"""FastAPI dependency injection — provides shared singletons to route handlers."""

from typing import Annotated

from fastapi import Depends

from navi.config import settings
from navi.core import (
    Agent,
    BackendRegistry,
    ProfileRegistry,
    SessionStore,
    SqliteSessionStore,
    ToolRegistry,
    build_default_registries,
)
from navi.workers import Worker, build_default_workers


_registries: tuple[ToolRegistry, ProfileRegistry, BackendRegistry] | None = None


def get_registries() -> tuple[ToolRegistry, ProfileRegistry, BackendRegistry]:
    global _registries
    if _registries is None:
        _registries = build_default_registries()
    return _registries


def get_tool_registry() -> ToolRegistry:
    return get_registries()[0]


def get_profile_registry() -> ProfileRegistry:
    return get_registries()[1]


def get_backend_registry() -> BackendRegistry:
    return get_registries()[2]


_session_store = SqliteSessionStore(settings.db_path)
_workers: list[Worker] = build_default_workers()


def get_session_store() -> SessionStore:
    return _session_store


def get_workers() -> list[Worker]:
    return _workers


def get_agent(
    session_store: Annotated[SessionStore, Depends(get_session_store)],
    profile_registry: Annotated[ProfileRegistry, Depends(get_profile_registry)],
    tool_registry: Annotated[ToolRegistry, Depends(get_tool_registry)],
    backend_registry: Annotated[BackendRegistry, Depends(get_backend_registry)],
) -> Agent:
    return Agent(session_store, profile_registry, tool_registry, backend_registry,
                 workers=get_workers())