import type {
  AtomId,
  Binding,
  Conformance,
  InterfaceRevisionId,
  OperationBinding,
  OperationId,
  WorkspaceRevision,
} from "./types.js";

export type ConcreteBinding = Exclude<Binding, { kind: "interface" }>;
export type ResolvedBinding = { conformance: Conformance; entry: OperationBinding; binding: ConcreteBinding };

/** Follow public operations on the same receiver, never private attachment names. */
export function resolveForwardedBinding(
  workspace: Pick<WorkspaceRevision, "conformances">,
  atomId: AtomId,
  interfaceRevisionId: InterfaceRevisionId,
  operationId: OperationId,
): ResolvedBinding {
  const visited = new Set<string>();
  for (;;) {
    const key = `${interfaceRevisionId}\0${operationId}`;
    if (visited.has(key)) throw new Error(`Forwarding cycle at ${interfaceRevisionId}/${operationId}`);
    visited.add(key);
    const conformance = workspace.conformances.find(
      (c) => c.atomId === atomId && c.interfaceRevisionId === interfaceRevisionId,
    );
    const entry = conformance?.operationBindings.find((b) => b.operationId === operationId);
    if (!conformance || !entry)
      throw new Error(`Missing forwarding target ${atomId} as ${interfaceRevisionId}/${operationId}`);
    if (entry.binding.kind !== "interface") return { conformance, entry, binding: entry.binding };
    interfaceRevisionId = entry.binding.interfaceRevisionId;
    operationId = entry.binding.operationId;
  }
}