"""FastAPI dependencies for authentication, RBAC, and RLS context."""

from __future__ import annotations

from enum import Enum
from typing import Annotated, AsyncIterator, Optional

import asyncpg
from fastapi import Cookie, Depends, HTTPException, Request, status

from .auth_types import AccountStatus
from .auth_sessions import get_session
from .config import Settings, get_settings
from .db import acquire


class Role(str, Enum):
    LEARNER = "learner"
    TEACHER = "teacher"
    ADMIN = "admin"


class AIView(str, Enum):
    CLIENT = "client"
    COUNSELOR = "counselor"
    EVALUATOR = "evaluator"


class Principal:
    """Authenticated human principal."""

    def __init__(
        self,
        user_id: str,
        role: Role,
        admin_access: bool = False,
        super_admin: bool = False,
        account_status: AccountStatus = "approved",
        cohort_ids: Optional[list[str]] = None,
        email: str = "",
        display_name: str = "",
        consent_at: float | None = None,
        profile_completed_at: float | None = None,
    ) -> None:
        self.user_id = user_id
        self.role = role
        self.admin_access = admin_access
        self.super_admin = super_admin
        self.account_status = account_status
        self.cohort_ids = cohort_ids or []
        self.email = email
        self.display_name = display_name
        self.consent_at = consent_at
        self.profile_completed_at = profile_completed_at

    def can_access_role(self, role: Role) -> bool:
        if self.role == role:
            return True
        if self.super_admin:
            return True
        if role == Role.ADMIN:
            return self.admin_access
        return False

    def with_role(self, role: Role) -> "Principal":
        return Principal(
            user_id=self.user_id,
            role=role,
            admin_access=self.admin_access,
            super_admin=self.super_admin,
            account_status=self.account_status,
            cohort_ids=list(self.cohort_ids),
            email=self.email,
            display_name=self.display_name,
            consent_at=self.consent_at,
            profile_completed_at=self.profile_completed_at,
        )


def get_settings_dep() -> Settings:
    return get_settings()


async def get_current_principal(
    request: Request,
    session_cookie: Annotated[Optional[str], Cookie(alias="__Host-vignette_sid")] = None,
    dev_session_cookie: Annotated[Optional[str], Cookie(alias="vignette_sid")] = None,
) -> Principal:
    """Restore the principal from the opaque HttpOnly browser session cookie."""
    raw_cookie = session_cookie or (dev_session_cookie if get_settings().environment == "dev" else None)
    session = await get_session(raw_cookie)
    if session is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="not authenticated",
        )

    try:
        role = Role(session.role)
    except ValueError as exc:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="invalid session role",
        ) from exc

    if session.account_status != "approved" and request.url.path != "/auth/me":
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=f"account_{session.account_status}",
        )

    return Principal(
        user_id=session.user_id,
        role=role,
        admin_access=session.admin_access,
        super_admin=session.super_admin,
        account_status=session.account_status,
        cohort_ids=session.cohort_ids,
        email=session.email,
        display_name=session.display_name,
        consent_at=session.consent_at,
        profile_completed_at=session.profile_completed_at,
    )


def require_role(*allowed: Role):
    """Role allowlist dependency factory."""

    async def _checker(
        principal: Annotated[Principal, Depends(get_current_principal)],
    ) -> Principal:
        if principal.role in allowed:
            return principal
        if principal.super_admin:
            effective = Role.ADMIN if Role.ADMIN in allowed else allowed[0]
            return principal.with_role(effective)
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=f"role {principal.role.value} not permitted",
        )

    return _checker


def require_admin_access():
    """기본 역할과 별개로 관리자 권한을 가진 사용자만 통과시킨다."""

    async def _checker(
        principal: Annotated[Principal, Depends(get_current_principal)],
    ) -> Principal:
        if not principal.admin_access:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="admin access required",
            )
        return principal

    return _checker


async def db_for_human(
    principal: Annotated[Principal, Depends(get_current_principal)],
) -> AsyncIterator[asyncpg.Connection]:
    """Acquire a DB connection with the human RBAC context attached."""
    async with acquire(
        role=principal.role.value,
        user_id=principal.user_id,
        cohort_ids=principal.cohort_ids,
    ) as conn:
        yield conn


def db_for_ai_view(view: AIView):
    """Dependency factory for AI-side RLS visibility context."""

    async def _provider() -> AsyncIterator[asyncpg.Connection]:
        async with acquire(ai_view=view.value, ai_context=True) as conn:
            yield conn

    return _provider


CurrentPrincipal = Annotated[Principal, Depends(get_current_principal)]
HumanDB = Annotated[asyncpg.Connection, Depends(db_for_human)]