1 files changed, 118 insertions, 0 deletions
diff --git a/hrc/dependencies.py b/hrc/dependencies.py
index e69de29..3a662fd 100644
--- a/hrc/dependencies.py
+++ b/hrc/dependencies.py
@@ -0,0 +1,118 @@
+import inspect
+from contextlib import AsyncExitStack, asynccontextmanager, contextmanager
+from typing import (
+    Any,
+    AsyncContextManager,
+    AsyncGenerator,
+    Callable,
+    ContextManager,
+    Dict,
+    Generator,
+    Optional,
+    Type,
+    TypeVar,
+    Union,
+    cast,
+)
+
+from .utils import get_annotations, sync_ctx_manager_wrapper
+
+_T = TypeVar("_T")
+Dependency = Union[
+    # Class
+    Type[Union[_T, AsyncContextManager[_T], ContextManager[_T]]],
+    # GeneratorContextManager
+    Callable[[], AsyncGenerator[_T, None]],
+    Callable[[], Generator[_T, None, None]],
+]
+
+
+__all__ = ["Depends"]
+
+
+class InnerDepends:
+
+    dependency: Optional[Dependency[Any]]
+    use_cache: bool
+
+    def __init__(
+        self, dependency: Optional[Dependency[Any]] = None, *, use_cache: bool = True
+    ) -> None:
+        self.dependency = dependency
+        self.use_cache = use_cache
+
+    def __repr__(self) -> str:
+        attr = getattr(self.dependency, "__name__", type(self.dependency).__name__)
+        cache = "" if self.use_cache else ", use_cache=False"
+        return f"InnerDepends({attr}{cache})"
+
+
+def Depends(  # noqa: N802 # pylint: disable=invalid-name
+    dependency: Optional[Dependency[_T]] = None, *, use_cache: bool = True
+) -> _T:
+
+    return InnerDepends(dependency=dependency, use_cache=use_cache)  # type: ignore
+
+
+async def solve_dependencies(
+    dependent: Dependency[_T],
+    *,
+    use_cache: bool,
+    stack: AsyncExitStack,
+    dependency_cache: Dict[Dependency[Any], Any],
+) -> _T:
+    if use_cache and dependent in dependency_cache:
+        return dependency_cache[dependent]
+
+    if isinstance(dependent, type):
+        # type of dependent is Type[T]
+        values: Dict[str, Any] = {}
+        ann = get_annotations(dependent)
+        for name, sub_dependent in inspect.getmembers(
+            dependent, lambda x: isinstance(x, InnerDepends)
+        ):
+            assert isinstance(sub_dependent, InnerDepends)
+            if sub_dependent.dependency is None:
+                dependent_ann = ann.get(name, None)
+                if dependent_ann is None:
+                    raise TypeError("can not solve dependent")
+                sub_dependent.dependency = dependent_ann
+            values[name] = await solve_dependencies(
+                sub_dependent.dependency,
+                use_cache=sub_dependent.use_cache,
+                stack=stack,
+                dependency_cache=dependency_cache,
+            )
+        depend_obj = cast(
+            Union[_T, AsyncContextManager[_T], ContextManager[_T]],
+            dependent.__new__(dependent),  # pyright: ignore[reportGeneralTypeIssues]
+        )
+        for key, value in values.items():
+            setattr(depend_obj, key, value)
+        depend_obj.__init__()  # type: ignore[misc] # pylint: disable=unnecessary-dunder-call
+
+        if isinstance(depend_obj, AsyncContextManager):
+            depend = await stack.enter_async_context(
+                depend_obj  # pyright: ignore[reportUnknownArgumentType]
+            )
+        elif isinstance(depend_obj, ContextManager):
+            depend = await stack.enter_async_context(
+                sync_ctx_manager_wrapper(
+                    depend_obj  # pyright: ignore[reportUnknownArgumentType]
+                )
+            )
+        else:
+            depend = depend_obj
+    elif inspect.isasyncgenfunction(dependent):
+        # type of dependent is Callable[[], AsyncGenerator[T, None]]
+        cm = asynccontextmanager(dependent)()
+        depend = cast(_T, await stack.enter_async_context(cm))
+    elif inspect.isgeneratorfunction(dependent):
+        # type of dependent is Callable[[], Generator[T, None, None]]
+        cm = sync_ctx_manager_wrapper(contextmanager(dependent)())
+        depend = cast(_T, await stack.enter_async_context(cm))
+    else:
+        raise TypeError("dependent is not a class or generator function")
+
+    dependency_cache[dependent] = depend
+    return depend
+\ No newline at end of file