from __future__ import annotations

from dataclasses import dataclass
from typing import Literal

from app.simulation.core.ports import VariableRole


EquationOwner = Literal["connection", "component"]
EquationRelation = Literal["equal", "sumToZero", "constitutive", "state"]


@dataclass(frozen=True)
class EquationResidual:
    """One executable scalar equation in the pressure-flow subsystem."""

    id: str
    owner: EquationOwner
    owner_id: str
    relation: EquationRelation
    variables: tuple[str, ...]
    value: float
    role: VariableRole | None = None

    def as_definition_dict(self) -> dict[str, object]:
        return {
            "id": self.id,
            "owner": self.owner,
            "ownerId": self.owner_id,
            "relation": self.relation,
            "variables": list(self.variables),
            "role": self.role,
        }

    def as_interface_dict(self) -> dict[str, object]:
        return {**self.as_definition_dict(), "residual": self.value}