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 jose import JWTError

from app.core.security import (
    IdleTokenExpired,
    decode_refresh_token_strict,
    decode_token,
)
from app.models.user import User
from app.models.plan_limits import PlanLimits
from app.core.tenant_context import set_current_account_id, clear_current_account_id
from app.core.admin_database import get_admin_db  # noqa: F401 — re-exported for use in endpoints

# 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_admin_db)],
    token: Annotated[str, Depends(oauth2_scheme)]
) -> User:
    """Get current authenticated user from JWT token.

    Must use get_admin_db (BYPASSRLS): this dep runs before require_tenant_context
    sets app.current_account_id, so the users table RLS would block the lookup.
    """
    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_current_user_optional(
    request: Request,
    db: Annotated[AsyncSession, Depends(get_admin_db)],
) -> Optional[User]:
    """Best-effort current user for endpoints that work both anonymous and authed.

    Returns None on missing/invalid/expired token instead of raising. Used by
    surfaces like /config/public that anonymous clients can hit but where an
    authenticated user gets a tailored response (e.g. INTERNAL_TESTER_EMAILS
    allowlist override).
    """
    auth_header = request.headers.get("Authorization") or request.headers.get("authorization")
    if not auth_header or not auth_header.lower().startswith("bearer "):
        return None
    token = auth_header.split(None, 1)[1].strip()
    if not token:
        return None

    payload = decode_token(token)
    if payload is None or payload.get("type") != "access":
        return None

    user_id = payload.get("sub")
    if user_id is None:
        return None
    try:
        user_uuid = UUID(user_id)
    except ValueError:
        return None

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


async def get_refresh_token_payload(
    token: Annotated[str, Depends(oauth2_scheme)]
) -> dict:
    """Extract and validate a refresh token from the Authorization header.

    Returns one of three outcomes via HTTP 401 `detail`:
    - `session_expired_idle` — JWT signature valid but `exp` past
    - `invalid_refresh_token` — any other decode failure, or `type != "refresh"`
    - (200 path) — returns the decoded payload

    The frontend uses these to choose between the "your session ended for
    security" banner and a plain logout redirect. See
    docs/plans/2026-05-13-session-expiration-policy.md §4.10.
    """
    try:
        payload = decode_refresh_token_strict(token)
    except IdleTokenExpired:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="session_expired_idle",
            headers={"WWW-Authenticate": "Bearer"},
        )
    except JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="invalid_refresh_token",
            headers={"WWW-Authenticate": "Bearer"},
        )
    if 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_admin_db)],
) -> User:
    """Ensure user is active (not disabled). Enforces must_change_password —
    blocks all routes except allowlist.

    Trial expiry enforcement now happens via require_active_subscription in
    individual routers, NOT here. This dep no longer mutates Subscription
    state.
    """
    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})

    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_l1(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """L1 tech exact-match (with super_admin bypass for support)."""
    if current_user.is_super_admin:
        return current_user
    if current_user.account_role != "l1_tech":
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="L1 tech role required",
        )
    return current_user


async def require_l1_or_coverage(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """L1 endpoints: l1_tech, owners, super_admin, or engineers with can_cover_l1=True."""
    if current_user.is_super_admin:
        return current_user
    role = current_user.account_role
    if role == "l1_tech":
        return current_user
    if role == "owner":
        return current_user
    if role == "engineer" and current_user.can_cover_l1:
        return current_user
    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail="L1 access requires l1_tech role or engineer coverage flag",
    )


async def require_l1_or_above(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Any tier from l1_tech upward (l1_tech, engineer, owner, super_admin)."""
    if current_user.is_super_admin:
        return current_user
    if current_user.account_role in ("l1_tech", "engineer", "owner"):
        return current_user
    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail="L1 or above required",
    )


async def require_team_admin(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require team admin, account owner, or super admin role."""
    if current_user.is_super_admin:
        return current_user
    if current_user.is_team_admin:
        return current_user
    if current_user.account_role == "owner":
        return current_user
    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail="Team 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"
    )


async def require_account_owner_or_admin(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require account owner or account-admin (blocks engineers); super_admin bypass.

    Delegates to ``User.can_manage_account`` so the rule lives in exactly one place.
    """
    if current_user.can_manage_account:
        return current_user
    raise HTTPException(
        status_code=status.HTTP_403_FORBIDDEN,
        detail="Account owner or admin 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)


async def require_tenant_context(
    current_user: Annotated[User, Depends(get_current_active_user)],
):
    """Set per-request tenant context for RLS.

