from typing import Annotated, Optional
from uuid import UUID
from fastapi import Depends, HTTPException, Request, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
import sentry_sdk

from app.core.database import get_db
from app.core.security import decode_token
from app.models.user import User
from app.models.plan_limits import PlanLimits

# Routes that are allowed even when must_change_password is True
_PASSWORD_CHANGE_ALLOWLIST = {
    "/api/v1/auth/password/change",
    "/api/v1/auth/logout",
    "/api/v1/auth/me",
}

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")


async def get_current_user(
    db: Annotated[AsyncSession, Depends(get_db)],
    token: Annotated[str, Depends(oauth2_scheme)]
) -> User:
    """Get current authenticated user from JWT token."""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    payload = decode_token(token)
    if payload is None:
        raise credentials_exception

    token_type = payload.get("type")
    if token_type != "access":
        raise credentials_exception

    user_id: str = payload.get("sub")
    if user_id is None:
        raise credentials_exception

    try:
        user_uuid = UUID(user_id)
    except ValueError:
        raise credentials_exception

    result = await db.execute(select(User).where(User.id == user_uuid))
    user = result.scalar_one_or_none()

    if user is None:
        raise credentials_exception

    return user


async def get_refresh_token_payload(
    token: Annotated[str, Depends(oauth2_scheme)]
) -> dict:
    """Extract and validate a refresh token from the Authorization header."""
    payload = decode_token(token)
    if payload is None or payload.get("type") != "refresh":
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid refresh token",
            headers={"WWW-Authenticate": "Bearer"},
        )
    return payload


async def get_current_active_user(
    request: Request,
    current_user: Annotated[User, Depends(get_current_user)],
    db: Annotated[AsyncSession, Depends(get_db)],
) -> User:
    """Ensure user is active (not disabled). Auto-downgrades expired trials.
    Enforces must_change_password — blocks all routes except allowlist."""
    if not current_user.is_active:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Account has been deactivated"
        )

    # Enforce must_change_password (backend hard lock)
    if current_user.must_change_password:
        if request.url.path not in _PASSWORD_CHANGE_ALLOWLIST:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="password_change_required"
            )

    # Set Sentry user context for error attribution
    sentry_sdk.set_user({"id": str(current_user.id), "email": current_user.email})

    # Lightweight trial expiry check
    if current_user.account_id:
        from app.models.subscription import Subscription
        from datetime import datetime, timezone
        result = await db.execute(
            select(Subscription).where(Subscription.account_id == current_user.account_id)
        )
        subscription = result.scalar_one_or_none()
        if (
            subscription
            and subscription.status == "trialing"
            and subscription.current_period_end
            and subscription.current_period_end < datetime.now(timezone.utc)
        ):
            subscription.plan = "free"
            subscription.status = "active"
            subscription.current_period_end = None
            subscription.current_period_start = None
            await db.commit()

    return current_user


async def require_admin(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require super admin access."""
    if not current_user.is_super_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Super admin access required"
        )
    return current_user


async def require_engineer_or_admin(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require engineer, account owner, or super admin role (blocks viewers)."""
    if current_user.is_super_admin:
        return current_user
    if current_user.account_role in ("owner", "admin", "engineer"):
        return current_user
    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail="Engineer or admin access required"
    )


async def require_account_owner(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require account owner or super admin access."""
    if current_user.is_super_admin:
        return current_user
    if current_user.account_role == "owner":
        return current_user
    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail="Account owner access required"
    )


def get_service_account_id(request: Request) -> Optional[UUID]:
    """Return the cached ResolutionFlow service account UUID from app.state.

    Returns None in test environments where lifespan startup did not run.
    """
    return getattr(request.app.state, "service_account_id", None)


async def get_plan_limits_for_user(
    current_user: Annotated[User, Depends(get_current_active_user)],
    db: Annotated[AsyncSession, Depends(get_db)],
) -> Optional[PlanLimits]:
    """Get plan limits for the current user's account."""
    from app.core.subscriptions import get_user_plan_limits
    return await get_user_plan_limits(current_user.account_id, db)