=self.watch.get('uuid'))

        # Pluggable content self.fetcher
        if not prefer_fetch_backend or prefer_fetch_backend == 'system':
            prefer_fetch_backend = self.datastore.data['settings']['application'].get('fetch_backend')

        # In the case that the preferred fetcher was a browser config with custom connection URL..
        # @todo - on save watch, if its extra_browser_ then it should be obvious it will use playwright (like if its requests now..)
        custom_browser_connection_url = None
        if prefer_fetch_backend.startswith('extra_browser_'):
            (t, key) = prefer_fetch_backend.split('extra_browser_')
            connection = list(
                filter(lambda s: (s['browser_name'] == key), self.datastore.data['settings']['requests'].get('extra_browsers', [])))
            if connection:
                prefer_fetch_backend = 'html_webdriver'
                custom_browser_connection_url = connection[0].get('browser_connection_url')

        # PDF should be html_requests because playwright will serve it up (so far) in a embedded page
        # @todo https://github.com/dgtlmoon/changedetection.io/issues/2019
        # @todo needs test to or a fix
        if self.watch.is_pdf:
           prefer_fetch_backend = "html_requests"

        # Grab the right kind of 'fetcher', (playwright, requests, etc)
        from changedetectionio import content_fetchers
        if hasattr(content_fetchers, prefer_fetch_backend):
            # @todo TEMPORARY HACK - SWITCH BACK TO PLAYWRIGHT FOR BROWSERSTEPS
            if prefer_fetch_backend == 'html_webdriver' and self.watch.has_browser_steps:
                # This is never supported in selenium anyway
                logger.warning("Using playwright fetcher override for possible puppeteer request in browsersteps, because puppetteer:browser steps is incomplete.")
                from changedetectionio.content_fetchers.playwright import fetcher as playwright_fetcher
                fetcher_obj = playwright_fetcher
            else:
                fetcher_obj = getattr(content_fetchers, prefer_fetch_backend)
        else:
            # What it referenced doesnt exist, Just use a default
            fetcher_obj = getattr(content_fetchers, "html_requests")

        proxy_url = None
        if preferred_proxy_id:
            # Custom browser endpoints should NOT have a proxy added
            if not prefer_fetch_backend.startswith('extra_browser_'):
                proxy_url = self.datastore.proxy_list.get(preferred_proxy_id).get('url')
                logger.debug(f"Selected proxy key '{preferred_proxy_id}' as proxy URL '{proxy_url}' for {url}")
            else:
                logger.debug(f"Skipping adding proxy data when custom Browser endpoint is specified. ")

        # Now call the fetcher (playwright/requests/etc) with arguments that only a fetcher would need.
        # When browser_connection_url is None, it method should default to working out whats the best defaults (os env vars etc)
        self.fetcher = fetcher_obj(proxy_override=proxy_url,
                                   custom_browser_connection_url=custom_browser_connection_url
                                   )

        if self.watch.has_browser_steps:
            self.fetcher.browser_steps = self.watch.get('browser_steps', [])
            self.fetcher.browser_steps_screenshot_path = os.path.join(self.datastore.datastore_path, self.watch.get('uuid'))

        # Tweak the base config with the per-watch ones
        from changedetectionio.safe_jinja import render as jinja_render
        request_headers = CaseInsensitiveDict()

        ua = self.datastore.data['settings']['requests'].get('default_ua')
        if ua and ua.get(prefer_fetch_backend):
            request_headers.update({'User-Agent': ua.get(prefer_fetch_backend)})

        request_headers.update(self.watch.get('headers', {}))
        request_headers.update(self.datastore.get_all_base_headers())
        request_headers.update(self.datastore.get_all_headers_in_textfile_for_watch(uuid=self.watch.get('uuid')))

        # 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', '')

        for header_name in request_headers:
            request_headers.update({header_name: jinja_render(template_str=request_headers.get(header_name))})

        timeout = self.datastore.data['settings']['requests'].get('timeout')

        request_body = self.watch.get('body')
        if request_body:
            request_body = jinja_render(template_str=self.watch.get('body'))
        
        request_method = self.watch.get('method')
        ignore_status_codes = self.watch.get('ignore_status_codes', False)