    Raises 403 if the authenticated user has no account_id — never falls back
    to PLATFORM_ACCOUNT_ID (that would grant platform-scope access to a
    malformed account).

    Sets the ContextVar that the SQLAlchemy transaction-begin listener reads to
    issue set_config('app.current_account_id', …, true) on every transaction.

    Applied to every user-facing router. NOT applied to /admin/* routers or
    public endpoints (auth, shared, webhooks).
    """
    if current_user.account_id is None:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="User account required",
        )
    token = set_current_account_id(current_user.account_id)
    try:
        yield
    finally:
        clear_current_account_id(token)


async def require_admin_db(
    db: Annotated[AsyncSession, Depends(get_admin_db)],
    current_user: Annotated[User, Depends(require_admin)],
) -> AsyncSession:
    """Return a BYPASSRLS admin DB session after verifying super_admin role.

    Use on /admin/* endpoints that query RLS-protected tables. Replaces
    Depends(get_db) on the db parameter of those endpoints.
    The current_user dep is still declared separately on the endpoint if
    the user object is needed in the handler.
    """
    return db


_SUBSCRIPTION_GUARD_ALLOWLIST = {
    "/api/v1/auth/me",
    "/api/v1/auth/logout",
    "/api/v1/auth/password/change",
    "/api/v1/auth/email/send-verification",
    "/api/v1/auth/email/verify",
    "/api/v1/billing/state",
    "/api/v1/billing/checkout-session",
    "/api/v1/billing/portal-session",
    "/api/v1/users/me",
    "/api/v1/users/me/onboarding-step",
    "/api/v1/users/me/onboarding-dismiss-rest",
}


async def require_active_subscription(
    request: Request,
    current_user: Annotated[User, Depends(get_current_active_user)],
    db: Annotated[AsyncSession, Depends(get_admin_db)],
):
    """Returns the Subscription row when the account has access; raises 402
    when locked. Mounted on routers requiring Pro entitlement.

    'Locked' = (trialing AND current_period_end < now()) OR
              (canceled OR incomplete OR no subscription).
    Active states: active, complimentary, trialing-with-time-remaining, past_due.
    """
    if request.url.path in _SUBSCRIPTION_GUARD_ALLOWLIST:
        return None

    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)
    )
    sub = result.scalar_one_or_none()

    if sub is None:
        raise HTTPException(
            status_code=402,
            detail={"error": "no_subscription", "upgrade_url": "/account/billing/select-plan"},
        )

    now = datetime.now(timezone.utc)
    is_live = (
        sub.status in ("active", "complimentary", "past_due")
        or (
            sub.status == "trialing"
            and sub.current_period_end is not None
            and sub.current_period_end > now
        )
    )
    if not is_live:
        raise HTTPException(
            status_code=402,
            detail={
                "error": "subscription_inactive",
                "status": sub.status,
                "plan": sub.plan,
                "current_period_end": sub.current_period_end.isoformat() if sub.current_period_end else None,
                "upgrade_url": "/account/billing/select-plan",
            },
        )

    return sub


_EMAIL_VERIFICATION_ALLOWLIST = {
    "/api/v1/auth/me",
    "/api/v1/auth/logout",
    "/api/v1/auth/email/send-verification",
    "/api/v1/auth/email/verify",
    "/api/v1/auth/password/change",
    "/api/v1/users/me",
    "/api/v1/users/me/onboarding-step",
    "/api/v1/users/me/onboarding-dismiss-rest",
    "/api/v1/billing/state",
    "/api/v1/billing/checkout-session",
    "/api/v1/billing/portal-session",
}

VERIFICATION_GRACE_DAYS = 7


async def require_verified_email_after_grace(
    request: Request,
    current_user: Annotated[User, Depends(get_current_active_user)],
):
    """Enforces 'this user has verified email OR is still in 7-day grace.'
    OAuth signups bypass cleanly because /auth/{google,microsoft}/callback
    sets users.email_verified_at = now() (provider-attested)."""
    from datetime import datetime, timezone, timedelta

    if request.url.path in _EMAIL_VERIFICATION_ALLOWLIST:
        return

    if current_user.email_verified_at is not None:
        return

    grace_ends = current_user.created_at + timedelta(days=VERIFICATION_GRACE_DAYS)
    if datetime.now(timezone.utc) < grace_ends:
        return

    raise HTTPException(
        status_code=403,
        detail={
            "error": "email_not_verified",
            "grace_ended_at": grace_ends.isoformat(),
            "resend_url": "/api/v1/auth/email/send-verification",
        },
    )