export const PLAY_RUNTIME_CONTRACT = 5;
export const PLAY_RUNTIME_CONTRACT_MIN_SUPPORTED = 1;
export const PLAY_RUNTIME_CONTRACT_HEADER = 'x-deepline-runtime-contract';
/** Shared runner/gateway envelope limit for unacknowledged progress recovery. */
export const RUNTIME_RUNNER_TERMINAL_PROGRESS_MAX_EVENTS = 2_000;
/**
 * Opaque, per-request correlation key generated inside the sandbox runner.
 * It contains no customer data and lets gateway logs distinguish a request that
 * never reached Fly from one that was accepted but failed downstream.
 */
export const PLAY_RUNTIME_TRANSPORT_ATTEMPT_HEADER =
  'x-deepline-runtime-transport-attempt';

const RUNTIME_TRANSPORT_ATTEMPT_ID =
  /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;

/**
 * Validate the opaque runner-generated correlation value before it appears in
 * any gateway log or response header. It is intentionally not a credential.
 */
export function resolvePlayRuntimeTransportAttemptId(
  raw: string | string[] | null | undefined,
): string | null {
  const value = Array.isArray(raw) ? raw[0] : raw;
  const trimmed = value?.trim();
  return trimmed && RUNTIME_TRANSPORT_ATTEMPT_ID.test(trimmed) ? trimmed : null;
}

export const RUNTIME_CONTRACT_CHANGELOG = [
  {
    contract: 5,
    changed:
      'Runtime Sheet completion and lazy launch lookup use bounded, cancellation-aware gateway operations.',
    compatOwner: 'runtime',
    compatRemoval: 'contract 4 runtime lane drain',
  },
  {
    contract: 4,
    changed:
      'Runtime receipt heartbeat requests can carry one positional lease ID per receipt key.',
    compatOwner: 'runtime',
    compatRemoval: 'contract 3 runtime lane drain',
  },
  {
    contract: 3,
    changed:
      'Runtime receipt completion responses are compact acknowledgements; receipt reads remain the payload replay path.',
    compatOwner: 'runtime',
    compatRemoval: 'contract 2 support window closure',
  },
  {
    contract: 2,
    changed:
      'Runtime receipt batch responses use positional nulls and v2 lease-aware receipt semantics.',
    compatOwner: 'runtime',
    compatRemoval: 'ledger cutover milestone M1',
  },
] as const;

export function runtimeReceiptCompletionResponse<
  T extends { output?: unknown },
>(runtimeContract: number | null | undefined, receipt: T | null): T | null {
  if (!receipt || (runtimeContract ?? 1) < 3) return receipt;
  const { output, ...ack } = receipt;
  void output;
  return ack as T;
}

export type RuntimeContractResolution =
  | { ok: true; contract: number }
  | {
      ok: false;
      requestedContract: number;
      currentContract: number;
      minSupportedContract: number;
    };

export function resolvePlayRuntimeContract(
  rawContract: string | null | undefined,
): RuntimeContractResolution {
  const trimmed = rawContract?.trim();
  const requestedContract = trimmed ? Number(trimmed) : 1;
  if (
    !Number.isInteger(requestedContract) ||
    requestedContract < PLAY_RUNTIME_CONTRACT_MIN_SUPPORTED ||
    requestedContract > PLAY_RUNTIME_CONTRACT
  ) {
    return {
      ok: false,
      requestedContract,
      currentContract: PLAY_RUNTIME_CONTRACT,
      minSupportedContract: PLAY_RUNTIME_CONTRACT_MIN_SUPPORTED,
    };
  }
  return { ok: true, contract: requestedContract };
}