From 4d7a9be45f11d80e9cec56bb0ebb7ae722906b1b Mon Sep 17 00:00:00 2001
From: hkc <hatkidchan@gmail.com>
Date: Sat, 27 Aug 2022 15:47:51 +0300
Subject: [PATCH] Added combined filter

---
 mastoposter/filters/base.py            | 18 ++++++++-----
 mastoposter/filters/combined_filter.py | 37 ++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 6 deletions(-)
 create mode 100644 mastoposter/filters/combined_filter.py

diff --git a/mastoposter/filters/base.py b/mastoposter/filters/base.py
index 90c0f80..5d3f043 100644
--- a/mastoposter/filters/base.py
+++ b/mastoposter/filters/base.py
@@ -1,19 +1,18 @@
 from abc import ABC, abstractmethod
+from configparser import SectionProxy
 from typing import ClassVar, Dict, Type
 from mastoposter.types import Status
 from re import Pattern, compile as regexp
 
+UNUSED = lambda *_: None  # NOQA
+
 
 class BaseFilter(ABC):
     FILTER_REGISTRY: ClassVar[Dict[str, Type["BaseFilter"]]] = {}
     FILTER_NAME_REGEX: Pattern = regexp(r"^([a-z_]+)$")
 
-    def __init__(self):
-        pass
-
-    @abstractmethod
-    def __call__(self, status: Status) -> bool:
-        raise NotImplementedError
+    def __init__(self, section: SectionProxy):
+        UNUSED(section)
 
     def __init_subclass__(cls, filter_name: str, **kwargs):
         super().__init_subclass__(**kwargs)
@@ -22,3 +21,10 @@ class BaseFilter(ABC):
         if filter_name in cls.FILTER_REGISTRY:
             raise KeyError(f"{filter_name=!r} is already registered")
         cls.FILTER_REGISTRY[filter_name] = cls
+
+    @abstractmethod
+    def __call__(self, status: Status) -> bool:
+        raise NotImplementedError
+
+    def post_init(self, filters: Dict[str, "BaseFilter"]):
+        UNUSED(filters)
diff --git a/mastoposter/filters/combined_filter.py b/mastoposter/filters/combined_filter.py
new file mode 100644
index 0000000..a211d7d
--- /dev/null
+++ b/mastoposter/filters/combined_filter.py
@@ -0,0 +1,37 @@
+from configparser import SectionProxy
+from typing import Callable, ClassVar, Dict, List, NamedTuple
+from functools import reduce
+from mastoposter.filters.base import BaseFilter
+from mastoposter.types import Status
+
+
+class FilterType(NamedTuple):
+    inverse: bool
+    filter: BaseFilter
+
+
+class CombinedFilter(BaseFilter, filter_name="combined"):
+    OPERATORS: ClassVar[Dict[str, Callable]] = {
+        "and": lambda a, b: a and b,
+        "or": lambda a, b: a or b,
+        "xor": lambda a, b: a ^ b,
+    }
+
+    def __init__(self, section: SectionProxy):
+        self.filter_names = section.get("filters", "").split()
+        self.operator = self.OPERATORS[section.get("operator", "and")]
+        self.filters: List[FilterType] = []
+
+    def post_init(self, filters: Dict[str, "BaseFilter"]):
+        super().post_init(filters)
+        for filter_name in self.filter_names:
+            self.filters.append(
+                FilterType(
+                    filter_name[:1] in "~!",  # inverse
+                    filters[filter_name.rstrip("!~")],
+                )
+            )
+
+    def __call__(self, status: Status) -> bool:
+        results = [fil.filter(status) ^ fil.inverse for fil in self.filters]
+        return reduce(self.operator, results)