[mod] addition of various type hints / tbc

- pyright configuration [1]_
- stub files: types-lxml [2]_
- addition of various type hints
- enable use of new type system features on older Python versions [3]_
- ``.tool-versions`` - set python to lowest version we support (3.10.18) [4]_:
  Older versions typically lack some typing features found in newer Python
  versions.  Therefore, for local type checking (before commit), it is necessary
  to use the older Python interpreter.

.. [1] https://docs.basedpyright.com/v1.20.0/configuration/config-files/
.. [2] https://pypi.org/project/types-lxml/
.. [3] https://typing-extensions.readthedocs.io/en/latest/#
.. [4] https://mise.jdx.dev/configuration.html#tool-versions

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Format: reST

2 files changed, 39 insertions, 32 deletions

diff --git a/searx/search/processors/__init__.py b/searx/search/processors/__init__.py
index ea049e79f..760513253 100644
--- a/searx/search/processors/__init__.py
+++ b/searx/search/processors/__init__.py
@@ -1,8 +1,5 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
-
-"""Implement request processors used by engine-types.
-
-"""
+"""Implement request processors used by engine-types."""
 
 __all__ = [
     'EngineProcessor',
@@ -14,8 +11,9 @@ __all__ = [
     'PROCESSORS',
 ]
 
+import typing as t
+
 import threading
-from typing import Dict
 
 from searx import logger
 from searx import engines
@@ -27,15 +25,18 @@ from .online_currency import OnlineCurrencyProcessor
 from .online_url_search import OnlineUrlSearchProcessor
 from .abstract import EngineProcessor
 
+if t.TYPE_CHECKING:
+    from searx.enginelib import Engine
+
 logger = logger.getChild('search.processors')
-PROCESSORS: Dict[str, EngineProcessor] = {}
+PROCESSORS: dict[str, EngineProcessor] = {}
 """Cache request processors, stored by *engine-name* (:py:func:`initialize`)
 
 :meta hide-value:
 """
 
 
-def get_processor_class(engine_type):
+def get_processor_class(engine_type: str) -> type[EngineProcessor] | None:
     """Return processor class according to the ``engine_type``"""
     for c in [
         OnlineProcessor,
@@ -49,34 +50,35 @@ def get_processor_class(engine_type):
     return None
 
 
-def get_processor(engine, engine_name):
-    """Return processor instance that fits to ``engine.engine.type``)"""
+def get_processor(engine: "Engine | ModuleType", engine_name: str) -> EngineProcessor | None:
+    """Return processor instance that fits to ``engine.engine.type``"""
     engine_type = getattr(engine, 'engine_type', 'online')
     processor_class = get_processor_class(engine_type)
-    if processor_class:
+    if processor_class is not None:
         return processor_class(engine, engine_name)
     return None
 
 
-def initialize_processor(processor):
+def initialize_processor(processor: EngineProcessor):
     """Initialize one processor
 
     Call the init function of the engine
     """
     if processor.has_initialize_function:
-        t = threading.Thread(target=processor.initialize, daemon=True)
-        t.start()
+        _t = threading.Thread(target=processor.initialize, daemon=True)
+        _t.start()
 
 
-def initialize(engine_list):
-    """Initialize all engines and store a processor for each engine in :py:obj:`PROCESSORS`."""
+def initialize(engine_list: list[dict[str, t.Any]]):
+    """Initialize all engines and store a processor for each engine in
+    :py:obj:`PROCESSORS`."""
     for engine_data in engine_list:
-        engine_name = engine_data['name']
+        engine_name: str = engine_data['name']
         engine = engines.engines.get(engine_name)
         if engine:
             processor = get_processor(engine, engine_name)
-            initialize_processor(processor)
             if processor is None:
                 engine.logger.error('Error get processor for engine %s', engine_name)
             else:
+                initialize_processor(processor)
                 PROCESSORS[engine_name] = processor
diff --git a/searx/search/processors/abstract.py b/searx/search/processors/abstract.py
index ff6c8f78a..2dd56855a 100644
--- a/searx/search/processors/abstract.py
+++ b/searx/search/processors/abstract.py
@@ -3,10 +3,12 @@
 
 """
 
+import typing as t
+
+import logging
 import threading
 from abc import abstractmethod, ABC
 from timeit import default_timer
-from typing import Dict, Union
 
 from searx import settings, logger
 from searx.engines import engines
@@ -15,8 +17,11 @@ from searx.metrics import histogram_observe, counter_inc, count_exception, count
 from searx.exceptions import SearxEngineAccessDeniedException, SearxEngineResponseException
 from searx.utils import get_engine_from_settings
 
+if t.TYPE_CHECKING:
+    from searx.enginelib import Engine
+
 logger = logger.getChild('searx.search.processor')
-SUSPENDED_STATUS: Dict[Union[int, str], 'SuspendedStatus'] = {}
+SUSPENDED_STATUS: dict[int | str, 'SuspendedStatus'] = {}
 
 
 class SuspendedStatus:
@@ -25,16 +30,16 @@ class SuspendedStatus:
     __slots__ = 'suspend_end_time', 'suspend_reason', 'continuous_errors', 'lock'
 
     def __init__(self):
-        self.lock = threading.Lock()
-        self.continuous_errors = 0
-        self.suspend_end_time = 0
-        self.suspend_reason = None
+        self.lock: threading.Lock = threading.Lock()
+        self.continuous_errors: int = 0
+        self.suspend_end_time: float = 0
+        self.suspend_reason: str = ""
 
     @property
     def is_suspended(self):
         return self.suspend_end_time >= default_timer()
 
-    def suspend(self, suspended_time, suspend_reason):
+    def suspend(self, suspended_time: int, suspend_reason: str):
         with self.lock:
             # update continuous_errors / suspend_end_time
             self.continuous_errors += 1
@@ -52,21 +57,21 @@ class SuspendedStatus:
             # reset the suspend variables
             self.continuous_errors = 0
             self.suspend_end_time = 0
-            self.suspend_reason = None
+            self.suspend_reason = ""
 
 
 class EngineProcessor(ABC):
     """Base classes used for all types of request processors."""
 
-    __slots__ = 'engine', 'engine_name', 'lock', 'suspended_status', 'logger'
+    __slots__ = 'engine', 'engine_name', 'suspended_status', 'logger'
 
-    def __init__(self, engine, engine_name: str):
-        self.engine = engine
-        self.engine_name = engine_name
-        self.logger = engines[engine_name].logger
+    def __init__(self, engine: "Engine|ModuleType", engine_name: str):
+        self.engine: "Engine" = engine
+        self.engine_name: str = engine_name
+        self.logger: logging.Logger = engines[engine_name].logger
         key = get_network(self.engine_name)
         key = id(key) if key else self.engine_name
-        self.suspended_status = SUSPENDED_STATUS.setdefault(key, SuspendedStatus())
+        self.suspended_status: SuspendedStatus = SUSPENDED_STATUS.setdefault(key, SuspendedStatus())
 
     def initialize(self):
         try:
@@ -135,7 +140,7 @@ class EngineProcessor(ABC):
             return True
         return False
 
-    def get_params(self, search_query, engine_category):
+    def get_params(self, search_query, engine_category) -> dict[str, t.Any]:
         """Returns a set of (see :ref:`request params <engine request arguments>`) or
         ``None`` if request is not supported.