        # Configurable per-watch or global extra delay before extracting text (for webDriver types)
        system_webdriver_delay = self.datastore.data['settings']['application'].get('webdriver_delay', None)
        if self.watch.get('webdriver_delay'):
            self.fetcher.render_extract_delay = self.watch.get('webdriver_delay')
        elif system_webdriver_delay is not None:
            self.fetcher.render_extract_delay = system_webdriver_delay

        if self.watch.get('webdriver_js_execute_code') is not None and self.watch.get('webdriver_js_execute_code').strip():
            self.fetcher.webdriver_js_execute_code = self.watch.get('webdriver_js_execute_code')

        # Requests for PDF's, images etc should be passwd the is_binary flag
        is_binary = self.watch.is_pdf

        # And here we go! call the right browser with browser-specific settings
        empty_pages_are_a_change = self.datastore.data['settings']['application'].get('empty_pages_are_a_change', False)

        self.fetcher.run(url=url,
                         timeout=timeout,
                         request_headers=request_headers,
                         request_body=request_body,
                         request_method=request_method,
                         ignore_status_codes=ignore_status_codes,
                         current_include_filters=self.watch.get('include_filters'),
                         is_binary=is_binary,
                         empty_pages_are_a_change=empty_pages_are_a_change
                         )

        #@todo .quit here could go on close object, so we can run JS if change-detected
        self.fetcher.quit()

        # After init, call run_changedetection() which will do the actual change-detection

    @abstractmethod
    def run_changedetection(self, watch):
        update_obj = {'last_notification_error': False, 'last_error': False}
        some_data = 'xxxxx'
        update_obj["previous_md5"] = hashlib.md5(some_data.encode('utf-8')).hexdigest()
        changed_detected = False
        return changed_detected, update_obj, ''.encode('utf-8')


def find_sub_packages(package_name):
    """
    Find all sub-packages within the given package.

    :param package_name: The name of the base package to scan for sub-packages.
    :return: A list of sub-package names.
    """
    package = importlib.import_module(package_name)
    return [name for _, name, is_pkg in pkgutil.iter_modules(package.__path__) if is_pkg]


def find_processors():
    """
    Find all subclasses of DifferenceDetectionProcessor in the specified package.

    :param package_name: The name of the package to scan for processor modules.
    :return: A list of (module, class) tuples.
    """
    package_name = "changedetectionio.processors"  # Name of the current package/module

    processors = []
    sub_packages = find_sub_packages(package_name)

    for sub_package in sub_packages:
        module_name = f"{package_name}.{sub_package}.processor"
        try:
            module = importlib.import_module(module_name)

            # Iterate through all classes in the module
            for name, obj in inspect.getmembers(module, inspect.isclass):
                if issubclass(obj, difference_detection_processor) and obj is not difference_detection_processor:
                    processors.append((module, sub_package))
        except (ModuleNotFoundError, ImportError) as e:
            logger.warning(f"Failed to import module {module_name}: {e} (find_processors())")

    return processors


def get_parent_module(module):
    module_name = module.__name__
    if '.' not in module_name:
        return None  # Top-level module has no parent
    parent_module_name = module_name.rsplit('.', 1)[0]
    try:
        return importlib.import_module(parent_module_name)
    except Exception as e:
        pass

    return False



def get_custom_watch_obj_for_processor(processor_name):
    from changedetectionio.model import Watch
    watch_class = Watch.model
    processor_classes = find_processors()
    custom_watch_obj = next((tpl for tpl in processor_classes if tpl[1] == processor_name), None)
    if custom_watch_obj:
        # Parent of .processor.py COULD have its own Watch implementation
        parent_module = get_parent_module(custom_watch_obj[0])
        if hasattr(parent_module, 'Watch'):
            watch_class = parent_module.Watch

    return watch_class


def available_processors():
    """
    Get a list of processors by name and description for the UI elements
    :return: A list :)
    """

    processor_classes = find_processors()

    available = []
    for package, processor_class in processor_classes:
        available.append((processor_class, package.name))

    return available