from __future__ import annotations

from dataclasses import dataclass

from fastapi import Depends, Header, HTTPException, status
from sqlalchemy.orm import Session

from app.db.models import ApiKey, AuthSession, User
from app.db.session import get_session
from app.security.api_keys import authenticate_api_key, has_scope as api_key_has_scope
from app.security.sessions import authenticate_session_token, collect_user_scopes


@dataclass(slots=True)
class ApiPrincipal:
    user: User
    tenant_id: str
    scopes: list[str]
    api_key: ApiKey | None = None
    auth_session: AuthSession | None = None


def _extract_token(authorization: str | None, x_api_key: str | None) -> tuple[str | None, str]:
    if x_api_key:
        return x_api_key.strip(), "api_key"
    if authorization and authorization.lower().startswith("bearer "):
        return authorization[7:].strip(), "bearer"
    return None, "none"


def get_api_principal(
    session: Session = Depends(get_session),
    authorization: str | None = Header(default=None),
    x_api_key: str | None = Header(default=None, alias="X-API-Key"),
) -> ApiPrincipal:
    token, source = _extract_token(authorization, x_api_key)
    if not token:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Missing API key or session token")

    # API keys remain supported for CLI/automation. Browser login uses session tokens.
    api_key = authenticate_api_key(session, token)
    if api_key:
        user = session.get(User, api_key.user_id)
        if not user or not user.is_active:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Inactive user")
        session.commit()
        return ApiPrincipal(api_key=api_key, user=user, tenant_id=api_key.tenant_id, scopes=api_key.scopes or [])

    auth_session = authenticate_session_token(session, token)
    if auth_session:
        user = session.get(User, auth_session.user_id)
        if not user or not user.is_active:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Inactive user")
        scopes = collect_user_scopes(session, user)
        session.commit()
        return ApiPrincipal(auth_session=auth_session, user=user, tenant_id=user.tenant_id, scopes=scopes)

    raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid API key or session token")


def has_scope(principal: ApiPrincipal, required_scope: str) -> bool:
    scopes = set(principal.scopes or [])
    if principal.api_key:
        return api_key_has_scope(principal.api_key, required_scope)
    return "*" in scopes or required_scope in scopes


def require_scope(required_scope: str):
    def dependency(principal: ApiPrincipal = Depends(get_api_principal)) -> ApiPrincipal:
        if not has_scope(principal, required_scope):
            raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail=f"Missing scope: {required_scope}")
        return principal

    return dependency