# Source code for searx.engines

    # SPDX-License-Identifier: AGPL-3.0-or-later
    """Load and initialize the ``engines``, see :py:func:`load_engines` and register
    :py:obj:`engine_shortcuts`.

    usage::

        load_engines( settings['engines'] )

    """

    from __future__ import annotations

    import sys
    import copy
    from os.path import realpath, dirname

    from typing import TYPE_CHECKING, Dict
    import types
    import inspect

    from searx import logger, settings
    from searx.utils import load_module

    if TYPE_CHECKING:
        from searx.enginelib import Engine

    logger = logger.getChild('engines')
    ENGINE_DIR = dirname(realpath(__file__))
    ENGINE_DEFAULT_ARGS = {
        # Common options in the engine module
        "engine_type": "online",
        "paging": False,
        "time_range_support": False,
        "safesearch": False,
        # settings.yml
        "categories": ["general"],
        "enable_http": False,
        "shortcut": "-",
        "timeout": settings["outgoing"]["request_timeout"],
        "display_error_messages": True,
        "disabled": False,
        "inactive": False,
        "about": {},
        "using_tor_proxy": False,
        "send_accept_language_header": False,
        "tokens": [],
        "max_page": 0,
    }
    # set automatically when an engine does not have any tab category
    DEFAULT_CATEGORY = 'other'

    # Defaults for the namespace of an engine module, see :py:func:`load_engine`

    categories = {'general': []}
    engines: Dict[str, Engine | types.ModuleType] = {}
    engine_shortcuts = {}
    """Simple map of registered *shortcuts* to name of the engine (or ``None``).

    ::

        engine_shortcuts[engine.shortcut] = engine.name

    :meta hide-value:
    """

    def check_engine_module(module: types.ModuleType):
        # probe unintentional name collisions / for example name collisions caused
        # by import statements in the engine module ..

        # network: https://github.com/searxng/searxng/issues/762#issuecomment-1605323861
        obj = getattr(module, 'network', None)
        if obj and inspect.ismodule(obj):
            msg = f'type of {module.__name__}.network is a module ({obj.__name__}), expected a string'
            # logger.error(msg)
            raise TypeError(msg)

    def load_engine(engine_data: dict) -> Engine | types.ModuleType | None:
        """Load engine from ``engine_data``.

        :param dict engine_data:  Attributes from YAML ``settings:engines/<engine>``
        :return: initialized namespace of the ``<engine>``.

        1. create a namespace and load module of the ``<engine>``
        2. update namespace with the defaults from :py:obj:`ENGINE_DEFAULT_ARGS`
        3. update namespace with values from ``engine_data``

        If engine *is active*, return namespace of the engine, otherwise return
        ``None``.

        This function also returns ``None`` if initialization of the namespace fails
        for one of the following reasons:

        - engine name contains underscore
        - engine name is not lowercase
        - required attribute is not set :py:func:`is_missing_required_attributes`

        """
        # pylint: disable=too-many-return-statements

        engine_name = engine_data.get('name')
        if engine_name is None:
            logger.error('An engine does not have a "name" field')
            return None
        if '_' in engine_name:
            logger.error('Engine name contains underscore: "{}"'.format(engine_name))
            return None

        if engine_name.lower() != engine_name:
            logger.warning('Engine name is not lowercase: "{}", converting to lowercase'.format(engine_name))
            engine_name = engine_name.lower()
            engine_data['name'] = engine_name

        # load_module
        module_name = engine_data.get('engine')
        if module_name is None:
            logger.error('The "engine" field is missing for the engine named "{}"'.format(engine_name))
            return None
        try:
            engine = load_module(module_name + '.py', ENGINE_DIR)
        except (SyntaxError, KeyboardInterrupt, SystemExit, SystemError, ImportError, RuntimeError):
            logger.exception('Fatal exception in engine "{}"'.format(module_name))
            sys.exit(1)
        except BaseException:
            logger.exception('Cannot load engine "{}"'.format(module_name))
            return None

        check_engine_module(engine)
        update_engine_attributes(engine, engine_data)
        update_attributes_for_tor(engine)

