Add database interface and in-memory database infrastructure

src/application/entities/user.py

@@ -1,4 +1,5 @@
 from dataclasses import dataclass, field
+from typing import Any, Self
 from uuid import UUID, uuid4
 
 
@@ -9,3 +10,22 @@ class User:
     password: str
     confirmed: bool
     id: UUID = field(default_factory=uuid4)
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "id": str(self.id),
+            "name": self.name,
+            "email": self.email,
+            "password": self.password,
+            "confirmed": self.confirmed,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any]) -> Self:
+        return cls(
+            id=UUID(data["id"]),
+            name=data["name"],
+            email=data["email"],
+            password=data["password"],
+            confirmed=data["confirmed"],
+        )

src/application/interfaces/database.py

@@ -0,0 +1,32 @@
+from abc import ABC, abstractmethod
+from typing import Generic, Protocol, TypeVar, Optional
+from uuid import UUID
+
+
+class HasID(Protocol):
+    id: UUID  # Enforce that any entity passed to the repository must have an `id` attribute
+
+
+T = TypeVar("T", bound=HasID)
+
+
+class Database(ABC, Generic[T]):
+    @abstractmethod
+    async def add(self, entity: T) -> None:
+        pass
+
+    @abstractmethod
+    async def get(self, id: UUID) -> Optional[T]:
+        pass
+
+    @abstractmethod
+    async def update(self, entity: T) -> None:
+        pass
+
+    @abstractmethod
+    async def delete(self, id: UUID) -> None:
+        pass
+
+    @abstractmethod
+    async def list_all(self) -> list[T]:
+        pass

src/infrastructure/databases/in_memory.py

@@ -0,0 +1,26 @@
+from typing import Optional
+from uuid import UUID
+
+from application.interfaces.database import T, Database
+
+
+class InMemoryDatabase(Database[T]):
+    def __init__(self) -> None:
+        self._data: dict[UUID, T] = {}
+
+    async def add(self, entity: T) -> None:
+        self._data[entity.id] = entity
+
+    async def get(self, id: UUID) -> Optional[T]:
+        return self._data.get(id)
+
+    async def update(self, entity: T) -> None:
+        if entity.id in self._data:
+            self._data[entity.id] = entity
+
+    async def delete(self, id: UUID) -> None:
+        if id in self._data:
+            del self._data[id]
+
+    async def list_all(self) -> list[T]:
+        return list(self._data.values())