refactor: media types rework, dynamically load preview renderers (#1498)

* feat!: establish new MediaType system

* further additions and changes

* begin making renderers classes, improve text thumbnails

* continue renderer work

* convert most remaining thumbnail renderers to classes

* feat: dynamically load preview renderers

* refactor: use individual ext registration, continued progress

* refactor: finish converting old types to new registration system

* chore: alphabetize lists

* fix: only use search context for searches

* refactor: remove legacy filetype equivalent usages

* feat: add aliases for type groups, used in search

* refactor: use new MediaTypes system in archive renderers

* fix: add missing types

* refactor: remove last uses of legacy media type system

* refactor: move media type search context init to new file

* fix: fix import formatting, add missing aliases

* chore: remove leftover logging

* chore: small tweaks and comments

* refactor: wrap filetype init in function, call in driver

* docs: add and update docstrings

* fix: use all intended fallback icons for each media type

* fix: fix misc issues

* tests: add test cases for media types

* refactor: rename register_all to register_types

* refactor: wrap preview renderer type registrations in methods

tests/conftest.py

@@ -1,6 +1,9 @@
 # SPDX-FileCopyrightText: (c) TagStudio Contributors
 # SPDX-License-Identifier: GPL-3.0-only
 
+# pyright: reportPrivateUsage=false
+# pyright: reportUnusedFunction=false
+
 
 import sys
 from collections.abc import Callable, Generator
@@ -13,6 +16,7 @@ from PySide6.QtWidgets import QScrollArea
 from pytestqt.qtbot import QtBot
 
 from tagstudio.core.library.alchemy.fields import TextField
+from tagstudio.core.media_types import MediaTypes
 
 CWD = Path(__file__).parent
 # this needs to be above `src` imports
@@ -148,11 +152,25 @@ def entry_full(library: Library):
 
 
 @pytest.fixture(autouse=True)
-def _init_qtbot(qtbot: QtBot):  # pyright: ignore[reportUnusedFunction]
+def _init_qtbot(qtbot: QtBot):
     """Ensures that a QtBot is initialized for all subsequent tests, regardless of order."""
     return qtbot
 
 
+@pytest.fixture(autouse=True)
+def _reset_media_types():
+    """Snapshot the MediaTypes state before each test, then restore it after."""
+    pre_snapshop = MediaTypes._snapshot()
+
+    yield
+
+    post_snapshop = MediaTypes._snapshot()
+
+    if pre_snapshop != post_snapshop:
+        MediaTypes._restore(pre_snapshop)
+        assert pre_snapshop == MediaTypes._snapshot(), "The MediaTypes state was not restored!"
+
+
 @pytest.fixture
 def qt_driver(library: Library, library_dir: Path):
     class Args:

tests/core/test_media_types.py

@@ -0,0 +1,85 @@
+# SPDX-FileCopyrightText: (c) TagStudio Contributors
+# SPDX-License-Identifier: MIT
+
+
+from pytestqt.exceptions import pytest
+
+from tagstudio.core.media_types import MediaTypes
+
+
+def test_register_and_contains():
+    MediaTypes.register("zzztest.basic", ".zzzfoo", "SEARCH")
+
+    assert MediaTypes.contains("zzztest.basic", ".zzzfoo", "SEARCH")
+    assert not MediaTypes.contains("zzztest.basic", ".zzzfoo", "RENDER")
+
+
+def test_additive_register():
+    MediaTypes.register("zzztest.additive", ".zzzfoo", "SEARCH")
+    MediaTypes.register("zzztest.additive", ".zzzbar", "SEARCH")
+
+    assert MediaTypes.contains("zzztest.additive", ".zzzfoo", "SEARCH")
+    assert MediaTypes.contains("zzztest.additive", ".zzzbar", "SEARCH")
+
+
+def test_contains_missing_group_raises_error():
+    with pytest.raises(AttributeError, match=r"is not registered"):
+        MediaTypes.contains("zzztest.does_not_exist", ".zzzfoo", "SEARCH")
+
+
+def test_dot_notation_chains_to_parents():
+    MediaTypes.register("zzztest.chain.parent.child", ".zzzchild", "SEARCH")
+
+    assert MediaTypes.contains("zzztest.chain.parent.child", ".zzzchild", "SEARCH")
+    assert MediaTypes.contains("zzztest.chain.parent", ".zzzchild", "SEARCH")
+    assert MediaTypes.contains("zzztest.chain", ".zzzchild", "SEARCH")
+
+
+def test_explicit_chain_group():
+    MediaTypes.chain_group("zzztest.composite", ["zzztest.composite_child"])
+    MediaTypes.register("zzztest.composite_child", ".zzzcomposite", "SEARCH")
+
+    assert MediaTypes.contains("zzztest.composite", ".zzzcomposite", "SEARCH")
+
+
+def test_equivalent_extensions():
+    MediaTypes.register("zzztest.equiv", [".zzzone", ".zzztwo"], "SEARCH")
+
+    assert MediaTypes.get_equivalent_exts(".zzzone") == {".zzzone", ".zzztwo"}
+    assert MediaTypes.get_equivalent_exts(".zzztwo") == {".zzzone", ".zzztwo"}
+    assert MediaTypes.contains("zzztest.equiv", ".zzzone", "SEARCH")
+    assert MediaTypes.contains("zzztest.equiv", ".zzztwo", "SEARCH")
+
+
+def test_get_equivalent_exts_defaults_to_itself():
+    assert MediaTypes.get_equivalent_exts(".zzzunregistered") == {".zzzunregistered"}
+
+
+def test_find():
+    MediaTypes.register("zzztest.find_a", ".zzzfind", "SEARCH")
+    MediaTypes.register("zzztest.find_b", ".zzzfind", "RENDER")
+
+    search_keys = {group.key for group in MediaTypes.find(".zzzfind", "SEARCH")}
+    render_keys = {group.key for group in MediaTypes.find(".zzzfind", "RENDER")}
+
+    assert "zzztest.find_a" in search_keys
+    assert "zzztest.find_a" not in render_keys
+    assert "zzztest.find_b" in render_keys
+    assert "zzztest.find_b" not in search_keys
+
+
+def test_add_name_aliases_and_lookup():
+    MediaTypes.register("zzztest.alias_target", ".zzzalias", "SEARCH")
+    MediaTypes.add_name_aliases("zzztest.alias_target", ["ZZZ Test Group", "zzztest"])
+
+    assert MediaTypes.get_group_key_from_name("ZZZ Test Group") == "zzztest.alias_target"
+    assert MediaTypes.get_group_key_from_name("zzz test group", case_sensitive=False) == (
+        "zzztest.alias_target"
+    )
+    assert (
+        MediaTypes.get_group_key_from_name(
+            "zzztestGroup", case_sensitive=False, ignore_whitespace=True
+        )
+        == "zzztest.alias_target"
+    )
+    assert MediaTypes.get_group_key_from_name("Not A Real Alias") is None

tests/qt/test_theme_system.py

@@ -9,7 +9,7 @@ from unittest.mock import Mock
 import pytest
 from PySide6.QtCore import Qt
 
-from tagstudio.qt.app_settings import Theme
+from tagstudio.core.enums import Theme
 
 
 @pytest.mark.parametrize(