        # avoid cyclic imports
        # pylint: disable=import-outside-toplevel
        from searx.enginelib.traits import EngineTraitsMap

        trait_map = EngineTraitsMap.from_data()
        trait_map.set_traits(engine)

        if not is_engine_active(engine):
            return None

        if is_missing_required_attributes(engine):
            return None

        set_loggers(engine, engine_name)

        if not any(cat in settings['categories_as_tabs'] for cat in engine.categories):
            engine.categories.append(DEFAULT_CATEGORY)

        return engine

    def set_loggers(engine, engine_name):
        # set the logger for engine
        engine.logger = logger.getChild(engine_name)
        # the engine may have load some other engines
        # may sure the logger is initialized
        # use sys.modules.copy() to avoid "RuntimeError: dictionary changed size during iteration"
        # see https://github.com/python/cpython/issues/89516
        # and https://docs.python.org/3.10/library/sys.html#sys.modules
        modules = sys.modules.copy()
        for module_name, module in modules.items():
            if (
                module_name.startswith("searx.engines")
                and module_name != "searx.engines.__init__"
                and not hasattr(module, "logger")
            ):
                module_engine_name = module_name.split(".")[-1]
                module.logger = logger.getChild(module_engine_name)  # type: ignore

    def update_engine_attributes(engine: Engine | types.ModuleType, engine_data):
        # set engine attributes from engine_data
        for param_name, param_value in engine_data.items():
            if param_name == 'categories':
                if isinstance(param_value, str):
                    param_value = list(map(str.strip, param_value.split(',')))
                engine.categories = param_value  # type: ignore
            elif hasattr(engine, 'about') and param_name == 'about':
                engine.about = {**engine.about, **engine_data['about']}  # type: ignore
            else:
                setattr(engine, param_name, param_value)

        # set default attributes
        for arg_name, arg_value in ENGINE_DEFAULT_ARGS.items():
            if not hasattr(engine, arg_name):
                setattr(engine, arg_name, copy.deepcopy(arg_value))

    def update_attributes_for_tor(engine: Engine | types.ModuleType):
        if using_tor_proxy(engine) and hasattr(engine, 'onion_url'):
            engine.search_url = engine.onion_url + getattr(engine, 'search_path', '')  # type: ignore
            engine.timeout += settings['outgoing'].get('extra_proxy_timeout', 0)  # type: ignore

    def is_missing_required_attributes(engine):
        """An attribute is required when its name doesn't start with ``_`` (underline).
        Required attributes must not be ``None``.

        """
        missing = False
        for engine_attr in dir(engine):
            if not engine_attr.startswith('_') and getattr(engine, engine_attr) is None:
                logger.error('Missing engine config attribute: "{0}.{1}"'.format(engine.name, engine_attr))
                missing = True
        return missing

    def using_tor_proxy(engine: Engine | types.ModuleType):
        """Return True if the engine configuration declares to use Tor."""
        return settings['outgoing'].get('using_tor_proxy') or getattr(engine, 'using_tor_proxy', False)

    def is_engine_active(engine: Engine | types.ModuleType):
        # check if engine is inactive
        if engine.inactive is True:
            return False

        # exclude onion engines if not using tor
        if 'onions' in engine.categories and not using_tor_proxy(engine):
            return False

        return True

    def register_engine(engine: Engine | types.ModuleType):
        if engine.name in engines:
            logger.error('Engine config error: ambiguous name: {0}'.format(engine.name))
            sys.exit(1)
        engines[engine.name] = engine

        if engine.shortcut in engine_shortcuts:
            logger.error('Engine config error: ambiguous shortcut: {0}'.format(engine.shortcut))
            sys.exit(1)
        engine_shortcuts[engine.shortcut] = engine.name

        for category_name in engine.categories:
            categories.setdefault(category_name, []).append(engine)

    def load_engines(engine_list):
        """usage: ``engine_list = settings['engines']``"""
        engines.clear()
        engine_shortcuts.clear()
        categories.clear()
        categories['general'] = []
        for engine_data in engine_list:
            engine = load_engine(engine_data)
            if engine:
                register_engine(engine)
        return engines