"""FastAPI dependency providers.

All ``Depends()`` callables that inject shared resources (database
connection, settings, services, auth guard) are defined here.
Routers import directly from this module — never from ``app.state``
directly — to keep coupling explicit and testable.
"""

from typing import Annotated

import aiosqlite
import structlog
from fastapi import Depends, HTTPException, Request, status

from app.config import Settings

log: structlog.stdlib.BoundLogger = structlog.get_logger()


async def get_db(request: Request) -> aiosqlite.Connection:
    """Provide the shared :class:`aiosqlite.Connection` from ``app.state``.

    Args:
        request: The current FastAPI request (injected automatically).

    Returns:
        The application-wide aiosqlite connection opened during startup.

    Raises:
        HTTPException: 503 if the database has not been initialised.
    """
    db: aiosqlite.Connection | None = getattr(request.app.state, "db", None)
    if db is None:
        log.error("database_not_initialised")
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Database is not available.",
        )
    return db


async def get_settings(request: Request) -> Settings:
    """Provide the :class:`~app.config.Settings` instance from ``app.state``.

    Args:
        request: The current FastAPI request (injected automatically).

    Returns:
        The application settings loaded at startup.
    """
    return request.app.state.settings  # type: ignore[no-any-return]


# Convenience type aliases for route signatures.
DbDep = Annotated[aiosqlite.Connection, Depends(get_db)]
SettingsDep = Annotated[Settings, Depends(get_settings)]