import type { EvalDetachedCellState } from "./detached-cell-manager.ts";
import type { EvalToolInput } from "./types.ts";

interface DetachedCellIdentity {
  readonly cellId: string;
  readonly input: EvalToolInput;
  readonly state: EvalDetachedCellState;
}

export function activeDetachedCellReuseError(
  cell: DetachedCellIdentity
): Error {
  return new Error(
    `Eval cell ${cell.cellId} from a previous call is still ${cell.state} in the ${cell.input.language} kernel. Use eval({ action: "peek", cell_id: "${cell.cellId}" }) to read it or eval({ action: "stop", cell_id: "${cell.cellId}" }) to end it before its id can be reused.`
  );
}

export function allowsDetachedCellTransition(
  from: EvalDetachedCellState,
  to: EvalDetachedCellState
): boolean {
  if (from === "running") {
    return (
      to === "detached" ||
      to === "complete" ||
      to === "error" ||
      to === "cancelled"
    );
  }
  if (from === "detached") {
    return to === "complete" || to === "error" || to === "cancelled";
  }
  return false;
}

export function detachedCellIsActive(state: EvalDetachedCellState): boolean {
  return state === "running" || state === "detached";
}